Implementation of a Pest Monitoring Network For Vegetable Growers In Yuma County

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1 Implementation of a Pest Monitoring Network For Vegetable Growers In Yuma County John Palumbo, David Kerns, Clay Mullis, and Francisco Reyes Abstract A n insect pest monitoring network spanning e major growing areas in Yuma was implemented in This project was designed to measure e relative activity and movement of adult populations during e growing season and provide important information to growers and PCA s. A series of pheromonebaited and yellow sticky traps were placed in 11 locations among e growing areas in e Yuma, Gila and s in Yuma county. Numbers of adults / trap /night were recorded weekly from tember-april. Seasonal differences in insect species activity and abundance among locations were observed, but difficult to precisely explain because of e lack of historical trap data. Information gaered from e trapping network will provide historical baseline data for pest activity on an area wide basis from which relationships between insect trap captures and seasonal factors at influence eir activity and abundance may be explained. The results of e monitoring network during e 9-99 growing season for is provided in is report. Introduction The perception of Integrated Pest Management (IPM) is becoming increasingly critical to agricultural production every year. First, e Government Performance and Results Act of 9 called for a % reduction in pesticide use by e year 2. This was quickly followed by e IPM Initiative set for by e Clinton Administration addressing a 7% adoption of IPM by 2. Most recently, e passage of e Food Quality Protection Act (FQPA) of 96 reatens to remove many important broad spectrum insecticides from vegetable cropping systems, and places more dependance on alternative IPM tactics. Since effective insecticides are e primary management tool in Lettuce IPM programs, e University of Arizona must increase it s efforts in developing new IPM approaches. Monitoring and detecting relative pest abundance on an area wide basis is one such way to begin achieving is goal. A monitoring network spanning e major growing areas in Yuma was implemented in This project was designed to measure e relative activity and movement of adult populations during e growing season and provide important information to growers and PCA s. The Vegetable Information Advisory was developed at served as a mechanism for delivering weekly monitoring information as well as timely IPM updates to e PCAs and growers at provides information describing new biological, ecological and management information on key pests. The Vegetable Information Advisory Website can be found at aes/yac/veginfo/. Furermore, e information gaered from e trapping network will provide historical baseline data for pest activity and occurrence on an area wide basis to measure future changes. The results of e monitoring network during e 9-99 growing season is provided in is report. Materials and Meods Information describing adult insect activity was generated from a network of traps at were monitored weekly from This is a part of e University of Arizona College of Agriculture 99 Vegetable Report, index at

2 ust rough ch. Traps were located at several sites roughout Yuma County's vegetable growing areas (Table 1). Three-four trapping stations were situated in e, and /Roll areas for a total of 11 trap locations. At least one location in each growing area was situated near an AZMET weaer station. The approximate location of traps in each valley was selected wi e assistance of local PCAs. The crops being grown adjacent to each monitoring site was documented in tember, ember and ch (Table ). At each site, eier pheromone-baited or yellow sticky traps were used to monitor beet armyworm, cabbage looper, corn earworm, tobacco budworm, aphids, rips and leafminers (Table ). Traps were checked 1-2 times per week. Pheromone lures were changed on a -week schedule to ensure consistent performance and sticky traps were replaced every sample. Mos captured in pheromone-baited traps were counted and recorded at each trapping site. Sticky traps were taken to e laboratory where all leafminers, rips and aphids were counted and recorded. Leafminers were identified to species (Liriomyza trifolii and L. sativae). Aphids and rips species were not identified to species, but traps were examined for e e presence of green peach aphid and potato aphids during spring captures. Data from trap captures was converted to e mean number of adults / trap/ night and presented in a graphic format. Weaer data was summarized for each sample date. Ambient temperatures for each AZMET site was prepared and provided graphically showing relative weekly trends across e season. Results and Discussion The desert vegetable growing areas of Arizona are characterized as multi-cropping systems where crops are grown roughout e year. Most insect pests encountered in ese areas are polyphagous (feed and reproduce on multiple hosts) and highly mobile. Thus, ey are able to readily disperse among numerous crops and build extremely high population densities. Understanding ese relationships may provide insight towards e development of improved IPM management tactics. In addition, monitoring pest activity during e growing season, can indicate when and where pests are moving, and can serve as an early warning mechanism to aid pest control advisors in determining which pest to watch for most closely. The results of e 9-99 monitoring network can be found in Fig 1-7 and Appendix. Based on seasonal trap counts, peak adult activity for each insect species generally varied among e ree growing locations (Fig 1-7). Differences in e time and duration of activity observed among e growing areas probably reflects regional differences in cropping patterns, cropping diversity, and to a lesser extent, temperatures. Oer factors such as wind, rain, dust, pesticide spraying and cultural management in surrounding fields, and experimental error undoubtedly influenced trap counts as well. Consequently, lacking historical trap data, it is difficult to precisely explain e seasonal differences we observed. However, we plan to continue e trapping next year and build a database so at in e future we may be able to determine relationships between insect trap captures and seasonal factors at influence eir activity and abundance. General comments on e trap catches for each species is described below. Tobacco budworm/corn Earworm. Trap catches of mos peaked at all locations during tember (Fig 1), but tobacco budworm catches were greater and significant activity extended into ober. Trap captures were negligible for e duration of e growing season. This is consistent wi our observations at Heliois larvae appear to be most abundant in lettuce fields during e fall. Figure 2 shows e relative proportion of e two species captured during e fall. The relative occurrence of each species differed among e growing areas, but corn earworm appeared to be most prominent in e area. Tobacco budworm/corn earworm was greatest in e, possibly a reflection of periodic movement out of Mexico. Beet armyworm/cabbage Looper. These two lepidopterous species are e primary worm pests in fall lettuce and is reflected in mo catches (Fig ). Beet armyworm adult activity appeared to extend considerably roughout tember and ober. Cabbage looper activity peaked a little later and extended into ember. Mo activity measured during e winter and spring mons was comparatively minimal. Again, is trend is consistent wi e occurrence of larval populations and e need for worm management in lettuce fields during e fall. Diamondback Mo. Alough not considered a primary pest of cole crops in our area, eir presence can be found each season. Trap captures remained low roughout e growing season (Fig 4), becoming active wi e cooler fall

3 temperatures. Because diamondback mo is host specific to brassica crops, we are sure weaer is pest is capable of over-summering in Yuma. More an likely, mos are reintroduced each fall via transplants. This factor, coupled wi warm fall temperatures, may suggest why diamondback mo populations remain low in e desert. Silverleaf Whitefly. The data from sticky traps reflects e reduced whitefly numbers we have experienced e past few years (Fig 4). Adult movement in e ree areas was greatest in early tember and may have bee related to warmer fall temperatures. Activity was greatly reduced by mid-ober. These peaks in activity are consistent wi termination of cotton crops and alfalfa harvesting near trapping locations. Liriomyza Leafminers. Leafminer activity was clearly greatest in e (Fig ). Trap catches peaked in late ust and again in mid-ober, coinciding wi cotton termination and melon harvests. Leafminer activity was negligible during e cooler winter mons, increasing again in April. As observed in previous studies, Liriomyza sativae appears to be e dominant leafminer species in all Yuma growing areas (Fig 6). In general, populations were almost non-existent in e Dome and s during e fall. Thrips. Thrips adults, as indicated by trap catches, were most active during e early fall and again in e late spring (Fig 6). Fall population movement was probably related to cotton/alfalfa harvest and cooler temperatures. Movement in e spring is probably closely related to e gradual increase in daytime temperatures. Previous studies have shown at adult rips will begin to fly when temperatures exceed 6 F during e day when light intensity is high. Furermore, harvest of vegetables, and drying of desert habitat and weed hosts undoubtedly contribute to is activity. Aphids complex. In general, alate aphids reached were most active during ember and ember, and again in late ruary and ch. The late fall activity, which accounted for e peak activity, probably reflected movement of many aphid species dispersing from desert habitat, weeds and oer alternate host plants to alfalfa, small grains and vegetable crops. Total aphid activity was greatest in e at at time. The second peak can be associated wi e normal spring movement seen in lettuce and cole crops as temperatures begin to increase again. Aphid activity was lower in an in e oer growing areas. Acknowledgment We would like to ank Bill Fox,Tanimura & Antle; Todd Hannan, Dune Co of Yuma; Paul Darroch, SoilServe Inc; and Jeff Nigh, Independent PCA, for providing us sites to locate our traps. We also ank Andreas Amaya and Luis Ledesma who assisted in e collection of trap data. Funding for is project was provided by e Arizona Iceberg Lettuce Research Council (9-6), e University of Arizona Cooperative Extension Enhancement Grants Program and e UA Statewide IPM Project. Table 1. Monitoring network locations in e Yuma growing area. Site Location GPS Position nd 1. Co. and Ave I N 2, W Co. 16 and Ave G N 2, W Co. 12 and Ave C N 2 9, W Co. and Somerton Ave N 2 9, W Co. and Ave E N 2 42, W Co. 7 and Ave E N 2 42, W Laguna Dam Rd and Chavez Ln. N 2 42, W Co. and Ave 7E N 2 46, W Co 7 and Ave 17E N 2 4, W Co and Ave 2E N 2 42, W Ave 2E near e Gila River N 2 4, W 1 12.

4 Table 2. Description of e cropping patterns associated wi trap locations Fields Adjacent to Traps (wiin. mile) Site Loc - - ch-apr Yuma 1 Broccoli, Fallow Broccoli, Wheat Cotton, Melons, Lettuce Valley 2 Lettuce, Fallow, Melons Lettuce, Fallow Cotton, Fallow, Lettuce Cotton, Melons, Broccoli Broccoli, Melons, Fallow Lettuce, Melons, Fallow 4 Sudan, Cotton, Fallow, Lettuce, Broccoli, Fallow Lettuce, Melons, Wheat, Lettuce Cotton Gila 1 Lettuce, Fallow, Sudan Broccoli, Fallow Cotton, Lettuce, Fallow Valley 2 Cotton, Lettuce Lettuce, Fallow Wheat, Cotton, Fallow Fallow Lettuce Wheat, Cotton, Lettuce, Fallow 4 Alfalfa, Fallow Alfalfa, Lettuce Alfalfa, Wheat, Fallow Dome 1 Fallow, Cotton, Lettuce Fallow, Lettuce Wheat, Cotton Valley 2 Alfalfa, Cauliflower, Beans, Alfalfa, Fallow Alfalfa, Wheat, Fallow Lettuce Cotton, Lettuce, Fallow Lettuce, Fallow Wheat, Cotton Table. Monitoring Techniques for trapping insect pests. Pest Species Beet armyworm, Spodoptera exigua Cabbage looper, Trichoplusia ni Corn Earwom, Helicoverpa zea Tobacco budworm, Heliois virescens Diamondback mo, Plutella xylostella Silverleaf whitefly, Bemisia argentifolii Monitoring Technique Pheromone-baited bucket traps Pheromone-baited bucket traps Pheromone-baited cone traps Pheromone-baited cone traps Pheromone-baited wing traps Yellow sticky cards Liriomyza Leafminers; L. trifolii and L. sativae Yellow sticky cards Western flower rips, Frankliniella occidentalis Onion rips, Thrips tabaci Aphid complex, multiple species Yellow sticky cards Yellow sticky cards Yellow sticky cards

5 Figure 1. Tobbaco Budworm & Corn Earworm Avg. Temperature ( o F) Ambient Temperature Tobacco Budworm Corn Earworm Yv vs tbw Gv vs Col 6 dv vs Col Apr

6 Figure 2. Proportion of Tobacco Budworm to Corn Earworm Tobacco Budworm Corn Earworm

7 Figure. Beet armyworm & Cabbage Looper Avg. Temperature ( o F) Ambient Temperature Beet Armyworm Cabbage Looper Yv vs BAW Gv vs Col 6 dv vs Col Apr

8 Figure 4. Diamondback Mo & Silverleaf Whitefly Avg. Temperature ( o F) Ambient Temperature Diamondback Mo Silverleaf Whitefly Yv vs DBM Gv vs Col 6 dv Yuma vs Col Valley Apr

9 Figure. Liriomyza Leafminers Avg. Temperature ( o F) Ambient Temperature Liriomyza trifolii Liriomyza sativae Yv vs LT Gv vs Col 6 dv vs Col Apr

10 Figure 6. Proportion of Liriomyza Leafminers Liriomyza trifolii Liriomyza sativae Liriomyza trifolii Liriomyza sativae Mean / Trap/ Night Liriomyza sativae

11 Figure 7. Aphids & Thrips Avg. Temperature ( o F) Ambient Temperature Thrips Aphid Complex Yv vs Thrip Gv vs Col Yuma 6 Valley dv vs Col Gila 9 Valley Apr