We demonstrate that vibrations carried in a food substrate induced escape behavior in the larvae of the sap beetle pest, Phenolia （Lasiodite） picta （MacLeay）（Coleoptera: Nitidulidae）, which infests Japanese apricot fruits. Accelerations of continuous vibrations from 8 to 32 m/s2 at a frequency of 120 Hz within 30 min induced escape behavior in 60% of larvae. Pulsed vibrations of 1-s duration at intervals from 1 to 29 s induced escape behavior in 40–50% of larvae at 120 Hz and 8 or 16 m/s2. Our findings suggest that the application of vibrations to a food substrate has a potential for removing larvae from the food by inducing escape behavior.
The sweetpotato whitefly, Bemisia tabaci（Gennadius）（Hemiptera: Aleyrodidae）, is a notorious agricultural pest worldwide. In this study, the inhibitory activities of several spiracle-blocking insecticides on its orientation and courtship were investigated to identify an effective control agent against this pest. The numbers of orientated adults, courting pairs, and eggs were found to decrease on tomato plants that had been sprayed with decanoyloctanoylglycerol, safflower and cotton oil, or rape seed oil. Furthermore, when virgin female and male adults were released on tomato plants, the progeny sex ratio was higher（i.e., a higher percentage of males）on the plants that had been sprayed with decanoyloctanoylglycerol or safflower and cotton oil than on the corresponding control plants. Under greenhouse conditions, a cohort of tomato plants that had been sprayed with 500-fold diluted decanoyloctanoylglycerol four times every 10 days had fewer whitefly adults, lower numbers of eggs and larvae, and a higher sex ratio than the control plants. These results indicate that spiracle-blocking insecticides containing liquid oil, decanoyloctanoylglycerol, safflower and cotton oil, and rape seed oil can inhibit orientation and courtship in B. tabaci and allow this pest species to be maintained at a low density.
Aquatic insects colonize the swimming pools of schools during the off-season. The present study aimed to investigate 30 swimming pools in southern Nagasaki Prefecture in spring（middle April to middle May）and autumn（late October to early November）2014. We found 11 families of aquatic insects including 9 Heteroptera, and 9 Coleoptera. Appasus japonicus（Heteroptera: Belostomatidae）, Hesperocorixa kolthoffi（Heteroptera: Corixidae）, and Cybister tripunctatus lateralis（Coleoptera: Dytiscidae）designated as “Red Data List” species（red list species）were collected from the school pools. The community composition of aquatic insects was divided into spring and autumn, and its variance was related to the water temperature and organic matter. The major environmental factor related to the number of red list species was considered to be location near the potential natural habitat of the species. The organic matter falling into the pools affected the existence of Orthetrum species nymphs（Orthoptera: Libellulidae）. Odonata nymphs, Notonecta triguttata（Heteroptera: Notonectidae）, Anisops ogasawaraensis（Heteroptera: Notonectidae）, Aquarius paludum paludum（Heteroptera: Gerridae）, and Eretes griseus（Coleoptera: Dytiscidae）were found from most of the pools studied, indicating that these species may be used as teaching materials for science in most schools irrespective of their location.
The sap beetle, Phenolia（Lasiodites）picta（MacLeay）（Coleoptera: Nitidulidae）, is a pest that feeds on fallen Japanese apricots（Prunus mume）. Understanding the spatial distribution and migration patterns of adults should contribute to developing sophisticated management methods for this species. We counted the number of adult beetles on each fallen ripe apricot in an orchard in early summer in 2015 and 2016. Then we calculated Morisita’s Iδ index, which is an index of the distribution pattern without an association with density; it was 1.31 for females, 0.62 for males, and 1.15 for both sexes. These scores suggest that females and males have aggregated and uniform distributions, respectively. To examine if they used sexual or aggregation pheromones that can affect their distribution patterns, we tested the olfactory responses of each sex to food in plastic containers and to other individuals in a Y-tube olfactometer. Males were significantly attracted to females, while females showed a stronger response to food than to males. These results suggest that the sexual differences in the demands for food and mating partners cause the different distribution patterns in the field.
To evaluate the relationship between the occurrence of split-hull paddies and incidence of pecky rice damage caused by two mirid pests, Stenotus rubrovittatus（Matsumura）（Heteroptera: Miridae）and Trigonotylus caelestialium（Kirkaldy）（Heteroptera: Miridae）, among eight rice varieties, we conducted release experiments in a greenhouse. For each variety, we released a male and female pair of adult mirids onto a rice panicle for 3 days with three replications. By examining the correlation between the percentage of split-hull paddies and the pest species to the incidence of pecky rice damage, only the percentage of split rice hulls was significant. There was no pest species effect, indicating adults of the two species examined have a similar potential to cause pecky rice damage. Thus, the number of split-hull paddies and the level of pecky rice damage caused by adults of the two mirid pests were related regardless of the rice variety. Further studies are needed to predict pecky rice damage caused by the two mirids in the field, because the abundance of both adults and nymphs of T. caelestialium are known to be related to the level of pecky rice damage.
We investigated the abundance of Scepticus uniformis Kono（Coleoptera: Curculionidae）on peanut Arachis hypogaea L. and four species of green manure crops in a frame field during summer to find plants antagonistic for nematodes that can be used in the habitat of this weevil. Weevils bred abundantly in the soil in plots of peanut and African marigold Tagetes erecta L., poorly in plots of showy crotalaria Crotalaria spectabilis Roth, and not at all in plots of sorghum Sorghum bicolor（L.）Moench or Sudan grass Sorghum×drummondii（Nees ex Steud.）Millsp. et Chase. Similar results were obtained in a connected frame field experiment using wild-collected adults which could migrate among frames planted with peanut, African marigold, sorghum, or nothing. These results suggest that showy crotalaria, sorghum, and Sudan grass are not suitable as hosts for S. uniformis, so we can use these nematode-suppressing green manure crops in areas where weevil are found. More detailed investigation of the actions of the plants on oviposition and the survival of weevils is needed to support their use in integrated pest management.
Trigonotylus caelestialium（Kirkaldy）（hereafter referred to as T.c.）and Stenotus rubrovittatus（Matsumura）（hereafter referred to as S.r.）（Hemiptera: Miridae）are major rice pests that cause pecky rice. Two Japanese companies, Shin-Etsu Chemical Co. Ltd. and Earth Biochemical Co. Ltd., have commercialized synthetic sex pheromones as lures for these two species for monitoring purposes. These lures differ in their chemical composition and the dispenser material used for each species. To elucidate the differences between the products in their attractiveness to males, we investigated T.c. and S.r. catches using traps baited with the lure products alone or in combination in paddy fields. When the products were used alone, the number of male T.c. catches was not significantly different between the traps baited with the Shin-Etsu product and those baited with the Earth Biochemical product, whereas the number of male S.r. catches in the traps baited with the Earth Biochemical product was significantly lower than that in the traps baited with the Shin-Etsu product. Moreover, with the combined use of either product for T.c. and the Earth Biochemical product for S.r., T.c. catches were significantly lower than in those combined with the Shin-Etsu product for S.r. In conclusion, for S.r., the attractiveness of the Earth Biochemical product was inferior to that of the Shin-Etsu product; furthermore, this product when used in combination with the product for T.c. inhibited the attractiveness for T.c.
Two generalist phytoseiid mites, Amblyseius eharai Amitai and Swirski and Euseius sojaensis（Ehara）（Acari: Phytoseiidae）, are useful biocontrol agents in citrus fields, and their reproduction is expected to be enhanced by supplying alternative foods. We reared phytoseiid mites on the pollen of six tree species and evaluated the effect on reproduction. The intrinsic rate of natural increase（rm）of A. eharai was 0.179 to 0.216 when the pollen of Pinus thunbergii, Distylium racemosum, Camellia sinensis, or Morella rubra was provided, suggesting that these four types of pollen were suitable for the reproduction of A. eharai. When pollen from Citrus natsudaidai and Cryptomeria japonica was provided, rm was lower（0.085, 0.082）but still positive, because the net reproduction rates（R0）were lower and the mean generation times（T）were longer than with the above four pollen types. E. sojaensis had rm of 0.166 to 0.196 when P. thunbergii, D. racemosum, C. sinensis, or M. rubra was provided, which appear to support E. sojaensis reproduction. However, with C. natsudaidai and C. japonica pollen, the R0 was extremely low and the rm was negative. Based on these results, the pollen of P. thunbergii, D. racemosum, C. sinensis, and M. rubra are suitable foods for the reproduction of these two species of generalist phytoseiid mites.
To estimate the generation period of citrus psyllid, Diaphorina citri Kuwayama（Hemiptera: Liviidae）, we examined the temperature-dependent development of the insect during the pre-oviposition period and determined the developmental zero and effective accumulative temperature for development in a laboratory. Adults were reared at 15.9, 17.4, 20.1, 22.3, 25.0, 27.4, 29.9, and 32.5°C on new leaves of orange jasmine, Murraya paniculata（L.）Jack var. exotica（L.）C. C. Huang. The average pre-oviposition period at each temperature was 52.5, 26.9, 14.8, 9.6, 7.9, 6.0, 5.3 and 3.0 days, respectively. The mortality rate was highest at 32.5°C. Based on the results from 17.4 to 29.9°C, the developmental zero and effective accumulative temperature for the development of D. citri were 14.39°C and 80.45 s degree-days, respectively, during the pre-oviposition period.