The tendency of the two-spotted spider mite, Tetranychus urticae, to lay eggs on the abaxial (lower) side of host plant leaves has been explained as an adaptation to avoid rainfall and solar ultraviolet radiation. However, differences in the nutrition and effects of gravity between the abaxial and adaxial (upper) leaf surface could affect mite fitness. We investigated the fecundity of mites using kidney bean leaf discs with their adaxial or abaxial sides facing upward or downward. Fecundity was greater on adaxial leaf surfaces and on leaf discs facing downward but did not differ between adaxial surfaces facing upward and abaxial surfaces facing downward, suggesting that the effects of gravity and nutrition compensated for each other. Consequently, although leaf surface nutrition and gravity direction affected fecundity, these factors do not explain the biased distribution of T. urticae.

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Six species of macrochelid mites were collected from scarabaeid dung beetles in Sempu Island, East Java, Indonesia. Of these, one species, Macrocheles insulicola was described as new to science. The remaining five species were Glyptholaspis asperrima (Berlese, 1905), Neopodocinum subjaspersi Hartini and Takaku 2003, M. dispar (Berlese, 1910), M. entetiensis Hartini and Takaku 2005, and M. jabarensis Hartini and Takaku 2003.

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We examined how Hypoaspis (Euandrolaelaps) yamauchii Ishikawa (Acari: Laelapidae), collected from accumulated rice husk in Hokkaido, northern Japan, preyed on Tyrophagus similis Volgin (Acari: Acaridae) at constant temperatures. An adult female H. yamauchii preyed on T. similis of any stage except for the egg and consumed an average of 16.1 ± 5.3 tritonymphs at 20°C during a 24-h experimental period. The ambient temperatures of 20°C and 25°C were suitable, whereas those of 15°C and 30°C were unsuitable for predation. At temperatures of 15-25°C, H. yamauchii survived for 21 days under fasting condition. These mites preyed on T. similis adults and laid eggs after the 96-h post-fast feeding at 20°C.

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An outbreak of the brown wheat mite, Petrobia latens (Müller), occurred on carrot cultivated in greenhouses of Tokushima Prefecture, Shikoku Island, southern Japan, in early spring of 2011. It caused a serious reduction of yield, because effective methods to control this mite were lacking. The present study determined the susceptibility of P. latens to 22 agricultural chemicals, including three physical control agents (thought to block the target organism’s spiracles) and two granulates, because chemicals will be used as the first line of pest control. When adult females of P. latens were treated with recommended concentrations of the chemicals, seven out of 17 pesticides and fungicides — i.e., bifenazate, DBEDC, emamectin benzoate, lepimectin, methomyl, milbemectin and pyridaben — caused 95-100% mortality after 96 h (lepimectin, methomyl and mibemectin caused 90-100% mortality even after 24 h). The three physical control agents had no effect on the adult females. The two granulates were also tested for an ovicidal effect against diapause eggs of P. latens. It appeared that only diazinon had a negative effect on egg hatching (ca. 45% reduction relative to control). These results suggest that this species could be controlled, in principle, with any of seven effective chemicals as a first method. Two of these seven chemicals — emamectin benzoate and methomyl — are registered as pesticides for carrot crops.

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