Preliminary Study On The Control Effect Of Inert Dust Treated On Acanthoscelides Obtectus(Say)

Acanthoscelides obtectus?Say??Coleoptera:Bruchidae?,also known as Bean weevil,which is a worldwide agricultural pest with strong adaptability and high fecundity and can feed with many kinds of host plants.Generally,A.obtectus is listed as one of the most important quarantine pests for leguminous crops in the world.As the whole life history can be completed in most parts of our country,the A.obtectus has been happening in some parts of our country and causing serious harm in two decades.In this paper,we studied the lethal effect of three kinds of inert dusts of"Liang zhibao"food grade inert dust,"Feifei"diatomaceous earth and pure diatomaceous earth on A.obtectus,and compared the lethal effect of inert dust on A.obtectus under different conditions and discussed simulation chamber of its control effect on import in order to evaluate the control effect of inert dust from different sources on A.obtectus and to find out more effective alternatives to Phosphine Reasonable reference as well as delve into its lay a foundation for its sustainable management.1.Evaluation of lethal effect of food-grade inert dust toAcanthoscelides obtectus?Say?.In order to evaluate the control efficiency of inert dust on the bean weevil Acanthoscelides obtectus?Say?,three different powders were tested against A.obtectus under the conditions of different concentration,time and temperature.The results indicated that when the inert dust treated on A.obtectus with a dosage of 20mg/kg for 72 hours or 40 mg/kg for 48 hours,the mortality of A.obtectus adult reached 100%.The food grade inert dust on A.obtectus lethal effect is best at 25?.The control efficiency of inert dust on adults and eggs was better than that of lower instar larvae,higher instar larvae and pupae.2.Effect of low concentrations of food-grade inert dust on thedevelopment and reproduction of Acanthoscelides obtectus?Say?Acanthoscelides obtectus?Say?is the most destructive insect pest of leguminous crops around the globe.Food-grade inert dust is an efficient protective agent used to control A.obtectus.Lethal concentrations of food-grade inert dust can cause mortality to A.obtectus.Whereas the concentrations of inert dust may have difference in different position of the grain by mixing inert dust with the surface of grain in horizontal warehouse.It may cause stored grain pests to be exposed to different amounts of drug.Therefore,it has great practical implication for studying the effect of low concentrations of inert dust on the development and reproduction of A.obtectus.In this study,we studied the changes of its developmental duration,survival rate and fecundity after Phaseolus vulgaris treated with low concentrations of food-grade inert dust.The results showed that when A.obtectus was exposed to the LC₁₀,LC₂₀ and LC₅₀ of food-grade inert dust,both the hatchability and the larval-pupal survival rates decreased,and significant differences on the larval-pupal survival rates were observed compared with the control group?P<0.05?.Compared with the control,the adult longevity was shortened by 7.49 d,8.74 d and 6.65 d,respectively,and the fecundity of single females was decreased significantly by 14.55 eggs,11.75 eggs and 15.40eggs,respectively.The developmental duration of different stages were affected after treating with the LC₁₀,LC₂₀ and LC₅₀ of food-grade inert dust.According to the survival rate and fecundity of A.obtectus treated by different concentrations of food-grade inert dust,the life table of fecundity was constructed.We found that for LC₁₀,LC₂₀ and LC₅₀ treatments the intrinsic rate of increase?r_m?decreased by 11.11%,22.22%and 44.44%,respectively,and the net reproductive rate?R₀?decreased by25.77%,37.37%and 69.11%,respectively,whereas the mean generation time?T?and population doubling time?t?were delayed.The results showed that low concentrations of food-grade inert dust could suppress the population growth of A.obtectus.3.Preliminary study on lethal mechanism of two food-grade inertdust to Acanthoscelides obtectus?Say?In order to clarify the mechanism of lethal effect of food grade inert dust on Acanthoscelides obtectus,study on the food grade inert dust“Liang zhibao”and diatomaceous earth“Fei fei”two kinds of diatomite powder by inert membrane method affects A.obtectus surface damage of body and weight loss.It records the A.obtectus crawling ability,the ability to fly of the A.obtectus.The results showed that two kinds of inert dust had certain effect on the treatment of A.obtectus.The effect of food grade inert dust is better,the action speed is fast and the dosage is small.When the dosage is higher than 0.2 g/m² 72 h,"Liang zhibao"food-grade inert dust can be better prevention and control of A.obtectus.By the preliminary judgment,the food-grade inert dust may be due to powder into the A.obtectus like joints,wear internodes membrane rapid adsorption of body fluids,greatly decrease or unable to exercise,eventually lead to the A.obtectus death of excessive body moisture loss.4.Inert dust in simulated storehouse,prevention and control ofAcanthoscelides obtectus?Say?and safety evaluationIn order to explore the control effect of food-grade inert dust on Acanthoscelides obtectus in the simulated warehouse and evaluation of the safety of Phaseolus vulgaris after treatment,this study used woven bags and plastic bags as simulation warehouses respectively.The results showed that"Liang zhibao"food-grade inert dust in the dosage of 30 mg/kg deal with 5d,the woven bag and the plastic bag A.obtectus mortality rates are above 99%,try insect mortality is slightly higher in plastic bags.The food-grade inert dust is effective for controlling the A.obtectus and the use of food grade inert dust in the simulation warehouse needs to be slightly increased or the processing time is extended.The series of experiments on the safety evaluation of P.vulgaris after treatment showed that the food-grade inert dust was used to control the A.obtectus in the P.vulgaris and it meets the requirements of the green prevention and control and the GB2760-2014 National Food Safety Standard for Food Safety?raw grain biggest added dose of 1.2 g/kg?.Food-grade inert dust can be used as an alternative to chemical pesticides such as phosphine.