Studies on insect pests of soy bean crop. 2. Ecological studies on lima bean pod borer, Etiella Zinckenella Treitschke, in Shikoku district with experiments on its control

Studies on insect pests of soy bean crop. 2. Ecological studies on lima bean pod borer, Etiella Zinckenella Treitschke, in Shikoku district with experiments on its control

1953

REP.SB-1169

Lima bean pod borer, Etiella zinckenella Treischke, is one of the serious pest insects infesting soy bean pod in the southern half of Japan, taking the place of the Soy bean pod borer, Grapholitha glycinivorella Matsumura, in the northern half of the country> It injures in Shikoku District not only soy bean but also pea, cowpea, kidney bean, Tunja pea and vetches as crop, in addition to Leguminous grasses such as Vicia spp., and is considered the most injurious pest insec to summer variety of soy bean. Recently introduction of this variety of soy bean into the said distirct is suggested for the increase of agricultural production by changing farming from annual two time to three time cropping, and urgent need occurred for the knowledges on this pest insect. However, there have hardly been accumulated the knowledges on the bionomics nor the control measures of this pest insect so far, investigations were commenced since 1948. This paper is the account of the studies made during the seasons from 1948 to 1950 on the damages of soy bean caused by respective brood of the borer, tirals to escape the damage by altering the sowing date of the crop; varietal difference in the damage, and seasonal prevalence of the borer emergence together with control experiments with newer insecticides such as BHC and chlordane. The results of the studies can be summarized as follows. The borer has four generation a year in Shikoku Distirct; the first brood moth appears during May and June and laysher eggs on garden pea pod; the second brood moth emerges in July and oviposition is made on the pods of cowpea, kidney bean and summer variety of soy bean; the third brood moth appears in August and oviposits on intermediate types of soy bean, while the fourth brood moth emerges in bean. The larvae of respective brood bore into the bean pod and chew the growing beans. The damage of the garden pea by the first brood larvae is practically slight, suggesting the presence of some other host plant to this brood, but this was not made clear so far. Infestation of summer and intermediate varieties of soy bean by the second and third brood larvae is found so severe and often the summer variety hardly give any yield, while the infestation of the antumnal variety of soy bean by the fourth brood larvae sharply drops. With both early and erdinary summer soy bean and intermedate soy bean, a tendency to escape the infestation by delaying the sowing date can be observed, but this is not so evident. Sowing these varieties late enough to escape perfectly the infestation results in not only perfect ignorance of their essential character on maturing period but also in poor growth and reduction in yield. Taking from the earliest to the latest varieties of soy bean as a whole, a tenency is detected that the variety whose pod is formed later suffers slighter infestation. SSome varietal difference in the infestation is also observed among varieties belonging to the same varietal group, but the difference cannot be explained in connection with varietal phylogeny. In the field, the second brood moth lays her eggs on early variety of summer soy bean from late June to the end of July, the maximum oviposition being observed in the beginning of the latter month. The third brood moth ovipoisits to the intermediate soy bean from the end of July or from the beginning of August to the beginning of September and the maximum oviposition is observed in the first or the second 10 days of August, while the fourthe brood moth ordinarily oviposition from the middle of September to the beginning or the middle of next month. Though these durations of oviposition seem to coincide generally to the emergence of moths of respective brood, these seems to exist some relation of oviposic response of moths to the growth of bean pod, and the maximum oviposition is observed five to ten days after the beginning of pod formation with summer and int

B.1:186-216, SHIKOKU AGRICULTURAL EXPERIMENT STATION, BULLETIN

Research > Published Articles