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.

Oecophylla smaragdina, arboreal ants in nature, is of economic interest in the Asian tropics for its potential as a low-cost biological control agent in commercial crops (cashew-nuts and recently oil palm trees). Population density-dynamics is fundamental in the study of control agents. In ants, such empirical data are scarce, considering their underground life where excavation destroys the colonies. Moreover, in the course of estimating the worker relative population size and density in a fixed area by nests counting, a population of O. smaragdina was investigated in oil palm plantations, to implement integrated pest management for controlling dominant bagworm defoliators. To minimize the estimation bias caused by the difference in nest characteristics, we analyzed the correlation of those variables to the nest contents. The models of the nest counting method found that the number of nests, the mean of total workers, and the number of trees (correlated with the occupied area) became the most significant variables in estimating the population density. No external nest characteristics was statistically significantly correlated with the number of workers. Hence, the total average worker number per nest, 6333+2907SE (52 undamaged nests, average mean total major-minor: 6332.55) multiplied by the total nest count is appropriate to estimate the relative population size and density of workers (over few million per colony in a fixed occupied area). Four absolute population-wide estimation of the worker density in four plantations was ensued. This study demonstrated the population dynamic stability of O. smaragdina with sufficient numerical resident ants by a long-term monitoring of the occurrence of incipient colonies. Controlling Metisa plana by such IPM might minimize the usage of broad-spectrum long-range contact life cycle disruptive chemicals on natural enemies’ balance in agro-ecosystems.

The Asian weaver ant (Oecophylla smaragdina) is a natural enemy, generalist predator of diverse major pest species (i.e. the highly destructive oriental fruit fly Bactrocera dorsalis) in economically strategic agricultural landscapes in Australia and Southeast Asia countries. For effective implementation of the weaver ant for biological control of the invasive bagworms Metisa plana, the dominant pest in the oil palm plantation, its distribution was investigated in Malaysia. From 2018-2022, censuses were first carried out to record Oecophylla colonies presence. Oecophylla colonies’ occupation patterns were monitored on 8 selected plantations. To distinguish between brood and barracks nests, 26 captured nests were evaluated to define the main predictor variable for its practical visual identification. More than 11000 palms with 10821 nests for over 500 colonies were sampled in this study. Results showed that O. smaragdina colonies distribution pattern exhibited three-dimensional ubiquitous occupation dominance. We also found that by observing the colony’s dense population spatial arrangements, it demonstrates them as spreading by waves featuring interconnected irregular geometrical patches shaped for each colony. The height to the ground nest location in palm canopies was the significant visual discriminant factor between Brood and barrack nests. Moreover, polydomous arboreal nesting behavior occupation occurred irrespective of palms or associated host plants sizes (≥ 3 m), throughout the year. However, colony nesting behaviors were polydomous and monodomous on shorter plants (≥ 2 m), while being strictly monodomous on small plants (≤ 1.5 m). Colonies occupied an average 3 to 4 palms yearly beginning from the newly founding phase up to the stable mature phase (3 to 4 years). Furthermore, we found that matured stable colonies (3 ≥ age ≥13) occupied 10-12 palms on average, on 800 m2 to 2500 m2 area delimited by a minimum average 20 m2 of “no ants land” zone between each colony. Our results suggest that a sustained agriculture system in this area would be possible with the presence of matured colonies nests exploitation which could provide an efficient biological control ecosystem service.

The bagworms Metisa plana is a recurrent indigenous invasive defoliator in oil palm plantations. A moderate foliar injury can cost up to 40% and above of yield loss for years. As an effective biological control agent (BCA) or by integrated pest management (IPM) on insect pests of economic significance affecting major crops of the countries in Asia-Pacific region, the adoption of the Asian weaver ant Oecophylla smaragdina might support farmers facing outbreaks. Information about the foraging activity and population dynamic (PD) of Oecophylla are important in implementing such program. Oecophylla being an obligate arboreal by nature was observed spending extended periods on the ground by occupying a vast territory under constant surveillance mode, which is significant and valuable feature for pest control. The foraging activity of major workers, their exploratory venture is closely related to systematic predation-hunting activity. The scarcity of population dynamic studies on the Oecophylla species contrast with the reports frequency of subterranean species. Estimation of population density of Oecophylla by direct nest counting method is feasible, practical and sustainable. This is contrasting with calculation done on excavated underground colonies consequential of their extinction. Simulation inaccuracy due to insufficient experimental evidence from using exclusively mathematical models is giving to real time long term field population dynamic more importance. Oecophylla colonies' stability, forager abundance and permanent patrol hunting oriented activity, are key factors for pest reduction. If the evaluation on O. smaragdina is higher, for this last decade, a significant upsurge of study on O. longinoda provided substantial novel highlights. The introduction of Oecophylla may alleviate pests management cost and offers a healthier environment by stopping the harmful usage of broad spectrum contact pesticides.