Here, I reviewed the studies on Stigmaeopsis spider mites to demonstrate their useful and unique aspects. Approximately 70 reports on Stigmaeopsis taxonomy, life history, diapause, life type, nesting behavior, feces depositing behavior, social behavior, male-to-male aggression, genetics, molecular phylogeny and predator-prey interaction were addressed. It is clear that Stigmaeopsis species are excellent materials for evolutionary ecology and genetic studies, because of their low mobility, rapid development, ease of rearing, diverse genetic systems and variable ecology. The main topics described here were as follows: Stigmaeopsis species show communal social and sub-social life types. Cooperation and aggressiveness vary among species, making them promising materials for the study of kin selection operating on behavior. Furthermore, despite their haplo-diploid genetic system, this spider mite group has retained female-limited recessive genes that cause inbreeding depression. Variations in sociality have evolved partly through predation pressure and kin selection. Furthermore, I pointed out the problems that have been—and others that still need to be—solved in order to learn how Stigmaeopsis species evolved.
The olive weevil, Pimelocerus perforatus（Roelofs）, is endemic to Japan and feeds on trees of Oleaceae. Although this species is a serious pest of olive, its ecological and behavioral traits have not been intensively studied because of a lack of continuous laboratory rearing techniques. In this study, we established a continuous rearing method for P. perforatus using an artificial diet for larvae and olive twigs for adults. Adult females were reared with olive twigs and they oviposited into moistened cotton plugs wrapped at the base of the twigs. The eggs were placed on moistened cotton plugs in microtubes until hatching. Larvae were individually reared in Petri dishes and fed an artificial diet of “Insecta F-II” or “Insecta LFS” until pupation, and then the pupae were transferred to other Petri dishes with a moistened Kimwipe. The pupal and total survival rates were higher when the weevils were reared with Insecta LFS than with Insecta F-II. In addition, the larval duration of the weevils fed Insecta LFS was shorter than that of the weevils fed Insecta F-II. Eggs were reared at 20, 25, 27, and 30°C to calculate the developmental zero and thermal constant. Larvae and pupae were reared at 25°C, and the developmental zero and thermal constant were estimated using the present results and data obtained from a previous study at 20, 27, and 30°C. In addition, adult prefeeding, precopulatory, and preoviposition duration were surveyed at 25°C.
We investigated the number of Leguminivora glycinivorella（Matsumura）adults using a sex pheromone trap and the abundance of infested seeds in soybean fields in Niigata Prefecture. The examined fields were uplands converted from rice paddy fields and are almost continuously used for cultivating soybean. The investigation was initiated at 6 fields in 2011 and continued until 2015. However, fields converted to paddies were excluded from the observation, and new soybean fields were included. Fluctuations in the numbers of captured adults of L. glycinivorella were similar between the fields and years, that is, capturing of adults began in the middle of August and ended in the end of September, and the peak period was from the 6th pentad of August to the 2nd pentad of September. The total number of captured adults and the percentage of infested seeds differed between the fields and increased with the number of years of continuous cropping. A significant positive correlation was observed between the total number of captured adults and the percentage of infested seeds. Furthermore, a significant positive correlation was observed between the percentage of infested seeds in the previous year and the number of captured adults in the present year. These results suggest that the number of years of continuous soybean cropping and the percentage of infested seeds in the previous year could be used as parameters for forecasting the abundance of this pest.
Flies infesting orchid flowers and fruits were collected from 16 orchid species from nine prefectures in Japan. Fifteen orchid species collected from Fukushima to Kumamoto Prefectures were infested by Japanagromyza tokunagai（Sasakawa）. These results suggest that this agromyzid fly feeds on a wide range of orchid species, and is widely distributed in Japan. On the other hand, two orchids were injured by Chyliza vittata Meigen. Because these orchids were collected from Hokkaido Prefecture or high-altitude areas in Yamanashi Prefecture, this fly species seems to be distributed in cool temperate areas, but further investigations are required.
Scirtothrips dorsalis Hood is one of the most important pest thrips on mango Mangifera indica L., trees cultivated in Okinawa Prefecture, southwestern Japan. Scirtothrips dorsalis has two strains, C and YT, but there is little information about their geographical distribution and composition ratio on mango in Okinawa Prefecture. In this study, we collected S. dorsalis infesting young leaves of mango from islands in Okinawa Prefecture and analyzed their strain based on a multiplex-PCR method. Among 80 localities investigated in Okinawa Prefecture, the number of localities with only strain C, both strains or only strain YT were 68 locations, 11 locations and 1 location, respectively. The composition ratio of strain C among the localities investigated, in which both strains were found, was high（77–95%）in 8 locations and low（5–29%）in 3 locations. These results show that the main strain of S. dorsalis infesting mango in Okinawa Prefecture is strain C.
We investigated the relationships between the timing of initial bud and fruit infestation by second-generation larvae of the persimmon fruit moth, Stathmopoda masinissa Meyrick, and the first catch dates of first-generation adult males in pheromone traps in persimmon orchards in Gifu, Hiroshima, and Shimane Prefectures, Japan, between 2010 and 2013. Seven to twelve days after the first trap catch of first-generation adults coincided with the period between initial bud infestation and initial fruit infestation, and insecticide spraying at this time was effective in suppressing fruit damage caused by second-generation larvae. Therefore, to control this pest, we recommended insecticide spraying from seven to twelve days after the first trap catch of the first generation.