Nestmate Recognition In Solenopsis Invicta Based On The Cuticular Hydrocarbons And 16S RRNA Sequence Analysis

The red imported fire ant,Solenopsis invicta(Buren),is one of invasive ants in southern China and has brought threat to the ecological environment,agricultural production and public safety.As social insects,aggression comprises a range of important social interactions with implications for individual behavior and the collective integrity of animal societies.However,there has been no unified account of the regulator that caused the attack.This thesis focused on the mechanism of nestmate recognition in S.invicta by integrating behavioural and chemical approaches,16 S rRNA-based microbial community profiling,to test whether food,cuticular hydrocarbons(CHCs),gut microbes or soil microbes may affect nestmate recognition.The ants for these experiments were collected from Guangdong,China,and the experimental results were showed as follows:1.Research on S.invicta intraspecific nestmate recognition with the total aggressive index(AI)between workers from nests with the same or different foods and with soil or without soil,were recorded and analyzed.The AI between workers from different nests were decreased by lab raring without soil and feeding with the same food for 30 days,while the AI of ants with soil had no significant difference compared with the untreated group.The ants from the same nest with different foods still behaved friendly.We also found that there was a certain correlation between AI and the mortality of the ants.With the increase of AI,the mortality of workers fighting after 12 hours also increased.2.Based on GC-MS technique,this paper analyzed the differences of CHCs composition among ants from different nests with different treatments.PCA results showed that there was no significant difference in the composition of CHCs between the workers from the fileds and the nests rared with soil(16-19 chemicals),but decreased when rared without soil(9-16 chemicals).The results proved the cuticular hydrocarbons are the nestmate recognition cues in S.invicta.The difference in CHCs spectrum were mainly reflected in the proportion of mono-and di/trimethyl-alkanes.3.Based on 16 S rRNA high-throughput sequencing mothods,this paper analyzed the differences of endosymbiont diversity among ants with different treatments.The results showed that there were some differences in the number of Operational Taxonomic Units(OTUs)among the ants in different environments.The dominant flora in the research samples were Acinetobacter、Enterobacter、Pseudomonas、Lactobacillus and Lachnospira.Principle Coordination Analysis(PCo A)suggested that the gut bacterial communities of samples reared with soil were closer to those of untreated ones sampled from original fields,and the gut bacterial samples of ants reared without soil exhibited a clear separation.There was no significant difference in gut bacterial samples between different diets,indicating that the ants acquired microbiomes from the soil rather than the food.Linear Discriminant Analysis Effect Size(Lef Se)showed significant differences in species composition of Lactobacillales and Enterobacteriales in the bacteria in the control group and the soil-reared group,suggesting that these bacteria may affect nestmate recognition.4.As the results of 16 S rRNA-seq showed that,the soil contained the highest diversity of both bacteria,and the gut of ants living without soil were the least diversity.The dominant flora in the soil and the guts were Enterobacteriaceae 、 Rhizobiaceae and Micrococcaceae.The guts of ants living with soil and without soil shared a common core microbiome which was also present in the soil(over 50% of their microbiome).PCo A analysis showed that the gut bacterial communities of ants reared with soil were closer to those of untreated ones from original fields,and the ants without soil exhibited a clear separation.Our data indicated that the nestmate recognition of ants may be associated with the bacterial communities in the guts and the soil.According to the results of these experiments as above,we concluded that the nestmate recognition of ants was affected by the composion and ratio of different Cuticular Hydrocarbons(CHCs)and symbois.These results led a new way for the control of red imported fire ant.