Prey Selection of Tylonycteris pachypus and T．Robustula (Chiroptera:Vespertilioninae) in Guangxi,China

We confirmed the foraging sites of Tylonycteris pachypus and T.Robustula using echolocation detecting and mist net catching,measured the potential food (insects) availability in the bats foraging area by sticky traps,and analyzed the bats food components using fecal analysis in Ningming County and Longzhou County,Nanning District,Guangxi Province,China,in the period from March to October,2002.We found that Diptera (above 45.93%,by volume per cent),Coleoptera (above 12.59%) and Hymenoptera (above 7.47%) were important in both Ningming County and Longzhou County,but Diptera and Hymenoptera were significant different between two counties.The results indicated that Diptera (40.33% by volume per cent) and Hymenoptera (38.46%) were important in the food components of T.Pachypus in Ningming County,following by Coleoptera (16.07%);while Hymenoptera (63.37%,62.34% respectively) was important in the food components of both T.Pachypus and T.Robustla in Longzhou County,following by Diptera (21.57%,29.62%) and Coleoptera (11.59%,5.96%).The food components of T.Pachypus in Ningming County also consisted of Hemiptera (2.55%),Homoptera (0.93%),Orthoptera (0.74%),Blattodea (0.52%),Ephemeroptera (0.23%) and Embioptera (0.17%);in Longzhou County also consisted of Hemiptera (1.77%),Homoptera (1.21%),Orthoptera (0.35%) and Trichoptera (0.14%).The food components of T.Robustula in Longzhou County also consisted of Hemiptera (1.54%),Orthoptera (0.26%),Trichoptera (0.16%) and Ephemeroptera (0.16%).Comparing the food components of T.Pachypus between Ningming County and Longzhou County,we found that Hymenoptera and Diptera were significant different.Comparing the food components of bats by fecal analysis with the potential food availability captured in the foraging area,we found that both species of bats positively selected Homoptera,but negatively selected other orders of insects,so both species of bats were prey selectors.