The insecticide susceptibility of the vegetable leafminer, Liriomyza sativae Blanchard, the serpentine leafminer, L. trifolii (Burgess), and the tomato leafminer, L. bryoniae (Kaltenbach), on kidney bean leaves were evaluated at 25°C under a 15L–9D photoperiod. Susceptibility to the tested insecticides varied among the developmental stages, species, and populations of the leafminer. Among the 25 insecticides tested on second instar larvae using an insecticide spraying tower, chlorpyrifos, isoxathion, cartap, thiocyclam, cyromazine, emamectin benzoate, pyridalyl, and spinosad were more toxic on the three Liriomyza species. Among the 20 insecticides tested on adult leafminers using the leaf dipping method, cartap and thiocyclam produced high mortality in the three Liriomyza species. The application of cartap, thiocyclam, emamectin benzoate, and spinosad reduced the number of feeding and oviposition punctures made by female adults of the three Liriomyza species on the leaves. None of the insecticides examined significantly affected the egg mortality of any of the three Liriomyza species.
The possibility of reducing insecticide use for controlling direct sucking damage to potatoes by Aphis gossypii was investigated under field conditions. A laboratory experiment was also conducted to determine the possible cause of resurgence in A. gossypii treated with acephate. The susceptibility of A. gossypii to this insecticide was much lower than that of two other inhabiting aphids (Myzus persicae and Aulacorthum solani) and predators (Harmonia axyridis and Orius minutus), indicating that the resurgence of A. gossypii was probably caused by the elimination of natural enemies and competitors by this insecticide. In the field plot without insecticide application, there was no outbreak of A. gossypii (or other aphid species) observed due to suppression by indigenous predators (ex. ladybirds, lacewings, Orius bugs); e.g., the density of A. gossypii did not exceed 10 insects per compound leaf, and no other insect pests were conspicuous. Consequently, both the tuber yield and the starch value were comparable to those in the insecticide-treated plot. The indigenous predators inhabited the environment around the field over a wide area during the potato-growing season. These findings suggested that there is a possibility of realizing potato cultivation without the application of insecticides.
Damage to the Japanese pear by Cossus insularis was confirmed in Naruto City and Matsushige Town in Tokushima Prefecture, Japan, in June 2001, which was the first recording of infestation of C. insularis in the Japanese pear. In 2002, the ratios of damaged trees were surveyed and found to average 27.7% in the “Kosui” cultivar and 2.5% in the “Hosui” cultivar. The seasonal prevalence of adult emergence was also surveyed on the Japanese pear in 2002 and 2003. Adults emerged between mid-June and mid-August with a peak in number in early to mid-July.
We investigated the effectiveness of three methods of release (“bottle settling”, “bottle hanging” and “tube insertion”) of aphids mummified by Diaeretiella rapae (mummies) against pest aphids in a greenhouse for growing komatsuna Brassica rapa nothovar. Plastic bottles with mummies were set in the passage for “bottle settling” and were set in paper cups hanging from the ceiling for “bottle hanging”, and small plastic tubes with mummies were inserted directly into the ground near the crop for “tube insertion”. Since the percentage of adult emergence of D. rapae from released mummies was low in some cases for “bottle settling” (50–61%) and “bottle hanging” (14–43%), probably because of exposure to water and sunlight, the original equipment for release of the three methods was improved to protect mummies from water and sunlight. The percentages of adult emergence of D. rapae were high in all of the improved equipment (93–96%), and were equivalent to those obtained in the laboratory (87–99%). We discuss the most useful method for komatsuna-growing greenhouses.
The effect of temperature on oviposition and adult longevity of the legume pod borer, Maruca vitrata (Fabricius) (Lepidoptera: Crambidae) was examined at four constant temperatures with a 14L10D photoperiod. The mean numbers of eggs laid per female were 838, 856, 777 and 644 at 27, 25, 22 and 20°C, respectively. Female adult longevity and pre-ovipositional period were shortened with increasing temperature. The net reproductive rate was highest at 25°C (342.2), and the intrinsic rates of natural increase were 0.1844, 0.1847, 0.1807 and 0.1661 at 27, 25, 22 and 20°C, respectively.