The ectoparasitic mite, Varroa destructor Anderson and Trueman（Mesostigmata: Varroidae）, causes tremendous damage to the beekeeping and pollination industries. These industries rely upon the naïve European honey bee, Apis mellifera L.（Hymenoptera: Apidae）, to which the mite has spread from its native host, the Asian honey bee, Apis cerana Fabricius. Researchers around the globe have been building our understanding of the ecology of V. destructor. However, the research has not been regularly reviewed in Japanese, and researchers and beekeepers in Japan have not had access to the most update reports over the past two decades. Here, I review recent developments in the study of the biology and ecology of V. destructor and the resistance of honey bees to the mite in Japanese.
We investigated the efficacy of various insecticides, including diamide, on the oriental tea tortrix, Homona magnanima Diakonoff（Lepidoptera: Tortricidae）, a major pest of tea（Camellia cinensis）, in Kagoshima Prefecture, Japan. The results showed that diamide insecticides had low efficacy against the oriental tea tortrix in the southern part of the prefecture（Nansatsu region； Makurazaki City, Minamikyushu City）. The LC50 values ranged from 28.26 to 267.62 ppm（Resistance Ratio（RR）: 41.0–387.9）for flubendiamide, 40.60 to 67.75 ppm（RR: 24.9–41.6）for chlorantraniliprole, and 40.33 to 107.49 ppm（RR: 93.8–250.0）for cyantraniliprole, indicating that the oriental tea tortrix has developed resistance to diamide insecticides. The insecticides other than diamide and benzoylurea IGR were highly effective. However, in other areas of the prefecture, all insecticides（including diamide）tested showed high efficiency. Furthermore, crossbreeding experiments showed that diamide resistance is autosomal, incompletely recessive. In the future, it is necessary to monitor the recovery of susceptibility against diamide insecticides in the Nansatsu region while avoiding the expansion of resistance development.
Five phytoseiid mite species: Phytoseiulus persimilis Athias-Henriot, Neoseiulus californicus（McGregor）, Neoseiulus womersleyi（Schicha）, Amblyseius eharai Amitai and Swirski, and Euseius sojaensis（Ehara）（Acari: Phytoseiidae）were collected from commercial Japanese pear orchards in Shizuoka Prefecture. To evaluate the suppressive effect of generalist phytoseiid species on the spider mite Tetranychus kanzawai Kishida（Acari: Tetranychidae）, we compared four treatments（E. sojaensis release, A. eharai release, synthetic pyrethroid application, and no-release）performed in a greenhouse. These treatments were conducted when T. kanzawai densities were low, and pine pollen was provided as alternative food for predatory mites in all treatments. At late June, the peak densities of T. kanzawai were significantly low in E. sojaensis release and in no-release compared with in pyrethroid application and in A. eharai release. The dominant phytoseiid species in E. sojaensis release and in no release was E. sojaensis. After July, however, E. sojaensis densities became lower in E. sojaensis release as well as no-release, and thus T. kanzawai densities became higher in all treatments at early August. These results suggest that conservation and augmentative release of E. sojaensis prior to T. kanzawai population increase, might suppress the outbreak of this spider mite in Japanese pear orchards until early summer.
We evaluated the effects of tannic acid and four major catechins present in tea on the insecticidal activity of Bacillus thuringiensis serovar kurstaki formulation against Adoxophyes honmai Yasuda（Lepidoptera: Tortricidae）using the oral administration method. We also evaluated the insecticidal activity of B. thuringiensis against A. honmai using the leaf dipping method with tea leaves plucked in different tea seasons in 2010 and 2011: in May（hereafter referred to as 1st tea）, June to July（hereafter referred to as 2nd tea）, August to mid-September（hereafter referred to as 3rd tea）, and late September to October（hereafter referred to as 4th tea）. The catechin content was measured at the time of each harvest in 2011. Tannic acid and catechins decreased the B. thuringiensis activity in a dose response-dependent manner. The insecticidal activity was decreased by the late tea season and was found to be lowest in the 4th tea. The content of the catechins in the four seasons was in the following order: 2nd tea＞3rd tea＞4th tea＞1st tea. Though these results suggest no direct relationship between the content of catechins and insecticidal activity on tea leaves, other factors might be involved to influence the effects of B. thuringiensis.
A method of rearing successive generations of the rice stink bug, Lagynotomus elongatus（Dallas）（Hemiptera: Pentatomidae）, was developed. The insects were supplied with rice spikelets and millet seedlings as food. Absorbent cotton sheets soaked with sufficient water were laid over the entire bottom of the rearing container； abundance of water was a key point. Use of this method decreased the mortality of young nymphs, resulting in a survival rate of 33% across the entire nymphal stage. Although the adult body length was on average 15% shorter than in field-collected adults, we were able to rear successive generations of L. elongatus over a year.