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Tran D.H.,Hue University | Ueno T.,Laboratory of Insect Natural Enemies
Journal of the Faculty of Agriculture, Kyushu University | Year: 2012

Compatible use of biocontrol agents with insecticides is often essential to integrated pest management because the targets of each agent are normally restricted to a single or only a few species of pests and because the agent does not always provide satisfactory pest control. Selective use of chemicals least harmful to biological control agents is then ideal. In the present study, five insecticides, namely imidacloprid, pymetrozine, lufenuron, ethofenprox and clothianidin, were tested to determine their toxicity to Neochrysocharis okazakii (Hymenoptera: Eulophidae), a larval parasitoid of pest Liriomyza leafminers. Individual adult parasitoids were placed in the grass vials whose internal surface was coated with the insecticides. The insecticides tested showed different degrees of toxicity to the parasitoid. The LC 50 values were 0.0035, 8.779, 0.0508, 0.0085 and 0.0231mg a.i l -1 for imidacloprid, pymetrozine, lufenuron, ethofenprox and clothianidin, respectively. Based on risk quotient, imidacloprid and enthofenprox are highly toxic. Pymetrozine was harmless to N. okazakii while lufenuron and clothianidin were slightly to moderately to toxic to the parasitoid. Since N. okazakii is an important natural enemy of Liriomyza leafminers, use of imidacloprid or enthofenprox should be avoided. Combination use of augmented N. okazakii with pymetrozine or lufenuron may be counterproductive in a vegetable IPM program.


Aung K.S.D.,Laboratory of Insect Natural Enemies | Takasu K.,Laboratory of Insect Natural Enemies | Takasu K.,Laboratory of Bioresources and Management | Ueno T.,Laboratory of Insect Natural Enemies | Takagi M.,Laboratory of Insect Natural Enemies
Journal of the Faculty of Agriculture, Kyushu University | Year: 2010

Ooencyrtus nezarae is an egg parasitoid of several hemipteran including the bean bug, Riptortus clavatus and is a good candidate for biological control of pest bugs. The present study focused the effects of temperature on egg maturation and longevity of Ooencyrtus nezarae as well as the interactive effect of temperature and food on its longevity. Egg maturation increased with increasing adult age, reaching a peak (between 5-10 days), thereafter declined with further advancement in age. It also increased with increasing temperature though the egg maturation ceased to occur at 35 °C. The longevity of O. nezarae was dependent on temperature and food availability. The longest longevity occurred at 15 °C providing with honey and the lowest longevity occurred at 30 °C providing with water. This study provides the biological information of O. nezarae which can be useful for biological control program as well as for its efficient mass rearing.


Uefune M.,Laboratory of Insect Natural Enemies | Nakashima Y.,Kyushu University | Tagashira E.,Kyushu University | Takabayashi J.,Kyoto University | Takagi M.,Kyushu University
Biological Control | Year: 2010

The effects of prey species [Thrips palmi Karny (Thysanoptera: Thripidae) and Tetranychus kanzawai Kishida (Acari: Tetranychidae)] and their densities per plant on the olfactory responses of females of the anthocorid predator Wollastoniella rotunda Yasunaga and Miyamoto (Hemiptera: Anthocoridae) to volatiles from plants that were either intact or infested by prey were investigated using a Y-tube olfactometer. W. rotunda females preferred the volatiles from intact eggplants (Solamum melongena) to clean air. The females preferred volatiles from eggplants infested with either of the two prey species at different densities (200 and 800 female prey species) over intact eggplant volatiles. The females also preferred volatiles from plants infested with 800 females to those from plants infested by 200 females of the same species. W. rotunda females preferred the odor from eggplants infested with 200 T. kanzawai to that from eggplants infested with 200 T. palmi. When the number of prey per plant was increased to 800, the predators showed equal preference for eggplants infested by either of the two prey species. W. rotunda females preferred the odor from the eggplants infested with 800 T. palmi to that from the eggplants infested with 200 T. kanzawai, and the odor from eggplants infested with 800 T. kanzawai to that from eggplants infested with 200 T. palmi. The preferences of W. rotunda for infested eggplants were discussed from the viewpoints of using this predator for the biological control of T. palmi and T. kanzawai. © 2010 Elsevier Inc. All rights reserved.


Aung K.S.D.,Laboratory of Insect Natural Enemies | Takagi M.,Laboratory of Insect Natural Enemies | Ueno T.,Laboratory of Insect Natural Enemies
Journal of the Faculty of Agriculture, Kyushu University | Year: 2010

Ooencyrtus nezarae is a facultative gregarious egg parasitoid and attacks a wide variety of several hemipterian bugs. In the present study, the influence of female parasitoid's age to progeny production and sex ratio of O. nezarae was evaluated under laboratory tests. The percentage parasitism and the number of progeny were significantly decreased in old female. The optimal age of O. nezarae for successful parasitism ranged from 1-4 days, and sex ratio and clutch size were not affected by female parasitoid's age. The reproductive potential of 4-day-old and 1-day-old females was significantly higher than 20-day-old females. At the same time, 4-day-old females are more fecund within short duration than 1-day-old female. Our findings revealed the optimal female's age for efficient reproduction of O. nezarae which can be useful for biological control program as well as for mass rearing to optimize its efficiency.


Aung K.S.D.,Laboratory of Insect Natural Enemies | Takagi M.,Laboratory of Insect Natural Enemies | Ueno T.,Laboratory of Insect Natural Enemies
Journal of the Faculty of Agriculture, Kyushu University | Year: 2010

Ooencyrtus nezarae is a parasitoid wasp attacking eggs of several pest Hemiptera in soybean fields, and plays an important role as a main natural enemy of soybean pests. However, many aspects of the biology of the parasitoid remain unknown. Laboratory experiments were carried out to study the influence of food for adult females on the longevity and egg maturation of O. nezarae. The mean longevity of the females provided with honey throughout their life span was 40.4 days and was significantly longer than that of females provided with limited food (honey for one day) (means: 5.5 days), water only (3.0 days) or control (2.0 days). The total number of eggs matured within 3 days by honey fed females was 15.9 and was significantly higher than that by one-day honey fed (11.0 mature eggs), water fed (3.0 mature eggs) or control (0 mature egg) females. The present study suggests that life expectancy is extremely limited if the females cannot obtain carbohydrate sources continuously during the adult lifetime. Also, egg maturation is largely restricted under poor food conditions. Thus, the availability of food for adult females should determine the reproductive success of O. nezarae.

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