Patch Assessment for Oviposition by a Predator: the Effect of Prey Density and Prey Oviposition Period
Density dependent numerical response is considered advantageous for biocontrol agents. Although density dependent behaviors have been examined in aphidophagous ladybirds, they haven’t been studied for coccidophagous ladybirds. The relationship of prey density and prey oviposition stage on the aggregating behavior and oviposition of the coccidophagous predator Nephus includens (Coleoptera: Coccinellidae) was empirically investigated. In a semi-field experiment potted citrus trees were artificially infested with Planococcus citri (Hemiptera: Pseudococcidae) prey in order to obtain two densities, one mealybug and ten mealybugs per tree. Released N. includens adults were found to aggregate at citrus trees with high prey density. In a subsequent laboratory experiment four prey densities of P. citri were used ranging from 1 to 8 adult mealybugs at 3 ovipositional stages, a) at the young gravid female stage, b) at mid oviposition (half of egg load oviposited) and c) at the end of the ovipositional period (full egg load oviposited). Nephus includens females increased their oviposition rate as prey density increased and as prey oviposition progressed. It is hypothesized that this behavior of the predator might be advantageous for offspring survival and the efficacy of N. includens as a biological control agent against mealybugs.
KeywordsColeoptera coccinellidae pseudococcidae Nephus includens oviposition
This work was conducted with the financial support from the General Secretariat of Research and Technology of the Greek Ministry of Research under a bilateral cooperation for research of Greece and France (GSRT 228 e). We would like to thank two anonymous reviewers for their helpful comments that greatly improved the manuscript.
- Dixon AFG (2000) Insect predator–prey dynamics: ladybird beetles and biological control. Cambridge University Press, CambridgeGoogle Scholar
- Evans EW, Youssef NN (1992) Numerical responses of aphid predators to varying prey density among Utah alfalfa fields. J Kansas Entomol Soc 65:30–38Google Scholar
- Kareiva P (1990) The spatial dimension in pest-enemy interactions. In: Mackauer M, Ehler L, Roland J (eds) Critical issues in biological control. Hants, Andover, pp 213–217Google Scholar
- Katsoyannos P (1996) Integrated insect pest management for citrus in northern Mediterranean countries. Benaki Phytopathological Institute, AthensGoogle Scholar
- Kindlmann P, Dixon AFG (1993) Optimal foraging in ladybird beetles (Coleoptera: Coccinellidae) and its consequences for their use in biological control. Eur J Entomol 90:443–450Google Scholar
- Kontodimas DC, Eliopoulos PA, Stathas GJ, Economou LP (2004) Comparative temperature-dependent development of Nephus includens (kirsch) and Nephus bisignatus (boheman) (coleoptera: coccinellidae) preying on Planococcus citri (risso) (homoptera: pseudococcidae): evaluation of a linear and various nonlinear models using specific criteria. Environ Entomol 33:1–11CrossRefGoogle Scholar
- Magro A, Araujo J, Hemptinne JL (1999) Coccinellids (Coleoptera: Coccinellidae) in citrus groves in Portugal: listing and analysis of geographical distribution. Bol San Veg Plagas 25:335–345Google Scholar
- Sokal RR, Rohlf FJ (2012) Biometry: the principles and practice of statistics in biological research, 4th edn. W. H. Freeman and Co., New YorkGoogle Scholar
- Walton VM, Pringle KL (2005) Developmental biology of vine mealybug, Planococcus ficus (Signoret) (Homoptera: Pseudococcidae), and its parasitoid Coccidoxenoides perminutus (Timberlake) (Hymenoptera: Encyrtidae). Afr Entomol 13:143–147Google Scholar