Understanding White Grubs in Turfgrass Coleoptera:Scarabaeidae

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1 Richard J Buckley, Director Soil Testing and Plant Diagnostic Services s Understanding s in Turfgrass Coleoptera:Scarabaeidae Photo: Richard Buckley, NJAES Photos: Sabrina Tirpak, NJAES Key features of scarab beetles Scarab Modified family spade-like spot identification characteristics Lamellate club include spade-like tibia tibia and lamellate club antennae Raster Scarabaeiform larvae or C-shaped grub 1

2 Metamorphosis Japanese beetle Oriental beetle European chafer Asiatic garden beetle masked chafer Egg L1 L2 L3 Pupa Adult black turfgrass ataenius green June beetle May/June beetle Life Cycle Scarab Feeding Injury Primary damage Feeding on roots near soil surface Kills grass outright Predisposes turf to environmental stress Secondary damage Vertebrate predators foraging for grubs *Japanese beetle, Oriental beetle, Asiatic garden beetle, European chafer, masked chafers, green June beetle Damage Thinning, yellowing, wilting Scattered, irregular patches Scarabs feed on organic matter (and roots) in the soil Dead patches join and grow Turf spongy, easily pulled up 2

3 Damage Damage damage first appears as turf that wilts in the afternoon heat, but recovers when irrigated ultimately, the turf will not recover for more than a day or several hours at this point it is near death Damage Damage Photo: Jake Talley Photo: Thomas Tresnan, Roxiticus Golf Club Damaged turf will pull up like a rug Damage Damage Turf easily pulled up C-shaped white grubs under turf Photos: Paul Precone, Irem Temple Country Club Foraging grub predator predator damage 3

4 Damage Damage small mammal damage Photos: Paul Precone, Irem Temple Country Club Photo: Joe Adkinson, Missouri Bluffs Golf Club Damage Damage Photo: Brian Woodward Photo: Joe Adkinson, Missouri Bluffs Golf Club Bird damage on golf course tee Skunk damage on bermudagrass Oriental Beetle Damage Remember those birds? Photo: Richard Buckley, NJAES Oriental Beetle Damage Photo: Richard Buckley, NJAES 4

5 Oriental Beetle Damage Damage Photos: Vineyard Golf Club Photo: Richard Buckley, NJAES Photo: Vineyard Golf Club Damage Scarab Turfgrass Pests of the Northeast Japanese beetle Popillia japonica European Chafer Rhizotrogus majalis Unanticipated consequences Masked chafers Cyclocephala spp. Oriental beetle Exomala orientalis Asiatic garden beetle Maladera castanea Key Introduced Grub Pests Oriental Beetle Japanese Beetle Asiatic Garden Beetle European Chafer Key Native Grub Pests May/June Beetle Green June Beetle Masked Chafer Black Turfgrass Ataenius 5

6 MB GJB EC SMC NMC JB OB AGB BTA MB GJB EC MC JB OB AGB BTA MB, May beetle; GJB, green June beetle; EC, European chafer; MC, masked chafer (S/N, southern/northern); JB, Japanese beetle OB, Oriental beetle; AGB, Asiatic garden beetle; BTA, black turfgrass ataenius 1 White grubs complex in NJ lawns (Fall 2001/2002: 11 counties / 120 sites) Oriental beetle (61%) Asiatic garden beetle (14%) Japanese beetle (12%) Masked chafers (7%) May/June beetles (3%) Green June beetle (2%) European chafer (1%) Oriental Beetle INSECT Exomala orientalis HOST All turfgrass Woody ornamentals in field nursery and pot production Oriental beetle adults are night flyers that feed on pollen Oriental Beetle Photos: Dr. David Shetler, Ohio State Oriental Beetle Raster Oriental Beetle Raster Oriental beetles exhibit significant color variation, but they usually have two dark spots on the pronotum Photo: Jeff Swanson, Ocean Edge Resort & Club 6

7 Japanese Beetle Japanese Beetle Distribution INSECT Popillia japonica HOST All turfgrass Foliage and flowers of many other plants Japanese Beetle Japanese Beetle Mating cluster of Japanese beetles in turf Scarabs have strong means of chemical communication. Adult beetles use pheromones for attracting a mate or aggregation at a food source. Photo: Corey Randall, Lancaster Country Club Japanese Beetle Japanese Beetle Photo: Richard Buckley, NJAES Japanese beetles skeletonize the leaves of many plants Japanese beetles skeletonize the leaves of many plants 7

8 Japanese Beetle Japanese Beetle Photos: James Dall, Pine Valley Country Club Photo: Richard Buckley, NJAES Japanese beetles skeletonize the leaves of many plants Japanese beetles terrorize flowers Japanese Beetle Raster Masked Chafer INSECT Cyclocephala spp. HOST All turfgrass Masked Chafer Northern Masked Chafer Southern Masked Chafer Southwestern Masked Chafer Western Masked Chafer Note: masked chafers head is dark 8

9 Masked Chafer Masked Chafer Photo: James Dall, Pine Valley Country Club Pair of masked chafers at night on turf Masked Chafer Raster Masked Chafer Pupa Photo: James Dall, Pine Valley Country Club Photos: James Dall, Pine Valley Country Club Masked Chafer Damage Masked Chafer Damage Photo: James Dall, Pine Valley Country Club Photo: James Dall, Pine Valley Country Club 9

10 Masked Chafer Damage Asiatic Garden Beetle INSECT Maladera castanea HOST All turfgrass Weeds, flowers, vegetables Foliage and flowers of many other plants Photo: James Dall, Pine Valley Country Club Asiatic Garden Beetle Asiatic Garden Beetle Raster Note: Asiatic garden beetles are small and have an iridescent sheen Green June Beetle INSECT Cotinus nitida HOST Decomposing organic matter Sugary foods (sap, nectar, fruit) Nuisance pest Green June Beetle Distribution Though distribution maps show that green June beetles shouldn't be in Florida, they have now been confirmed to be throughout that state 10

11 Green June Beetle Green June Beetle Raster Green June Beetle Pupae Green June Beetle Green June Beetle Damage Green June Beetle Green June beetle grub in overwintering burrow the two smaller grubs are overwintering Japanese beetle grubs Note: thinning of turf where grubs have come to the surface to feed 11

12 Green June Beetle Damage Scouting and Monitoring Diagnostic vs. Proactive Sampling Spring "clean-out" mounds from green June beetles on a golf course fairway. Chemical Control Curative vs. Preventive Control A golf course cup changer makes an effective grub sampling tool Note: each core is 1/10 square foot - 1 grub per sample equals 10 grubs per sq. ft. Diagnostic Sampling Diagnostic Sampling Sample damaged areas quantify the populations and compare your numbers to published action thresholds Sample damaged areas Photo: Paul Precone, Irem Temple Country Club 12

13 Damage Thresholds European Chafer Oriental Beetle Japanese Beetle Masked Chafer Green June Beetle Asiatic Garden Beetle May/June Beetle Black TG Ataenius 3 to- 8 sq. ft. 6 to- 20 sq. ft. 6 to- 20 sq. ft. 6 to- 20 sq. ft. 6 to- 20 sq. ft. 12 to- 20 sq. ft. 3 to- 4 sq. ft. 15 to- 80 sq. ft. Curative control Use trichlorfon Target grubs near the soil surface April and mid-august Target early instars mid-august Irrigate before and after moves grub and insecticide into target zone Biochemical Class Organophosphates - IRAC group 1B - Acetylcholinesterase (AChE) inhibitors - Acetylcholine (Ach) = synaptic neurotransmitter - AChE breaks down ACh after nerve impulse - Binds to AChE and prevent ACh removal = tremors - Chronic inhibition - Fast acting short residual - High mammalian toxicity; toxic to beneficial insects - Trichlorfon (Dylox) and acephate (Orthene) Note: if more than 1/2 inch of thatch is present, it will be very difficult to get the insecticide to the target grubs. A golf course cup changer makes an effective grub sampling tool Note: each core is 1/10 square foot - 1 grub per sample equals 10 grubs per sq. ft. 13

14 1/19/16 Proactive approach Proactively identify grub hot spots ü Survey 2 nd instar grubs ü Sample in grid ft sports field or fairway ü Use raster patterns to identify species ü Record # s ü Map populations ü Several adjacent samples equals a hot spot X X X X X X X X X X X X X X X X O O X X X X X X X X O O O X X X X X X O O O X X X X X X X O O O X X X X X X X X X X X X X X X X X X X X X X Photos: Sabrina Tirpak, NJAES Scouting is of little use UNLESS YOU RECORD & SAVE THE DATA Proactive approach Pheromone Traps Proactive approach Black Light Traps Photos: Richard Buckley, NJAES Species specific sexual attractants Attracts night flying insects - Bug zapper not useful Proactive approach Number of Insects Peak Adult Flight Peak # of Adult Insects Captured PEST LIFE CYCLE Peak # of Feeding Immature Insects Time Use traps to monitor insect emergence Continuous monitoring can identify peaks in life cycle Peak Adult Flight European Chafer late June Oriental Beetle late June Japanese Beetle early July Masked Chafer early July Green June Beetle mid July Asiatic Garden Beetle - July May/June Beetle April to- August Black TG Ataenius late May and mid July 14

15 Preventive control Monitor peak adult flight Target hot spots Choose long residual material Biochemical Class Neonicotinoid - IRAC group 4A - Nicotonic acetylcholine receptor agonist/ antagonist - Persistent Ach response = overstimulation - Systemic long residual - Low application rates - Low mammalian toxicity - imidacloprid (Merit), clothianidin (Arena), thiamethoxam (Meridian) Biochemical Class anthranilic diamides IRAC group 28 Newer class of insecticides Ryanodine receptor modulator leaves it open Causes insect muscles to leak calcium ions; mammals have few of these receptors Virtually non toxic; category IV toxin chlorantraniliprole (Acelepryn), cyantraniliprole (Ference) Class IGR Diacylhydrazine IRAC Group 18A MACH2; molt accelerating compound halofenozide #2 Ecdysone mimic causes premature and lethal molts Six week soil activity; highly systemic Low toxicity good environmental characteristics Excellent choice for many grubs Labeled for several ornamental pests Pesticide alternatives Alternatives to synthetic chemical controls Sound agronomy practice Increase tolerance and recuperative potential Irrigate and spoon feed hot spots Mask damage and stimulate recovery 15

16 Pesticide alternatives Pesticide alternatives Masked chafer eggs 48 hours in moist soil Dry out the site during egg laying Entomopathogenic nematodes Native parasites of insect larvae Large natural populations Steinernema spp. Ecomask, Millenium Heterorhabditis spp. Cruiser, Grubstake-Hb, Grubstake-Hm, Heteromask Harmless E.P.A. exempt newly laid Steinernema carpocapsae Entomopathogenic Nematodes Photos: Vineyard Golf Club After Treatment Before Treatment Pesticide alternatives Entomopathogenic fungi fungal parasites of insects Beaveria bassiana Metarhizium anisopliae Natural enemies Big-eyed bug Mites Ground beetles Tiphia wasps Pesticide alternatives 16

17 Tiphia Wasps young larvae Healthy Pesticide alternatives Milky spore disease, Paenibacillus popilliae grubs ingest spores colonizes body fluid grub starves to death in ~4 wk forms spores à white color spores released from dead grub survive for years in soil adult mature larvae pupae milky Parasporal body Conclusions IPM for s: 1. Maintain sound cultural practice 2. Mask damage with added inputs 3. Properly identify the insect and life stage 4. Use site specific monitoring tools to identify hot spots 5. Make targeted treatments with least toxic synthetic insecticides or biorational materials Soil Testing and Plant Diagnostic Services