Applied Entomology and Zoology最新文献

Syrphid larvae are well-known predators of aphids; however, we sometimes observed them on onion plants with thrips and without any aphids, which intercropped with barley in our previous study. Therefore, we hypothesized that syrphid larvae fed on thrips in the onion field in the absence of aphids, their main prey. This hypothesis was tested by analyzing the prey DNA from syrphid larvae collected from onion plants intercropped with barley. We found that they preyed on three thrips species: Thrips tabaci (Lindeman), Frankliniella occidentalis (Pergande), and Anaphothrips obscurus (Müller). Moreover, we observed that syrphid larvae collected from onion plants fed on larval T. tabaci in a laboratory setting. According to COI sequencing of their genomes, the syrphid species occurred from the onion plants were Sphaerophoria macrogaster (Thomson), Melanostoma scalare (Fabricius), Melanostoma mellinum (L.), and Platycheirus pennipes (Ohara); all of them were found to prey on thrips in the prey DNA analyses. These results and observations supported the hypothesis and suggested that intercropping barley as a living mulch may become an option for enhancing the potential of native syrphid species as generalist predators in the onion fields.

Wild small bees are known to visit apple flowers along with honeybees and other bees. However, their species composition in Japan has not been well investigated for more than 50 years. Here, we identified 791 wild small bee individuals captured in seven apple orchards in four prefectures. Andrena semirugosa brassicae (Hymenoptera: Andrenidae) was the predominant species visiting apple flowers in five orchards, although it had not been listed as a major visitor in past studies. This species was also the major visitor to dandelion flowers in the orchards. We deposited the sequences of the cytochrome c oxidase subunit I gene (CO1) of 250 individuals (7 genera; 32 species) in DDBJ to support the genetic identification of small bees widely observed in apple orchards in Japan.

Management of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) populations is a key strategy to reduce the transmission of viruses to crops. Yellow sticky traps are widely used tools to monitor and/or reduce B. tabaci populations. Nevertheless, these traps also allow the collection of debris and nontarget organisms including B. tabaci natural enemies. Covering the surface of the traps with a mesh is an alternative to mitigate those unwanted effects. Two field experiments were carried out to determine the color and size effect of the mesh on the capture of B. tabaci and nontarget organisms. The color experiment showed that among the 13 colors evaluated, only the yellow mesh did not reduce statically the number of B. tabaci captured compared with the uncovered traps. On the size experiment, among the three sizes evaluated, no statistical effect on the number of B. tabaci captured was exhibited. For the capture of nontarget organisms, the significative lowest values were showed in the small diamond and hexagon grooves. Those mesh traits were validated with two additional field experiments. The results of this study indicate that yellow sticky traps covered with a yellow mesh reduce the collection of nontarget organisms without affecting the capture of B. tabaci.

Japanese farmers who grow Oriental persimmon, Diospyros kaki Thunb. (Ericales: Ebenaceae), occasionally introduce Apis mellifera L. (Hymenoptera: Apidae) hives into their orchards during the flowering season, mainly because cultivars such as ‘Fuyu’ require pollination for stable fruit set. However, wild pollinators might serve this function. Thus, we aimed at identifying the most important pollinators of D. kaki in Japan by surveying visitation frequency across ten prefectures and pollination efficiency. The predominant flower visitors were Bombus ardens ​ardens Smith (Hymenoptera: Apidae) and A. mellifera, with similar pollination efficiencies. The estimated threshold number of pollen grains for fruit set of D. kaki ‘Fuyu’ was 27, which was comparable to the number deposited by a single visit of either species, meaning one visit of these dominant visitors probably induces fruit set. However, more pollen grains deposited by multiple visits further ensured fruit set. To achieve > 80% fruit set, more than about 70 pollen grains were needed. These results indicate that several visits by the bees would be sufficient for fruit set of D. kaki ‘Fuyu’.

Photoperiodism is an adaptive response used by organisms to assess day length and anticipate upcoming seasons and to coordinate their (or their offspring’s) development and physiology with the environmental changes. These physiological mechanisms have long been studied to understand insect life cycles, combat pests, conserve endangered species, and rear beneficial insects. Recent genetic manipulations have greatly expanded our knowledge of the molecular mechanisms underlying photoperiodism. Here, I review our current knowledge of the physiological and molecular mechanisms underlying photoperiodic time measurement, photoreception, and circadian clocks, which constitute insect photoperiodism modules, with a special emphasis on photoperiodic time measurement models.

The fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), is one of the most important pests, which was first found in Japan (Kagoshima Prefecture) in 2019. This study reports the morphological characteristics of all the larval instars in order to identify S. frugiperda among common polyphagous noctuid pests in Japan. In general, several larval characteristics of S. frugiperda are rudimentary or indistinct in early instars larvae, yet sufficiently distinguishable from the larvae of other species apart from the first instar. This stage shows considerable overlap among different species in the proportion of D1 and D2 pinacula widths to the spiracle on 8th abdominal segment, cuticle texture and prothoracic L setae arrangement.

To monitor and control the Japanese orange fly Bactrocera tsuneonis (Miyake) (Diptera: Tephritidae), it is important to determine their dispersal ability. Therefore, to determine the genetic structure of this species, we developed microsatellite markers at 17 loci for B. tsuneonis. A total of 80 adult females and males randomly collected from abandoned orchards in the Oita and Yamaguchi Prefectures, in the western part of Japan, were used for polymorphism analysis using the microsatellite markers. The average number of alleles was 2.65 for the 17 loci, in which two loci did not show polymorphism. The expected heterozygosity ranged from 0 to 0.663, although the observed heterozygosity was relatively low between 0 and 0.105. The null allele frequencies varied among populations. Moreover, no polymorphism was found in the three larval populations collected in the Oita Prefecture. These results suggested a high degree of inbreeding for this species. Significant genetic differentiation between females and males of the same population was not observed, although it was observed between the Oita and Yamaguchi populations. A bottleneck effect was detected in Yamaguchi but not in Oita, and this is congruent with the history of an expanding distribution in this species. These markers could be used for population discrimination and to expand the geographic history of this species, potentially contributing to the pest management of B. tsuneonis.

Prey mothers at risk of predation sometimes change the morphology and/or antipredator behaviour of their offspring to reduce predation risk. When maternal exposure to predation risk changes the morphology of some offspring, it is unclear whether and how the other offspring, which have normal morphology, exhibit antipredator behaviour. We aimed to clarify these behaviours using pea aphids, Acyrthosiphon pisum Harris (Hemiptera: Aphididae), and aphidophagous Asian ladybird beetles, Harmonia axyridis Pallas (Coleoptera: Coccinellidae), which induce aphids to release the alarm pheromone (E)-β-farnesene (EBF) and to exhibit antipredator responses. Pea aphids exposed to EBF reduced reproduction through changes in the number of wingless offspring, producing more winged offspring than unexposed conspecifics. Wingless aphids whose mothers had been exposed to EBF showed higher dispersal from host plants with predators than the offspring of unexposed mothers. These results suggest that pea aphids at risk of predation increase their offspring survival by increasing the number of winged offspring and antipredator dispersal of wingless offspring.

A highly invasive alien species in North America and Europe, the Asian longhorned beetle Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae), has been detected in various parts of Japan since 2020. In addition to damaging host trees, A. glabripennis may severely impact the Japanese ecosystem by interfering with A. chinensis (Foster) (formerly called A. malasiaca), a common and related native species with a similar niche. To assess the potential risk of reproductive interference between the two species, mating behavior between interspecific females and males was examined in the laboratory using field-collected sample individuals. Males of both species mounted on female A. glabripennis and attempted to insert genitalia at similar frequencies (approximately 50%), but A. chinensis males always failed to copulate. In contrast, male A. glabripennis did not have sexual behavior with female A. chinensis. The results show that mating between the two species is typically unsuccessful, although recent research showed that the two species could produce a hybrid when paired for 4 weeks. The erroneous interspecific mating attempts may reduce both species’ fitness. Therefore, the population-level impact of this reproductive interference should be assessed.

Solenopsis invicta Buren (Hymenoptera: Formicidae; red imported fire ant) is an invasive species in several parts of the world. A major contributor to the spread of S. invicta is infested shipping containers. The vapor of allyl isothiocyanate (AITC), a naturally occurring organosulfur compound, is highly toxic to S. invicta; however, AITC is highly volatile. Microencapsulation of AITC in polyethylene (PE) resin slows the release of AITC, making it a potentially useful material for preventing S. invicta infestations. Here, we examined the efficacy of AITC microencapsulated in PE (mAITC) as a repellent against S. invicta infestation of cardboard boxes, a common containerized cargo. Using baited cardboard boxes, we found that the number of S. invicta individuals entering boxes containing an mAITC sheet was significantly less than that entering boxes without an mAITC sheet. When a PE cover, which is often used to protect carboard boxes during shipping, was used, vapor concentrations of AITC inside the boxes were increased and the number of S. invicta individuals entering the boxes was reduced almost to zero. These findings indicate that mAITC sheeting, especially in combination with a PE cover, is a promising material for the protection of containerized cardboard-box cargo against S. invicta infestation.