Male and female mating strategies as they relate to the spermatheca in Melanoplus bivittatus (Orthoptera: Acrididae).

Abstract

Grasshoppers in the genus Melanoplus are known to transfer accessory reproductive gland proteins during mating, and these have been demonstrated to be incorporated in eggs. In this study, the mating strategies of males and females are explored as they relate to spermatophore transfer as a male-controlled resource. Three trials in which a female was caged with two males demonstrate that heavy males are more successful (a > .042) in initially mating with a female. Females do not appear to discriminate between males over the course of their lifetime, however. Males were shown to mate preferentially with virgin females and with females who have recently oviposited. From histological preparation of the spermathecae from interrupted matings, sperm can be found in all three of the chambers by five hours of mating, but in different forms. Sperm bundles remain intact in the long apical chamber, but are increasingly more degraded over time in the distal chamber. By 8.5 hours, half of the sperm bundles in the distal chamber are completely disassociated, and loose sperm becomes increasingly scarce as time progresses. Melanoplines do not oviposit immediately after mating, delaying an average of 4.7 days from mating to oviposition. This would suggest that a part of a male's sperm contribution, like the accessory gland proteins, is being used for nourishment. The role of sperm from secondary matings is discussed.