Monday, 15 November 2004 - 9:06 AM

Benefits of polyandry in the blue milkweed beetle, Chrysochus cobaltinus (Coleoptera: Chrysomelidae)

Steven K Schwartz, and Merrill A Peterson, Western Washington University, Biology Department, Bellingham, WA

There is growing evidence that females of many species mate with multiple males, a strategy termed polyandry. The benefits of such a strategy are many, and include enhanced reproductive success due to having more genetically diverse offspring, and also due to greater overall fecundity. Females of the leaf beetle, Chrysochus cobaltinus, are extremely polyandrous in nature. To assess the benefits of this behavior to females, we compared the reproductive success of females mated once with a single male (single), females mated multiple times with the same male (repetitive), and females mated multiple times with multiple males (multiple). We found that the females in the repetitive and multiple treatments enjoyed fecundity benefits from the multiple matings. Specifically, compared to singly-mated females, polyandrous females exhibited a significant increase in daily egg production and in the number of eggs produced per egg mass. There were no significant differences between the repetitive and multiple mating treatments, and longevity was the same across all treatments. These findings indicate that although there are fecundity benefits for females that mate multiple times there is no evidence that the identity of their mates influences those benefits.

Species 1: Coleoptera Chrysomelidae Chrysochus cobaltinus
Keywords: reproductive success, polyandry

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