Effects of Different Setting Heights of Noctuid Trappers on Trapping Tobacco Noctuids

[ Objective ] To figure out the optimal setting height of gyplure trappers for controlling such pests as Spodoptera litura, Helicoverpa assuha, Helicoverpa armigera Hubner and Agrotis ypsilon that endanger tobacco leaves, and screen trappers suitable for the tobacco production. [ Method] In the growth season of to- bacco plants, moth trapper, new moth trapper lure/insect inlet are set up at four different heights （70, 110, 150 and 190 cm vertically from soil surface in the field）, to investigate the quantity of trapped moths. [ Result ] For both trappers, the height of trapping the most moths is 70 - 150 cm, so the initial height of lure/ insect inlet should be 120 cm, considering the 1-m mature tobacco plant height and the 20-cm distance between lure/insect inlet and crop canopy. [ Conclusion] Mother trapper is cheaper, and the new moth trapper is convenient and requires less management cost. The former is favorable for trapping S. litura, and the latter for H. assulta, H. armigera Hubner, and both of them are suitable for trapping A. ypsilon. In tobacco producing regions of Yunnan, population bases of the four noctuids endangering tobacco leaves show the sequence of S. litura 〉 A. ypsilon 〉 H. armigera Hubner 〉 H. assuha. But in tobacco production, H. armigera Hubner, H. assuha, and A. ypsilon cause the most serious damages, so the four noctuids must be controlled. Key words Tobacco noctuid; Sex lure; Trapper; Setting height

Performance of parasitoid Aphidius giftiensis Ashmead parasitizing Myzus persicae fed on artificial media

Aphidius gifuensis Ashmead is an economically important aphid parasitoid,particularly for pest Myzus persicae.The aim of the study was to feed M.persicae using a formulated artificial medium instead of tobacco to maintain parasitoid A.gifuensis in winter.The development,survival and reproduction of M.persicae fed with four artificial media(AM1-AM4),as well as the parasitism,emergence and longevity of A.gifuensis when reared on F3 M.persicae fed with AMI,were assessed.Over 15 days of the study,the survival rates of A.gifuensis for the AM1 and AM2 treatments were significantly greater than those for the AM3 and AM4 treatments.The highest fecundity of F,A.gifuensis females was observed on AM1 feeding.No differences were noted in survival rate,development or nymph production between F:and F,M.persicae fed with AM1.No differences were recorded in the number of mummies,parasitism rate,adult Iongevity or proportion of A.gifuensis females between Treatment I(4.gifuensis parasitizing AM1-reared M.persicae)and the control.However,the emergence rate of Treatment I was lower than that of the control.The rearing of.A.gifuensis on M.persicae fed with an artificial medium was found to be a feasible proposition.This could save time,space and cost compared with traditional production methods.

A new technology for coal and gas control based on the in situ stress distribution and the roadway layout

An auxiliary gas control technology is described that can reduce coal and gas outburst accidents when there is no existing protective coal seam and gas pre-draining is not effective.Numerical simulation methods were used to study the stress distribution ahead of the roadway face for different in situ stresses.The results from the simulation can then provide a new gas control technology.The results show that a high stress concentration,high stresses,and high displacement gradients appear ahead of the roadway face when the maximum in situ stress is aligned perpendicular to the roadway axis.The risk of gas outburst is higher when the stresses decrease rapidly over distance and when the release of more energy occurs immediately after driving the roadway.The gas outburst risk is much smaller when the in situ stress is aligned parallel to the roadway axis.During design of the coal mine most of the coal roadways should be arranged to parallel the maximum in situ stress.This will decrease the outburst risk in general and may be considered a new gas outburst prevention method.