|Elliott, Norman - Norm|
Submitted to: Southwestern Entomologist
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/27/2001
Publication Date: 12/27/2001
Citation: FUENTES-GRANADOS, R.G., GILES, K.L., ELLIOTT, N.C., PORTER, D.R. ASSESSMENT OF GREENBUG-RESISTANT WHEAT GERMPLASM ON LYSIPHLEBUS TESTACEIPES CRESSON (HYMENOPTERA: APHIDIDAE) OVIPOSITION AND DEVELOPMENT IN GREENBUG OVER TWO GENERATIONS. SOUTHWESTERN ENTOMOLOGIST. 2001. V. 26(3). P. 187-194. Interpretive Summary: Biological control of pest insects by natural enemies and use of agricultural plants with genetically built in resistance to pest insects are two of the most important and cost effective ways to control pest insects in agricultural crops. Thus, the compatibility of biological control by natural enemies with control conferred by genetically resistant agricultural plants is a concern when considering the plants for use in a pest management program. The greenbug is the most economically damaging insect pest of wheat in the Southern Plains region. We studied the effects of greenbug resistant wheat varieties on the biology of an important natural enemy of the greenbug, the parasitic wasp Lysiphlbus testaceipes. Resistance was conferred to wheat by the resistance genes GRS-1201 and Largo. Several biological parameters involved in determining the effectiveness of L. testaceipes in biological control of greenbugs were evaluated. Over two generations, no negative effects of wheat with resistance were observed on the biology of L. testaceipes, except that the number of days required for the parasitic wasp to develop to adulthood was slightly greater for L. testaceipes developing in greenbugs living on resistant wheat varieties compared to those living on susceptible varieties. However, the difference in development time was very small and likely would have little effect on the level of biological control exerted by L. testaceipes on greenbugs. Our results indicate that wheat varieties containing greenbug resistance genes can be successfully integrated into holistic greenbug management programs.
Technical Abstract: We compared ovipositional patterns and developmental times of L. testaceipes attacking greenbugs that were reared on either GRS-1201 wheat germplasm with the Gb6 resistance gene, Largo wheat germplasm with the Gb3 resistance gene, or the susceptible wheat cultivar Triumph-64. Parameters evaluated over two generations were greenbugs parasitized per day, oviposition rate, percent parasitism, percent superparasitism and days to adult emergence. Over two generations, no significant negative effects of resistant wheat germplasm on ovipositional patterns of L. testaceipes were observed. However, compared to the susceptible control (greenbug hosts on Triumph-64), days required for adult wasp emergence were significantly longer for L. testaceipes developing in greenbug hosts from GRS-1201 and Largo colonies. These differences in development amounted to less than 0.5 days per wasp generation, and would likely have little effect on population interactions between L. testaceipes and greenbugs infesting resistant wheat. Our results indicate that wheat cultivars containing Gb6 can be successfully integrated into holistic greenbug management that incorporate biological control by L. testaceipes.