Comparison of the effects of neonicotinoids and pyrethroids against Oebalus pugnax (Hemiptera: Pentatomidae) in rice

Abstract

The rice stink bug, Oebalus pugnax (F.) (Hemiptera: Pentatomidae), is an economically important late-season pest of rice in the southern United States. Stink bug feeding results in yield reduction and discounted purchase price due to broken or discolored ("pecky") rice grains. The primary tactic for O. pugnax management is the application of insecticides once adults reach an action threshold. Recent surveys show that pyrethroids are preferred by southern U.S. rice farmers over all other insecticides to reduce O. pugnax densities. However, preliminary tests in 2009 suggested resistance to pyrethroids may be developing in an O. pugnax population in Texas, where applications are more frequent than in other rice-growing areas. This study compared the effects of pyrethroids and neonicotinoids on O. pugnax behavior and mortality in the laboratory and in a number of field experiments conducted between 2011 and 2014. Results from these experiments showed that control of O. pugnax given by the neonicotinoid, dinotefuran, was similar to that given by pyrethroids in the laboratory and field. Results from small-plot field studies were influenced by movement of adult rice stink bugs from surrounding untreated plots, and the data from commercial-scale trials and from sampling of nymphs in small plots may provide more useful information on the efficacies of insecticides. Two experiments provided limited evidence for longer residual activity of dinotefuran compared to the pyrethroid-cyhalothrin, and a laboratory study showed that both insecticides reduced feeding activity of rice stink bugs. Tests also confirmed the increased tolerance of a Texas population of rice stink bugs to-cyhalothrin, suggesting the need for insecticides with different modes of action in the O. pugnax management program.