Insect Predators and Pests on Tobacco Following Applications of Systemic Insecticides

Abstract

Soil incorporated systemic insecticides applied to flue-cured tobacco were evaluated for their effects on beneficial insects. Tobacco treated with aldicarb, aldoxycarb, disulfoton 15G, and fosthietane had significantly fewer spined stilt bugs than the untreated checks during at least one of the 2 yr of the experiment. During 1977, the disulfoton 6EC and ethoprop treatments had as many or more stilt bugs than the check, while oxamyl had the most stilt bugs of the chemical treatments during 1978. There were serious outbreaks of the tobacco hornworm, Manduca sexta (L.), and the tomato hornworm, M. quinquemaculata (Haworth), in the aldoxycarb and aldicarb plots during 1977 and 1978 and in the disulfoton 15G plots during 1978. Stilt bug to hornworm ratios for aldicarb and aldoxycarb treatments were 14–25% of the untreated check during 1977 and 31 – 46% of the check during 1978. Carbofuran treated tobacco had stilt bug to hornworm ratios of 1.7 – 2.6 times higher than the check during 1977 and 2.6 – 49 times higher than the check during 1978. The high stilt bug to hornworm ratios in the carbofuran treatments were due to the excellent hornworm control. Geocoris spp., Nabis spp., and the convergent lady beetle, Hippodamia convergens Guerin-Meneville, were most abundant in the treatments with poor green peach aphid, Myzus persicae (Sulzer), control including oxamyl, ethoprop, and a1doxycarb broadcast.