Got worms? Biological control of a cranberry pest with entomopathogenic nematodes

The United States is the largest producer of cranberry in the world. Rising reports of the cranberry pest Systena frontalis (Coleoptera: Chrysomelidae) prevalence and plant damage make S. frontalis a serious pest of cranberry. The larvae are subterranean and present a good target for control as they are not highly mobile. Larval population differences between beds are unexplained and may relate to soil conditions. One promising biological control is entomopathogenic nematodes (EPNs) which kill larvae in partnership with internal symbiotic bacteria. EPNs are nonpolluting, and are safe for humans. The objectives of this study was to test the efficacy of EPNs at controlling S. frontalis in the field and compare beetle ovipositional preference for soil types in the lab. The field study used one square meter plots in a commercial cranberry bed. EPNs were applied into the soil when S. frontalis are larvae, and emergence cages were placed over each plot to contain and track adult emergence throughout the summer. Two objectives were assessed: 1) compare the efficacy of three species of commercially available EPNs (Heterorhabditis bacteriophora, Steinernema carpocapsae, and Steinernema feltiae) at reducing adult emergence and foliar injury; and 2) compare different timings of fewer number of applications of EPNs. In the lab field-collected adult beetles were allowed to oviposit in a no-choice test of sand, peat, sand above peat, or peat above sand. Depth and number of eggs per female were recorded. This study improves knowledge for integrated pest management of S. frontalis.