Irradiation of melon (Cucumis melo) seedlings with red LED light (wavelengths of 620 to 630 nm) at an intensity of 1×1018 photons m－2 s－1 decreased the number of Thrips palmi (melon thrips), a major insect pest that causes serious damage during greenhouse melon cultivation. Thrip populations were significantly lower than in treatments without LED, both with continuous 24-h irradiation and with 12-h daytime (06:00 to 18:00) irradiation. Transplanted seedlings were also irradiated with red LED light of two different intensities (4.7×1018 photons m－2 s－1 or 1.0×1018 photons m－2 s－1) in two cultivation environments (glass or plastic greenhouse). These findings suggest that irradiation with red LEDs may be an effective means of controlling Thrips palmi in greenhouse melon cultivation.
The effects of eggplants illuminated by red LED (Light Emitting Diode) on the population density of the melon thrips, Thrips palmi Karny, were investigated in June and October of 2013 in a greenhouse. The peak wavelengths of the red LED arrays were 635 nm and 660 nm. The LED array was placed on the upper part of the eggplants, directly illuminating the plants. As a result, the density of thrips was significantly lower on eggplants with red LED illumination than on eggplants without LED.
Orius sauteri is used as a biological control agent against agricultural pests such as thrips and whiteflies. We investigated the spectral wavelength preference of O. sauteri in a hexagonal arena equipped with six LED lights of different colors: UV (365 nm), violet (405 nm), blue (450 nm), green (525 nm), orange (590 nm), and red (660 nm). Adults were released in the center of the arena and their phototactic behavior toward the LED lights was observed. Approximately 50% of non-mated individuals moved toward the violet light, with no difference between sexes. The spectral preference of males did not change after mating, whereas the preference of females changed dramatically from violet to UV after three days' mating.
The Asian citrus psyllid, Diaphorina citri Kuwayama, transmits pathogenic bacteria that cause the citrus greening disease (Huanglongbing). To examine an effective method to reduce the orientation of D. citri adults, the effect of a UV-absorbing film was compared with that of a normal film in the laboratory. The number of adults oriented under the UV-absorbing film was significantly fewer than those under the normal film. The UV-absorbing film is could be used as a physical pest control material against Diaphorina citri.
A lot of sterile males need to be released continuously in the target area in the sterile insect technique (SIT). Therefore, mass-rearing of the target pest insects is indispensable for SIT programs. The West Indian sweet potato weevil, Euscepes postfasciatus, has been maintained for over 44 generations (～8 years) for its eradication program in the Okinawa Prefectural Plant Protection Center (Naha, Okinawa, Japan). The selective pressures under mass-rearing conditions are likely to be very different from those of wild ones. The specific selective pressures over many generations under mass-rearing conditions would adversely affect the reproductive capacity of mass-reared insects. Therefore, evaluation of the mating performance of mass-reared males compared with that of wild ones is indispensable in SIT eradication programs. Although we compared mating performance with respect to four reproductive characteristics (duration of mating behavior, mating success, mating competitiveness ability and number of transferred sperm in female spermatheca during copulation) between mass-reared and wild males in E. postfasciatus, there was no evidence that the mass-reared males were inferior to the wild males in terms of mating performance. Thus, we considered that the mass-rearing procedure for at least 44 generations did not adversely influence the male mating activity in E. postfasciatus.
Alternative food sources provided by wheat and barley living-mulch were evaluated for the effect on the life history traits of the predatory bug, Geocoris proteus Distant. As alternative food sources, Rhopalosiphum padi (Linnaeus) and Anaphothrips obscurus (Müller) were provided to larvae and adults of G. proteus. Onion thrips, Thrips tabaci Lindeman and a standard food, Ephestia kuehniella (Zeller) eggs served as control food sources. The results showed that R. padi significantly prolonged the larval period and preoviposition period of G. proteus compared to the other prey species. However, R. padi made the female bugs more fecund than T. tabaci, though not so much as the standard food. Anaphothrips obscurus, though less than the standard food, was also nearly equal to T. tabaci in fecundity of the bugs. As a result, R. padi and A. obscurus were superior or nearly equal to T. tabaci in affecting the intrinsic rate of natural increase of G. proteus. These results suggest that wheat and barley would provide preferable alternative foods to G. proteus, thus serving well as living mulch.
We investigated the dispersal distance of the onion thrips, Thrips tabaci Lindeman, using traps. In a greenhouse, fourteen hours after releasing thrips, we found insects at sticky traps up to 54 m from the release point. The estimated mean dispersal distance (±SE) was 7.4±0.25 m at thirty-nine hours after releasing thrips. In a field, forty-eight hours after releasing thrips applied with the fluorescent brightening agent, we found insects at traps up to 119 m from the release point. The estimated mean dispersal distance (±SE) was 66.6±10.7 m.