Blister Beetles (Coleoptera: Meloidae) in Kansas Alfalfa: Influence of Plant Phenology and Proximity to Field Edge

Abstract

A 2-yr survey of blister beetles ( Epicauta spp.) infesting Kansas alfalfa ( Medicago Sativa L.) assessed the influence of in-field location, harvest cycle, and host phenological stage on insect density. Relative estimates of blister beetle densities were made, using a sweep net, along three in-field and one noncropped strata, oriented parallel to the field edge. Densities of beetles were very low during the first and fifth harvest cycles, suggesting that hay from these cuttings has lower cantharidin contamination risk and, therefore, requires minimal blister beetle management. Significant differences among strata were observed when blister beetles were summed over all phenological stages within second, third, and fourth harvest cycles. Blister beetle densities varied significantly among three in-field and one noncropped strata during vegetative, bud, and bloom phenological stages of the second harvest cycle and in bud and bloom stages of the third harvest cycle. Significantly lower numbers of blister beetles per field were observed in vegetative-stage than in bud- or bloom-stage alfalfa during harvest cycles two, three, and four. Blister beetles tended to occur with slightly to significantly greater frequency in alfalfa sampled 3 m into the field.