Biological Control Strategies for Invasive Woodwasps

Invasive woodwasps such as Sirex noctilio pose significant threats to pine forests worldwide by vectoring symbiotic fungi that degrade sapwood and impair tree health. Biological control strategies have been developed to suppress woodwasp populations by exploiting natural enemies, antagonistic microorganisms and host-tree interactions. Key approaches include the release of entomopathogenic nematodes that sterilise adult females, augmentation of fungal endophytes that inhibit the growth of woodwasp symbionts, and deployment of pheromone-based lures for monitoring and mass trapping. Parasitoid wasps and predatory insects also contribute to mortality, although their efficacy varies with local ecological communities. Integrating these tactics with silvicultural practices—such as stand thinning and removal of weakened trees—enhances the resilience of pine plantations. Recent advances in understanding woodwasp sensory biology and mutualistic symbioses are informing the design of targeted control agents and improving early-detection systems. Collectively, these strategies offer environmentally sustainable alternatives to chemical insecticides and underpin adaptive management programmes aimed at mitigating the global impact of invasive siricids.

Research from Nature Portfolio

Analyses of endophytic fungal communities in various conifer species have revealed that certain host trees harbour high proportions of fungi capable of inhibiting the growth of Amylostereum areolatum, the mutualistic symbiont of Sirex noctilio. Variations in endophyte diversity and colonisation rates correlate with tree species and geographic region, suggesting that selective inoculation of antagonistic endophytes could reduce successful woodwasp establishment and larval development.

Electrophysiological and genomic studies of Sirex noctilio have demonstrated a dichromatic visual system sensitive to green (527 nm) and ultraviolet (364 nm) wavelengths. The absence of a short-wavelength receptor implies that trap designs incorporating specific UV-green light spectra could enhance attraction and improve monitoring efficiency in forest surveillance programmes.

Biological Control Strategies for Invasive Woodwasps publication trend

The graph below shows the total number of articles in biological control strategies for invasive woodwasps across all publications each year (not limited to Nature Index journals).

Technical terms

Endophyte: A fungus or bacterium living within plant tissues without causing harm, some of which can inhibit pathogen growth.

Entomopathogenic nematode: A microscopic roundworm that infects and often kills insect hosts, used as a biological insecticide.

Aggregation-sex pheromone: A chemical signal emitted by insects, typically attracting both sexes to form mating aggregations.

Symbiotic mutualism: A close biotic interaction in which two species derive reciprocal benefits from association.

Parasitoid: An organism whose immature stages feed on a single host organism, ultimately leading to host death.

References

1. Effects of endophytic fungi diversity in different coniferous species on the colonization of Sirex noctilio (Hymenoptera: Siricidae). Scientific Reports (2019).
2. Evidence for UV-green dichromacy in the basal hymenopteran Sirex noctilio (Siricidae). Scientific Reports (2021).
3. Efficacy of Kamona strain Deladenus siricidicola nematodes for biological control of Sirex noctilio in North America and hybridisation with invasive conspecifics. NeoBiota (2019).
4. Biology of a putative male aggregation-sex pheromone in Sirex noctilio (Hymenoptera: Siricidae). PLOS ONE (2020).
5. Do Native Insects and Associated Fungi Limit Non-Native Woodwasp, Sirex noctilio, Survival in a Newly Invaded Environment?. PLOS ONE (2015).
6. The Effects of Silvicultural Treatment on Sirex noctilio Attacks and Tree Health in Northeastern United States. Forests (2014).