The effect of floral intercropping on beneficial insects in cucumbers

Cucumbers (Cucumis sativus) are among the most widely grown vegetable crops in the North Central U.S., but they often face pollination and biological control deficits. Natural enemies and pollinators require resources that are typically not found in conventional agricultural fields. We hypothesized that pollinator and natural enemy abundance would increase in plots with flower strips added and that the effect would be greatest in the cucumber rows closest to the strips.  Four flower treatments were used: 1) cucumbers (control), 2) buckwheat (Fagopyrum esculentum), 3) yellow mustard, (Brassica hirta), or 4) sweet alyssum (Lobularia maritima). Flowers were planted in a commercial cucumber field in a randomized complete block design with six replications in 2015. Natural enemies were collected on sticky traps placed in the center of floral and cropped areas. Pollinator observation occurred within the flower strips and in cucumber rows at 1.5, 5, and 10m away from the flower strips. The number and identity of all pollinators observed over a 10-minute sampling period per transect were recorded. Floral strips were also sampled by sweep net. Data were analyzed with generalized linear mixed models. Natural enemies and pollinators were significantly more abundant in flower strips than in cucumbers. Our results suggest that while within-field flower strips may support beneficial insects, natural enemies and pollinators do not significantly disperse from insectary plants to cropped areas in this system.