Abstract:
BACKGROUND: Gonipterus platensis Marelli, 1926 (Coleoptera: Curculionidae) is one
of the main defoliating beetles in Eucalyptus plantations. Biological control with egg
parasitoids is one of the main control strategies for this pest and a constant supply of
fresh host eggs is required to rear the parasitoids. Polyandry can influence Gonipterus
oviposition by increasing female fecundity and fertility; however, the high density of
individuals in laboratory colonies can lead to male harassment, resulting in lower
reproduction rate. The aim of this study was to measure the effects of monoandry
and polyandry on the reproduction of G. platensis and the effects of male harassment
on laboratory rearing conditions.
METHODS: Reproductive parameters were compared between three treatments:
monoandry, where the female was allowed to mate daily with the same male; no
choice polyandry, where the female was allowed to mate daily with a different male;
and polyandry with choice, where the female was allowed to mate daily, but with a
choice between five different males. Another experiment varying the density of males
was conducted to evaluate the effect of male harassment.
RESULTS: Polyandry with choice resulted in the longest period of oviposition, highest
fecundity and highest number of eggs per egg capsules when compared to
monoandrous females. No negative effect related to male harassment in the
laboratory, such as decreased fertility, fecundity, or number of eggs per egg capsule,
was detected.
CONCLUSION: Polyandry contributes to mass rearing as it increases fecundity and
oviposition period on females and there is no evidence of male harassment on
G. platensis.
