News and Reviews

Biological Control at National Entomology Society Meetings

Biological control of insects was the topic of numerous oral and poster presentations at the National Meeting of the Entomological Society of America in Nashville, Tennessee December 14-18, 1997. Many of these will be the basis of future articles in MBCN. The following are very brief summaries of a few presentations. (Only the presenting author is mentioned.)

1. Source of Orius insidiosus colonists of corn in Minnesota - Y. Pang, Univ. Minnesota

Minute pirate bugs move into corn fields from surrounding barley and wheat fields where they develop on the abundant thrips. In corn they also eat aphids and European corn borer eggs.

2. Development of artificial eggs for mass-rearing of Trichogramma spp. - S. Chenus, Cornell Univ., NY

Trichogramma ostriniae will accept artificial structures as potential hosts. The wasps show a similar response to real and fake eggs, and oviposit in the artificial structures. However, a better diet needs to be developed to actually rear the insects.

3. Assessing the feasibility of inundative field-release of Trichogramma exiguum to suppress damaging populations of Platynota idaeusalis - P. Shetty, NC State Univ.

Natural parasitism of tufted apple bud moth eggs in North Carolina is quite low until late in the season. Weekly releases of 60 female Trichogramma wasps/m2 of apple foliage provided control equal to that achieved with methyl parathion applications.

4. Overview of musk thistle biological control and the flea beetle Psylliodes chalcomera - J. Nechols, Kansas State Univ.

Five natural enemies have been released in the U.S. and Canada since a biological control program against musk thistle was established in the 1960's. Two weevils (Rhinocyllus conicus and Trichosirocalus horridus) are established in both countries and a tephritid fly is established in Canada. Recently a bud-feeding flea beetle (P. chalcomera) was released in Texas and Kansas to complement the activities of the other natural enemies.

5. Evidence for nontarget ecological effects of Rhinocyllus conicus, the musk thistle flowerhead weevil - S. Louda, Univ. Nebraska

Long-term studies show this weevil is drastically reducing seed production of some native thistles. It was known this weevil would attack species other than musk thistle when it was first released, but it was thought the impact would be minimal. This research highlights the need to thoroughly evaluate such potential effects prior to the introduction of biological control agents.

6. Aphid predator guild on apple in West Virginia: Sequence of arrival and impact - M. Brown, Appalachian Fruit Research Station, WV

Since the multicolored Asian lady beetle, Harmonia axyridis, arrived in West Virginia, aphid control had improved there. This beetle has replaced sevenspotted lady beetle as the dominant lady beetle in apple orchards and is now the key predator of spirea aphids on apple. It was one of the earliest predators to arrive and responded quickly to aphid population changes. The aphid midge Aphidoletes aphidimyza was the most abundant predator and was also quick to move into apple orchards when aphid populations increased.

7. Field performance and resistance management of Bt sweet corn - G. Dively, Univ. Maryland

Three processing sweet corn Bt-hybids were tested in field trials in 1997. Corn earworm damage was reduced by 95% and damage was confined to the ear tip only. Bt sweet corn does not necessarily eliminate chemical sprays since other pests may be present that require control.

8. Effect of surface wax on pea aphid population reduction by two key predators - C. White, Univ. Idaho

Convergent lady beetle and a green lacewing were more effective at reducing pea aphid populations on glossy mutants than on normal-wax peas. On the normal wax plants the lady beetles interfered with each other, reducing individual performance.

9. Effects of area-wide spraying of Bacillus thuringiensis on nontarget caterpillars and insectivorous birds - M. Lih, Univ. Arkansas

Large areas of the Arkansas Ozarks were sprayed with Bt to control gypsy moth in 1995 and 1996. Caterpillar populations were low for several weeks following the applications, but then rebounded (although the species complex probably was different). Insectivorous bird populations were relatively unaffected by the sprays; most migratory birds can tolerate some fluctuations in prey abundance.

10. Dispersal of Muscidifurax raptorellus in a high-rise poultry facility - P. Tobin, Penn. State Univ.

The commercially produced filth fly parasitoid M. raptorellus rarely dispersed more than 12 feet. Releases may provide control to "hot spots," but need to be used in conjunction with other control tactics to adequately suppress house fly populations.

11. Chinese coccinellidae for biological control of Adelges tsugae - W. Lu, Univ. Rhode Island

Two of 25 species of lady beetles found feeding on hemlock wooly adelgid in China are in the USDA Forest Service Quarantine Lab being evaluated for release against this imported pest. Scymnus sinuanodulus may be released in 1998.

12. Autoinoculative dispersal of bioactive agents by sap beetles - P. Dowd, USDA-ARS, Peoria, Illinois

Sap beetles picked up Bacillus subtilis a strain that inhibits growth of Aspergillus flavus -- which produces highly toxic aflatoxins -- from one autoinoculative device and spread the protective bacteria throughout the 40 acre study site to milk-stage corn. B. subtilis suppresses A. flavus as long as the beetles get into the plant first.

13. Pathogens and parasitoids that cause mortality of European corn borer in Illinois- M. Venditti, Univ. Illinois

The wasp parasitoid Macrocentrus grandii was the most important mortality factor of both 1st and 2nd generation corn borer, although overall parasitization was higher in the 1st. Infection by Beauveria bassiana was low (<3%), but up to 22% with Nosema pyrausta.

14. Spread of Entomophaga maimaiga in Michigan's lower peninsula - M. Mott, Michigan State Univ.

This fungus has dispersed in 5 years throughout most of the lower part of the state and seems to be successfully controlling gypsy moth outbreaks. Infection levels averaged 32% where the fungus was present; 15.5% over all sites.

15. Straw shelters enhance the abundance, diversity, and reproduction of spiders in a soybean ecosystem - J. Halaj, Miami Univ., Oxford, Ohio

Ground spider populations decline when fields are tilled. Temporary shelters (chicken wire cages loosely filled with straw) allowed 15-37 times more spiders to survive in tilled fields, and insect damage to soybean seedlings near the shelters was significantly reduced.

16. Post-dispersal weed seed removal by invertebrates in agroecosystems - D. Landis, Michigan State Univ.

Many species of ground beetles feed on seeds rather than on other insects. More of these seed predators were found in a switchgrass strips than in a legume-grass strip or in the soybean crop, which resulted in greater weed seed removal.

- to be continued -

in the next issue of MBCN!

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