Amblyseius (Neoseiulus) californicus is an indigenous mite in Japan that feeds on many spider mite species. We evaluated the development, survivorship and life-history parameters of A. californicus on a diet of eggs of Tetranychus urticae (red form). More than 97.3% of A. californicus eggs hatched and more than 81.6% of newly hatched larvae attained maturity at temperatures between 15 and 35 degrees C. Females oviposited at 37.5 degrees C, but no eggs hatched. At 40 degrees C, no females laid eggs. The lower threshold temperature from egg to oviposition was 10.3 degrees C and the thermal constant was 86.2 degree-days. Based on these data, the maximum number of generations that could complete development in a year under field conditions in Ibaraki, central Japan, would be between 21 and 28. At 25 degrees C, females laid a mean of 41.6 eggs during a mean oviposition period of 19.4 days. The intrinsic rates of natural increase (rm) were 0.173 at 20 degrees C, 0.274 at 25 degrees C and 0.340 at 30 degrees C.

Stethorus japonicus Kamiya (Coleoptera: Coccinellidae) is an indigenous ladybird beetle in Japan, which feeds on many spider mite species. We evaluated the development, survivorship and life-history parameters of this lady beetle on a diet of eggs of the two-spotted spider mite, Tetranychus urticae Koch (red form) (Acari: Tetranychidae). In addition, the effect of short photoperiod on its reproduction was assessed. Survival rates from egg to adult were more than 71% at temperatures between 17.5 and 30°C. The highest immature mortality was 100% at 35°C followed by 76% at 15°C and 52% at 32.5°C. The lower threshold temperature for development from egg to egg-laying adult was 13.0°C and the thermal constant was calculated as 238.7°days. Based on these data, the maximum number of generations that could complete development in a year under field conditions in Ibaraki, central Japan, would be between five and seven. The intrinsic rates of natural increase (r m ) were 0.093 at 20°C, 0.156 at 25°C and 0.241 at 30°C. Reproductive diapause was induced at photoperiods with light phases shorter than 13 h at 18°C.

A 3.5-kb DNA fragment that confers resistance to D-cycloserine (DCS) was cloned from the chromosomal DNA of a DCS-producing Streptomyces garyphalus into Streptomyces lividans by a shot-gun cloning technique. Nucleotide sequence analysis revealed the existence of four open reading frames (ORFs B, C, D, and E), together with two incomplete ORFs, A and F. By introduction of the cloned fragment into Escherichia coli, the host obtained resistance to DCS. We showed that ORF B, which consists of 903bp, is a DCS resistance gene. The hydropathy plot analysis of a protein deduced from ORF B revealed that the protein carries membrane-integral domains spanning the membrane 10 times, which suggests that the DCSresistance determinant may be a factor associated with DCS transport.

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Scolothrips takahashii is an indigenous thrips in Japan that feeds on many spider mite species. To evaluate whether S. takahashii has potential as a biological control agent for spider mites, we investigated the development, survivorship and life-history parameters of S. takahashii on a diet of Tetranychus urticae (red form) eggs at different temperatures. More than 74% of thrips eggs hatched and more than 76% of newly hatched larvae attained maturity at 15-35°C. No females laid eggs at 37.5 or 40°C. The lower threshold temperature for development from egg to oviposition was 11.7°C and the thermal constant was calculated as 204.1 degree-days. Based on these data, the maximum number of generations that could complete development in a year under field conditions in Ibaraki, central Japan would be between seven and ten. Mating was unnecessary to induce oviposition but unmated females produced only male progeny. At 25°C, females laid a mean of 90.5 eggs during a mean oviposition period of 17.8 days. The values for the intrinsic rate of natural increase (r m ), one important life-history parameter, were 0.113 at 20°C, 0.195 at 25°C, and 0.246 at 30°C. These results suggest S. takahashii has considerable potential as a biological control agent against spider mites.