Effects of male to female ratio and number of females per nesting tunnel on sex ratio and number of progeny of the alfalfa leafcutter bee Megachile rotundata (Hymenoptera: Megachilidae)


  • D. F. Mayer Department of Entomology Washington State University, IAREC Prosser, WA 99350


This paper reports the results of two 3-year studies on the effects of: 1) the ratio of males to females in the parental generation on percent female progeny; and 2) the ratio of females to nesting tunnels on percent female progeny. In study 1): there were no significant differences between treatments in percent females in the progeny or total number of nesting cells produced each year. The average percentages of females were 22% in 1990, 27% in 1991, and 28% in 1992. In study 2): there were significantly fewer female progeny with 2 females per tunnel in 1991, and in all years, significantly fewer progeny when the females were crowded. The total number of cells produced was inversely related to crowding with ratios of females per tunnel of 1:2, 1:1 and 2:1.

Key words: alfalfa leafcutter bee; Megachile rotundata; alfalfa seed