Effect of some environmental factors on arthropod communities in bat guano

Data are presented on the taxonomic composition of arthropod fauna found in bat guano in 6 limestone caves of southern Thailand, collected by Berlese's funnel type trap. There were 2 sampling periods; the first from 29 April to 7 May 1996 and the second from 1 to 4 August 1996. Combined samples of bat guano comprised 4,430 individuals of 32 families of the following : 13 orders (2 classes ; Arachnida and Hexapoda) Araneae, Acari, Pseudoscorpiones, Collembola, Blattaria, Hemiptera, Thysanoptera, Psocoptera, Neuroptera, Diptera, Coleoptera, Lepidoptera and Hymenoptera. The relationships between arthropods and physical factors such as cave temperature, relative humi-dity of the cave, moisture in guano, pH of guano, total nitrogen in guano and organic matters in guano were explored. The results showed that the number of individuals of Leptonetidae (P<0.05), Araneae (P<0.05) and Psocoptera (P<0.05) positively correlated with total nitrogen in guano but numbers of Blattellidae (P<0.05) and Blattaria (P<0.05) negatively correlated with total nitrogen in guano. The total numbers of families of arthropods (P<0.05) and the number of individuals of Leptonetidae (P<0.05), Sphaeropsocidae (P<0.05), Liposcelidae (P<0.05), Alleculidae (P<0.01), Chironomidae (P<0.05), Formicidae (P<0.05), Araneae (P<0.05), Psocoptera (P<0.01) and Hymenoptera (P<0.05) positively correlated with organic matters in guano. None of all arthropods correlated with cave temperature, relative humidity of the cave, moisture in guano and pH of guano. Study on the effect of type of bat guano (insectivore or frugivore bat guano) and the light factor (light or dark zone) on arthropods showed that type of bat guano has an effect on total numbers of families (P<0.05) and the number of individuals of Leptonetidae (P<0.01), Laelapidae (P<0.05), Blattellidae (P<0.05), Sphaeropsocidae (P<0.01), Liposcelidae (P<0.05), Dermestidae (P<0.01), Staphylinidae (P<0.01), Tineidae (P<0.05), Araneae (P<0.01), Blattaria (P<0.05), Psocoptera (P<0.01), Coleoptera (P<0.01), Lepidoptera (P<0.05) and Diptera (P<0.05). The light factor has an effect on the number of individuals of Carabidae (P<0.05) and Psocoptera (P<0.05). Interaction between type of bat guano and light affects only the number of individuals of Psocoptera (P<0.05). This study concludes that at least one of these physical factors is important in determining the number of families and the number of individuals in each family, particularly the scavenger or detritivore arthropods, and that bat guano is the food source and larva nursery for arthropods in tropical limestone caves