Environmentally Relevant Concerntrations Of Triclocarban Induced Gut Microbiota Dysbiosis And Olfactory Behavioral Disorder In Honeybees(Apis Mellifera L)

The honeybee is the most important pollinator in agroecosystems,maintaining bee colony health plays an important role in promoting agricultural economic development.However,the global Colony Collapse Disorder(CCD)has threatened the safety of honeybees,which has attracted extensive attention from ecologists and environmentalists.So far,the specific causes of colony collapse disorder are still controversial,and there are few studies on the effect of environmental concentrations of pollutants,except for pesticides,on bee safety.Triclocarban(TCC)is a widely used broad-spectrum antibacterial agent,which has become one of the pollutants widely detected in environmental water.Since the environmental water is the main source of drinking water for honeybees,TCC in the environmental water is highly likely to enter the honeybee gut system through honeybees' drinking.Based on the bactericidal properties of TCC,the honeybees' gut microbes can easily become the toxic target of TCC,which in turn has a potential adverse effect on the health of honeybees.In this paper,we aim to assess the effect of TCC on the diversity of honeybees' gut microbes under environmental concentration.The effect of TCC exposure on the growth and development,midgut tissue,immune system and olfactory behavior of honeybees have also been evaluated.The toxicity mechanism and ecological risks of TCC at environmental concentrations on honeybees through the brain-gut-gut microbes axis have been revealed.This paper draws the following conclusions:1.The survival rate of honeybees decreased after the exposure of TCC at environmental concentration.After 10 consecutive days of TCC intake,honeybees showed obvious chronic poisoning symptoms,such as body crouching and proboscis extension.2.The environmental concentration of TCC changed the richness and diversity of honeybee gut microbiota.The colonization of gut microbiota has been altered by TCC at the level of phylum.At the level of genus classification,the imbalance of the proportion of beneficial microflora affected the nutriention,metabolism,absorption and immunity,and made the honeybees themselves infected by the pathogen Serratia.3.The response rate of the proboscis extension response(PER)of honeybees after TCC exposure was significantly lower than that of the control group,and the abundance of gut beneficial microbiota decreased and then affected appetite through the brain-gut-gut microbes axis regulation,leading to inhibition of olfactory response.4.After TCC exposure,the expression of relevant immune regulatory genes such as detoxification and antioxidant in honeybees significantly changed,which affected the immune response of honeybees,and then led to oxidative damage.After TCC exposure,the peritrophic membrane was damaged,and the number of goblet cells and epithelial cells decreased,leading to pathological damage in the midgut tissue of honeybees and destruction of the physical barrier of gut immunity.