LAYING SEQUENCE, DIPLOID MALES, AND NEST USURPATION IN THE LEAFCUTTERBEE, MEGACHILE-ROTUNDATA (HYMENOPTERA, MEGACHILIDAE)

Variations from the normal female-male sequence of eggs in nests of th e leaf-cutter bee, Megachile rotundata, were examined. Three alternati ves were considered: Out-of-sequence males (i) were diploids, (ii) wer e the result of supersedure of nests or intraspecific brood parasitism , or (iii) were the result of females occasionally laying a male-femal e sequence. Electrophoretic data provided definitive evidence of diplo id males and of multiple females laying in 7 of 18 nests. In the other s, the remaining explanation is that females occasionally lay male egg s before female eggs in a nest.