Environmental risks of pest management practices in smallholder coconut plantations

Oryctes rhinoceros, the coconut rhinoceros beetle, remains one of the most damaging pests of coconut (Cocos nucifera) across South and Southeast Asia, the Pacific, and increasingly, new invasion fronts in the Americas. Although climatic alterations may redistribute the geographic footprint of the hazard, predictive assessments underscore non-linear and variable outcomes. Regional expansions in vulnerable or suitable extents are largely contingent upon the analytical scenario and structural parameters of the model utilized. This reinforces the case for treating its management as an environmental, not solely agronomic, concern. The study objectives were to characterize how smallholder-level management choices translate into differentiated environmental and health risk. Smallholder coconut plantations, which supply most world coconut production, are disproportionately exposed because of fragmented land holdings, limited capital, and constrained extension access. This review evaluates the translation of management interventions into distinct environmental and health hazards by systematically reviewing evidence on coconut rhinoceros beetle biology, intervention efficacy, smallholder socioeconomic dynamics, and insecticide risk literature through a standardized four-tier risk framework. Smallholders commonly rely on chemical control options such as organophosphates and pyrethroids. These options carry documented risks: non-target toxicity, soil and water contamination, and occupational exposure. In the absence of beetle-specific metrics, elevated occupational exposure risks are inferred from prevailing normative practices in smallholder agriculture concerning the omission of protective equipment. Biological and cultural alternatives include O. rhinoceros nudivirus, Metarhizium anisopliae, Bacillus thuringiensis, botanical larvicides, and pheromone-based trapping. These present a substantially lower environmental risk profile: laboratory bioassays report ۹۰ to ۱۰۰ percent larval mortality for Metarhizium isolates from East Java, comparable to the up to ۹۸ percent larval and ۹۰ percent adult mortality reported for a granular carbamate alternative, indicating technical efficacy is not the limiting factor, with field-deployed monitoring documented in Jepara and Bengkulu. Uptake of these lower-risk options is nonetheless constrained less by technical efficacy than by production economics, extension access, and the fragmented governance of smallholder replanting and pest-management programs. The evidence suggests that attenuating this risk burden is predominantly constrained by the disparity between existing lower-risk technological interventions and their operational uptake, among other compounding determinants. Risk-management strategies must therefore be designed around smallholder economic and institutional realities rather than efficacy data alone.

کلیدواژه ها:

Coconut rhinoceros beetle ، Environmental Risk Assessment ، Integrated pest management (IPM) ، Oryctes rhinoceros ، Smallholder agriculture.