| The beet armyworm(BAW),Spodoptera exigua(Hiibner),is an important lepidopteran pest,which can occur frequently in the world and cause huge losses every year in China.BAW is known for its large appetite,wide range of hosts,and high resistance to pesticides.It has become one of the most dangerous pests of concern.With the adjustment of agricultural planting structure and the change of farming system,the area of greenhouse vegetable cultivation in Pinghu is expanding,and the mixed planting pattern is quite common.The higher cropping index provides suitable living environment for BAW,so this pest has become a great threaten for the development of agricultural production in Pinghu.Asparagus,which is of important economic value and edible value,is very popular in the domestic and foreign markets,and has become an important source of income for local farmers and a new growth point of rural economy.Howover,asparagus is one of the favorite hosts of BAW.In recent years,BAW cause severe damage to asparagus in in Pinghu.In addition,the pesticide resistance and pesticide residues became increasingly serious.In order to solve the problems,this paper studied the occurrence regularity and green control technology of the asparagus BAW in greenhouse in Pinghu by means of indoor experiment and field experiment.The results are as follows:1.The field survey in Pinghu of Zhejiang Province showed that the occurrence partten of BAW was:The overwinter or non-occurrence period of BAW is from October 26th to April 5th in the following year.The first adult was found on April 5th.The average temperature on April 5th was about 15?,which was in agreement with the temperature at which the developmental starting point of BAW was reported.BAW occurred in a small amount in May.The number of BAW increased slightly in June,which was the best time to start pest control.From July to September,when field temperature and humidity is more suitable for the occurrence of BAW,the population size of BAW increased dramatically.This period is the critical period of control.August to October is the outbreak period for BAW and the population size peaked on August 21th.2.Through the test of the supercooling point and freezing point of BAW,the most suitable overwintering stage was determined,then a series of studies on the overwintering situation of BAW were studied.The results of laboratory tests showed that the subcooling points of the different stages were significantly different(P<0.05):pupae had the lowest subcooling point,followed by prepupae,adults,eggs and larvae.So pupae is the most suitbale stage for overwintering.Among different larvae stages,the supercooling point of the third instar larvae was the lowest,followed by the second instar larvae,and the fifth instar larvae had the highest supercooling point.The freezing point of different stages was significantly different(P<0.05),and the freezing point of eggs was the lowest,followed by pupae,adults,larvae and prepupae.The temperature difference between the cooling point and the freezing point in different stages was large and the overcooling was obvious.Daejeon test data show that the BAW in Zhejiang Pinghu could overwinter,the average overwinter rate in greenhouse was 30.67%,and the average overwinter rate outside greenhouse was 7.33%.There were significant differences between the emergence rate of BAW inside and outside greenhouse(P<0.05).3.Through the field test,the trapping effect of six BAW lures from four manufacturers was measured,and the relatively cost-effective type of lure was determined.The results show that A lure was the best,followed by E,F,C,D and B.the rubber head was better than the PVC material.The results also showed that the amount of BAW trapped in traps placed at the top of the stem was higher than that in traps placed in the middle part of the stalk and the former could trap 8.64 times compared with latter.4.The control effect of 1.5 billion PIB/ml S.exigua nuclear polyhedrosis virus(SeNPV)was investigated.The results showed that the control effects of SeNPV diluted 2000 times,1000 times and 500 times is better than that of 5%chlorantraniliprole.SeNPV diluted 500 times had the best effect.The control effect of SeNPV was 75.76%on the tenth day after application,and the control effect of 5%chlorantraniliprole was 52.92%after ten days,indicating that the SeNPV had a long duration.5.In order to screen out the active pesticide preparations for the agricultural production,this experiment used eleven local commonly used pesticides for indoor testing.The results showed that the effect of the eleven pesticides were different from each other.The corrected mortality rate of the insecticidal nitrile,ethyl spirocetin and chlorantraniliprole diluted 1000 times can reach over 90%after 1 day,and reach 100%after5 days.However,the control effect of SeNPV and other biological pesticides was reletively low.The corrected mortality rate of SeNPV and other biological pesticides was low after 1 day,and reach 80%after 5 days.Howver,those biological pesiticides had long-term benefits for the economic crops with short growth period and high harvest frequency. |
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