ARTHROPOD BIOLOGY Effect of Diet and Mating on Oviposition in the Twospotted Stink Bug Perillus bioculatus (F.) (Heteroptera: Pentatomidae)

Control females of the twospotted stink bug, Perillus bioculatus (F.), and those given an artiÞcial diet mated repeatedly over their lifetimes when held with males. The average number of observed matings was 4 and 8.4 in the controls and those given the artiÞcial diet, respectively. Mating and an adequate diet are prerequisites for laying a full compliment of eggs in this insect. Virgins laid an average of 22 eggs compared with 138 in the multiply mated controls, 84 in singly mated females and 42 in multiply mated females given an artiÞcial diet. The number of clutches deposited was not signiÞcantly affected by treatment, but the number of eggs per clutch was signiÞcantly lower in virgins and those given the artiÞcial diet than in the controls or once mated females. The number of eggs per clutch showed no signiÞcant changes as the female aged. Oviposition rates were calculated over 5-d periods for each female and presented as eggs per day. In all experimental groups the number of eggs deposited per interval decreased as the females aged. By 27.5 d after the start of oviposition, females from all treatments laid one or fewer eggs per day. The decrease in eggs per day deposited by females as they aged is attributed to an increase in the time betweenclutchdeposition.Eggviability showedno signiÞcantdifferences among themultiplymated controls, once mated females, or the multiply mated females given the artiÞcial diet. This suggests thatmultiplemating is not required tomaintain egg viability, but is necessary tomaintain oviposition over the lifetime of the female. Low numbers of eggs oviposited by females given the artiÞcial diet is attributed to theproduction of fewermature follicles than in the controls andnot to an impairment of the process of oviposition. In contrast, the lower number of eggs laid by virgin females results from an impairment of the oviposition process and not the impairment of ovarian follicle maturation.