Megachile rotundata

Megachile rotundata
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Megachilidae
Subfamily:	Megachilinae
Tribe:	Megachilini
Genus:	Megachile
Subgenus:	Eutricharaea
Species:	M. rotundata
Binomial name
Megachile rotundata (Fabricius, 1787)

Megachile rotundata, the alfalfa leafcutter bee or lucerne leafcutter bee^[1] is a European bee that has been introduced to other regions. As a solitary bee species, it does not build colonies or store honey, but is a very efficient pollinator of alfalfa, carrots and some other vegetables.

In North America the species was deliberately imported to assist in the pollination of food crops, but has now become feral and widespread.^[2] In New Zealand and Australia it was also introduced to assist in the pollination of alfalfa (known locally as lucerne), in 1971 in New Zealand,^[3][4] and 1987 in Australia.^[5][6]

Megachile rotundata pollinator on alfalfa flower

Female alfalfa leafcutter bees have stingers, but both sexes will use their mandibles as a defensive mechanism, usually only defending themselves when squeezed or antagonized. Therefore bee suits, such as those required with honey bees, are not necessary when dealing with these bees. The ratio of males to females is generally one to one.

Females in the wild create nests in small holes in the ground or in available cracks/crevices in trees or buildings. The nests are composed of a string of individual cells, as many as the space will allow. When managed for pollination, the females are induced to nest in drinking straws or drilled blocks of wood.^[2]

Each cell is made from circular disks cut from plant leaves using the bee's mandibles, hence the name "Leafcutter". While the bees do not store honey, females do collect pollen which they store in the cells of their nests. Each cell contains one pollen ball and one egg.^[2] The larva develops rapidly, consuming the pollen ball and entering diapause when the pollen is fully consumed. The next spring, the mature larva pupates and completes its development. Once the bee is developed it cuts its way out from the nest. The incubation period is approximately 30 days and requires a constant temperature of greater than 30°C (86°F).

References

1. ^ "Megachile rotundata (Fabricius)". Australian Insect Common Names. CSIRO. 19 September 2004. http://www.ento.csiro.au/aicn/name_s/b_2468.htm. Retrieved 2009-07-14. 
2. ^ ^{a b c} Milius, Susan (January 6 2007). "Most Bees Live Alone: No hives, no honey, but maybe help for crops". Science News 171 (1): 11–3. doi:10.1002/scin.2007.5591710110. 
3. ^ "Introduced Bees in New Zealand", New Zealand Entomologist Vol 33: 92-101 (February 2010)
4. ^ "Selection and importation of new pollinators to New Zealand", B. J. Donovan, DSIR Plant Protection
5. ^ "There have been several importations of the alfalfa leafcutting bee, beginning in 1987...", Australian Honey Industry Monthly Review, January 2001
6. ^ "Introducing the Alfalfa Leafcutting Bee..."

External links

• Effectiveness of the Alfalfa Leafcutter Bee as a pollinator of legume forage crops (ISHS membership required)
• How To Manage alfalfa Leafcutting Bees for Wild Blueberry Pollination