The Investigation And Screening Of Pesticide For Controlling Grubs In Taixing And Guanyun Counties Of Jiangsu Province

With the expanding of the plant area of peanut and soybean in Jiangsu Province recently, grubs’damage raised gradually. Grubs, the assemblage of different species, are ruinous pests on peanut and soybean. Grubs are considered as one of the most difficultly preventing pests because of their complex life history and various population dynamics. In order to figure out an efficient controlling strategy, best time for controlling and screening out effective pesticides, we carried out an investigation on grub species composition, population dynamics in Taixing and Guanyun counties in Jiangsu Province, as well as the field trial of three biological pesticides against grub. The major results are as follows:1) The main underground pests in investigated area that be harm to woodland and field are grub, and the dominant species are from Melolonthidae. Howeverthe dominant species is Metabolus flavescens Brenske in Taixing city, while Holotrichia parallela Motschulsky is the dominant species in Guanyun county.2) From March to September, the field surveys showed that the abundance of grub community had overall upward trend inTaixing, excep the controlled peanut land in Dingzhuang..Based on the light trap results during the period of2008to2012,Guanyun county, it showed hat the occurrence of adult lasted three months from June to August, with a peak occurred in late June.3) The species compositon and abundance of grubs community were significantly varied in different types of farm plots, as well as regions. For example, Metabolus flavescens Brenske is the dominant species of forest area in farmland in Taixing, with its density up to45ind./5m2, while farmland grub had much lower density of5ind./5m2, of which Anomala corpulenta Motschulsky and Anomala heydeni Frivaldszky were the dominant species. Moreover, Soil types (silty loam and clay) also had significant difference in abundance of grubs, Such as the grubs in the sandy loam (140ind./10m2) was about45times as that in the clay(3ind./10m2)in Guanyu county.4) Field trial of three insecticides:chemical agent:N4、N5(Xin’an Chemical Company); Bt preparations:N1、N3(Chinese academy of agricultural sciences) and release agent: N2(Anhui province academy of agricultural sciences) were carried out in peanut field plot, the results showed that Bt-AA, Bt-DD strains and the chemical pesticide had effects on the prevention and control of peanut grub. However, the difference is big between treatments, with N3(Bt-DD strains) treatment had the best effect, its protection effect of fruit was54.34%with a yield of321.99kilograms, which was11.16%higher than that of the ck N7; in addition, the protection effect of N5, N2are48.36%and46.79%, respectively, which was also10.51%and9.59%higher than that of the ck N7, respectively; The protection effect of fruit of N1was41.08%and7.15%higher than that of the ck N7.