Providing evidence to improve practice

Individual study: No-tillage farming increases abundance of wild bees on squash and pumpkin farms in Maryland, Virginia and West Virginia, eastern USA

Published source details

Shuler R.E., Roulston T.H. & Farris G.E. (2005) Farming practices influence wild pollinator populations on squash and pumpkin. Journal of Economic Entomology, 98, 790-795


Squash and pumpkin Cucurbita spp. are valuable crops requiring pollination by insects. In the USA, they are commonly visited by the wild squash bee, Peponapis pruinosa, a specialised feeder on plants of the genus Cucurbita. This bee depends on farmed crops in the eastern US (where there are no wild Cucurbita species). Females nest in the soil near squash plants. This study examined the effects of tillage and pesticide use on squash bee populations in the states of Maryland, Virginia and West Virginia (eastern USA).


Twenty-five farms with large squash or pumpkin plantings (from <0.5 to 40 ha) were selected. Twelve had no pesticides applied, 13 had one or more pesticides applied.

Bees visiting pumpkin flowers were identified and counted at each farm on a slow walk along rows, taken from 07:30 and 09:00 h on one day between 7 July and 5 August 2003.



Farms that practised no-tillage agriculture had significantly more squash bees, with an average of around 0.7 squash bees per flower on untilled farms, compared to 0.2 squash bees per flower on tilled farms.
Squash bee population density was not related to pesticide use (the types and quantities of pesticides were not recorded).
Honey bee Apis spp. and bumblebee Bombus spp. numbers were not significantly related to pesticide use or tillage.
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