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Thesis (Ph. D.)--University of Chicago. / Extracted from the Journal of the Linnean society of London, Zoology, vol. XXX (1908): p. 157-184, plates 23-26. Includes bibliographical references (p. 181-183). Also available on the Internet.

In 1980-81, teneral and fully melanized adult flea beetles were monitored with water traps. Phyllotreta cruciferae, P. striolata and Psylliodes punctulata are univoltine in southwestern Quebec. Their spatial distributions were estimated by D-Vac('(REGTM)) sampling in rutabaga and cabbage an the proportions of flea beetle species varied in time and space. Dispersal studies, using interception traps coupled with statistics of directional data, showed four immigrations to and seven emigrations from a rutabaga field. P. cruciferae was more attracted to allyl isothiocyanate than P. striolata, whereas the behavior of Ps. punctulata was not affected. Sex ratio estimations were affected accordingly. The color white significantly attracted more flea beetles than yellow, green and red. Overwintered adult flea beetles were more prevalent on later sown rutabaga, and the species proportions were slightly affected by the sowing date. Flea beetle infestations were simulated by punching out holes in cabbage seedlings.

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Understanding the factors influencing mate choice is a major focus of sexual selection. Many factors are potentially involved, including age of the individual. The good genes model and the youth advantage model both make predictions about the effect of age on mate choice. Under the good genes model older mates would be the more preferable due to their proven high survivability. The “youth advantage” model, predicts that young to intermediate age males would be more advantageous as mates because of a decrease in sperm quality and the possibility of increased germ-line mutations in older animals. I examined the effects of age on behavioral and physiological factors in Diaprepes abbreviatus experimentally. Both males and females were found to be the least optimal as mates during the intermediate stage of their lives, with preferences for young and old age classes. Females had higher fertilization rates when young and fertilization steadily declined with age, consistent with the youth advantage model. Males overall had higher fertilization rate and procured matings faster when they were older, which was in accordance with the good genes model, though experience could also play a role in this result. These data here suggest that in D. abbreviatus age may play an important role in mate choice decisions.

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