Foraging Behaviour and Population Dynamics of Asian Weaver Ants: Assessing Its Potential as Biological Control Agent of the Invasive Bagworms Metisa plana (Lepidoptera: Psychidae) in Oil Palm Plantations

Abstract

The bagworm (Metisa plana) is a recurrent indigenous invasive defoliator in oil palm plantations. Moderate foliar injury can cost up to 40% yield loss and more for years. The main objective of this review is to disseminate published research demonstrating the versatile services that would benefit farmers by adopting the Asian weaver ant into their pest management agenda. Oecophylla smaragdina is a natural indigenous enemy applied as a successful biological control agent (BCA) and strong component of integrated pest management (IPM) against important damaging pest infestations of commercial crops in the Asia-Pacific region. Farmers facing invasion could benefit by introducing Oecophylla ants as a treatment. The foraging behavior and population dynamics of this species are poorly documented, and hence need further evaluation. Ants of the Oecophylla genus, while exhibiting an intrinsic obligate arboreal pattern, demonstrate additional lengthy diurnal ground activity. The absolute territorial characteristic via continuous surveillance is significantly valuable to maintain pest balance. The exploratory scheme of major workers over large territories is derived from their inner predation instinct. The insufficient understanding of the population dynamics of this weaver ant species diverges from the knowledge of underground species. However, population density estimations of weaver ants by direct nest visual recordings are practicable and viable. The abundance assessment of individual underground ant species colonies by excavation ends with their extinction, which is not a sustainable model for O. smaragdina. Mathematical model estimation by simulation could not resolve this issue, adding inaccuracy to the deficiency of experimental proof. Thus, long-term monitoring of the population dynamics in real time in the field is compulsory to obtain a valid dataset. Oecophylla colonies, with the criteria of population stability, individual profusion, and permanent daily patrol services, are eligible as a BCA and alternative IPM treatment. The last decades have witnessed the closing of the scientific applied research gap between Asian and African species in favor of O. longinoda with comprehensive novel findings. By introducing Oecophylla ants, two main goals are reached: easing the burden of management costs for injurious insects and ending the practice of applying highly toxic pesticides that are harmful to non-target taxa, thus promoting environmental restoration.

Distribution and Nest Occupancy Patterns of <em>Oecophylla smaragdina</em> (Hymenoptera: Formicidae) Colonies in Southeast Asia Oil Palm Plantations

“…Functionally, Oecophylla colonies brood nests location at top of palm canopies having higher insolation is verified in the literature with a tendency towards sunshiny exposure, because they are being unable to capitalise on the heat radiance of the soil [18]. Beside that aspect, another important point touches to the territorial defensive strategy of O. smaragdina [28]. The characteristic arrangement observed between brood and barrack nests in the palm trees is seen as a pure safety and survival strategy [1].…”

“…This paper engaged in this investigation to widen the latitude of information and knowledge contributing to understand better the versatile functions of this generalist predator. Previous studies mentioned the omnipresence of Oecophylla colonies in oil palm plantations but without defining the extension of their distribution nationwide [28]. O. smaragdina established prevalence by its abundance and rapid spatial expansion and colonization in the Australian, Brunei and Sulawesi forest canopies [43,44] and oil palm trees of Southeast Asia, as it rarely was challenged by other ant species [45].…”

“…The Asian weaver ants in South-East Asia represents a strategic potential influential of the ecological and evolutionary paths of plantpollinator interactions [84]. The future introduction of the Asian weaver ant might ease management burden costs, terminate highly toxic pesticides applications harmful to non-target taxa and accordingly provide environmental preservation [28].…”

“…This is necessary to convince the industry entrepreneurs of the worth if the Asian weaver ants could provide an important ecosystem service, by biological control of the recurrent outbreaks of the invasive dominant bagworms in the oil palm crop [26,27]. This may help planters to enhance their pest management program implementation for different agricultural products to attain higher quality with lower cost of management minimizing the use of phytosanitary applications [28]. This study proposes to gather information to estimate the average age of O. smaragdina colonies in oil palm plantations.…”

The Social Organisation of <em>Oecophylla smaragdina</em> (Hymenoptera: Formicidae) Colonies and Their Functional Activity

“…The colony structure composition of Oecophylla smaragdina is not completely documented (Schlüns et al, 2009) and further investigation may unveil more information on the workers caste (Exélis et al, 2023). A colony is defined by the presence of a founding depositing eggs dealate queen (shed wings), winged reproductive individuals composed of virgin queens and drone males.…”