A Population Study of reduviidae insect in oil palm plantation with different historical Darna trima caterpillars' infestations stages

Abstract

Enriching biodiversity using beneficial refuge plants can expedite the recolonization process of predatory insects for sustainable control of Darna trima nettle caterpillar infestation in oil palm plantations. The recolonization process of predatory insects, including Reduviidae, will affect the differences in environmental factors, feeding availability, and landscape type. This research objective is to compare the population of Reduviidae insects (predator) in different historical D. trima infestation stages in oil palm blocks with various refuge plants, i.e., Antigonon leptopus, Cassia cobanensis, Turnera subulata, and Nephrolepis biserrata. The research was conducted in an existing oil palm plantation in Central Kalimantan from July to December 2022. An experimental 2-factor nested design involving the history of D. trima attacks and the type of refuge plants was implemented in 8 blocks (ca 40 ha each) to enumerate of predatory insect population using visual observation, sweep net, and yellow trap methods. The study revealed that the dominant Reduviidae species were Cosmolestes picticeps and Sycanus dichotomus. The population of C. picticeps was 35% higher in blocks with no historical D. trima outbreaks are significantly different from blocks with historical outbreaks. In both locations, the highest populations of Reduviidae insects were found in C. cobanensis and N. biserrata plots at 61-72 individuals and 58-67 individuals, respectively. Combining both refuge plants in oil palm blocks exhibited the most significant potential as a microhabitat for Reduviidae insects and for enhancing recolonization. To further enhance the role of S. dichotomus as an environmental service in the agricultural ecosystem, it is necessary to study proper propagation and augmentation techniques in oil palm plantations.