Ambrosia Beetle Threatens Kerala Rubber Plantations
The rubber plantations of Kerala face a serious threat from a beetle-fungus alliance. Researchers at the Kerala Forest Research Institute have identified the ambrosia beetle, *Euplatypus parallelus*, as the key pest. This beetle carries two fungal species, *Fusarium ambrosia* and *Fusarium solani*, which damage rubber trees. The infestation causes leaf fall, trunk drying, and reduces latex production, impacting the economy.
Identification of the Pest and Fungal Partners
The ambrosia beetle is native to Central and South America and was first reported in India in 2012 on cashew trees in Goa. It bores tunnels called galleries into stressed or dead trees. The beetle carries fungi into these galleries. The fungi grow and provide nutrients to beetles and larvae. This mutualistic relationship weakens the tree’s wood and allows deeper beetle penetration. The recent discovery of *Fusarium solani* with adult beetles is novel. Unlike other beetles, these ambrosia beetles lack mycangia, sacs that usually carry fungi.
Impact on Rubber Trees
Infected rubber trees show latex oozing and severe leaf fall. The fungi block the tree’s xylem vessels, disrupting water transport. Enzymes secreted by fungi degrade wood strength, causing rapid drying and sometimes death of the tree. The damage reduces latex yield, threatening farmers’ livelihoods. Once infected, trees take a long time to recover. Fungicides and insecticides often fail to reach the fungi deep inside the tree.
Current Control Measures
To manage the infestation, experts recommend removing and destroying infected parts of trees. Traps are used to catch adult beetles. Antifungal treatments are applied but have limited success. Preventive actions include monitoring plantations and early detection. The systemic nature of the infection makes control difficult once it spreads inside the tree.
Broader Risks and Future Threats
The ambrosia beetle can attack over 80 broadleaf tree species, including economically important crops like cashew, teak, coconut, and coffee. There is concern that the beetle may form alliances with other pathogenic fungi, increasing its threat. Fusarium fungi also pose risks to other organisms and humans, especially those with weak immunity. The increasing spread of invasive ambrosia beetle species calls for urgent research and policy action.
Recommendations for Sustainable Management
Experts suggest location-specific management strategies for plantations in Kerala. Practices successful elsewhere may not work locally. Sustainable methods like using antagonistic fungi or diverse microbial consortia inside plants show promise. Collaborative efforts between researchers, policymakers, and farmers are essential to develop effective control and prevention measures.
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