1. 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

2. 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

3. 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

4. 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)

5. 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--

6. 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) eggs per mass. Spend between 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!

7. 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.

8. 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

9. 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

10. 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

11. Surveyed Eggs
Total: 12, 479 eggs

12. Percent Parasitism

13. (cont.)

14. (cont.)

15. (cont.)

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

17. E. servus-- Telenomus podisi

18. M. histrionica-- Trissolcus basalis & a Mymarid

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

20. 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.

21. 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

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

23. Questions?