Applied Entomology and Zoology最新文献

Predacious insects have rarely been implemented for biological pest control in open-field cultivation in Japan, partly because they may be readily dispersed from crops. The Asian lady beetle, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), is an indigenous natural enemy of aphids in Japan. In recent years, technology for establishing lady beetles on plants using an artificial diet has been advanced for greenhouse cultivation. In open-field cultivation, however, there are problems such as deterioration of food quality due to environmental conditions, and this technology has yet to be put to practical use. Flight-controlled adults of the lady beetle are commercially available as ‘Tentrol’ and are utilized for aphid control in Chiba Prefecture. In this study, the effects of a gummies-like diet developed for flight-controlled adults of the lady beetle were examined in laboratory and outdoor experiments. The laboratory findings showed that the gimmies-like diet is more persistent than two commercial diets as food for the beetle. In the outdoor experiment, the diet had a significant effect on retaining the beetles in stocks of eggplants. These results indicate that use of the diet together with flight-controlled lady beetles may be an effective aphid control method in open-field cultivation.

Three major sweet potato pest species, sweet potato weevil Cylas formicarius (Fabricius) (Coleoptera: Brentidae), West Indian sweet potato weevil Euscepes postfasciatus (Fairmaire) (Coleoptera: Curculionidae) and sweet potato vine borer, Omphisa anastomosalis (Guenée) (Lepidoptera: Crambidae), were examined for their utilization patterns and spatial distribution in the wild host plant, blue morning glory, Ipomoea indica ((Burm.) Merr.) (Solanales: Convolvulaceae) in Okinawa, Japan. We investigated 18,720 samples of I. indica and showed that 649 individuals of C. formicarius were found at an infestation rate per 1 m of the vine of 2.44%, which was significantly higher at height levels 0 m than the other levels (0–1 m, 1–2 m and 2–3 m), and tended to be higher at height level >3 m. In the case of E. postfasciatus, 131 individuals were found, and its infestation rate (0.37% on average) was significantly higher at height levels 0–1 m than the other level (2–3 m), and tended to be higher at height level >3 m. In the case of O. anastomosalis, 65 individuals were found and its infestation rate (0.32%) was significantly higher at the 0–3 m height level than at the other level (0 m). The results of analysis of the spatio-temporal dynamics of populations within and across species showed that the pests are randomly distributed across the study area throughout the year. Stochastic simulations showed that E. postfasciatus and the other two species tend to infest the same vines, but C. formicarius and O. anastomosalis tend to infest different vines. We provide valuable information on the distribution patterns of these pests that can their effectively control.

While the fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), has invaded Asia, whether it uses local weeds as alternative hosts remains understudied. This knowledge gap is significant as alternative hosts may facilitate fall armyworm expansion. Here we conducted three experiments to investigate the potential use of Asteraceae weeds (Emilia sonchifolia var. javanica [E. sonchifolia hereafter] and E. praetermissa) by fall armyworm in Taiwan: (1) The feeding experiment examined fall armyworm performance on the two Emilia species against the control (artificial diet). (2) The host-plant shift experiment tested if fall armyworm can survive on the Emilia species after depleting its primary host (maize). (3) Spatial analysis mapped current fall armyworm invasions, maize production areas, and the distribution of Emilia host plants (if confirmed) to demonstrate the potential of Asteraceae weeds as fall armyworm’s untapped resource. The results indicated that fall armyworm could complete its life cycle on E. sonchifolia but not E. praetermissa. Compared to the control, both sexes of fall armyworms on E. sonchifolia performed similarly in survivorship, larval weight, larval and pupal duration, but worse in pupal length and weight. In addition, larvae can switch to E. sonchifolia after depleting maize, reaching adult emergence and producing fertile eggs. The spatial analysis demonstrated hotspots of fall armyworm invasions and a large area of E. sonchifolia as potential food resource for future fall armyworm expansion. Overall, our results raise concerns that overlooking the use of weeds from the Asteraceae family may lead to an underestimation of future fall armyworm expansion.

The Japanese orange fly, Bactrocera tsuneonis (Miyake) (Diptera: Tephritidae), is a univoltine tephritid pest of citrus fruits. Its occurrence in citrus-growing regions restricts the export of citrus fruits owing to plant quarantine regulations. We investigated whether the B. tsuneonis infestation rate could meet export quarantine standards if proper preharvest management were carried out. Our approach involved using orchards unsuitable for B. tsuneonis occurrence, implementing appropriate pesticide control, and removing suspected infested fruits. Sunny, open orchards away from any thickets that could serve as hiding places for the adults were chosen as the demonstration orchards. During the peak adult emergence and larval hatching periods, pesticides were sprayed to protect the fruits from infestation. We observed a total of 724,296 fruits throughout the fruit coloring period and removed 1027 suspected infested fruits. We dissected 58,193 harvested fruits and confirmed that they were not infested. No adults were captured during trap surveys in these orchards. In contrast, poorly managed orchards in the same area consistently exhibited fruit damage by B. tsuneonis larvae, and adults were captured in trap surveys. These results prove the feasibility of establishing damage-free orchards through appropriate preharvest management, even in regions where B. tsuneonis is distributed.

Culex quinquefasciatus Say 1823 (Diptera: Culicidae), a vector of lymphatic filariasis and various arboviruses, is the most abundant mosquito owing to its breeding capacity in polluted stagnant water. Alphacypermethrin (C₂₂H₁₉Cl₂NO₃) is a highly effective synthetic pyrethroid insecticide, used for the management of agricultural pests as well as vector control. In this study, two strains of Cx. quinquefasciatus were reared in the laboratory with the same genetic background, one strain was selected against alphacypermethrin (AS) and another strain was devoid of insecticide treatment and reared as susceptible (S) for 15 generations. It was observed that the sub-lethal exposure to insecticide led to a low fecundity rate, less hatchability, longer larval developmental time, low pupation rate, and less emergence rate but no significant differences in sex ratio. AS strain showed 37.4-fold, 2.85-fold, fivefold, and 8.6-fold higher activity in comparison to S strain in monooxygenases, alphaesterases, betaesterases, and glutathione-S-transferases activity respectively, implying the role of detoxifying enzyme in metabolic resistance development. This study was conducted to elucidate the sub-lethal effects of insecticide on the life history traits of the exposed strain and their association with metabolic resistance which would ultimately help to design vector control programs against insecticide resistance.

Varroa mite, Varroa destructor Anderson and Trueman (Acari: Varroidae), causes severe damage to honeybee colonies and facilitates the transmission of several bee viruses, such as deformed wing virus (DWV), which causes wing deformity in newly molted bees. In Japan, western honeybees Apis mellifera Linnaeus (Hymenoptera: Apidae) are reared for both honey production and pollination and are infested with Varroa mites. Detailed surveillance of bee viruses in both A. melliferra and V. destructor has not been conducted in Japan. We surveyed eight major bee viruses in A. mellifera and Varroa mites from Japanese apiaries. DWV is the predominant virus in both A. mellifera and V. destructor in Japan. Two strains of the virus, DWV-A and DWV-B, are considered virulent in honeybees, but only DWV-A was detected in this study. The DWV levels in honeybees were strongly correlated with the Varroa infestation rate. We also detected other viruses in both the bees and mites, such as black queen cell and Lake Sinai viruses, but at much lower infection rates than DWV. Infection rates of these viruses were higher in colonies that did not contain Varroa mites than in Varroa-infested bee colonies. Therefore, Varroa mites in Japanese apiaries could be associated with DWV transmission, but they may rarely be associated with the transmission of other viruses.

The invasive longhorn beetle Apriona swainsoni (Hope) (Coleoptera: Cerambycidae) is a serious pest of Maackia amurensis in Fukushima Prefecture, Japan. Since there is no effective control measure except the felling of damaged trees, the establishment of biologic control methods is expected. We have conducted inoculation experiments to evaluate whether the domestic parasitoid beetle Dastarcus longulus Sharp (Coleoptera: Bothrideridae) is effective as a biologic agent to control A. swainsoni. Estimated first-year larvae and newly emerged larvae of A. swainsoni were frequently parasitized by inoculated and newly emerged larvae of D. longulus. However, estimated second-year larvae were not parasitized. These results suggest that D. longulus could be used as a biologic agent against A. swainsoni, but we must carefully consider the timing and methodology to apply this parasitoid for the control of A. swainsoni.

The fairyfly Cosmocomoidea tenuis Xu, Lin and Hu (Hymenoptera: Mymaridae), which was previously known only from mainland China (Fujian) and Taiwan, is for the first time recorded from Japan where it was reared from organic kiwifruit, Actinidia chinensis and A. deliciosa (Actinidiaceae), leaves in Yamanashi Prefecture on Honshu Island. Both sexes of C. tenuis are redescribed and illustrated based on specimens from Japan. Its apparent host association with black-tipped leafhopper Bothrogonia ferruginea (Fabricius) (Hemiptera: Cicadellidae: Cicadellinae) is discussed. This sharpshooter leafhopper is a common but minor pest in organic vineyards and kiwifruit orchards in Japan and a known vector of the phytopathogenic bacterium Xyllella fastidiosa on cultivated grapes in Taiwan. Egg parasitoids of B. ferruginea, a widespread species in parts of Asia, have been previously unknown. Cosmocomoidea tenuis is also identified as an egg parasitoid of another known vector of X. fastidiosa in Taiwan, a sharpshooter (Cicadellinae) leafhopper Kolla paulula (Walker).

Insect growth is affected by various factors, and the elucidation of these factors is important from both basic and applied perspectives. This study examined the effects of temperature and diet on larval development of the endangered carabid beetle Pterostichus (Nialoe) isumiensis in laboratory rearing experiments. Three temperatures (10, 15, and 20 °C) and three diets (mealworms, dipteran larvae, and mealworms + dipteran larvae) were used in a 3 × 3 factorial design, and the survival rate and developmental duration of pre-overwintering stages (first and second instars) were compared. Survival was higher at lower temperatures, and the mealworm diet was associated with lower survival than other diets at lower temperatures. The developmental duration was shorter at high temperatures; at the same temperature, the mealworm diet was associated with a longer developmental duration. These results provide basic information useful for ex situ conservation of this endangered species, which may be required in future, and also inform several working hypotheses on the effects of temperature, diet, and their interaction on larval development in the Carabidae.

We examined the predation of two synanthropic jumping spiders, Hasarius adansoni (Araneae: Salticidae) and Plexippus paykulli (Araneae: Salticidae), on Tribolium castaneum (Herbst) (Coletptera: Tenebrionidae), a grain storage pest, that is sometimes found with these species to determine whether the predatory success of synanthropic and grassland jumping spiders on T. castaneum differs. We examined the predation of two synanthropic and three grassland jumping spiders on T. castaneum adults and larvae. We found that the two synanthropic species preyed on T. castaneum adults and larvae, while the three grassland species never attacked T. castaneum adults. The success or failure of predation on T. castaneum adults also depended on the body size of the jumping spiders.