Polyandry contributes to Gonipterus platensis (Coleoptera: Curculionidae) rearing

Gonipterus platensis (Coleoptera: Curculionidae) is one of the main defoliating beetles in Eucalyptus plantations worldwide and biological control with egg parasitoids has been widely used as a control strategy. To rear these parasitoids a constant supply of G. platensis eggs is necessary and thus it is important to understand the factors that influence the reproduction of G. platensis in rearing. Polyandry behavior, when a female mates with more than one male, can influence G. platensis oviposition by increasing female fecundity and fertility. However, the high density of individuals in laboratory colonies (that favors polyandry) can lead to male harassment, resulting in negative effects such as lower reproduction rate. The aim of this study was to measure the effects of monogamy / polyandry and male harassment on the reproduction of G. platensis in laboratory rearing conditions. The experiment was conducted with one month old adults divided according to the treatments: monogamy, no choice polyandry, and polyandry with choice. Reproductive parameters were evaluated for seven months. Another simultaneous experiment varying the density of males (none, one and two males per treatment) was conducted to evaluate negative effects associated with male harassment. Polyandry with choice resulted in the longest period of oviposition, and highest fecundity and number of eggs per egg capsule when compared to monogamous females. No negative influences related to male harassment in the laboratory, such as decreased fertility, fecundity or number of eggs per egg capsule, were detected. In 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.