Food resource and temporal partitioning amongst a guild of predatory agroecosystem-inhabiting ant species

摘要

Prey diversity and temporal foraging patterns of six abundant,predatory ant species were investigated seasonally in an agroecosystem with two main vegetable crops.Pheidole sp.demonstrated the highest predation success and therefore appears to be the dominant species while Tapinoma melanocephalum showed the lowest success under the natural field conditions.Investigation of prey diversity and temporal activity patterns with the null model tests of niche overlap revealed a significant overlap indicating that the activity periods and prey diversity may not be solely influenced by interactions among the co-existing ant species.However,niche partitioning in the daily peak activity periods was demonstrated during all the three seasons(summer,rainy and winter)particularly between Pheidole sp.and T.melanocephalum.Pheidole sp.exhibited a high intensity,broadly extended mono-modal foraging pattern.Camponotus compressus and C.paria showed bi-modality in their foraging activity during the rainy season and mono-modal patterns during summer and winter seasons.Pachycondyla tesserinoda,Tetramorium sp.and T.melanocephalum exhibited peak foraging activities in the morning hours during the summer and rainy seasons.The activity profiles of C.compressus and T.melanocephalum were skewed towards late afternoon hours during the winter season indicating avoidance of foraging activity during the favourable periods when the more aggressive Pheidole sp.is active.In the sponge gourd agroecosystem,the ants captured predominantly hymenopteran,orthopteran and coleopteran insects.While Pheidole sp.hunted mainly the large orthopteran prey,other ant species captured worker ants in the sponge gourd agroecosystem.In the cauliflower agroecosystem,while other species captured prey chiefly belonging to six orders,i.e.,Lepidoptera,Hymenoptera,Coleoptera,Hemiptera,Isoptera and Diptera,Pheidole sp.and P.tesserinoda were the only species to also hunt many orthopteran prey.The agroecosystem-inhabiting ant species prey on a large number and wide variety of insect herbivores as evident from the differences in the peak foraging times and the proportion of each type of prey hunted.Overall,our results indicate that the structure of agroecosystem-inhabiting ant assemblage may be influenced by a variety of factors including competition,temporal heterogeneities,prey availability and its characteristics such as size and mobility.