Effect of crowding, food deprivation, and diet on flight initiation and lipid reserves of the lesser grain borer, Rhyzopertha dominica

Effects of crowding, food deprivation, and type of cereal diet upon flight initiation, development, body weight, lipid content, and fatty acid composi tion of the lesser grain borer, Rhyzopertha dominica (F.), were studied in two field strains and one laboratory strain. Beetles of all strains reared under crowded conditions had significantly higher flight initiation than be etles reared on isolated kernels (uncrowded). Regardless of degree of crowd ing, flight initiation increased with the period of food deprivation up to a maximum at 24 h, after which flight initiation declined. Body weight and lipid content decreased as the food deprivation period increased, whereas f atty acid composition was not significantly affected by food deprivation. B eetles from a field strain collected in 1995 had higher flight initiation a nd increased lipid content compared with beetles from the laboratory strain . However, beetles from the laboratory strain were larger, developed faster , and were more fecund than beetles from this field strain. The cereal diet on which beetles were reared also had a significant effect on flight initi ation, lipid content, and fatty acid composition. Beetles reared on whole r ice and wheat produced adults with higher flight initiation, higher lipid c ontent, and higher oleic acid concentration than beetles reared on whole co rn and sorghum.