No abstract

Larvae of the tobacco hornworm, Manduca sexta, respond to intrahemocoelic injection of bacteria or bacterial cell wall peptidoglycan with induced synthesis of a suite of antibacterial proteins. Previous studies have demonstrated peptidoglycan regulation of the synthesis of these antibacterial proteins. In addition to eliciting enhanced synthesis of antibacterial proteins, peptidoglycan fragments also elicit a "malaise syndrome" characterized by decreased feeding and growth, delayed metamorphosis, and altered excretion. We speculate that these symptoms may be components of a mechanism to flush out and sterilize the midgut lumen, one of the primary sources of bacterial infection in insects. Studies of naive larvae have demonstrated the accumulation of lysozyme in the differentiating pupal midgut epithelium and release of lysozyme into the pupal midgut lumen after the larval midgut epithelium has been sloughed off. These observations have been extended by the identification of potent bactericidal activity against E. coli and immunoreactive hemolin, together with lysozyme, in the lumen of the newly differentiated pupal midgut.

Field tests determined the relative efficacy and residual life of six spray treatments: 0.1% Tempo EC (TEC); 0.1% Tempo EW (TEW); 0.2% permethrin, 0.2% pyrethrins, and 0.5% piperonyl butoxide (PPPB); 0.1% cyfluthrin, 0.05% pyrethrins, 1.0% Baygon, 1.0% piperonyl butoxide (CPBPB); 1.0% Baygon (B); and 0.1% pyrethrins, 0.4% tetramethrin, and 0.15% cypermethrin (PTC). The Dorie Miller Homes, Dorie Miller Homes East, Ivanhoe Gardens, Duneland Village, and Concord Village, multi-family public housing complexes located in Gary, Indiana, served as the test sites; individual apartments served as the replicated experimental unit. PPPB, CPBPB, B, and PTC treatments were made with self-pressurized aerosol cans containing formulated active ingredients. The other treatments were applied using 3.8 liter compressed air sprayers equipped with Multee-jet nozzles. Due to the high cockroach populations and poor sanitation, a general “clean-out” procedure was followed. All accessible harborages throughout the apartment were treated. After 4 wk, all apartments received a second treatment. Population levels were estimated by visual counts throughout the kitchen and bathroom areas, and a minimum pretreatment count of 20 cockroaches was required for any apartment to be considered as a test. Each treatment was replicated in 10-15 apartments, but posttreatment counts varied due to apartment vacancy or lack of resident cooperation. To determine insecticidal efficacy, posttreatment visual counts were reduced to percentage of reductions of the pretreatment counts. Some counts were terminated after 10 wks. Prior to statistical analysis, percentage of reduction data were transformed to ranks. These were analyzed with ANOVA models, followed by the Fisher’s protected least significant difference (P = 0.05) to determine significance among the treatments at each posttreatment census.

Laboratory tests determined the contact activity and residual persistence of formulations of 3 cyano-pyrethroids. Test 1 evaluated cyfluthrin formulations: Tempo 20WP (0.05%), Temp 2EW (0.05%), and FCR-4545 10WP (0.025%) applied to tempered masonite panels. Test 2 evaluated deltamethrin 5SC (0.06%) and 2 formulations of cypermethrin: Demon 25.3% EC (0.1%) and Demon 40% WP (0.1%), applied to tempered masonite and stainless steel panels. In both tests, sprays were applied to 225 cm2 panels at the rate of 3.8 ml/900 cm2 using a mechanized spray tower apparatus equipped with a stainless steel nozzle tip (TeeJet 8001E), at a constant 25 psi. Treated panels were allowed to dry horizontally and then stored in vertical racks in a greenhouse (high temperatures and exposed to sunlight) for residual aging. At the appropriate aging period, insects were confined to the treated panel in a 12.7-cm diam Plexiglas ring lightly greased with a mixture of petrolatum and mineral oil. Three exposure times were evaluated (range: 10 s to 60 min) at each aging period. Following exposure, insects were transferred to 1 pt holding jars and mortality was recorded 48 h after exposure. Six replicates of 10 adult male cockroaches (<2 wk old) were conducted for each exposure time, at each aging period, for each insecticide treatment. Experiments were conducted as a completely randomized design; mortality data were subjected to ANOVA followed by Fisher’s Protected LSD multiple t-test (P = 0.05).

Laboratory tests determined the contact activity and residual persistence of three chlorpyrifos formulations on tempered masonite and stainless steel panels. Test 1 (1992) evaluated Dursban LO with FN-5354, while Test 2 (1993) evaluated Dursban LO with NAF-53. In both tests, spray dilutions (0.25 or 0.5% AI) were applied at 1 of 2 rates (0.25 or 0.5%) at 3.8ml/900 cm2 using a mechanized spray tower apparatus equipped with a stainless steel nozzle tip (TeeJet 8001E), at a constant 25 psi. Treated panels were allowed to dry horizontally and then stored in vertical racks in a laboratory (constant temperatures and dark conditions) for residual aging. At the appropriate aging period, insects were confined to the treated panel in a 12.7-cm diam Plexiglas ring lightly greased with a mixture of petrolatum and mineral oil. Four exposure times were evaluated (2, 4, 8, and 16 h) at each aging period (1, 7, and 21 d). Following exposure, insects were transferred to 1 pt holding jars and mortality was recorded 48 h after exposure. Six (or 4 in test 2) replicates of 10 adult male cockroaches (<2 wk old) were used for each exposure time, at each aging period, for each insecticide treatment. For each aging period, the experiment was conducted as a completely randomized design with factorial arrangement of treatments. Analysis of percentage mortality among treatment combinations was conducted independently for each aging period and exposure time period independently; data were subjected to ANOVA (P = 0.05).