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Investigations into mating disruption, delayed mating, and multiple mating in oriental beetle, Anomala orientalis (Waterhouse), Coleoptera: Scarabaeidae
Oriental beetle, Anomala orientalis (Coleoptera: Scarabaeidae) is a pest of turf, ornamentals, and several crops, including cranberry; damage is caused by larval feeding on plant roots. Imidacloprid---the only new pesticide registered against scarabs in cranberry since the ban on organochlorines in the 1970s---is expensive and relatively ineffective against later instar larvae. I evaluated the potential management of oriental beetle in cranberry by mating disruption using female sex pheromone deployed from wax disks. I found strong trap shutdown in mating disruption treatments. Because attempts to disrupt mating may be compromised if males eventually find females, I studied the effects of delayed mating on female reproductive output in the lab. Females were relatively resilient to mating delay, exhibiting only a gradual decline in fecundity with increased age at mating. Thus, in order for mating disruption to be a successful management tool, mating must be prevented rather than delayed. I deployed tethered virgin females deployed in the field and found that mating is indeed largely prevented in pheromone-treated bogs. These results demonstrate the strong potential of mating disruption for management of oriental beetle in cranberry. ^ I also studied relative fertilization success between males in successive matings of the same female. Characters of the first male to mate---including male body size and genitalia morphology---had primacy in influencing relative paternity, an uncommon pattern in sperm precedence studies. Surprisingly, relative paternity of the first male was inversely correlated with his size. Because this result is at odds with the general positive relationship between male size and reproductive success in insects, I hypothesized that larger males experience greater lifetime reproductive success when mating multiply. I then examined how male size and mating history impacted reproduction. Only for smaller males was reproductive output reduced in successive matings. These results suggest that after their first mating, smaller males must either compete using a lower quality ejaculate or submit to a longer refractory period to replenish ejaculate reserves. Thus, the sexually selected advantage of smaller males in their first mating is apparently balanced by lower lifetime reproductive potential relative to larger males. ^
Erik J Wenninger,
"Investigations into mating disruption, delayed mating, and multiple mating in oriental beetle, Anomala orientalis (Waterhouse), Coleoptera: Scarabaeidae"
(January 1, 2005).
Electronic Doctoral Dissertations for UMass Amherst.