Beneficial Insects & Natural Enemies

The good guys - insects and natural enemies that help control FAW

Source: Istock

Introduction

The Fall Armyworm (Spodoptera frugiperda) is a serious pest that causes heavy losses to important crops such as maize in Southeast Asia. Because of its rapid spread and the damage it causes, researchers are looking for sustainable solutions, one of which is exploring natural enemies such as predatory insects like beetles and wasps, parasitic species, beneficial mites, and microbial pathogens such as fungi, bacteria, and viruses that can infect and kill the pest. In Southeast Asia, researchers in countries like Indonesia, Vietnam, Thailand, The Philippines and Lao PDR are actively studying beneficial organisms that could serve as effective biological control agents.

This page highlights research from Southeast Asia on the natural enemies and predators of the Fall Armyworm, exploring their potential role in advancing sustainable pest management.

Parasitoids of Fall Armyworm

Parasitoids are one of the most important groups of natural enemies being studied for the management of Fall Armyworm (Spodoptera frugiperda) in Southeast Asia. Unlike predators, which consume multiple prey during their lifetime, parasitoids lay their eggs in or on the body of the pest, eventually killing it. In its native range in the Americas, more than 150 species of parasitoids have been reported to attack Fall Armyworm (Molina-Ochoa et al., 2003). These include egg parasitoids such as Telenomus remus and Trichogramma spp., as well as larval parasitoids like Cotesia spp.

Species diversity and abundance of parasitoids of Fall Armyworm in Indonesia

The presence of parasitoids of FAW has been reported in some regions of Indonesia. Species that have been confirmed to attack FAW are listed below:

West Sumatera province: Microplitis sp., Chelonus sp. (Sari et al., 2023)
Nusa Tenggara Barat province: Apanteles spp., Eriborus spp., Exorista spp. (Supeno et al., 2021)
South Sumatera province: Chelonus formosanus Sonan, Chelonus oculator F., Chelonus annulipes Wesm., Chelonus cautus Cresson, Microplitis anila Ashmead, Microplitis, marshallii Kokujev, Euplectrus corriemoreauae Hansson, Compsilura concinnata Meigen, Sarcophaga sp., Macrocentrus sp., Exorista sp., and Megaselia sp (Herlinda et al., 2023)

Figure 1. Species of egg and larval parasitoids of FAW: A) Telenomus remus (Nixon), B) Chelonus formosanus Sonan, C) Chelonus annulipes Wesm., D) Chelonus oculator F. , E) Chelonus cautus (Cresson) F) Microplitis manilae Ashmead, G) Microplitis marshallii Kokujev, H) Euplectrus corriemoreauae Hansson, I) Compsiluracon cinnata (Meigen).

Source: Herlinda et al., 2023

Eggs Parasitoids

Egg parasitoids are considered among the most effective natural enemies of the Fall Armyworm (FAW), as they target the pest before larval emergence. Two species have emerged as the most important egg parasitoids in Southeast Asia are Telenomus remus and Trichogramma spp.

Telenomus remus is recognized as a specialist parasitoid of FAW, with high parasitism capacity; field studies in East Java, Indonesia, reported parasitism rates ranging from 15.6–52.5% of egg masses (overall, depending on the ecosystem and sampling time), with up to 43.7-81% of eggs parasitized in individual masses (Wahyuningsih et al., 2021). This test was conducted in three corn-growing ecosystems: agroforestry, rice fields, and rainfed fields. Telenomus sp. was more abundant and effective than Trichogramma sp. in all locations. This research supports the results of Herlinda et al. (2023), who reported Telenomus remus Nixon as the most dominant parasitoids of FAW among 14 identified natural enemies.

Figure 2. Telenomus remus, parasitising fall armyworm eggs.

Source: ICIPE

Previous studies in other countries also indicate that both parasitoids have been effective in reducing infestations of Spodoptera frugiperda in the field, achieving parasitization levels ranging from 37.5% to 84.7% in Cameroon (Abang et al., 2021) and 64% in Nigeria (Laminou et al., 2020).

Telenomus remus already mass-produced and released in several Asian countries as augmentative agents (FAO, 2019). For example, an FAO/ICRISAT workshop in 2019 trained researchers from Vietnam, Cambodia and other countries to rear FAW egg parasitoids using FAW eggs to produce T. remus and factitious hosts for Trichogramma with the goal of early-season releases to suppress FAW.

Larval and Pupal Parasitoids

In addition to egg parasitoids, several larval and pupal parasitoids of Fall Armyworm have been identified in Southeast Asia. These parasitoids attack the pest during its later life stages, reducing populations by parasitizing caterpillars and pupae.

A sampling and monitoring study of the FAW and its natural enemies was conducted across six rice and corn-growing municipalities in Northern and Central Luzon, Philippines (Valdes et al., 2023). This led to the first identification of two new parasitoid species attacking FAW. Molecular analysis conducted by CABI identified the two parasitoid species as Brachymeria lasus Walker (Chalcididae), which is a solitary pupal parasitoid, and Copidosoma floridanum (Ashmead), a larval parasitoid. While B. lasus has previously been reported to parasitise various Lepidopteran pests, this study provides the first evidence of its association with S. frugiperda (Valdes et al., 2023).

Figure 3. Female of Chelonus formosanus Sonan. A) dorsal

B) lateral.

Source: Calcetas et al., 2023

Another parasitoid was identified in a study by Calcetas et al. (2023) called Chelonus formosanus Sonan, which is a parasitoid wasp species. It was collected emerging from a parasitised FAW larvae in the Philippines. This was the first record of C. formosanus in the country. Globally, ten Chelonus species are associated with FAW, most occurring in Central America, Africa, and Asia.

A study by (Gupta., 2020) also confirmed that Chelonus formosanus can naturally parasitize Spodoptera frugiperda in maize fields and complete its life cycle under laboratory conditions, making it suitable for mass rearing. The parasitism rate ranged from 10% to 19.4%, with 45% to 57.5% of C. formosanus adults successfully emerging from their cocoons.

Figure 4. Chelonus formosanus: Left) Larva emerging from the larva of fall armyworm. Right) Larva feeding on the larva of fall armyworm.

Source: Calcetas et al., 2023

Predators of fall armyworm reported from Southeast Asia

Predators of Fall Armyworm in Southeast Asia include a wide range of insects and arthropods that feed on its eggs, larvae, and pupae. Most are generalist predators, meaning they also consume other crop pests, making them valuable allies in natural pest control.

A list of the predators that have been recorded in Indonesia:

In Indonesia, 16 predator species have been recorded, including five ant species (Rizali et al., 2021), four lady beetle species (Ginting et al., 2020; Rizali et al., 2021), one earwig species (Tarigan et al., 2023), and six spider species (Rizali et al., 2021; Tarigan et al., 2023).

Ants

Anoplolepis gracilipes

Dolichoderus sp.

Pheidole sp.

Polyrhachis sp.
Tapinoma sp.

Earwig

Doru sp.

Lady beetles

Coleomegilla maculate (De Geer)

Harmonia sp.

Menochilus sexmaculatus (F.)

Micraspis discolor

Spider

Oxyopes sp.

Amaurobiidae sp.

Clubionidae sp.

Gnaphosidae sp.

Lycosa sp.

Miturgidae sp.

Figure 5. (A) Earwig, (B and C) fall armyworm eggs and larvae attacked by earwig, (D and E) fall armyworm larvae attacked by ants.

Source: Ahissou, et al., 2021

Figure 6.(F) Fall armyworm larvae attacked by lady beetle (G) spider on maize plant.

Source: Ahissou, et al., 2021

Predatory Bugs on Fall Armyworms reported from Malaysia (Jamil et al. 2021)

A field survey in Kedah identified two generalist predatory soldier bug species, Andralus spinidens and Eocanthecona furcellata, attacking Spodoptera frugiperda (fall armyworm) on grain corn farms. A single A. spinidens male and nine E. furcellata adults were collected and brought to the Entomology lab at MARDI Serdang. While E. furcellata was mass-reared for three generations, the colony eventually collapsed (Jamil et al., 2021).

A feeding experiment confirmed that both soldier bug species pierced and consumed S. frugiperda larvae (instar 2 and above), but only E. furcellata was observed feeding on pupae. These preliminary findings suggest that E. furcellata may have potential as a biological control agent. However, further studies are needed to assess its life cycle, feeding behavior, and predation efficiency before considering its introduction in pest management programs (Jamil et al., 2021).

Figure 7. Adult of Andralus spinidens.

Source: Jamil et al., 2021

Figure 8. Eocanthecona furcellata is feeding on a larva.

Source: Jamil et al., 2021

Research in Kham district, XiengKouang province (2019–2020) explored the role of natural enemies such as insect predators and parasitoids in controlling Fall Armyworm on maize and sweet corn

Insect pathogens and beneficial insects recorded in Laos

Insect pathogens

Beauveria bassiana
Nomuraea sp.
Nuclear Polyhedrosis Virus (NPV)

Figure 9. Insect of FAW Larvae: affected by (A) Nomuraea sp, (B) Beuveria bassiana and (c) Nuclear Polyhedrosis Virus (NPV).

Source: Soysouvanh et al., 2021

Insect Predators

Stink bug (Eocanthecona furcellata)
Assassin bug (Rhynocoris sp.)
Assassin bug (Sycanus collaris)
Assasin bug
Earwig
Lady beetle
Spider
Tiger beetle
Ants

Figure 10. Predators: (A) Stink bug (Eocanthecona furcellata), (B) Assassin bug (Rhynocoris sp.), (C) Assassin (Sycanus collaris), (D) Assassin bug.

Source: Soysouvanh et al., 2021

Parasitoids

Charops sp.
Chelonus sp.
Cotesia sp
Microplitis sp
Telenomus sp.

Figure 11. Predators: (E) FAW larva being eaten by ants, (F) earwig, (G) lady beetle, (H) FAW moth eaten by spider, and (I) tiger beetle.

Source: Soysouvanh et al., 2021

Utilising supplementary food spray to harness predatory insects against fall armyworm in maize crops of Vinh Phuc Province, Vietnam

Effective pest management in maize production requires strategies that minimize insecticide use while enhancing the role of natural predators. Generalist predatory insects play a significant role in controlling pests; however, their populations need support to maximize their effectiveness (Mensah et al., 2024). One promising approach is using supplementary food sprays that attract and sustain natural predators.

A study by Mensah et al. (2024) examined the potential of food spray formulations to attract and maintain beneficial insect populations in Vietnamese maize fields. They developed a novel, locally sourced formulation called the "Vietnam Food Product" (VFP), a cost-effective and farmer-friendly alternative to chemical pest control.

The results indicated that VFP significantly increased the abundance of predators, leading to a notable reduction in fall armyworm populations. Notably, the plots treated with food sprays achieved a higher net margin of $3,467 compared to $3,394 for conventional insecticide-treated plots, emphasizing the economic viability of this approach. Additionally, the study recorded an average predator-to-prey ratio of 9.2:1 in the food spray-treated fields, which proved sufficient for the long-term suppression of the FAW throughout the season (Mensah et al., 2024).

Study on the Efficacy of Thai indigenous entomopathogenic nematodes for controlling fall armyworm

A recent study assessed the effectiveness of two Thai Indigenous entomopathogenic nematodes (EPN) isolates: Heterorhabditis indica AUT 13.2 and Steinernema siamkayai APL 12.3 in controlling fall armyworm (FAW) under laboratory and greenhouse conditions (Wattanachaiyingcharoen et al., 2021).

In laboratory trials, six concentrations of nematodes (50–300 infective juveniles (IJs) per ml) were tested against second and fifth-instar FAW larvae. The results indicated that the second-instar larvae were more susceptible than the fifth instar. H. indica AUT 13.2 proved the most effective, achieving 83% mortality at 250 IJs per ml, while S. siamkayai APL 12.3 resulted in 68% mortality at 300 IJs per ml. The fifth instar larvae exhibited lower mortality rates, with H. indica AUT 13.2 achieving 45% and S. siamkayai APL 12.3 achieving 33% mortality at 250 IJs per ml (Wattanachaiyingcharoen et al., 2021).