The Indian meal moth, Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae), is a very common stored-product pest. The mature larvae wander around searching for suitable places to pupate, offering an opportunity to control this pest. We evaluated the efficacy of 5 insecticide dusts: Alpine (0.25% dinotefuran, 95% diatomaceous earth [DE]), CimeXa (92.1% amorphous silica gel), DX13 (100% DE), Tempo (1% cyfluthrin), and Tri-Die (1% pyrethrin, 10% piperonyl butoxide, 40% amorphous silica) against P. interpunctella wandering larvae by allowing larvae to pass 1-inch treated band, expose to treated vinyl tiles for 5 min, and expose to treated harborage (with or without the presence of an untreated harborage). A commercially treated harborage product (Nattaro band) served as a positive control in the exposure to the treated harborage test. Tempo was significantly more effective than other insecticide dusts in the 1-inch band and forced exposure tests but caused only 44% and 54% larvae mortality in the 2 tests. In contrast, CimeXa, Tri-Die, and Tempo caused 84%-89% mortality when the larvae were provided with treated harborages. When both treated and untreated harborages were present, Tempo caused a significantly higher mortality and a lower percentage of emerged adults from larvae than Tri-Die, but not significantly more than CimeXa. Deploying Tempo or CimeXa-treated harborages and/or applying insecticide dust directly into the wall crevices, perimeters of the floor, shipping pallets, and other areas where P. interpunctella larvae hide could be an effective method for the management of the wandering stage of P. interpunctella larvae in storage facilities.

Insecticide dust formulations are considered as more effective for controlling the common bed bug, Cimex lectularius (L) (Hemiptera: Cimicidae), than residual sprays. Various environmental factors may affect the efficacy of insecticide dusts. In this study, we evaluated the effect of moisture on the efficacy of three insecticide dusts against C. lectularius. Moisture was created using two methods: applying steam to insecticide dust-treated tiles and aging insecticide dust-treated tiles in chambers with various levels of relative humidity (RH). In the steam treatment, three insecticides including Cimexa (92.1% amorphous silica gel), Alpine (0.25% dinotefuran, 95% diatomaceous earth), and Tempo (1% cyfluthrin) were evaluated. Exposure to steam significantly reduced the efficacy of all three insecticide dusts. Among the three insecticides, the efficacy of Cimexa was significantly higher than Alpine and Tempo. In the different RH treatments, Cimexa treated tiles that were aged under different (52, 75, and 100%) RH conditions for 1 and 2 mo caused significantly lower mortality to C. lectularius than nonaged Cimexa. We conclude that both, a short period of exposure to steam and long-period aging in a moist environment, can significantly reduce the efficacy of insecticide dusts. Moisture needs to be considered when applying insecticide dusts for controlling bed bug infestations.

Bed bugs have reemerged recently as a serious and growing problem not only in North America but in many parts of the world. These insects have become the most challenging pest to control in urban environments. Residual insecticides are the most common methods used for bed bug control; however, insecticide resistance limits the efficacy of treatments. Desiccant dusts have emerged as a good option to provide a better residual effect for bed bug control. Several studies have focused on determining the efficacy of dust-based insecticides against bed bugs. However, behavioral responses of bed bugs to insecticide dusts could influence their efficacy. The behavioral responses of bed bugs to six insecticide dusts commonly used in the United States were evaluated with an advanced video tracking technique (Ethovision). Bed bugs took longer to make first contact with areas treated with the diatomaceous earth (DE)-based products MotherEarth D and Alpine than pyrethroid, pyrethrins or silica gel based products, DeltaDust, Tempo 1% Dust and CimeXa, respectively. Lower visitation rates of bed bugs were recorded for areas treated with MotherEarth D, Alpine and CimeXa than that of DeltaDust, Tempo 1% Dust, and Tri-Die Silica + Pyrethrum Dust. Bed bugs spent less time in areas treated with Tri-Die Dust, CimeXa, Alpine, and MotherEarth D than DeltaDust and Tempo 1% Dust, and they exhibited a reduction in locomotor parameters when crawling on areas treated with CimeXa and Alpine. The implications of these responses to bed bug control are discussed.

Bed bugs, Cimex lectularius L., are one of the most difficult urban pests to control. Pest management professionals rely heavily on insecticide sprays and dusts to control bed bugs. Dust formulations are considered to provide longer residual control than sprays. However, there are no scientific data available on the comparative efficacy of the commonly used insecticide dusts. We evaluated the efficacy of eight insecticide dust products using three exposure methods: 1) brief exposure-bed bugs crossed a 2.54-cm-wide dust-treated band, 2) forced exposure-bed bugs were continuously exposed to a dust-treated substrate, and 3) choice exposure-bed bugs were given a choice to stay on either dust-treated or untreated substrate. The brief exposure method was the most sensitive in detecting the differences among the insecticides. Only CimeXa (silica gel) dust caused 100% mortality from all three exposure methods. Other tested dusts (1% cyfluthrin, 0.05% deltamethrin, 0.075% zeta-cypermethrin + 0.15% piperonyl butoxide, 1% pyrethrins, 1% 2-phenethyl propionate + 0.4% pyrethrin, 0.25% dinotefuran + 95% diatomaceous earth, 100% diatomaceous earth) caused ≤65% mortality in a brief exposure assay. We also evaluated the horizontal transfer effect of the silica gel dust. Silica gel dust-exposed bed bugs transferred the dust horizontally to unexposed bed bugs resulting in 100% mortality at 4:6 donor: recipient ratio and 88.0 ± 5.0% mortality at 1:5 donor: recipient ratio. The results suggest silica gel is the most promising insecticide dust for controlling C. lectularius.