Species diversity of ants and their association with plants and other arthropods in vegetable ecosystem

Abstract

The study titled “Species diversity of ants and their association with plants and other arthropods in vegetable ecosystem” was carried out at Department of Agricultural Entomology, College of Agriculture, Vellayani during 2019 to 2021. The study was conducted with an objective to document ant species in vegetable ecosystem and their association with plants and other arthropods The documentation was conducted from nine vegetable ecosystems such as coccinia, cowpea, sword bean, okra, chilli, brinjal, amaranthus, bitter gourd and snake gourd in Thiruvananthapuram district. Eighteen ant species belonging to sixteen genera were documented from these vegetable fields. The ants documented were trap-jaw ant (Odontomachus simillimus Smith), African ant, Bothroponera sulcata (Mayr), Bornean queenless ant (Diacamma rugosum (Le Guillou)), Ponerinae ant (Leptogenys sp.), belonging to Ponerinae subfamily. Ants of the subfamily Dolichodorinae include white footed ant (Technomyrmex albipes (Smith)). Ants of the subfamily Myrmecinae include acrobat ant (Crematogaster rothneyi Mayr), shield ant (Meranoplus bicolor (Guerin-Meneville)), hunch back ant (Myrmicaria brunnea Saunders), Asian marauder ant (Carebara diversa (Jerdon)), tropical fire ant (Solenopsis geminata (Fabricius)), destructive trailing ant (Trichomyrmex sp.). Ants of the subfamily Formicinae include yellow crazy ant (Anoplolepis gracilipes (Smith)), carpenter ants (Camponotus compressus (Fabricius)), Camponotus sericeus (Fabricius), Camponotus parius Emery, weaver ant (Oecophylla smaragdina (Fabricius)), black crazy ant (Paratrechina longicornis Latreille) and spiny ant (Polyrhachis exercita (Walker)). Morphological characters of eighteen species were documented in this study. The ant species D. rugosum, M. brunnea, P. exercita and A. gracilipes were observed to be highly diverse and Leptogenys sp., C. diversa and T. albipes were found to be the least diverse ant species. Coccinia and cowpea were observed to have the highest diversity of ants foraging on it. Amaranthus was found to have the least number of ant species foraging on it. Association of ants with vegetable seeds in the nursery was observed. Larger black ants like C.compressus, C. sericius and D. rugosum were seen foraging the area. It was found that ant species involved in various functions in the vegetable ecosystem. They are found to be phytophagous, in mutualistic associations with sucking pests, as predators, plant foragers feeding on extra floral nectaries on the crop and pollinators. Five species of ants were found to be phytophagous. D. rugosum, M. brunnea , C. diversa,149 Trichomyrmex sp., C. Compressus and C. diversa was observed making holes on the shoots and fruits of okra. C. compressus was observed cutting the shoots of nursery plants. C. compressus was also observed chewing on the brinjal shoot and feeding on them by making holes, M. brunnea is found making holes on young cowpea pods. Eight species of ants were observed associated with other arthropods in these vegetable ecosystems. They are C. compressus, T. albipes, A. gracilipes, M. brunnea, O. smaragdina, P. longicornis, S. geminata and C. parius. Ant arthropod associations were observed more in brinjal. C. compressus was found to be associated with homopterans. Five genera of ants were seen tending to homopteran sucking pests, they were Oecophylla, Anoplolepis, Paratrechina, Solenopsis and Camponotus. In okra four genera of ants were observed tending to homopteran sucking pests. They were Camponotus, Technomyrmex, Anoplolepis and Solenopsis. In chilli four genera of ants were seen tending to homopteran sucking pests. They were Camponotus, Solenopsis, Anoplolepis and Paratrechina. In cowpea four genera of ants viz. Myrmicaria, Camponotus, Solenopsis and Anoplolepis were seen associated with various sucking insect pests. Thus, these ant species are indirect pests by promoting ant- homopteran mutualisms and thereby destroying the crop. Seven species of ants viz. O. simillimus, D. rugosum , M. brunnea , S. geminata, C. compressus, O. smaragdina and A. gracilipes were observed to have predatory nature. Extra floral nectaries were observed to be fed upon by T. albipes, C. rothneyi, C. compressus, C. parius, O. smaragdina, A. gracilipes and P. longicornis. M. bicolor, M. brunnea, C. compressus, C. parius, A. gracilipes and P. longicornis were seen foraging inside the flowers, giving a possible indication of aiding in pollination of flowers. The study concluded that eighteen species of ants were found associated with vegetable ecosystems. D. rugosum, M. brunnea, P. exercita and A. gracilipes were observed to be highly diverse and coccinia and cowpea were observed to have the highest diversity of ants foraging on it. They were found to be phytophagous, in mutualistic association with sucking pests, as predators, plant foragers feeding on extra floral nectaries on the crop and foraging inside the flowers and acting as pollinators.