| The Asian Longhorned Beetle.Anoplophora glabripennis(Motschulsky),is native to China and the Korean peninsula.It is an important quarantine pest in the world,which is rampant in both origin and colony.As an important natural enemy of ALB,the D.helophoroides(Fairmaire)can not be used in Inner Mongolia,Jilin and heilongjiang province etc where ALB occur seriously due to the limitation of cold tolerance.For this reason,this study also studied the cold tolerance of D.helophoroides(Fairmaire)to provide a theoretical basis for biological control of A.glabripennis by using D.helophoroides in its unsuitable areas.The results of the study are as following:1.The orthogonal test method was used for the comprehensive analysis of multiple factors and multiple levels.The orthogonal test was the orthogonal test of 11 factors and 3 levels,with a total of 27 treatments.The criteria used to justify the quality of diet were based on the survival rate of larvae,the survival time and the increased weight.If the effect of artificial diet is similar to that of wood section feeding,it can be judged that this artificial formula can be used to successfully feed the larvae of A.glabripennis which can replace the wood section feeding method.In this way,the effect of artificial diet was evaluated.(1)According to the results of the range analysis of the effect of artificial diet prepared in 27 formula we can come to a conclusion that in this experiment,agar was the most important factor influencing the survival rate and survival time of the larvae,and casein was the most important factor influencing the weight growth.(2)On the basis of the frequency of optimal level statistics for each factor and comprehensive analysis method,we improved the diet recipe and finally obtained an optimal diet formula for A.glabripennis larvae.The optimal formula was as followed:agar(5.5%),willow powder(7.5%),potassium sorbate(0.26%),tetracycline hydrochloride(0.3%),ampicillin(0.2%),soybean flour(2.5%),ascorbic acid(0.15%),cellulose(15%),cane sugar(0.8%),soybean oil(0.5%),Webster's salt(0.5%),yeast(3.1%),casein(1.5%),water(62.19%).(3)The artificial diet formula was verified.Comparing the artificial diet with the wood(natural diet),there was no significant difference in survival rate and survival time,but the weight of larvae fed with artificial diet was significantly higher than that of larvae fed with wood log.The larval reared on this diet displayed choice survival rate,survival time and weight.The result demonstrate that the dietcan successfully feed the larvae of the A.glabripennis which can assist further studies on the development and rapid screening of artificial diets for other longicorn larvae.2.D.helophoroides(Fairmaire),an important natural enemy of Anoplophora glabripennis(Motschusky),has been widely used in China.In order to explore the cold hardiness of A.glabripennis collected from Hunchun,Jilin province,and to clarify the feasibility of releasing D.helophoroides there to control A.glabripennis,for biological control of A.glabripennis by using D.helophoroides in its unsuitable areas.The host trees of A.glabripennis from fields were dissected to measure supercooling points of A.glabripennis at different stages and instars.Meanwhile,five rapid cold hardening treatments,8?/0.5 h,4?/0.5 h,0?/0.5 h,4?/1 h,4?/4 h,were set up to compare the effects of different treatments on the supercooling points of D.helophoroides.The eggs of A.glabripennis living between phloem and xylem had the lowest supercooling point,-25.70? on average,which means that A.glabripennis can overwinter with higher supercooling point than the extreme low temperature in Hunchun.With the development and boring process of A.glabripennis in trees,the supercooling points increased subsequently,and the cold resistances declined.The supercooling points at different stages and instars were:egg<small larva<large larva,indicating that the overwintering ability of insects is related to their microhabitat in addition to supercooling ability.Research on rapid cold hardening of D.helophoroides showed that four treatments except one,4?/4 h,had significant effects on the supercooling points.The 4?/0.5 h treatment had the lowest supercooling point,which was-19.14? on average.The rapid cold hardening can be very effective to reduce the supercooling point of D.helophoroides and improve its cold hardiness.3.This study also to evaluated the influence of different concentrations of exogenous trehalose on the survival and cold hardiness of D.helophoroides(Fairmaire)adults,an important and most effective natural enemy of longhorned beetles.D.helophoroides adults were feed on a semi-artificial diets containing 3%,6%and 9%of trehalose respectively in the laboratory.The control group the D.helophoroides adults which had not eaten trehalose.After 10 weeks,the survival rate of adults were calculated.In addition,the supercooling point and water content of adults in non-low temperature treatment and low temperature treatment(10? for 3 d)were measured respectively.The survival rate of D.helophoroides adults feeding on artificial diets containing 6%trehalose was the highest(86.67%)among all the treatments,Regardless of the non-low temperature treatment and low temperature treatment of adults,adults fed 9%trehalose had the lowest supercooling point compared to other treatments and the control.The supercooling point of non-low temperature treatment was-19.3? and supercooling point of low temperature treatment was-21.6?.Low temperature had a significant effect on the water content of adults feeding on diet without trehalose but had no significant effects on water content of those adults feeding on diet with trehalose.Exogenous trehalose has significant influence on the survival rate and cold hardiness of D.helophoroides adults,thus exogenous trehalose can be utilized to improve the survival in laboratory rearing and cold hardiness of D.helophoroides adults.4.To investigate the effects of different hosts on the development and cold hardiness of D.helophoroides(Fairmaire),development duration,number of adults' production,size and supercooling point of adults of D.helophoroides were collected and analysed by taking pupa of Zophobas morio,larvae of Thyestilla gebleri and Monochamus alternatus as hosts indoors.The results showed that there was no significant effect in number of adults' production among different hosts,while larval duration,pupal duration,body length,weight and supercooling point of adults showed significant differences.Taking pupa of Z.morio as host,larval duration(10.58 d)and pupal duration(30.17 d)of D.helophoroides were longest,adult body length(8.68 mm)was longest,adult weight(360.22 mg)was heaviest and supercooling point(-18.81?)of adult was lowest.However,things were completely opposite when taking larva of.gebleri as host,like larval duration(8.94 d)and pupal duration(22.84 d)of D.helophoroides were shortest,adult body length(6.33 mm)was shortest,adult weight(184.38 mg)was lightest and supercooling point(-16.50?)of adult was highest.Compared with T.gebleri and M.alternatus,Z morio is an ideal alternative host which can breed larger and more cold-resistant populations of D.helophoroides.In the study screened a kind of high quality artificial feed for longicorn beetles,it also provides a reference for other methods of rapid screening and preparation of artificial feeds of other longicorn beetles.In addition,this study also found that the cold tolerance of D.helophoroides has strong plasticity.By the reasonable rapid cold hardening and the change of nutritional conditions,the cold tolerance of D.helophoroides can be improved remarkably,to expand the region of the control of ALB. |
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