Understanding spatial genetic structure and connectivity is important for characterizing population structure at different geographic scales. Orius sauteri (Poppius) (Hemiptera: Anthocoridae) is a widespread indigenous predator in Japan, yet its population-genetic structure at regional and fine spatial scales remains poorly understood. In this study, 137 individuals collected from 28 sites in central Japan were genotyped using eight microsatellite markers to evaluate genetic diversity, regional-scale isolation by distance (IBD), population clustering, and fine-scale spatial genetic structure. Bayesian clustering revealed extensive admixture across sampling sites with no clear geographic subdivision. At the regional scale (up to approximately 60 km), the Mantel test detected no significant relationship between geographic distance and genetic relatedness (Mantel r = − 0.003, P = 0.512), indicating no detectable regional-scale IBD. Fine-scale spatial genetic structure was further evaluated by restricting kinship-distance regression to pairwise distances ≤ 0.55 km. The regression slope was shallow and non-significant (blog = − 0.00323, P = 0.643), and the resulting Sp statistic was low (Sp = 0.00323; approximate 95
The golden apple snail Pomacea canaliculata (Lamarck, 1822) (Gastropoda: Ampullariidae) is a destructive invasive pest that feeds on young rice seedlings in paddy fields. Low-speed and high-gear rotary tillage during winter is an effective method of physically controlling overwintering snails in paddy soil. However, the onerous time and fuel costs associated with this tillage prevent control over wide areas. This study was conducted to formulate a more efficient and labor-saving control method. During November–December in 2022, we dug up paddy fields in the southern part of Shiga Prefecture, Japan, to ascertain the distribution of overwintering snails. We investigated up to 5.5 m from the inner side of the levee, where high overwintering densities were expected in the paddy fields after harvest. On the short side of paddy fields shaped as an elongated right-angled trapezoid, many overwintering snails were found up to 5.5 m from the inner side of the levee. On the long side, we also found many snails within 0.5 m of the inner side of the levee. Subsequently, rotary tillage was conducted in December at 1.0 km/h using second-speed PTO gearing (795 RPM) in areas with many overwintering snails. Compared to control fields without tillage, tilling 22–37
Harvested fruits infested by insect larvae, such as Japanese apricot (Prunus mume), are routinely immersed in water before processing to induce larvae to exit, yet the behavioral mechanism underlying this escape response has remained unclear. In the present study, the effect of different environmental factors on phototaxis was examined in third-instar larvae of the sap beetle Phenolia (Lasiodites) picta (MacLeay) (Coleoptera: Nitidulidae). Phototactic responses were examined under four environmental conditions: normal air, water immersion, cold air, and CO2 condition (air replaced with 95
Subterranean termites primarily utilize decaying wood as both food and nest material, and a portion of individuals within the worker caste engages in the exploration and colonization of new decaying wood. Because these processes take place inside decaying wood or underground, the details have remained unknown for a long time. However, recent studies have revealed chemical interactions between workers and between workers and their surrounding environment during the process by which workers discover new decaying wood, feed on it collectively, and exploit it as part of their nest. Furthermore, sophisticated chemical analyses are beginning to shed light on the enigmatic process by which the nutrients from the wood and soil consumed by workers are converted into special food for termite kings and queens. Here I summarize our current knowledge of termite attractants in wood, aggregation pheromones, and antimicrobial substances secreted by termite workers, and the pathways through which nutrients are supplied to termite kings and queens. I also highlight unresolved issues regarding termite foraging behavior and strategies for future studies.
Okra Abelmoschus esculentus L. Moench (Malvales: Malvaceae) is expected to act as an insectary plant to conserve and enhance Orius spp. (Heteroptera: Anthocoridae) when planted in open-field cultivations of eggplant. Since it is known that the occurrence of thrips (Thysanoptera: Thripidae) on okra plant is insufficient as their prey, it possibly provides another food resource for these predators. The present study compared some characteristics that positively effect the growth of Orius populations between two varieties of okra: Marumichan and Earlyfive. In the olfactory response test, both Orius sauteri and O. minutus were attracted to volatiles of Earlyfive. In the oviposition test, there was no significant difference in the numbers of eggs laid on the two varieties. In the 2-year field surveys, the seasonal occurrence of thrips was similar on the two varieties, but significantly more Orius spp. occurred on Marumichan than Earlyfive. Also, significantly more pearl bodies, which contain valuable nutrition for insects, was secreted from Marumichan than Earlyfive. From these results, we concluded that the effectiveness of okra as an insectary plant is supported primarily by pearl bodies.
