Applied Entomology and Zoology最新文献

The apple snail Pomacea canaliculata (Lamarck) (Architaenioglossa: Ampullariidae) is a large freshwater snail from South America and has become a severe pest of rice plants in many countries, including Japan. There are known predators, such as carp and turtles, that can control the number of apple snails, but many of these predators are rarely found in paddy rice fields. The carrion crow Corvus corone Linnaeus (Passeriformes: Corvidae) has recently been found to prey on apple snails in rice fields in limited locations in western Japan. We evaluated the effects of predation by carrion crows on apple snail populations in rice fields at four locations in Japan (Fukuoka, Ehime, Hyogo, and Nara) from September 2019 to 2021. The densities of not only snails larger than 17.5 mm but also those between 7.5 and 17.4 mm were lower in fields with crow predation than in those without it. Moreover, the greater the number of snails preyed upon on the levee, the lower the snail density in the adjacent field. These results suggest that crow predation effectively reduces snail density in rice fields.

When threatened by the giant hornet Vespa mandarinia Smith (Hymenoptera: Vespidae), the Japanese honey bee Apis cerana japonica Radoszkowski (Hymenoptera: Apidae) collects substances from the surrounding environment and applies them to the entrance of its hive. This behavior is thought to help avoid mass attacks by hornets. To investigate the substances collected by the bees, we analyzed the DNA extracted from the applied spots using three methods. First, we placed glass slides at the hive entrance, extracted DNA from the spots mounted on the glass slides, and amplified the internal transcribed spacer (ITS) 1 using PCR. Sequencing of the cloned PCR products revealed the presence of both plant and fungal DNA. Second, we performed an amplicon analysis targeting ITS2 of plants and fungi using next-generation sequencing. A diverse array of fungi was detected; however, unexpectedly, no plant DNA was detected. The reason for this remains unclear; however, amplicon analysis appears to be biased toward the detection of fungi. Therefore, in the third experiment, we extracted DNA from individual spots on glass slides, amplified ITS1, and directly sequenced the PCR products. This experiment allowed us to quantify the utilization of plants and fungi based on the number of spots containing each type of material. We determined the sequences of 165 PCR products, including 56 obtained from plants, 68 from mushrooms, and 41 from non-mushroom fungi.

Social insect colonies harbor various inquiline species that exploit nest resources. In particular, comparing the ecology of closely related inquilines that utilize the same host provides key insights into the evolution of parasitic strategies. Myrmecophilus kubotai Maruyama, 2004 (Orthoptera: Myrmecophilidae) comprises two genetically distinct lineages (M. kubotai lineage 1 and 2) that associate with different ant species. Myrmecophilus kubotai lineage 1 and its allied species M. tetramorii Ichikawa, 2001 share the host ant Tetramorium tsushimae Emery, 1925 (Hymenoptera, Formicidae), making them a valuable model for studying host exploitation. In this study, we describe M. kubotai lineage 1 as a new species, M. affinis sp. nov., and recognize lineage 2 as the true representative of M. kubotai. This classification is based on morphological observations of the pronotal surface structure, which is a character traditionally used for species identification within the genus. Additionally, we identified morphological differences between M. affinis and M. tetramorii. Furthermore, we developed a non-invasive identification method to distinguish M. affinis and M. tetramorii based on the relative lengths of three pairs of setae on the tenth abdominal tergite. These findings clarify the taxonomic status of the M. kubotai species complex and facilitate species identification, thereby significantly contributing to comparative studies on M. affinis and M. tetramorii, which share the same host.

The effects of climate change on life-history traits and the boundary between bivoltine and trivoltine areas in the northern Kanto district were investigated in 5 populations of the fall webworm Hyphantria cunea (Drury) (Lepidoptera: Arctiidae), inhabiting from 36.1 ºN to 36.6 ºN in the mid-2010s. Photoperiodic responses controlling diapause induction were investigated at 25ºC and developmental traits were examined at 5 temperatures between 18 and 25ºC. The photoperiodic responses of Utsunomiya, Tsukuba, and Maebashi populations were compared with those investigated in the early 1990s. The critical photoperiods were the longest in the Utsunomiya population and the shortest in the Maebashi population among all of those studied, and these were nearly the same as those of the early 1990s. The critical photoperiod of the Tsukuba population had been shortened by 11 min from that of 1993, indicating that the life cycle of this population had shifted from mixed to trivoltine. The Mito population showed a critical photoperiod near that of the Utsunomiya population, and the Ashikaga population had a value very similar to that of the Tsukuba population obtained in 1993. Life cycles of all populations were estimated from the life history traits and climate data at each site. The estimations suggested that trivoltine life cycles would prevail in Ashikaga, Tsukuba, and Maebashi populations and others would be bivoltine although the Ashikaga population may show a mixed life cycle.

Cockroaches, embracing some 4500 species in the world, are found in a variety of environments, including human settlements. The ecological success of cockroaches is attributable to the ability to endure long periods of starvation and to thrive on nutritionally poor diets, which is underpinned by the capability of storing their own nitrogenous waste products as uric acid in the fat body and also by the endosymbiosis with bacteriocyte-dwelling bacteria Blattabacterium that recycle the stored uric acid for the synthesis of amino acids. Previous histological studies on cockroaches described that uric acid is accumulated within the fat body, especially in urocytes. Here we report that cockroaches also accumulate uric acid in the wings. In our observation of the German cockroach Blattella germanica Linnaeus (Blattodea: Blattellidae) under different nutritional conditions, we found that well-fed cockroaches exhibited whitish aggregates in the wing veins, which is ascribed to the accumulation of uric acid granules. The uric acid granules in the wings disappeared by starvation and were restored by feeding in B. germanica. The uric acid granules in the wings were found not only in B. germanica but also in other diverse cockroach species.

Scepticus tigrinus (Roelofs) (Coleoptera: Curculionidae) and its related species are polyphagous weevil pests that damage various vegetables and crops. Despite their agricultural importance, scalable and straightforward rearing methods using artificial diets have not been established, limiting physiological and developmental studies necessary for effective pest control. The present study evaluated a commercially available artificial diet (F1675) for rearing S. tigrinus. We found that this artificial diet is suitable for the larval growth of S. tigrinus. However, the pupation rate was markedly low. To address this issue, we established a combined-diet-rearing protocol in which larvae are fed with an artificial diet until the final instar and then exposed to raw carrot pieces during the late final instar stage. This method significantly improved pupation success compared to the artificial diet alone (21.68%) and demonstrated higher pupation efficiency relative to labor input than the conventional raw plant-based rearing. Notably, some final instar larvae appeared to have pupated without feeding on the plant material, suggesting that non-nutritive cues—possibly chemical signals from the plants—may trigger pupation. The proposed combined-diet protocol offers a practical approach for mass rearing and facilitates physiologic and genetic studies of S. tigrinus and related weevil pests.

Three ladybird species, Hyperaspis sinensis (Crotch), Nephus phosphorus (Lewis), and Chilocorus renipustulatus (Scriba) (Coleoptera: Coccinellidae), attack mealybugs (Hemiptera: Pseudococcidae) on citrus trees in Japan. They may have the potential to effectively control mealybug populations in citrus groves and would therefore need to be protected from pesticide applications. Seasonal change in adult abundance of each ladybird species was monitored using yellow sticky traps set within citrus tree canopies for four years in citrus groves at an experimental site and for two years in commercial groves in Shizuoka City, central Japan; these groves varied in the level of pesticide application. At the experimental site, adults of each ladybird species were clearly more abundant in a pesticide-free grove than in reduced-pesticide and conventionally managed groves. More H. sinensis and N. phosphorus adults were trapped from mid-March to mid-May and from mid-March to late May, respectively, in the pesticide-free grove, while more C. renipustulatus adults were captured in October–November there. As for the commercial groves, a number of H. sinensis and C. renipustulatus adults were caught mainly in organic and reduced-pesticide groves, while N. phosphorus adults were rarely collected. The seasonal adult occurrence of H. sinensis and C. renipustulatus in the commercial groves was similar to that observed at the experimental site. These results suggest that application of pesticides that could have detrimental impacts on ladybird adults should be avoided in March–May (for H. sinensis and N. phosphorus) and October–November (for C. renipustulatus) to conserve these ladybird populations in central Japan citrus groves.

Aromia bungii (Coleoptera: Cerambycidae) is native across the south-eastern Palaearctic and Oriental regions. It is an important wood-boring pest of species of the genus Prunus. It is now present in Germany and Italy, and has previously been intercepted in the UK and the USA. It was first recognized in Japan in the early 2010s and is now present in almost 30% of prefectures. The larvae feed within the wood and eject their frass. Several wood-boring insect species eject frass, but they cannot be distinguished without being dug out. Recently, we developed a method to detect four wood-boring beetle species, including A. bungii, by chemical analysis of hydrocarbon components in their frass, making it possible to non-destructively detect specific wood-boring beetles. The hydrocarbon components in the frass are derived from the larval cuticle. This method can detect larval species regardless of tree species, the passage of time, or larval age. However, we used samples only from Tochigi. Introductions into different habitats can alter species characteristics, including perhaps cuticular hydrocarbons. To validate our method for frass samples from different habitats, we analyzed and compared hydrocarbon profiles in frass between the beetle’s native habitat (Korea) and two more Japanese habitats (Aichi and Saitama). We found no difference in hydrocarbon composition, although relative proportions differed slightly. Thus, our method can be used in both native and invaded areas.

The rice stink bug Niphe elongata (Dallas) (Hemiptera: Pentatomidae) is a serious pest of rice in central and western Japan, causing grain sterility and grain surface discoloration. Effective management of this pest requires knowledge of its overwintering habitats and the seasonal movements of overwintering adults. We surveyed potential habitats of the overwintering population of N. elongata on several plant species in Tsukuba, Ibaraki Prefecture, Japan, in February. Adults were found in high densities on clumps of mondo grass (Ophiopogon japonicus; Asparagales: Asparagaceae). Over the following 2 years, we monitored the seasonal occurrence of adults on mondo grass and in rice fields. Adults were present on mondo grass from September to early July, with peak densities in early autumn and late spring. These findings indicate that mondo grass is a habitat for N. elongata during the overwintering period, mainly in autumn and late spring. Mondo grass is a promising monitoring site for overwintering populations to predict subsequent infestations in rice fields. In early autumn, adults appeared in late-season rice fields and their density on mondo grass increased, suggesting that they migrated to mondo grass for overwintering. In early summer, light trap catches suggested that overwintering adults dispersed from these sites then.

For infectious diseases, the transmission capacity of disease-inducing parasites is one of the key traits determining the extent and rate of disease incidence. In the pine wilt disease system, the pinewood nematode Bursaphelenchus xylophilus (Steiner et Buhrer) (Nematoda: Aphelenchoididae) is transmitted to healthy pine trees by cerambycid beetle adults of the genus Monochamus, causing rapid wilting. To express the nematode transmission capacity, we proposed the probability (q) of a nematode being transmitted to trees by a beetle individual and the nematode transmission probability (Q) by a beetle population. The q value was calculated as n_t/n_i, where n_i was the initial number of nematodes that a beetle carried and n_t was the number of nematodes transmitted by it. The Q value was calculated as the proportion of nematodes transmitted by a beetle population and estimated using the n_i–q relation and the frequency distribution of n_i. Application of nematode transmission probabilities indicated that the q value decreased with increasing n_i value and that the negative slope of regression line of ({text{arcsin}}sqrt q) on ({text{log}}_{10} n_{i}) was steeper for the B. xylophilus–M. alternatus Hope (Coleoptera: Cerambycidae) and B. xylophilus–M. carolinensis systems than for the B. mucronatus–M. saltuarius system. The Q value was greatest for the system containing M. alternatus and lowest for the system containing M. carolinensis. Those transmission probabilities would help to deeply understand the transmission biology of B. xylophilus.