| Honeybees are an important pollinating insect,which plays an important role in agricultural production and natural ecosystem,as well as providing abundant honey products for human beings.Neurobiologists take the honeybees as study model organisms due to its' superior ability to learn and remember in fields such as social behavior and navigation in learning and memory.Colony collapse disorder(CCD)occurred United States since 2006 and reported in many countries with varying severity.Eventhough,the exact cause of honeybee loss is still unknown,pesticides are considered to be a major threat to honeybee health.At present,the sublethal effects of pesticides on non-target insect honeybees have been studied in depth,including the influence of pesticides on honeybees' learning and memory,positioning and navigation,collecting ability and other behavioral activities.However,there are few studies on the information exchange mechanism and the internal molecular mechanism of honeybee waggle dance.In this study,we explored the effects of pesticides on dance behavior of honeybees(Apis mellifera)and the related molecular mechanisms.In this study,honeybees were fed with 50% sucrose solution and 24 ?g/kg imidacloprid sucrose solutions at test sites 300 m,500 m and 1000 m away from hives.The duration of the waggle phase,divergence angle and duration of the return phase of the two groups were compared respectively.The q RT-PCR was used to analyze the expression profiles of four learning and memory related genes,two dopamine receptor genes,one dopamine transporter gene,four detoxification and immune related genes induced by imidacprid in western honeybees.The results showed that the sublethal dose of imidacloprid could affect the foraging behavior of honeybees,the sucking time decreased and the returning time increased.At the distance of 300 m away from the hive,the divergence angle and incorrect turns in pesticide group showed a significant difference than control group.At the distance of 500 m and 1000 m away from the hive,the duration of the return phase in pesticide group increased significantly.At the distance of 300 m and1000 m away from the hive,the number of followers and crop content in pesticide group had significant difference than control group.At the distance of 300 m and 1000 m,the gene expression level of Tyr1 was down-regulated.At the distance of 500 m,the gene expression level of Amdat was down-regulated.At the distance of 300 m,the gene expression level of Dop R2 was up-regulated.The expression level of c AMP was decreased due to the dopamine receptor gene(Dop R2)was activated.Therefore these specific expressions may affect the learning and memory ability of honeybees.At the mean time,the expression level of detoxification genes Catalase and CYP450 were down-regulated at the distance of 1000 m from the hive,and the expression level of immune genes defensin1 was down-regulated at the distance of 300 m from the hive,which may affect the detoxification and immune defense system of honeybees.Additionally,honeybees were fed 50% sucrose solution and 235 ?g/kg deltamethrin sucrose solutions at test sites 300 m,500 m and 1000 m away from hives,respectively.The duration of the waggle phase,divergence angle and duration of the return phase of the two groups were again compared respectively.The q RT-PCR was used to analyze the expression characteristics of 4 learning and memory related genes,2 dopamine receptor genes,1 dopamine transporter gene and 4 detoxification and immune related genes induced by deltamethrin in western honeybees.The results showed that the sublethal dose of deltamethrin could affect the foraging behavior of bees with the decrease of the sucking time and the increase of returning time.At the distance of 500 m away from the hive,the circuits per 15 s in pesticide group showed a significant difference than control group.At the distance of 300 m away from the hive,the divergence angle in pesticide group showed a significant difference than control group.And the incorrect turns in pesticide group had a significant difference than control group at the distance of 500 m away from the hive.At the distance of 500 m and 1000 m away from the hive,the duration of the return phase and crop content in pesticide group had a significant difference than control group.At the distance of 500 m away from the hive,the number of followers in pesticide group had significant difference than control group.At the distance of 1000 m,the expression level of gene Glu RA1 was down-regulated.At the distance of 500 m and 1000 m,the expression level of gene NMDAR was down-regulated.At the distance of 300 m,the expression level of gene Tyr1 was down-regulated.At the distance of 1000 m,the expression level of genes Dop R1 and Amdat were down-regulated.But the expression level of gene Dop R2 was up-regulated at the distance of 300 m from the hive.The level of c AMP was decreased due to the dopamine receptor gene(Dop R2)was activated.So these specific expressions may affect the learning and memory ability of honeybees.There were no significant differences of the detoxification and immune genes Catalase,CYP450 and defensin1 of honeybee.But there only have significant inhibition of immune genes(Hymenoptaecin)expression,which may damage the immune systems of honeybees.The RNA-sequencing technique was used to detect transcriptome differences of the dancing honeybees fed the sublethal dose of imidacloprid,deltamethrin and the dancing bees fed normal sugar water.The results showed that the learning and memory related gene(calmodulin-like protein 4)was up-regulated.The detoxification and immunity genes(CYP450 6a14,CYP450 6k1,apidaecins type 73,hymenoptaecin preproprotein)were up-regulated,but the immunity gene(defensin-1 preproprotein)was down-regulated.The royal jelly master protein genes(Mrip1,Mrip2,Mrip7)were significantly down-regulated.According to GO analysis,significantly differentially expressed genes are mainly involved in biological activities such as defense response,sensory response,signal transduction and receptor activity.KEGG analysis showed that the pathways involved in significantly differentially expressed genes mainly include amino acid metabolism,lipid metabolism,transport and catabolism,signal transduction and sensory system.The genetic background between dancing bees and follower bees in the colony was analyzed by SSR technique.The results showed that the subfamily between the dancing bee and the follower bee was randomly distributed during natural conditions,and the honeybee colonies in which the queens have been naturally mated.And there was no nepotism in waggle communication of honeybees. |
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