Pii: S0022-474x(98)00044-7

E€ects of geographical origin of strain, season of ®eld collection, genetic background, and number of generations of laboratory rearing on ̄ight initiation, body weight, and lipid content of lesser grain borer, Rhyzopertha dominica, were studied. Signi®cant di€erences in ̄ight initiation, body weight, and total lipid content occurred among the four ®eld strains collected from Kansas, Oklahoma, Texas, and Mexico. Flight activity tended to be higher for strains with higher average body weight. Oleic, palmitic, and linoleic acids accounted for about 95% of all fatty acids present in the strains tested. However, the percentage of lipids per fresh body weight was not signi®cantly di€erent among these four ®eld strains. Beetles collected in summer tended to ̄y more and have a higher percentage of lipid content than beetles collected in spring and autumn. Results from crosses between strains with high and low ̄ight responses suggested that the female contributes a higher proportion of additive genetic variance for ̄ight initiation than the male. Rearing for 17 generations in laboratory conditions had no discernible e€ect on ̄ight initiation of a strain of R. dominica collected from the ®eld. Thus, ̄ight behavior can persist for many generations of laboratory rearing. # 1999 Published by Elsevier Science Ltd. All rights reserved.