|Elliott, Norman - Norm|
Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2005
Publication Date: 12/1/2005
Citation: Giles, K.L., Dillwith, J.W., Berberet, R.C., Elliott, N.C. 2005. Survival, development, and growth of Coccinella septempunctata fed Schizaphis graminum from resistant and susceptible winter wheat. Southwestern Entomologist 30(2):113-120. Interpretive Summary: The nutritional quality of greenbugs reared on greenbug resistant wheat cultivars compared to susceptible cultivars to naturally occurring greenbug predators is important to know to assess the compatibility of host plant resistance and biological control as pest management tactics. Lady beetles are important predators of greenbugs, which could be adversely affected if greenbugs reared on greenbug resistant cultivars had reduced nutritional quality to the beetles compared to greenbugs reared on susceptible cultivars. We conducted laboratory tests to assess whether greenbugs reared on greenbug resistant and susceptible wheat cultivars differed in their suitability to larvae of a common lady beetle (Coccinella septempunctata) as food. No significant differences in survival or development of larvae were observed between wheat cultivars. Resistant cultivars differed slightly from susceptible ones in that adult lady beetles were slightly smaller than adults from susceptible cultivars. Overall, results of the study indicate that winter wheat cultivars incorporating the Amigo and Largo resistance genes would have little effect on the nutritional value of greenbugs to the lady beetles. Our results support the idea that host plant resistance to greenbugs and biological by lady beetles are compatible tactics in a pest management system.
Technical Abstract: Coccinella septempunctata L. (Coleoptera: Coccinellidae) larvae were supplied daily with 4 or 16 mg of Biotype-E Schizaphis graminum Rondani (Homoptera: Aphididae) reared on either resistant TAM-110 (TAM 105*4/Amigo*5//Largo), TAM-107 (TAM 105*4/Amigo), or the susceptible isoline TAM-105. No significant differences in survival ratios or developmental times were observed among C. septempunctata larvae supplied with increasing daily levels of greenbugs from each winter wheat cultivar. However, cultivar had a small but significant effect on adult dry weight; at the 16 mg daily prey level, individuals supplied with greenbugs reared on TAM-105 were greater than or equally to 2.5 mg heavier than those supplied with greenbugs reared on TAM-107 or TAM-110. Results from our study suggest that winter wheat cultivars incorporating Amigo and Largo resistance genes would have little effect on the nutritional value of S. graminum for C. septempunctata.