Sex ratio effects on copulation, fecundity and progeny fitness for Agasicles hygrophila, a biological control agent of alligator weed

Abstract

Determining the best ratio of females to males of an insect's natural enemy is important for maximising population increase and promoting population establishment of a natural enemy. In this study, copulation behaviour, fecundity, progeny fitness and rate of population increase for the flea beetle, Agasicles hygrophila Selman & Vogt (Coleoptera: Chrysomelidae), were compared at different female percentage treatments (i.e., 80%, 66.7%, 50%, 33.3% and 20% females). The results showed that the copulation frequency and duration in males decreased, whereas those in females increased as the number of males increased. At 20%, 33.3% and 66.7% females, the rates of population increase were 3.4-, 2.17- and 0.79-fold higher than that at 50% females. Females at 20% and 33.3% were found to be optimal for mass rearing of the beetle.

Keywords:

• Agasicles hygrophila
• Alternanthera philoxeroides
• sex ratio
• copulation
• fecundity
• rate of population increase

Acknowledgements

We are very grateful to Prof. Mark S. Goettel, editor-in-chief of Biocontrol Science and Technology for editing the English of the manuscript and thank two anonymous reviewers whose appropriate commentary strengthened the manuscript. We thank Elsevier Webshop (Order No. 37730) for editing the language of the manuscript. We thank Mr. Yan Li and Ms. Yan-Ping Lu (Fujian Agriculture and Forestry University, Fuzhou, China) for their help during the experiment.

Funding

This work was funded by the National Science Foundation of China [grant number 31272107]; National Basic Research and Development Program of China [grant number 2009CB119200].

Additional information

Funding

Funding: This work was funded by the National Science Foundation of China [grant number 31272107]; National Basic Research and Development Program of China [grant number 2009CB119200].