| The infection,feeding,and growth of pests on grains are related to the safety of grain storage.The common species in China are Cryptolestes ferrugineus(Stephens),Cryptolestes pusillus(Schoenherr)and Cryptolestes turcicus(Grouville).Exploring the adaptability of the three species of Cryptolestes to different grains can provide a reference for the comprehensive prevention and control.In this paper,the volatile components and relative contents of wheat,corn and brown rice with different degrees of crushing were studied,the attraction effects of these grains on three species of Cryptolestes were determined.The electroantennogram(EAG)responses of three species of Cryptolestes to different degrees of broken grains and some volatiles were explored,and the behavior responses to sensitive volatiles were measured.The growth and development of three species of Cryptolestes were observed under different temperature and grain conditions.From the selection and feeding behavior,the adaptability of three species of Cryptolestes to different grains was compared.The main results are as follows:(1)The volatile components of grains were analyzed by headspace solid-phase micro-extraction(SPME)and GC-MS at 28℃.The results showed that compounds can be divided into alkanes,alkenes,aldehydes,alcohols,acids,ketones and furans.The types and components of volatile compounds were different.The number of volatiles in whole wheat,broken wheat and whole wheat flour were 17,20 and 20,respectively;the number of volatiles in whole corn,broken corn and corn flour were23,25 and 25,respectively;and the number of volatiles in whole brown rice,broken brown rice and brown rice flour were 16,18 and 18,respectively.The relative contents of aldehyde in wheat were the highest,and alkanes in corn and brown rice were the highest.The unique volatile components in wheat,corn and brown rice were3,4 and 2,respectively.(2)There were significant differences in the selective response of the three test insects to degrees of broken grains.Except for the whole brown rice,the other several kinds of grains all had a significant attraction effects on the female and male adults.The reaction rate and attration rate increased after grains were broken,among them,corn flour had the best attraction effect on C.ferrugineus,C.pusillus and C.turcicus.The attration rates of females were 48.66,45.09 and 40.93%,respectively;and the attration rates of males were 47.59,43.20 and 40.93%,respectively.In the same broken degree,the attration rates of females were higher than that of males.(3)The three species of Cryptolestes showed different EAG responses to different degrees of broken grains.The EAG responses to corn were the greatest.And the higher degree of grain breakage,the greater EAG responses.When the corn changed from intact kernels to powder,the EAG responses of the female and male of C.ferrugineus increased by 0.022 and 0.024 m V,respectively;the female and male of C.pusillus increased by 0.038 and 0.051 m V,respectively;the female and male of C.turcicus increased by 0.098 and 0.052 m V,respectively.(4)Twelve representative volatiles were selected from the different degrees of broken grains.The results showed that there were significant differences in the EAG responses of three species of insects to 12 volatiles with different concentrations.In the three tested concentrations,the EAG responses increased with the increase of volatiles concentration.Three species of insects had higher EAG responses to valeraldehyde,hexanal,nonanal,trans-2-decenal and 1-octen-3-ol at a concentration of 10 μg/μL,and had the lowest EAG responses to 2-octanone.The five sensitive volatiles at different concentrations had different attration responses to the three test insects.(5)The three test insects had different behavioral response to 5 sensitive volatiles with different concentrations.The female and male of C.ferrugineus had a significant tropism to valeraldehyde,nonanal,trans-2-decenal and 1-octen-3-ol at a concentration of 0.1 μg/μL.When the concentration was increased to 1 μg/μL,females had a significant tendency to valeraldehyde,hexanal,nonanal and 1-octen-3-ol.The females of C.pusillus had a significant tendency towards valeraldehyde,hexanal,nonanal and1-octen-3-ol at concentrations of 0.1 and 1 μg/μL,The males of C.pusillus had a significant tendency to hexanal at concentrations of 0.1 and 1 μg/μL.Both females and males of C.turcicus had a significant tendency towards valeraldehyde and hexanal at the concentration of 1 μg/μL,and nonanal at the concentration of 0.1 and 1μg/μL.(6)The three kinds of grains had no significant effect on the hatching rate of the eggs,but had a significant effect on the larval stage,the total development durations and the survival rates.In the temperature range of 24～32℃,with the increase of temperature,the hatching rate the eggs,the survival rate of larvae and pupae increased,and the developmental duration shortened.In the same temperature environment,the three test insects had the shortest developmental duration and the highest survival rate in whole wheat flour. |
