Survey of stink bug (Heteroptera: Pentatomidae) egg parasitoids in wheat, soybean and vegetable crops in Southeast Virginia Amanda L. Koppel Dr. Ames Herbert, Tidewater AREC Dr. Tom Kuhar, Eastern Shore AREC 12/11/06 http://www.entsoc.org/annual_meeting/current_meeting/Submit/Info-Oral-Ten-Minute-Paper-Competitors.htm

Outline Introduction Methodology Results Discussion & Further Study About stink bugs Stink bugs in SE Virginia Control Methodology Field survey Sentinel eggs Results Rates of parasitism Egg parasitoid species complex Discussion & Further Study

Stink Bugs (Heteroptera: Pentatomidae) Phytophagous and predatory species Pentatominae include spp. of economic importance Feed with stylets Damage to plants Cosmetic Growth and development Yield and quality - 4 subfamilies in Pentatomidae - Pentatominae has 40 genera and 180+ spp. …. Only in the last 5 yrs has been recognized as a pest group - Mandibular and maxillary stylets pierce plt. tissue, often the fruiting body of plt is targeted - DMG ~ punctures --> small discolorations ~ esp bad for aesthetic crops (ie tomato) ~ less/no seed germination ~ deformation of fruiting struct ~ decrease in plant fluids ~ delayed maturation of both plant and fruit ~ increased risk to pathogens and decay

Stink Bug Economic Damage of Selected US Commodities Production Values: 79,000 tons alfalfa 9.3 million bushels of grain field corn Almost 19,000 bales cotton 2.7 million bushels soybean MORE RECENT Years soybeans can exceed $68 million (McPherson & McPherson, 2000)

Stink Bugs in SE Virginia Treatment: Economic thresholds Pyrethroids are insecticide of choice Stink bugs may not be seen as a threat! Monitoring Blacklights Pyramid traps Field survey Most common species? No action thresholds have been developed for SB to determine the need or timing of pesticides (LESKEY & HOGMIRE 2005) Why pyrethroids? Farmers are used to it inexpensive already used for corn earworm therefore convenient Many farmers don’t even see SB as a major threat yet because they have other insects which cause greater economic problems for them (is. Corn borers) MONITOR Pyramid bait = methyl (2E,4Z) decadienoate Field survey= sweep nets and beat sheets, which we just heard about from Kathy! Common spp. include: spined solder bug (benefic.), rice sb, harlequin bug, different Euschistus species. NO SOUTHERN GRN IN CMPLX!!! 2 most common spp are--

Brown stink bug (Euschistus servus) Green stink bug (Acrosternum hilare) Kathy’s Research showed that these were the two most common SB sound in cotton and soybean. Both are bivoltine (2 gen/yr) and overwinter as adults. Brown: prefers herbaceous hosts i.e. mullien. Eggs are laid in April (gen 1) and Aug (gen 2). 19-23 eggs per mass. Spend between 33-36 days as nymphs (5 instars). Green: Similar life cycle. spend 1st gen on wild hosts (ie black cherry or elderberry trees) and move to field at 2nd gen. This lets them build up numbers early in the season before switching plants. So what do we do about these pests? Is there an alternative to pesticides? Of course!

Biological Control of Stink Bugs Egg parasitoids are most common Natural enemy surveys Carolinas (Jones et al. 1996) Louisiana (Orr et al. 1986) Kentucky (Yeargan 1979) Florida (Temerak & Whitcomb 1984) California (Ehler 2002) Brazil (Correa-Ferreira & Moscardi 1995) I saw that no NE surveys have been done in Virginia yet, so I decided to do one myself.

Virginia Stink Bug NE Survey (2005-06 field seasons) Objectives To determine if there are stink bug natural enemies (specifically, egg parasitoids) in SE VA Determine rates of parasitism Determine parasitoid species composition

Field Eggs Swept and visually inspected field and vegetable crops for stink bug egg masses Masses returned to the lab Noted Parasitoids Stink bug nymphs No hatch

Sentinel Eggs From lab colony Placed in the field for a week Pinned to the underside of leaves Collected and returned to quarantine Observed as field eggs

Surveyed Eggs Total: 12, 479 eggs

Percent Parasitism

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Parasitoid IDs All Hymenoptera Mymaridae Scelionidae-- Telenomus and Trissolcus Used keys by N.F. Johnson, Ohio State

E. servus-- Telenomus podisi

M. histrionica-- Trissolcus basalis & a Mymarid

A. hilare Trissolcus eddesae Trissolcus basalis Not pictured: Trissolcus euschisti

Not So Generalist? Egg parasitoids tended to stick to certain host species Some crossover Stink bug host crop was irrelevant Okuda and Yeargan (1988a) studied habitat partitioning between these two scelionids by raising P. maculiventris in the lab and placing its eggs on various plants in the field: alfalfa, hackberry trees, and black cherry trees. The results showed that Telenomus podisi parasitized more egg masses in alfalfa whereas Trissolcus euschistii only parasitized eggs in the hackberry trees. Okuda and Yeargan (1988b) also studied intra- and interspecific host discrimination between Telenomus podisi and Trissolcus euschisti. Parasitoids were placed in a plastic bag with a P. maculiventris egg mass and observed. When all the eggs had been oviposited and marked, some of the eggs were rinsed off and allowed to dry. Then one rinsed and one unrinsed egg were placed in a plastic bag with a female parasitoid and observed for host preference. There was found to be a significant amount of intraspecific host discrimination, however, there was no evidence of interspecific host discrimination.

Significance Great deal of heretofore unknown biological control in VA Meaning to farmers Effect of chemical sprays on parasitoid oviposition Parasitization in both 1st and 2nd generations Choice testing of Telenomus podisi

THANK YOU!! Faculty: Graduate Students Dr. Douglas Pfeiffer Dr. Scott Salom Dr. Kim Hoelmer, USDA-ARS-BIIR Graduate Students Kathy Kamminga, SB Survey Data

Questions?