Assessment of Fruit Fly Damage and Implications for the Dissemination of Management Practices for Mango Production in the Upper West Region of Ghana

Transcription

1 Journal of Developments in Sustainable Agriculture -: (,**2) Assessment of Fruit Fly Damage and Implications for the Dissemination of Management Practices for Mango Production in the Upper West Region of Ghana Wih Kwasi Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki -*/ 2/1,, Japan Ghana s mango ( Mangifera indica) industry is facing potentially serious problems with fruit flies (Diptera: Tephritidae), which endanger the industry s contribution to the national economy. Asian fruit flies in the genus Bactrocera are destructive pests of fruits and vegetables worldwide, but little is known about their prevalence in Ghana since the first detection of Bactrocera invadens in,**/. This paper reports the results of a study of the occurrence of B. invadens in Ghana s Upper West Region and assesses the pest s distribution, the damage it causes, and potential management options. Despite limited collections of B. invadens in,**1 (the first formal survey of this pest), the results of weekly trapping provide a good preliminary understanding of its presence in the region. Systematic trapping and host fruits surveys confirmed its presence in all eight districts and at three experimental stations. The highest density ( +*. 2 flies per trap per day) was recorded in Nadawli district and the lowest ( +. 0 flies per trap per day) in Lawra district. In total, +*,-.3 flies were captured during the study period which lasted for 0 months. The counts were highest in August, when the flies attack developed fruits. Late-maturing cultivars (mostly exotics) were more severely attacked than early (local) cultivars, and B. invadens also attacked cashew ( Anacardium occidentale) and shea tree ( Vitellaria paradoxa) in the study area. Mango farmers were interviewed to obtain information about the pest. Sixty percent reported that the fruit fly, although a recent pest on mangoes in the study area, had decreased fruit production. Mealybugs ( Rastrococcus invadens) accounted for +- of the pests in mango fields, but ants ( Oecophylla longinoda) and termites ( Microtermes spp.) were also important pests that negatively a# ected mango production. Fruit fly control is still at an experimental stage in Ghana. Therefore, control should focus on integrated pest management to protect important crops. Training of agricultural extension o$ cers, mango farmers, and other stakeholders, and international cooperation, will be imperative to ensure e# ective management of this invasive pest. Key words: Bactrocera invadens, invasive species, mango, methyl eugenol, Ghana +. Introduction tions imposed by importing countries to avoid entry and establishment of these pests. Bactrocera species ++. Background are well-documented invaders, and rank high on Asian fruit flies in the genus Bactrocera Mac- quarantine lists worldwide (Clarke et al.,,**/). quart (Diptera: Tephritidae) are regarded as some Bactrocera invadens Drew, Tsuruta and White of the most destructive pests of fruits and vegeta- (Diptera: Tephritidae), an invasive species, belongs bles worldwide (White and Elson-Harris, +33, ). to the Bactrocera dorsalis (Hendel) complex of Losses result from direct feeding damage, decay by tropical fruit flies (French,,**/). This group opportunistic pathogens, and the loss of export includes about 2* described species (and possibly market opportunities through quarantine restric- with some undescribed specimens remaining in col- Received: October,,,**2, Accepted: November +-,,**2 Corresponding author s current address: Ministry of Food and Agriculture, P.O. Box,+, Upper West Region, Ghana. Tel:,--,*2,3..21, kwasiwih@yahoo.com

2 118 J. Dev. Sus. Agr. - (,) lections (Lawson et al.,,**-). They are native to ver, studies of field infestation rates in orchards are a region that extends between tropical Asia and important for establishing the pest status of B. northern Australia (Drew and Hancock +33. ). invadens and for formulating control strategies. The group is arguably one of the most important The objectives of the present study were thus to pest species complexes in world agriculture (Clarke confirm the identification of the fruit fly, define its et al.,,**/; Drew et al.,,**/). distribution and the extent of damage it causes, and Preliminary results from host range studies show use this knowledge to explore possibilities for manthat species of the B. dorsalis complex attack both aging it. This paper reports the results of surveys cultivated and wild hosts, including mango Mangifera for the fruit fly and interviews with mango farmers indica ( Anacardiaceae), lemon orange Citrus in the Upper West Region of Ghana in,**1. limon Burman (Rutaceae), tomato Lycopersicon The results of this study will guide strategies to esculentum (Solanaceae), banana Musa spp enhance the food security and income generation (Musaceae), guava Psidium guajava (Myrtaceae), capacity of mango farmers in the region, where the marula Sclerocarya birrea (Anacardiaceae), cus- mango crop accounted for an average of more than tard apple Annona muricata (Annonaceae), avoca-.* of the total household farm income. Other do Persea americana (Lauraceae) and Indian al- important goals of the study were to perform a mond ( Terminalia catappa (Combretaceae) (Ekesi region-wide delimiting survey that could help deterand Billah,,**0; Rwomushana et al.,,**2). mine appropriate methods for the control or man- The latest arrival in Africa of a member of the B. agement of the pest; to provide a basis for training dorsalis complex is B. invadens, a highly prolific and the various stakeholders in the mango production phytophagous species that is particularly invasive. subsector to identify and manage the fruit fly and Work done by ICIPE scientists (M.K. Billah, Afri- other mango-related pests and diseases; and to excan Fruit Fly Programme, ICIPE, Kenya - pers. plore the possibility of using an integrated pest Comm.) in comparing field collections of fruit flies management (IPM) approach to protect mangoes over the period between,**+ and,**1 seem to in the study area. point to a gradual displacement of the previously prevalent mango fruit fly ( Ceratitis cosyra). B. +,. Importance of Agriculture in the Ghanaian invadens is thought to have invaded Africa from Economy the Indian subcontinent, and it was discovered in Ghana, a relatively small country with a total Sri Lanka after it was first reported from Africa population of +2.. million and an area of,-2,/-- (Drew et al.,,**/). It was reported in Ghana in, km, lies in the center of the West African coastline,**/ (Drew et al.,,**/; Billah et al.,,**0). The (Ghana Statistical Service,,***). It is a tropical route or means by which it entered Kenya is still country that consists of three broad ecological unclear. However, it is thought that the intense zones: forest, forest-savanna transition, and savanmovement of commodities and humans within na. These broad categories are further divided into Africa, coupled with frequent exchanges with Asia, coastal savanna, rainforest, semi-deciduous forest, the Middle East, and Europe, is a likely source of forest-savanna transition, Guinea savanna, and the introduction (Lux et al.,,**-; Billah et al., Sudan savanna.,**0). The forest zone covers about one-third of the The pest has been detected in a number of east country ( 2,. million ha), and supports two-thirds African countries (Mwatawala et al.,,**. as well of the country s population (World Bank, +322). as north of Sudan, and has since spread to western Most of the country s economic activities are also and central Africa (Drew et al.,,**/). There is located in this zone, including activities associated little information available about prevalence of the with the production of cocoa, minerals, oil palm pest in Ghana since its initial detection in,**/ products, rubber, and timber. The zone has a (Billah et al.,,**0). The data resolution upon bimodal rainfall pattern (with the majority of the which pest management decisions rely cannot be rain falling in July and September, with annual attained without an explicit knowledge of the biol- precipitation ranging from +,-** to,, +** mm. ogy of the pest and the damage it causes. Moreo- Ghana s northern savanna zone covers about 01

3 Kwasi: Assessment of Fruit Fly Damage and Implications for the Dissemination of Management Practices 119 ( +/. 1 million ha) of the country s total area. The provided on credit and technical advice. Owing to zone has a unimodal rainfall pattern, with erratic ITFC s involvement in the mango sector, small and usually unpredictable precipitation that occurs farmers are able to grow mangoes in addition to primarily in August and that ranges between 3** performing their other farming activities. On averand +,,** mm annually. Industrial crops such as age, yields are estimated to be about,.. ha- +. cotton and shea nuts and food crops such as rice, Ghana s temperature averages,., but ranges maize, sorghum, millet and yam are predominant. from,+ to -. in the southern zone and from +2 Ghana s major farming systems are largely to.* in the northern zone. The lowest temperadefined by the agro-ecological zones. They include tures occur between December and mid-february ( + ) rotational bush-fallow systems, (,) permanent tree crop systems (such as mango farming in the in the northern zone. About 2/ of the mangoes produced in Ghana are the Keitt cultivar, and the north), (-) compound farming systems, (.) mixed remaining +/ are Kent, Tommy Atkins, Julie, farming systems (such as the maize-yam system). Palmer, Zill, Irwin, Haden, Springfield, and Agriculture is the dominant sector of the Ghanaian Ja# na, plus a range of local cultivars. economy. It employs about 0* of the workforce and contributes about.* of the GDP. The major agricultural exports include cocoa, timber and Ghana is one of the few countries in the world with two mango seasons, and with the right cultural practices, both seasons can yield fruits for the interwood products, and horticultural crops (e.g., pine- national mango market. The major season in the apple, papaya, mango, vegetables), which account northern sector starts in November-December. for more than /1 of total foreign exchange earnings. The non-cocoa subsector includes cereals (e. Fruits normally mature - to - months after flo- wering, and take. to 0 weeks to ripen su$ ciently g., maize, rice, sorghum, millet), legumes and for harvesting. In the minor season, flower initiapulses (e.g., cowpea, groundnut, beans), roots and tion starts in late July or early August and mature tubers (e.g., cassava, yam, cocoyam, sweet potato), in October. Improved cultivars are grown primarindustrial crops (e.g., cotton, oil palm, rubber, co- ily for export, but production di$ culties, inadeconut, shea nut, cola nut), horticultural crops (e.g., quate management skills, and pest and disease propineapple, mango, papaya, avocado, citrus, pepper, blems have made that aim di$ cult to achieve. tomatoes, cashew, watermelon, eggplant, okra, Losses due to fruit flies in Ghana are estimated at onion, cabbage, lettuce), and other crops (e.g., between 0* and 2/ of the crop, depending on plantain, banana, ginger). the cultivar and season (Billah et al.,,**0). This deprives communities of an important source of +-. Mango Production in Ghana nutrition (particularly vitamin A) and leads to the Ghana has ideal sites for the production of loss of highly valuable market share. Apart from mangoes in the north and in parts of the south, as pineapples, most horticultural products are suscepthe crop develops well under conditions ranging tible to fruit fly attack. Fruit flies can also trigger a from semi-humid to semi-arid (Billah,,**1). The quarantine in many countries, and their detection mango industry is divided into the southern and in exports leads to complete banning of a crop by northern sectors. The coastal and transitional importing nations. Ghana began exporting manzones form the southern sector, and the savanna goes to the EU in,**., with a total export of +11 zone forms the northern sector. In the southern t, making mangoes one of the country s largest zone, large businesses with huge acreages operate as exports of fresh produce to the EU. However, in both producers and exporters. Small farmers are,**/, a ban was placed on Ghanaian mangoes to mostly organized into associations, as it is very South Africa (it remains in force) for fear of di$ cult to enter the business individually (because potential invasion by B. invadens. of its capital-intensive nature). In the northern zone, the Integrated Tamale Fruit Company +.. Life Cycle of Fruit Flies (Diptera: (ITFC), a nongovernmental organization, has Tephritidae) created a scheme that allows participating farmers Adult fruit flies mature sexually between. and to grow *.. ha-+ of mangoes with input support +* days after emergence, and begin to mate almost

4 120 J. Dev. Sus. Agr. - (,) immediately. Soon after mating, the female uses dorsalis complex and according to Drew et al. her sharp ovipositor to lay her eggs in fruit by (,**/), the origin and identity of the invading piercing it to a depth of, to / mm before oviposit- species was originally unknown, although it was ing. The banana-shaped eggs are deposited in recognized as belonging to an Asian species combatches of - to 2, depending on the species. The plex. The species appears to have invaded Africa eggs hatch into tiny white maggots (larvae) within from the Indian subcontinent, and was only disto +, days, depending on the temperature condi- - covered in Sri Lanka after it was found in Africa, tions. Inside the fruit, the maggots molt twice. when large numbers of specimens were identified When fully grown, the maggots leave the fruit and from a collection of tribe Dacini made in Sri Lanka bury themselves in the soil, where they pupate in by K. Tsuruta, now head of the Insect Identifichard cases called puparia. The duration of the ation & Diagnostics Lab, Japan thereby confirming pupal stage ranges from +* to,* days, depending its provenance. on climatic conditions. In di# erent countries, The fruit fly is of great economic significance in depending on the climatic conditions and abun- Africa (Mwatawala et al.,,**.), where its rapid dance of host fruits, fruit flies may complete more spread across tropical Africa and growing numbers than a dozen generations in a year. of reports in fruit crops strongly indicate its potentially devastating pest status. Bactrocera invadens +/. Damage Symptoms may initially have been overlooked in some areas, Direct damage begins when the female fly punc- and thus its original discovery should not be astures the fruit skin and lays eggs underneath it. sumed to indicate its point of invasion into Africa, Damage symptoms subsequently vary from fruit to but rather should demonstrate the vigilance of the fruit, but invasion by various pathogens is common. African Fruit Fly Program (AFFP) at the Interna- When the eggs hatch, the rotten fruit tissue caused tional Centre of Insect Physiology and Ecology by these pathogens makes it easier for the larvae to (ICIPE) in Nairobi, Kenya. The species was first feed. The puncture and feeding galleries made by found soon after the completion of an extensive the developing larvae provide access for pathogens programme of monthly fruit and baiting collections to develop and increase the extent of the decay. carried out from February +333 to January,**- by Generally, the fruit falls to the ground as the the AFFP (Copeland et al.,,**.). The first detecmaggots pupate, or just before. Attacked fruits tions were made by M. K. Billah (AFFP Taxoften have puncture marks made by the entry of the onomist, Nairobi) from mango fruits from the female s ovipositor. Sometimes there may be some Hawkers Market in Nairobi. This was followed by tissue decay around these wounds, and some fruits the first field collection at Tiwi, in the coastal with a very high sugar content exude globules of province of Kenya, by A. Manrakhan (ICIPE) sugar that can attract other pests. from a McPhail trap baited with NuLure protein +0. Current Status of B. invadens in Africa (Miller Chemical and Fertilizer Corporation, Hanover, USA), during a routine survey and the first The fruit fly, first reported in Kenya in,**- reared specimens from the field by Copeland from (Lux et al.,,**-) and then in Tanzania fruits of Strychnos mellodora from the Shimba Hills (Mwatawala et al.,,**.), has now been formally of Kenya. The species was subsequently found to named. Drew et al. (,**/) have described the be a serious pest of mangoes, and the first specispecies as B. invadens Drew, Tsuruta and White in mens from Tanzania were obtained from mangoes reference to its rapid invasion of Africa. The collected from a market place in Matombo on,/ description is based on specimens from several Af- July,**- (Mwatawala et al.,,**.). rican countries and from Sri Lanka. Bactrocera The species has already spread rapidly across invadens is morphologically very similar to B. Africa and, according to Drew et al., (,**/), has dorsalis from Southeast Asia, to Bactrocera now been recorded from Kenya (February,**-, kandiensis (Drew and Hancock) from Sri Lanka, reared from fruit), Tanzania (December,**-, and to Bactrocera rubigina Wang and Zhao from fruit), Sudan (May,**., fruit), Benin (June,**., China. Bactrocera invadens belongs to the B. methyl eugenol trap), Uganda (July,**., methyl

5 Kwasi: Assessment of Fruit Fly Damage and Implications for the Dissemination of Management Practices 121 eugenol), Cameroon (August,**., fruit), Togo should be reassessed. This is especially important (October,**., methyl eugenol), Senegal (October because there is currently no scientific basis to,**., torula liquid trap), Ghana (January,**/, assume that the fruit fly will be susceptible to the methyl eugenol) and Nigeria (January,**/, normal cold treatment procedures used to eliminate methyl eugenol). It is also known to have been pests. Cold treatment experiments are also strongly observed in the Democratic Republic of Congo recommended until the pest s temperature toler- (uncertain date and source of collection) and in Sri ance can be determined. Lanka (Tsuruta et al., +331, Tsuruta and White,,**+; M.K. Billah, unpublished data).,. Materials and Methodology One characteristic of B. invadens is that it is,+. The Study Area strongly attracted to methyl eugenol, which con- The Upper West Region (UWR) of Ghana was trasts with African Dacini species, including created in +32+ from what was then the Upper Bactrocera cucurbitae which are attracted by the Region, and covers a geographical area of approx- Cue Lure (White,,**0). Although methyl eugenol imately, +2,.12 km ( 1. 1 ) of the total area of had not been widely used, it was deployed at sites in Ghana. The region is divided into eight administra- Kenya and other African countries (including Tan- tive districts: Wa Municipal, Wa West, Wa East, zania) in +333 and,**, by ICIPE s African Fruit Jirapa Lambussie, Nadawli Lawra, Sissala East, Fly Program. Samples from the programme ex- and Sissala West (Fig. + ). It has an approximate amined by M. K. Billah (of ICIPE) and confirmed population of 0**,*** people (Ghana Statistical by Dr. I.M. White (of the Natural History Mu- Service,,***), of whom about 23 derive their seum, UK, and a leading authority on dacine fruit income from agriculture and related activities. The flies) did not contain the species, suggesting that it region is situated in the Guinea savanna ecological was not yet established in,**,, or that it was zone, which is bordered to the north by the Repubpresent in very low numbers. The rapid increase in lic of Burkina Faso, to the east by Ghana s Upper collections of the pest between,**- and the present East Region, to the south by Ghana s Northern is a further indication of the rapidity of its invasion Region, and to the west by Côte d Ivoire. The of Africa. The host plant list is also growing at a rapid rate; B. invadens has now been recorded on guava, citrus, papaya, tomatoes, and especially mango, as well as on a number of wild hosts, including Strychnos spp. See most current list from Rwomushana et al.,,**2. This new species is of high phytosanitary risk, especially to the countries of southern Africa (where it is not yet present) (M.K. Billah pers. comm.) and ultimately to trading partners, including the USA. Countries such as South Africa, Botswana, Namibia, Lesotho, Swaziland, Mozambique, Malawi, Zambia, Zimbabwe, Angola, and their trading partners should consequently institute immediate measures to prevent the introduction of B. invadens from infested countries. Because of fear of introduction of the pest to the Republic of South Africa, mango imports from Ghana were Fig. +. Map of the Upper West Region (UWR) banned in,**/ (M.K. Billah, pers. comm.).the of Ghana, showing the catches of Bactrocera species should also be of great concern in the context of plant protection and quarantine measures where the survey was undertaken in,**1. and pest risk analyses being developed for vulnera- (Source: http: / / www. maplibrary. org / stacks / invadens per trap per day, and the locations ble fruits in a# ected countries, both of which Africa/Ghana/Upper,* West/index.php)

6 122 J. Dev. Sus. Agr. - (,) vegetation of this zone is characterized by grasses, digitata) are characteristic of areas of former hushrubs, and stunted trees. The major staple foods man settlement. Of the introduced trees, the neem grown in the region are sorghum, millet, maize, ( Azadirachta indica) and mango ( M. indica) are rice, cowpea, groundnut, and yam. The cash crops common in villages and increasingly common as include soybean, cotton, and cashews. The shea escapes in uncultivated areas. tree, which grows in the wild, is one of the major cash crops for rural farmers. Other crops include,-. Rainfall and Climate bambara groundnut, Kersting s groundnut, and The climatic regime of the UWR is semi-arid, sweet potato. with annual rainfall of 3** to +,** mm. The,3 Wa is the capital of the region and its only urban -year mean for three local weather stations was 323 center. No all-weather roads connect the major mm. The rain mostly falls in a /-month season towns, and electricity can be sporadic even in the from May to September. Temperature is considercapital. Mobile phone networks have recently ably less variable than rainfall, and ranges from linked some of the districts, but a substantial invest- -* in August to -2 in February. ment will be needed to bring the UWR s infrastructure up to the standard of the rest of Ghana. The,.. Insect Collections (Traps and Lures) poor transport networks have important conse- The Lynfield trap was used during present study quences for farmers, since crops that must be sold monitoring survey. The trap was locally made shortly after harvesting, such as tomatoes, are di$ - from a recyclable cylindrical plastic container with cult to market compared with the situation in the four holes (each,1. cm in diameter) evenly spaced Upper East Region, which has asphalt roads that around the upper half of the trap. The lure was link it with southern markets. The typical land- methyl eugenol (AgriSense, London) mixed.: + scape is a gently undulating plain with hills and with malathion (EC /* a.i.). Methyl eugenol small mountains rising up to -/* m above the sur- attracts male Bactrocera species (e.g. B. invadens, rounding plains. The Black Volta river, the only B. zonata and B. dorsalis). It also attracts a few perennial water system, runs from north to south Dacus species. Methyl eugenol can be chemically across the region. The floodplain soils vary from described as benzene, +,,-dimethoxy-.-(,- brown sandy clays to silty clay loams (FAO, +301). propenyl). It is also a naturally occurring com- The highly weathered soils, derived primarily from pound reported from +* di# erent plant families. granites, are easily waterlogged and eroded. Traps were suspended on mango, cashew, and shea Geologically, these rocks are characterized as the trees at a height of approximately, m and were upper and lower Birrimian series; the upper can be checked to determine fly catches -* min after setseen in flat plains cut by granite outcrops, whereas ting, and were then rechecked at weekly intervals. the lower can be seen as outcrops of red laterite that The e# ectiveness of the lure was about six weeks mostly lies just below the surface. This patchy and was refreshed after that interval. geology may well explain why farming systems are so diverse across the region.,/. Data Collection and Sampling To determine the extent of spread of the flies, in,,. Vegetation the UWR, the survey covered all the eight districts. The UWR is covered by Guinea savanna, with Towns where the traps were installed were chosen relatively high density of certain typical tree species randomly. Three experimental fields of the Minis- (Chipp, +3,, ). Broadly speaking, the low human try of Food and Agriculture, all located in Wa population densities in this area have permitted Municipal District, were also surveyed. Overall, remarkable conservation of the savanna vegetation, we used a total of ++ sample locations which were quite unlike much of the remainder of northern chosen by random sampling of identifying mango Ghana. Typical indigenous species are the plantations within each district. At each location, a dawadawa ( Parkia biglobosa), shea ( V. paradoxa), methyl eugenol trap was installed on a mango, mahogany ( Khaya senegalensis), and silk- cashew, and shea tree, m above the ground, and cotton ( Ceiba pentandra). Baobabs ( Adansonia fruit fly catches were recorded weekly for 0

7 Kwasi: Assessment of Fruit Fly Damage and Implications for the Dissemination of Management Practices 123 months. To determine the e# ects of the flies on specimens per trap per day) was recorded in fruit production and the current damage caused by Nadawli District where a total of +33. B. invadens fruit flies and other related pests of mangoes, +3* were captured (Table,). In contrast, Lawra disfarmers were interviewed using a semi-structured trict recorded the lowest density:,3/ specimens, questionnaire to obtain first-hand knowledge about which amount to +0. specimens per trap per day. A the pests. Field observations and focus group dis- total of +*,-.3 flies were captured from the eight cussions were also conducted. Information ob- districts and three experimental fields during the tained in the interviews covered the host plants, the pests and their social e# ects, the control e# orts, and study period (Table,. The severity of the infest- ation appears to be higher in the districts that share the damage caused by the pests. a border with neighboring countries that have high -. Results and Discussion levels of mango production, where the pest has also been identified. The number of catches or counts -+. Identification of the Fruit Fly in the Upper reached the highest level in August, which was also West Region the primary time when the flies to attack the It is clear that good knowledge of the biology and developed fruits (Fig. /). Vayssieres et al. (,**/) behavior of the species responsible for the crop reported that increases in the population of B. damage is required to successfully establish and invadens appear to be directly linked to the ripening perfect integrated pest control methods. This of di# erent mango cultivars. Temperatures in July, necessitated the identification of the actual fruit fly August and September (an average of -*. 2 ) were species responsible for mango damage in the UWR. warmer for the development of B. invadens. Figure Morphological examination of the fruit fly species / shows a strong increase in the B. invadens popucaptured from the study area confirmed that B. lation as the season progressed from July to Octowas present (Drew et al.,,**/; Fig.,). invadens ber. The pest is believed to thrive well in moist weather and at high temperatures (Rwomushana et -,. Distribution of B. invadens in the Upper al.,,**0). Figure / shows that the highest incidence West Region of B. invadens concentration occurred at the Table + and Figures - and. show the total B. peak of the rainfall season in the study region. The invadens catches and variation in catches among fly s abundance also remained higher in most of the months and districts during the present monitoring districts during the rainy season (Table,). This survey. The relationship between average monthly confirms the suggestion of Amice and Sales ( +331) rainfall and monthly catches of B. invadens is that climatic variables such as rainfall and tempershown in Figure /. The highest pest density ( +*. 2 ature play a role in the abundance of B. invadens. Fig.,. Photograph of a male invadens. Bactrocera Fig. -. Trends in Bactrocera invadens capture (number per trap per day) in the Upper West Region of Ghana from July to December,**1.

8 124 J. Dev. Sus. Agr. - (,) Table +. Catches of Bactrocera invadens and its distribution in the Upper West Region of Ghana in,**1 District Nadawli Wa West Lawra Wa Municpal Type of crop Mango Mango Mango Mango Area Total No. Total No. Flies caught per No. of (ha) of insects of trees trap per day* traps * * +*42 + *4+1 /*- +1,41 + *4.,3/.* *4. +3,/,/ +*4. + Municipal Wa East Mango and shea *4+/ 0** +* -4, + Sissala West Mango *4+/ 1** Sissala East Mango and cashew *4*. 0/ Jirapa-Lambussie Mango *4+, 23* MOFA Exp. Field ( + ) Cashew +4* 13/ +/*.4- + MOFA Exp. Field (,) Mango *42 +-,/ 2* 14, + MOFA Exp. Field (-) Shea *4. 00/,* Total.4*- +*-.3.*2 /4+ ++ Source: Field monitoring report,,**1, MOFA (Ministry of Food and Agriculture). * Number of flies caught per trap per day was calculated as follows (IAEA,,**-): Flies per trap per day F/( T D) Where F total number of flies, T number of serviced traps per station ( + ), D average number of days traps were exposed in the field (July to December, +2. days). Fig... Bactrocera invadens catches in methyl eugenol traps in the eight districts and three Ministry of Food and Agriculture (MOFA) experimental fields during the survey from July to December,**1. The monitoring data revealed that males could remain abundant throughout the year. This is conbe trapped throughout the mango season (Fig. /). firmed by the report of White and Elson-Harris This suggests that in regions with the potential to ( +33, ) that Bactrocera species are multivoltine and grow two mango crops per year, the flies may that they can attack fruits belonging to several

9 Kwasi: Assessment of Fruit Fly Damage and Implications for the Dissemination of Management Practices 125 Fig. /. Relationship between average monthly rainfall, temperature and catches of invadens in the Upper West Region of Ghana in,**1. Bactrocera Table,. Catches of Bactrocera invadens from July to December,**1 in the Upper West Region of Ghana District July August September October November December Total Nadawli Wa West Lawra Wa Municipal Wa East Sissala West Sissala East Jirapa-Lambussie MOFA exp. field + MOFA exp. field, MOFA exp. field - /+3 3/.* -33 +,/,+* +.3,/- +/0 +2/ 03./3 +,/ /, 0,/ +-3,,/ +12,3/,.1,23 2/.-/ / +, /. +32.*- +,2-3/ 3/ 02, / ,2/ +10 +**.*.* +/ / 1, 12 +*, 20 -/,. 23 /. -3,1 /*.- 2/ +*/ +33. /*-,3/ +3,/ 0** 1** 0/1 23* 13/ +-,/ 00/ Total Flies caught per trap per day,,**,1+3,,1, +1+, 2* *-.3 04/ 24* 042 /4*, unrelated families of plants. This further compli- for general population monitoring in a region and cates any potential control measure because of the for on-farm monitoring to determine when conpossibility of reinvasion of a region if the control trol measures should be deployed. However, it is measures only target cultivated crops or a subset of di$ cult to calibrate traps to determine the thresthe available host species. hold levels that would lead to control activities The successful use of methyl eugenol traps (Stonehouse et al., +332). The only reliable techdemonstrated the value of this non-hazardous nique for arriving at such estimates appears to be method of monitoring fruit fly populations and its the mark-release-recapture technique (Ito and possible use as a control method (Control methods Koyama, +32, ). This technique, if made easily are discussed in section -.. ). Parapheromone lure available, could have a profoundly positive impact traps thus allow fast, inexpensive monitoring of for mango farmers in the UWR, because thus far, insect populations, and are potentially useful both no e# ective control measures have been found for

10 126 J. Dev. Sus. Agr. - (,) B. invadens. making mangoes one of the country s largest fresh As is the case for many crop pests, the population produce to the EU. Of the estimated., 20* MT of B. invadens varies between months, as does the produced annually, only +,/.*1 MT (, ) severity of the associated attacks. In such cases, the are exported (GEPC,,**0; R.N. Attatsi, Presiapplication of a threshold rule may provide ec- dent, Pineapple and mango producers and exportonomically optimal control (Mumford and Norton, ers association of Ghana (Pampeag,,**1; un ). However, threshold-based control strategies published data).the UWR contributed only about are uneconomical if the return on the investment in controls is less than the cost, which is often the case / of this total. However, these statistics seem to include only plantations, not the scattered trees that when the pest density is low. Thus, it is important are found all over the country. In addition, the to determine whether these returns are positive in statistics do not include the fact that each housemonths with light levels of attack; if so, control can hold has at least two trees of local cultivars, with a be applied routinely and prophylactically. If not, production of around,* kg per tree. However, the then a threshold-based program of supervised con- survey performed in the present study determined trol measures may be a better course. For example, that farmers in the region have started to create control measures against Anastrepha spp. in man- large plantations and that the average mango progoes in Peru begin when McPhail trap catches duction is expected to rise sharply. average two adults per trap per week (Herrera and --,.. Mango trees as a component of the Vias, +311). Upper West Region s Farming System The survey in the present study further revealed Mango farms vary considerably in size, and are that Bactrocera species attack plants such as cashew seldom grouped into uniform production blocks in and shea tree in the UWR (Table +, Fig..). This the UWR. They are scattered among areas that shows that the pest is capable of reproducing in contain both wild and abandoned fruit trees that these plantations in the wild, and that there is a act as reservoirs for a range of pests. Di# erent su$ ciently large population of alternative hosts for mango cultivars were recorded in the present study, the species to thrive even outside the main mango but only two categories were retained in the analyseason. Host availability has been shown to have sis: local cultivars with small, fibrous fruits and an important impact on the seasonal abundance of grafted (exotic) cultivars with large fruits that lack fruit flies in orchards (Tora Vueti et al., +331). fibers. Of all the farmers that were interviewed, Aluja et al. ( +323) support the theory that since fruit flies attack di# erent crops in the same area, 1/ preferred the local cultivars because of the free availability of their seedlings, the long survival their management must be based not only on a of trees from the local varieties, and the value of the single crop such as mango, but also on control fruit on the local market. Other reasons included measures in wild hosts and other commercially the resistance of the local cultivars to insect pests, grown host plants. Thus, to improve e$ ciency of diseases, and climatic stress, and subjective factors fruit fly management, the phenology of all potential such as taste preferences. host plants in a region must be elucidated. Among all the producers, / preferred exotic cultivars because of the good quality of the fruits --. Extent of Economic Losses and their high commercial value for distant markets Importance of mangoes in the Upper Other advantages of the exotics that the West Region producers reported were the small size of the trees Mangoes are large trees that can reach -* m in and the fact that they begin to produce fruit at a height. They are very popular in the UWR for their young age. An additional,* planted both local fruit and for the shade they provide. Mangoes can and exotic cultivars. Large-scale cultivation of the be produced in plantations, with a typical density of exotic cultivars has started in the region owing to +** trees/ha, or scattered in villages, towns, and the high demand for their fruit in both local and fields. Yields vary between /* and,** kg of fruit international markets. A fruit processing factory per tree (i.e., / to,* t/ha). Export of mangoes in has also been established in the region to take Ghana began in,**. with a total of +11 tonnes, advantage of the availability of these fruits.

11 Kwasi: Assessment of Fruit Fly Damage and Implications for the Dissemination of Management Practices 127 Mango production in the UWR generally involves Objectives of mango cultivation few special cultural practices. The mango The major purpose of planting mango trees is to trees are found scattered around houses, towns, and produce fruit for domestic consumption. The fruit fields, whereas plantations are found in marginal is high in sugar and vitamins, especially in vitamin land that cannot support other crops, and in low- A. In towns, it is a valuable dessert fruit, and in lands, where they play a major role in soil erosion rural areas, it can serve as a whole meal during control. Inputs such as fertilizer and pesticides are working days in the field. Almost all the mango rarely used, and none of the farmers interviewed producers that were interviewed said that they ate irrigated. Almost 2+ of the respondents used no chemical control measures in their mango fields. mangoes, and 31 declared that they had planted mango trees for fruit production and as a cash Some of the reasons for this were inadequate crop. Mangoes are also considered valuable for knowledge of the pests and a lack of access to their esthetic value (shade) by - of the producappropriate chemicals. The major technology ad- ers. Various community activities are held under opted by these farmers is the increased use of exotic the trees, such as formal and informal meetings, cultivars. games, and commercial activities. Because of the The educational level of mango farmers in the size of the trees and the density of their foliage, UWR is low, and training facilities are both rare mangoes are often planted in schoolyards, near and of low quality, which creates a significant bar- administrative buildings, along avenues, and in rier to adopting and using the available tech- parks, where social and commercial activities take nologies. In the UWR, men (especially those older place. Various parts of the mango tree are used to than.* years) are responsible for cultivation and prepare medicinal mixtures to combat a range of management of the trees, whereas women take part diseases. Additional uses such as protection of the in the marketing. Most fruits are usually sold in soil against soil erosion, the creation of windbreaks, local markets. A traditional belief in the UWR, and rootstock production for nurseries were also which says that you will die when you plant a tree mentioned. When the tree is trimmed, the leaves and eat its fruit or sit under its shade, has scared are used to feed livestock and the wood is used for many youth away from planting mangoes. In some fuel. ethnic groups, only nephews and very old people Impact of B. invadens and other pests on with a short lifespan are allowed to plant the trees mangoes for food and shade. However, this taboo is gradu- The main problems mentioned by mango producally fading away owing to educational campaigns. ers throughout the survey were the infestation of mango trees by fruit flies (i.e., B. invadens, Ceratitis Fig. 0. Mango fruits (a) attacked by Bactrocera invadens and (b) that dropped prematurely as a result of B. invadens attack.

12 128 J. Dev. Sus. Agr. - (,) cosyra, Ceratitis capitata and mealybugs ( Rastrococcus mostly generalists, and management schemes for invadens) (Fig. 0a). Most of the producers had these pests must therefore account for the other some knowledge of the mango mealybug, which has host crops used by these species. Aluja et al. ( +331) been present in the region for longer than the fruit suggested that in the case of fruit flies, an assessfly. One of the descriptions given for a mealybug ment of vegetation adjacent to the infested mango infestation was a white worm with black powder orchard is crucial. In the tropics and subtropics that produces a honey-like oil. Some producers where mango is grown, the management of key described the more recently introduced fruit fly as pests (e.g., fruit flies, seed weevils) must become responsible for premature dropping of mango mandatory in order to have a significant e# ect fruits, and described maggots found in the sliced within a large region. The use of measures such as fruit (Fig. 0b) Most producers ( 0* ) agreed that the fruit fly was a serious pest and that it decreased quarantine must be practiced by neighboring pro- ducing areas in order to have a positive e# ect on fruit production. Mealybugs accounted for +- of sanitation for a particular crop. In areas where the pests found in mango fields, and were being maximizing yields and the proportion of unblemcontrolled by biological means (by Gyranusoidea ished fruit are not priorities, the emphasis should be tebygi) (Hymenoptera: Encyrtidae). The reap- placed on biological control. Fruit fly control in pearance of this pest in some areas in two years sub-saharan Africa is still in an experimental stage back may have resulted from indiscriminate use of (Ekesi and Billah,,**0). Therefore, fruit fly conchemical pesticides in cotton production. In most trol should focus on an IPM approach to ensure cases, the incidence of pests was reported to be e# ective protection of the crop. Some management higher at the beginning of the rainy season. Other strategies that could be adapted for use in Ghana farmers (,1 ) cited the red ant Oecophyllya longinoda are described below. (Hymenoptera: Formicidae) as another con Selective pesticides straint, and others reported problems with termite Pesticides that are used in IPM programmes ( Microtermes spp). Many of these pests cause must have selective toxicity so that they do not damage at subeconomic levels and become serious a# ect non-target organisms. The current trend is pests only locally, as a result of changes in cultural the development of insect growth regulators that practices or indiscriminate use of pesticides. are highly e# ective for a limited group of insects. For example, Diaz et al. ( +330) suggested the use -.. Possibilities for Managing the Fruit Fly of cyromazine to reduce the fertility of Anastrepha Problem: A General Overview obliqua (Diptera: Tephritidae). Cunningham ( +32. ) Current pest management practices are a# ected suggested that oils (e.g., petroleum and olive oil) not only by the domestic and export fruit markets, could be used to control scales on mango. Howbut also by consumer attitudes toward health concerns ever, most of the recommendations from other coungeneral, and the cosmetic appearance of the fruit. In tries are based on highly toxic or illegal, unreg- mango pest management depends strong- istered, persistent chemicals (Singh, +33+ ). Thus, ly on the use of pesticides (Galan-Sauco, +33* ; there is a great need to research safe, pest-specific, Nachiappan and Baskaran, +320 ; Pẽna, +33- ). e# ective chemicals that could be used in Ghana. However, control of pests of mango fruit by chemicals -.,.. Biological control alone has been complicated by the develop- Biological control has great potential for regulat- ment of resistance and a resurgence of minor pests ing pest populations in IPM programmes in mango that have been elevated to major pest status orchards. However, it may be di$ cult for biologi- (Cunningham, +32. ). The costs of pest control cal control alone to reduce a fruit pest from an have also escalated, and in some cases, increasing economic problem to nuisance status. A combinaamounts of pesticides are required to keep the large tion of releases of parasitoids to augment their number of pest species under control. populations a and the release of sterile insects has In addition, most mango pests also attack other been considered, at least in theory, to be more fruit crops. Fruit flies, scales, mites, thrips, lepi- e# ective for fruit flies than either method applied dopteran flower feeders, weevils, and beetles are alone (Barclay, +321).

13 Kwasi: Assessment of Fruit Fly Damage and Implications for the Dissemination of Management Practices 129 In Africa, several parasitoids are being tried to laying eggs (Ekesi and Billah,,**0). Despite the combat B. invadens, and Fopius arisanus (Hy- cost of this approach, protective coverings are still menoptera: Braconidae) seems to be promising for being used to a certain extent by producers of controlling the species (Dr. M.K. Billah,,**2, high-value fruits for export and by home gardeners. pers. comm.). Fopius arisanus only attacks the fruit For this approach to be e# ective, the fruits should fly s eggs, and is currently reported to be the dom- be wrapped or bagged before the period when fruit inant fruit fly parasitoid in Hawaii (Purcell et al., flies are mostly likely to begin oviposition. If this +332 ; Wong and Ramadan, +321), partly owing to method is shown to be practical in the UWR, its intrinsic competitive superiority against all mango farmers may be able to easily adopt this larval fruit parasitoids (Wang and Messing,,**-). method to reduce fruit fly damage in the region. It was also reported as the most abundant parasitoid -./.. Cultural controls in Sri Lanka during the exploratory mission Two principal cultural methods can be used to to that country in search of natural enemies for control fruit flies: field sanitation and the use of possible use in classical biological control against B. trap crops. Field sanitation is particularly imporin invadens Africa (M.K. Billah, unpublished tant. The method focuses on the destruction of all data). The government of Ghana must therefore unmarketable and infested fruits and the disposal of invest in trials of this method, as was done in the crop residues immediately after harvesting. This is past to control mealybugs on mangoes, (Moore, a laborious exercise, but can be e# ective if the fruits,**.) since it would be di$ cult for any individual are collected twice a week and destroyed throughor group of farmers to a# ord the cost of this out the entire growing season. Infested fruits technology. should be buried at least - feet under the soil Host plant resistance surface. The addition of lime can help to kill Mango is tolerant to Noorda spp. and Idioscopus emerging larvae. The fruits can also be chopped up spp. (Bagle and Prasad, +32. ; Cunningham, +32. ) and soaked to prepare bio-fertilizer or to feed liveand resistant to Sternochetus mangiferae (Cole- stock. The use of trap crops around the perimeter optera: Curculionidae) Hansen ( +33-). Carvalho of a plantation can intercept pests during their et al. ( +330 ) have also demonstrated di# erent de- migration, regardless of the direction of attack. grees of susceptibility of mango cultivars to A. This approach then concentrates the pest populaobliqua. Angeles ( +33+ ) reported that Mangifera tions in the trap crops, where they can be controlled altissima does not seem to be a# ected by mango (e.g., by sanitation), thus preserving natural enpests such as leafhoppers, tip borers, and seed emies in the main crop (Aluja et al., +331). Beborers in the Philippines. There is little doubt that cause many insect pests act as vectors of important wild mangoes have potential value in breeding that crop diseases, reducing pest populations on the has not yet been documented in relation to fruit main crop may also reduce losses to these diseases. flies. The tolerance or insect resistance of mango Early harvesting could also be done to reduce incultivars and related species should be determined festations, particularly for crops that will be exin natural stands or in established germplasm col- ported (i.e., where the fruit will ripen in transit). lections. Therefore, tests for mango resistance to Release of sterile insects fruit flies should include provisions for exposure to The release of sterile insects is an environthe insects under varying conditions whenever pos- mentally friendly, species-specific method of insect sible, and researchers in the UWR should work control that has been described as birth control for towards achieving this goal. insects (Knipling, +33, ). It involves mass breeding Mechanical fruit protection (bagging or of huge quantities of target insects in a facto- wrapping) ry and sterilizing the males. These sterile males Fruit wrapping has been found to be e# ective in are then released in the air over infested areas, controlling fruit flies after their population has been where they mate with wild females, thereby reducreduced by baiting and trapping devices. Protec- ing the number of viable eggs. The Sterile Insect tive coverings such as newspaper, plastic and paper Technique depends on the ability to mass rear bags are e# ective in preventing fruit flies from millions of sterile flies for release at the appropriate

14 130 J. Dev. Sus. Agr. - (,) time (when the pest population has not reached its introduction. They also require rigorous operationpeak) in order to overwhelm the pest population, al standards and are expensive, since resources have and over very wide areas (Tan,,***). This leads to be mobilized for large operations at very short to a decrease in the reproductive potential of the notices. However, given the scarcity of the reresident pest population and ultimately to its sources and the virtually non existent regular fruit eradication. For example, almost +/. billion flies fly monitoring programs, the design of any managewere released in +33+ against C. capitata in the ment strategy in this regard must be pragmatic and Kauai Co# ee Plantation in Hawaii, resulting in a realistic. population suppression of /0 compared with a Protein bait sprays control of no release (Vargas et al., +33. ). These In this approach, the protein baits acts as a food features make the SIT approach complex and ex- attractant and its e# ectiveness relies on the fact that pensive, and its e$ cacy may be compromised in immature females need to consume protein (Ekesi situations where the population density of the pest and Billah,,**0) before they can produce mature flies are very high (Knipling, +33, ). For example, eggs. The fly suppression is mainly based on use of eradicating the melon fly ( B. cucurbitae) from food baits (hydrolyzed protein or their ammonium southwestern Japan using this method cost more mimics) combined with a killing agent such as than / billion Japanese Yen (about US- million) pesticide and applied in localized spots. These and,**,*** worker-days (FAO, +320). Such an sprays are less harmful to beneficial insects, making approach also requires cooperation from neighbor- them suitable for use in IPM programmes. Costs ing countries to be e# ective and sustainable. are considerably lower than in broadcast-spraying Male-annihilation technique because less material is used per tree or per hectare. The male-annihilation technique involves the use This method could easily be used by mango farmers of a high density of bait stations consisting of a in the UWR if they are taught how to apply the male lure combined with an insecticide (usually method and if the sprays are a# ordable. malathion, and more recently fipronyl) to reduce Post-harvest fruit treatment the population of male fruit flies to such a low level Without post-harvest treatment to provide quarthat mating does not occur. This approach has antine security, the export of fruits and vegetables been used successfully to control several Bactrocera to lucrative markets is limited by quarantine respecies, such as B. dorsalis in Rota Island (Steiner strictions. In fruit fly control, some of the available et al., +30/ ) and Japan (Ushio et al., +32, ). For quarantine treatment technologies may include the example, coconut husk blocks impregnated with following: methyl eugenol and malathion could be used in (i) heat treatment to increase the temperature Ghana. Findings from Ibrahim et al. ( +313) and of the host fruit above the insect s thermal Qureshi et al. ( +310, +32+ ), demonstrated that limit increasing the number of traps baited with methyl (ii) cold treatment to decrease the temperature eugenol significantly decreased damage caused by of host fruit below the insect s thermal limit Dacus fruit flies. As indicated by Lux et al. (,**-), (iii) the use of radiation to kill the insects the new pest responds strongly to methyl eugenol, These approaches could be implemented by plant and it is technically possible to suppress it using the quarantine units and other experts at ports and male-annihilation technique, as has been achieved border posts to ensure that only pest-free products in other tropical regions (Tan,,***). This method are allowed to move between regions or countries. could be easily applied in the UWR if mango However, these treatments must not be detrimental farmers are introduced to it because of its ease of to the fruits and vegetables, and therefore require application, provided the materials are made a# ord- trained expert users. able. But there are serious considerations and pre-requisites in the technical application of this -/. Strategic Plans to Manage the Fruit Fly strategy. According to Billah et al. (,**0), this, Problem in the UWR however, requires that such actions are undertaken Based on the various interventions being adapted within hours after first detection or shortly after its by various countries, I propose the following ap-

15 Kwasi: Assessment of Fruit Fly Damage and Implications for the Dissemination of Management Practices 131 proach to manage the fruit fly problem in the lations of the insect pest in a target area. The UWR. preliminary knowledge of the B. invadens distribution -/+.. Enhance the knowledge of agricultural pattern in the UWR provided by the present extension o$ cers about appropriate methods for study should serve as baseline data from which managing fruit fly damage to mangoes further investigations could be carried out, starting (i) Organize training for agricultural extension with a district-wide delimiting survey that would o$ cers on the identification and manage- help to determine appropriate methods for the dement of mango pests and diseases. tection, control, and management of the pest. As -/,.. Teach mango farmers the knowledge and indicated by Lux et al. (,**-), the new pest responds skills they need to identify mango pests and strongly to methyl eugenol, and it is techni- diseases and to control them cally possible to suppress it using the male- (i) Organize meetings with farmers in mango- annihilation technique, as has been achieved in growing communities to create awareness of other tropical regions (Tan,,***). This approach, mango pests and diseases. however, requires that such actions be undertaken (ii) Organize radio talk shows to educate within hours after the first detection of a problem farmers about the management of mango (i.e., before most of the males have a chance to pests and diseases. breed) or shortly after the introduction of an insect (ii) Facilitate the formation of mango farmer into an area. Such programs also require rigorous groups. operational standards and are expensive, since re- (iv) Organize training for mango farmer groups sources must be mobilized to conduct large operaon how to identify and manage mango pests tions at very short notice. and diseases. Given the scarcity of resources and the lack of -/-.. Give development partners access to information regular fruit fly monitoring programmes in the on mango pests and their management UWR, the design of any fruit fly management at the regional plant protection o$ ce strategy must adopt a more pragmatic and realistic Establish an inventory programme to monitor approach that relies on educating all stakeholders fruit flies and other pests that are responsible for and getting them involved in developing and imdamage to mangoes in the target area. plementing solutions. Since there has been a recent (i) Develop and produce publications (e.g., upsurge of fruit growing and export in Ghana, control manuals and handbooks) on mango treating the fruit fly with a sense of urgency will go pests and diseases for stakeholders who need a long way toward improving the entire horticulthis information. For those who are not ture industry: solutions learned and implemented su$ ciently literate to use these publications, from controlling fruit flies can be extended to other provide training sessions based on these ma- pests. terials. -/... Monitor and supervise.,. Recommendations (i) Monitor the fruit fly situation and report to Since B. invadens is of great quarantine concern the national Plant Protection and Regulato- and because it is capable of devastating Ghana s ry Services Directorate (PPRSD). agricultural industry (especially mango production),.. Conclusion and Recommendations the results of the present survey should be immediately communicated to the relevant quarantine.+. Conclusion authorities in Ghana: the district o$ ce of the Detection of economically important fruit flies is Ministry of Food and Agriculture in the districts critical to the sustainability of agriculture. Survey where the pests have been captured, the Savannah data can reveal changes in the relative abundance Agricultural Research Institute (SARI), and the of the fly population over time and indicate when PPRSD Head O$ ce in Pokuase. The following populations have built up to dangerous levels in an recommendations should be implemented as soon area. This information can be used to define the as feasible to reduce the spread of the pest: measures that must be taken to reduce local popu- Trapping and survey programs by the Minis-

16 132 J. Dev. Sus. Agr. - (,) try of Food and Agriculture in the UWR to provide up-to-date data that can be used to support decision-making. Implementation and enforcement of phytosanitary measures to control the movement of materials that can host fruit flies. Fruit disinfection and the operation of roadblocks to prevent the movement of infested fruits between areas should be implemented, especially with cooperation from neighboring countries..-. Issues for Future Study Many of the techniques discussed in section - of this paper, such as the development of speciesspecific control methods, require detailed investigation to determine whether they will be e# ective in the UWR and how they can be adopted most e# ectively and economically. Further studies on the use of geographic information systems and Global Positioning System technologies to monitor the locations and dispersal of fruit flies and to allow prediction of outbreaks and spread of the insect would be helpful. Such studies can help managers to locate infestations, assess their condition, and detect trends and patterns (e.g., the relationship between infestations and rainfall patterns). Both tools can be very e# ective ways to manage trap locations and analyze capture data. Acknowledgements I am profoundly grateful to my supervisors, Prof. Hiroshi Honda and Dr. Yooichi Kainoh, both of the University of Tsukuba, Japan for their tremendous support and guidance throughout my research work. I especially thank Dr. Maxwell K. Billah, formerly of ICIPE-Kenya (now with the Zoology Department of the University of Ghana, Legon-Accra) for his continuous support in providing information on the fruit fly and for taxonomic identification of the flies. I sincerely thank the National Director of Ghana s Plant Protection and Regulatory Services Directorate, Mr. Vesper Suglo; the Regional Director of Agriculture, UWR, Mr. Emmanuel Eledi; and all the sta# of the Ministry of Food and Agriculture, UWR, for their support and encouragement. I am also grateful for the financial support provided by the Japan International Cooperation Agency-Tsukuba Training Center (JICA- TBIC). References Aluja, M., Cabrera, M., Guillen, J., Celedonio, H. and Agora, F., Behaviour of Anastrepha ludens, A. obliqua and A. serpentina (Diptera Tephritidae) on wild mango tree ( Mangifera indica) harbouring three McPhail traps. Insect Sci. Appl. +* : -* Aluja, M., Jimenez, A., Camino, M., Pinero, J., Aldana, L., Caserjon, V. and Valdes, M.E., Habitat manipulation to reduce papaya fruit fly (Diptera: Tephritidae) damage: Orchard design, use of trap crops and border trapping. Journal of Economic Entomology, 3* : +/01 +/10. Amice, R. and Sales F., Seasonal abundance of fruit flies in New Caledonia. In: Management of fruit flies in the Pacific. Ed. By Allwood AJ, Drew RAI. ACIAR, Canberra, Angeles, D.E., Mangifera altissima. In: Coronel, R.E. and Verheij, E.W.M. [Eds.] Edible Fruits and Nuts. Plant Res. S.E. Asia, (PROSEA), Pudoc, Wageningen, the Netherlands. pp.,*0,*1. Bagle, B. and Prasad, V., Varietal incidence and control of stone weevil Sternochetus mangiferae Fabricius. Indian J. Entomol..0: -23-3,. Barclay, H. J., Models for pest control: complementary e# ects of periodic releases of sterile pests and parasitoids. Theor. Popul. Biol. -,: Billah, M.K.,,**1. ECOWAS fruit fly scoping study and regional action programme. Evaluation of the fruit fly problem in Ghana. A report on Ghana..1 pp. Billah, M.K., Wilson, D.D., Cobblah, M.A., Lux, S.A. and Tumfo, J.A.,,**0. Detection and preliminary survey of the invasive fruit fly, Bactrocera invadens (Diptera: Tephritidae) in Ghana, Journal of the Ghana Science Association,, () Carvalho, R.S., Nascimento, A., Morgante, J. and Fonseca, N., Susceptibility of di# erent mango varieties to the attack of the fruit fly, Anastrepha obliqua. In: McPherson, B. and Steck, G. [Eds.] Fruit Fly Pests: A World Assessment of Their Biology and Management. St. Lucie Press, Delray Beach, FL, USA. pp. -,/ --+. Chipp, T.F., +3,,. The f orest o$ cer s handbook of the Gold Coast, Ashanti and the Northern Territories. Published for the Government of the Gold Coast by the Crown Agents for the Colonies. London: Clarke, A.R., Armstrong, K.F., Carmichael, A.E., Milne, J.R., Raghu, S., Roderick, G.K. and Yeates, D.K.,,**/. Invasive phytophagous pests arising through a recent evolutionary radiation: the Bactrocera dorsalis complex of fruit flies. Annual Review of Entomology /*: Copeland, R.S., White, I.M., Okumu, M., Machera, P. and Wharton, R.A.,,**.. Insects associated with the fruits of the Oleaceae (Asteridae: Lamiales) in Kenya, with special reference to the Tephritidae (Diptera). In: D. Elmo Hardy Memorial Volume. Contributions to the systematics and evolution of Diptera. Eds: Evenhuis, N.L. and Kaneshiro, K.Y. Bishop Museum Bulletin in

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