Oviposition of potato tuber moth, Phthorimaea operculella Zell. (Lepidoptera: Gelechiidae); the influence of adult food, pupal weight, and host-plant tissue on fecundity

Abstract

Starved potato tuber moths laid only slightly more eggs (mean 83.8 ± S.E. 3.8) than the complement of fully developed eggs present in the ovaries at eclosion from the pupa (68.7 ± 4.1). Provision of water resulted in almost a doubling of eggs laid (155.4 ± 7.7). Provision of 5% sucrose solution did not significantly increase fecundity further. Life span was increased significantly (P < 0.01) when moths were provided with water compared to those starved, and was further increased by the provision of 5% sucrose. With starved moths and those provided with water only, fecundity was positively correlated with pupal weight (r = 0.334–0.501), but moths provided with sugar solution showed such correlation only if potato peel was present. Continued presence of whole potato tubers increased fecundity by 40–100% and accelerated the rate of egg deposition, particularly when additional oviposition sites were provided. The stimulus appears to be primarily one of odour, but may be enhanced by contact with the tuber surface. These effects were not produced with isolated portions of potato peel.