The spider mite Tetranychus pueraricola infests kudzu vines throughout Japan and causes conspicuous brownish feeding scars. It is possibility that T. pueraricola may get out of hand after invasion of agricultural leguminous crops. To better evaluate its potential severity as a pest, we determined the development, survivorship and life-history parameters of T. pueraricola on kidney bean. At temperatures between 15 and 30°C more than 89% of eggs hatched and of the newly hatched larvae ca. 89% attained maturity. There was no significant difference in eclosion rate of eggs or survival rate of immature stages among the temperatures. The lower threshold temperature from egg to oviposition was 10.9°C and the thermal constant was 147.1 degree-days. Based on these data, the maximum number of generations that can theoretically complete development under average field conditions in Ibaraki, Central Japan is between 11 and 14 generations per year. At 25°C, females laid on average 125 eggs during a mean oviposition period of 12.6 days. The intrinsic rate of natural increase (r m ) was 0.102 at 15°C, 0.179 at 20°C, 0.299 at 25°C and 0.377 at 30°C. Thus, T. pueraricola has the second highest r m -value among tetranychid mites reported so far at 25°C, with T. okinawanus having the highest (0.316). This indicates that T. pueraricola has the potential to become a serious pest on agricultural crops.
Carpoglyphus lactis(L.) has been documented as one of the most important pest contaminants of dried fruits during storage. Dried apricots are especially sensitive to the mite infestation, although data concerning bionomics and control of the mite on this subject is rare. In this study, the biological aspects of C.lactis fed on dried apricots were examined under laboratory conditions at 25±2 o C and 85±5% RH in complete darkness. Eggs required an average of 15.2 and 12.2 days to develop into adult females and males, respectively. The oviposition period averaged 10.2 days during which females deposited an average of 31.8 eggs with a daily rate of 3.18 eggs per female. Mean life span of females was longer than that of males being 29.33 and 22.0 days, respectively. The hatch rate was 78.83% and the female to male ratio was 1:0.87. The deutonymph (hypopus) stage was not found in the entire C.lactis life cycle. On the other hand, the acaricidal activity of the three plant oils extracts, cinnamon, chrysanthemum, and eucalyptus oils against C.lactis adults was bio-assayed after a 24h period via direct contact application. As measured by LC50 values, the most toxic oil was cinnamon (LC50 = 5.6 ppm) followed by chrysanthemum (LC50 = 13.9 ppm), and eucalyptus (LC50= 89.2ppm).
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