The stink bug assassins: Exploring biological control options using molecular techniques

Stink bugs (Hemiptera: Pentatomidae) have emerged as significant pests of cotton and soybeans in the southeastern United States with annual losses exceeding $70 million. Three of the most prominent pests are the southern green, Nezara viridula, brown, Euschistus servus and green stink bug, Chinavia hilaris. However, interactions with their predators are poorly understood, especially in respect to early season predation, which has the capacity to limit pest population growth. As field observation of predation is difficult, molecular gut content analysis offers an alternative to traditional approaches. Species-specific 16S molecular markers were designed and used to quantify the presence of prey DNA in predator gut contents and allow accurate estimates of predation efficiency to be calculated. Large numbers of predators were collected throughout the growing season in cotton and soybean in southeastern Georgia and predation frequency was examined relative to prey availability. Predation rates were significantly higher on N. viridula than on E. servus and C. hilaris, despite relatively similar availability of all prey resources. Our results showed that N. viridula was consumed primarily by the predators Coleomegilla maculata, Geocoris punctipes, Orius insidiosus and Notoxus monodon, with proportions screening position for stink-bug DNA as high as 40% during some months. These data suggest generalist predators could provide valuable biological control service targeting stink bugs, but additional research examining the spatio-temporal nature of predator-prey interactions is required to better understand the structure of such food webs relative to pest management.