Effects of Chilling, Humidity and Seasonal Conditions on Emergence of the Alfalfa Leafcutting Bee12

Alternation of Sex Ratio in a Partially Bivoltine Bee, Megachile rotundata (Hymenoptera: Megachilidae)

“…All comparisons between numbers of emerging and diapausing males and females by week were significant (X 2 tests, all P ~ 0.001) except for the 17-20 July collection dates (P > 0.25). The overall pattern of increasing percentage of offspring entering diapause with season has been reported previously (Krunic 1972, Johansen & Eves 1973, Parker 1985.…”

“…S is also influenced by developmental rates and emergence curves of spring and summer generations; these, in turn, are critically influenced by temperature (Stephen & Osgood 1965, Krunic & Rinks 1972, Johansen & Eves 1973, Tasei 1975, Rank & Goerzen 1982, Richards 1984. Thus, it is possible that subtle differences in the temperatures at which immatures were stored and reared among the three studies used to construct Fig.…”

“…Second, emerging bees destroy some of their nonemergent siblings when they leave the nest (Tepedino & Frohlich 1984). Although some workers report success in reducing secondgeneration emergence in Canada through appropriate temperature treatments of immature stages (Richards 1984), others find voltinism of immatures unresponsive to temperature or photoperiodic treatments (Johansen & Eves 1973, Tasei 1975, Bitner 1976, Tasei & Masure 1978, Parker & Tepedino 1982, Tepedino & Parker 1986). Present evidence suggests that diapause is maternally controlled.…”

Characterization of triacylglycerols from overwintering prepupae of the alfalfa pollinator Megachile rotundata (Hymenoptera: Megachilidae)

“…rotundata with alfalfa bloom (Johansen and Eves, 1973;Taséi and Masure, 1978;Richards et al, 1987;Richards and Whitfield, 1988;Murrell, 1991;Kemp and Bosch, 2000). At most North American latitudes, M. rotundata emerge and mate during June and July, and female bees build nests in abandoned beetle burrows in timber, in cavities associated with farm buildings, or artificial nesting materials provided by alfalfa seed producers (Stephen, 1981;Rank and Goerzen, 1982;Richards, 1984).…”

“…Other evidence that prepupal dormancy in M. rotundata is diapause-mediated comes from empirical results showing that prepupae artificially wintered for insufficiently long periods take much longer to resume development after being exposed to incubation temperatures (Johansen and Eves, 1973;Taséi and Masure, 1978;Richards et al, 1987). Other studies have addressed glycerol production and supercooling points in M. rotundata prepupae (Gusta, 1982;Krunic et al, 1982).…”