Abstract The efficacy of pheromone traps is affected by trap placement and pest biology, as well as by the trap and lure design. We evaluated the effect of trap height and placement in relation to surfaces on tobacco moth catches using release-capture experiments. Six traps were mounted vertically in a 9 × 15 × 4.2-5.8 m shed on a wall at heights of 0, 1, 2, 3, 4 and 5 m. More catches were obtained near the ceiling and at 1 m above the floor in the dark. Catches at 1 m were negligible when light shone through the upper windows. In a 42.3 × 36.5 × 4 m tobacco warehouse, the respective efficacies of aerially suspended traps and surface-mounted traps were examined. The number of catches obtained using traps mounted on pillars was significantly higher than that obtained in traps suspended from poles. These results suggest practical considerations for monitoring in warehouses. We recommend eliminating any night lighting and placing traps on surfaces, such as walls and stored commodities, at higher positions that are within reach (1 m) to facilitate convenient inspection.
In a previous study, we developed an accurate and laborsaving method to determine the effective phosphine concentration for the fumigation of cigarette beetles based on the knockdown time. To successfully control beetles with phosphine, it is important to evaluate the resistance level of the target beetle population in advance. However, the population often contains males and females, mated and unmated, and adult beetles of different ages, and the effects of these factors on the knockdown time were unclear. In the present study, we investigated the effects of sex, mating status, adult age, and prior exposure to phosphine in the pupal stage on the knockdown time using a phosphine-resistant strain IWT. The log KT50 value of the strain IWT was ca. 3.5 regardless of sex, experience of mating, adult age and experience of prior exposure, demonstrating that these factors are not important in evaluating the resistance level using knockdown time. The recommended phosphine concentration for the strain IWT was ca. 450–530 ppm, while the recommended concentration for a susceptible strain TSC was ca. 35 ppm.
Herbivory by the death's head hawkmoth, Acherontia lachesis (F.) (Lepidoptera: Sphingidae), on tobacco was recorded in Oyama, Tochigi Prefecture. The larvae attacked leaves in the lower to middle portion of the plants. They consumed a large area of leaf except the mid-rib. Typically, one larva consumed several leaves from a few adjacent plants. Observation in a 570 m2 tobacco field (1,110 plants; var. Tsukuba 1), where no pesticides had been applied since transplanting, revealed that 80 plants (7.2%) were injured by final instar larvae of this species. The overall decrease in yield is estimated to be less than 1% by defoliation due to this pest.
Abstract Pheromone traps have been widely used for monitoring insect pests in tobacco factories and warehouses. Generally, these traps are placed 10-20 m apart, although a precise scientific rationale for this practice is not available. We examined the effect of trap density on the recovery and localization of tobacco moths released in a 42.3 × 36.5 × 4.0 m tobacco warehouse compartment (1540 m 2 ). In single-trap experiments (0.06 traps/100m 2 ), 15-51% (33% on average) of the released male moths were captured. The capture ratio was not correlated with the distance between the trap and the release point; the highest catch rate was attained when a trap was placed at the most distant position: 47 m from the release point. Capture data from experiments using groups of 4-23 traps revealed that the highest catch rates were always attained by the trap nearest the release point when more than eight traps (0.5 traps/100 m 2 ) were set. These results indicate that the number of traps required for monitoring purposes should be changed - one trap is sufficient for detecting the presence or absence of infestation in a 1540 m 2 warehouse compartment (0.06 traps/100 m 2 ); more than eight traps (0.5 traps/100 m 2 ) should be set for localization, allowing the location of the infestation to be inferred from the trap with the highest catch rate.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)
