Prolonged copula duration in the parthenium beetle,Zygogramma bicolorata: an alternative male tactic to amplify sperm transfer,reproductive attributes,and paternity outcomes

Male traits are expected to evolve on the basis that they help maximize reproductive success. Prolonged copula duration is a commonly observed trait and this may sometimes be an adaptive male tactic that results in increased paternity against rival males. This study evaluated direct and indirect influences of prolonged copula duration on reproduction and offspring development in the parthenium beetle, Zygogramma bicolorata Pallister (Coleoptera: Chrysomelidae). Prolonged copula duration was correlated with a reduction in the time until oviposition and with increased fecundity in female beetles. Furthermore, extended copula duration was correlated with increased offspring survival and reduced offspring development times. Thus, there appear to be both direct and indirect benefits associated with prolonged copula in the parthenium beetle (i.e., increased adult reproductive performance and improved offspring fitness). Possible explanations for these reproductive benefits may be that a longer copula increases the availability of sperm for females and seminal fluid may boost maternal protein reserves which can then be invested in higher quality of offspring.