Acetylated glyceride（AG）is a unique pesticide composed of food additives that regulate insect behaviors. Our previous findings showed a reduction in male courtship songs and courting pairs on AG-treated host leaves, as well as repellence of adult MEAM1（Middle East Asia Minor 1）of Bemisia tabaci（Gennadius）（Hemiptera: Aleyrodidae）. Here, we investigated the efficacy of AG on the mutual courtship behaviors of MEDQ1（Mediterranean Q1）B. tabaci, Trialeurodes vaporariorum（Westwood）（Hemiptera: Aleyrodidae）, and Liriomyza sativae（Blanchard）（Diptera: Agromyzidae）. We acoustically analyzed the courtship and response songs of test pairs on leaves after exchanging AG-treated leaves with non-treated leaves. Sexual communication and the rate of mating success for MEDQ1 both decreased significantly on treated leaves. A significant reduction in male courtship songs with AG application was also observed in T. vaporariorum. For L. sativae, courtship songs were performed in 88.2% of the test pairs on non-treated leaves, with a mating success rate of 58.8%； in contrast, only 29.6% of the test pairs on the treated leaves produced courtship songs, with a mating success rate of 7.4%. These results suggest that AG negatively influenced the continuity of mutual courtship behavior, which consists of male songs and female response songs.
Plautia stali Scott（Hemiptera: Pentatomidae）is widely distributed in Japan. Plautia stali damages fruit trees, and the primary control method is to spray insecticides based on monitoring and predicting the abundance of P. stali. Plautia stali overwinters and develops in coniferous trees and then flies to orchards. In this study, we aimed to disrupt the behavior of P. stali using artificial vibrations. We examined the behavior of P. stali exposed to different frequencies and accelerations of vibrations under laboratory conditions. Several responses were observed, such as freezing, squatting with bending all legs, and walking. Notably, the responses to vibrations at 150 and 500 Hz were induced by low accelerations. Next, we attached an electromagnetic shaker to the base of a citrus tree and observed the responses of P. stali. The responses were similar to those in the laboratory test. Moreover, when several citrus seedlings were branched via jigs and vibrated simultaneously, adults also responded to the vibrations. In order to develop optimal methods for vibrational application, further studies on the control of the feeding behavior of P. stali and the effects of substrate-borne vibrations on fruit trees are required.
I explored the mating behavior, adult longevity, and number of eggs oviposited in Diomea cremata（Butler）（Lepidoptera: Noctuidae）under laboratory conditions. Calling and mating behaviors were observed at 24°C under a 16 : 8-h light : dark regimen. Calling and mating were evident in the scotophase. Calling activities were observed in 59–89% of 0–6-day-old female adults and did not differ by age. The mating duration was 93.6±3.7（mean±SE）min. Most males did not copulate on the day of emergence, but females did. Adult longevity and ovipositing were investigated at 24°C under a 16 : 8-h light : dark regimen. The adult longevity（mean±SE）was 8.8±0.7 days for males and 11.5±1.3 days for females. The proportion of ovipositing females increased at 3 days after adult emergence. On average, 160.2±29.7 eggs were oviposited; this number was significantly correlated with adult survival. These results suggest that D. cremata has a reproductive strategy to exploit fruiting bodies whose numbers were unpredictable over time and space, i.e. female adults copulate soon after emergence, after that they search for fruiting bodies which are adequate to their larval food and lay eggs throughout their lifetime.
Entomopathogenic microsporidia are pathogens of various arthropods and therefore cause disease in important host species ranging from agricultural pests to beneficial insects. Here, we investigated three genera of entomopathogenic microsporidia from dragonflies； these were isolated in Kanagawa, Japan, in 2014. In total, the infection rate was 0.85%（16 of the 1,886 surveyed dragonfly adults）. Four strains of microsporidia selected from infected Orthetrum albistylum speciosum（Uhler）（Odonata: Libellulidae）adults were measured for spore size and analyzed at the molecular level. According to spore size, the four strains were roughly divided into two groups. Analysis of small-subunit ribosomal RNA sequences indicated that the microsporidia strains belonged to the Trachipleistophora, Vavraia, and Paranosema clusters. Microsporidia species that are closely related to the strains isolated in this study have previously been reported to infect insects other than dragonflies. Therefore, we suggest the possibility that the microsporidian strains we isolated in O. albistylum speciosum may also infect other insect species.
The smaller tea tortrix, Adoxophyes honmai Yasuda（Lepidoptera: Tortricidae）, a polyphagous pest insect, is a serious pest on 43 plants, including tea. It is well known that tea leaves contain a variety of polyphenols such as catechin derivatives. Since some polyphenols in tea may have an influence on Bacillus thuringiensis activity against A. honmai, we examined how different host plants and the polyphenols of tea leaves influence B. thuringiensis activity. We evaluated B. thuringiensis activity by the leaf dipping method using the leaves of tea, Japanese pear, grape, and peach. The LC50 value for tea was 0.158 g/L（formulation weight/water volume）, whereas Japanese pear, grape, and peach showed significantly lower LC50 values ranging from 0.0095–0.0111 g/L. Hence, it was evident that tea leaves suppressed B. thuringiensis activity compared with other tree leaves. We identified that（−）epigallocatechin gallate（hereafter referred to as EGCG）, （−）epigallocatechin（hereafter referred to as EGC）, （−）epicatechin gallate（hereafter referred to as ECG）, and（−）epicatechin were the major components of tea polyphenols. The influences of polyphenols on B. thuringiensis activity were evaluated by the oral administration method, and EGCG, EGC, ECG, （＋）catechin, and myricetin showed higher inhibitory effects on B. thuringiensis activity compared to other polyphenols. These results indicate that tea leaves can deteriorate the insecticidal activity of B. thuringiensis mainly due to the influence of EGCG, EGC, and ECG.
In peach cultivation in Yamanashi Prefecture, fruit growers used insecticides to control Pseudaulacaspis prunicola（Maskell）（Hemiptera: Diaspididae）, but serious damage occurred. Therefore, we investigated the dominant species of scale insects on peaches. P. prunicola has a closely related species, P. pentagona（Targioni-Tozetii）, and the occurrence period of P. pentagona larvae of the 1st generation has been observed 9–13 days later than that of P. prunicola. However, the dominant species observed was P. prunicola. We suspected a time lag due to climate change between the occurrence of the 1st generation of P. prunicola larvae and the spraying of insecticides. However, the peak time of larval occurrence calculated from the effective accumulated temperature（144.1 degree-days; lower development threshold temperature 10.0°C; calculated from January 1）matched the timing of spraying. Furthermore, we observed the highly control effects of buprofezin at variously timed applications on P. prunicola larvae collected from Japanese plums cultivated under low pest control pressure. Buprofezin has been used as a principal insecticide for P. prunicola in Yamanashi Prefecture. However, the effect of buprofezin on P. prunicola, collected from five peach orchards cultivated by the practice method, was low. This suggests that low sensitivity to buprofezin is one of the causes of the frequent occurrence of P. prunicola.
Aromia bungii（Faldermann）（Coleoptera: Cerambycidae）is an exotic pest of Rosaceae trees in Japan. For the purpose of pest control management of A. bungii, this study assessed seasonal changes in its larval frass ejection in the western Tokyo Metropolis. The presence or absence of frass ejection and the number of ejecting holes were evaluated on 294 cherry trees, Cerasus×yedoensis “Somei-yoshino,” in late spring as well as in late summer. Additionally, we assessed the relationship between the basal circumferences of the tree trunks and the presence or absence of A. bungii frass ejection. The proportions of trees with frass ejection doubled from late spring（10%）to late summer（20%）. The occurrence probability of frass ejection was higher as the basal circumferences of the tree trunks were larger. The results of this study will be utilized for pest control management of A. bungii.