Egg load dynamics and the risk of egg and time limitation experienced by an aphid parasitoid in the field Christine Dieckhoff1, Julian C. Theobald2, Felix L. Wackers€ 2 & George E. Heimpel3 1Department of Entomology & Wildlife Ecology, University of Delaware, Newark, Delaware 19716 2Lancaster Environment Centre, Centre for Sustainable Agriculture, Lancaster University, Lancaster, LA1 4YQ, UK 3Department of Entomology, University of Minnesota, St Paul, Minnesota 55108 Keywords Abstract Aphis glycines, Binodoxys communis, biological control, egg load, soybean aphid. Insect parasitoids and herbivores must balance the risk of egg limitation and time limitation in order to maximize reproductive success. Egg and time limita- Correspondence tion are mediated by oviposition and egg maturation rates as well as by starva- C. Dieckhoff, University of Delaware, tion risk and other determinants of adult lifespan. Here, we assessed egg load Entomology & Wildlife Ecology, 250 and nutritional state in the soybean aphid parasitoid Binodoxys communis under Townsend Hall, Newark, DE 19716, USA. field conditions to estimate its risk of becoming either egg- or time-limited. Tel: 302-731-7330 (ext 222); The majority of female B. communis showed no signs of egg limitation. Experi- Fax: 302-368-1674; E-mail:
[email protected] mental field manipulations of B. communis females suggested that an average of 4–8 eggs were matured per hour over the course of a day. Regardless, egg loads Funding information remained constant over the course of the day at approximately 80 eggs, suggest- This research was funded through a USDA- ing that egg maturation compensates for oviposition. This is the first case of NRI grant to G.