Agricultural Risk and Input Cost Escalation in Oil Palm Smallholdings: Pesticide Use, Pest Resistance, and Yield Stability Under Oryctes Rhinoceros Pressure

Abstract

This study investigates the effects of insecticide application on the population dynamics of Oryctes rhinoceros and its natural enemy Platymeris laevicollis in oil palm smallholder systems in Malaysia. A Completely Randomized Design (CRD) was employed, comprising three treatment regimes Cypermethrin, Carbofuran, and an untreated control with four replications across twelve plots. Pest and predator populations were monitored from January to October 2017 using pheromone and sticky traps. The results reveal significant differences in pest population abundance across treatments (F(2,9) = 27.424, p < 0.01). Unexpectedly, untreated plots recorded the lowest mean population of O. rhinoceros (0.21), while higher populations were observed in Carbofuran (2.63) and Cypermethrin (3.12) treatments. Temporal analysis indicates that treated plots exhibited greater fluctuation and instability in pest populations, whereas untreated plots maintained consistently low levels throughout the study period. In contrast, no significant differences were observed in the abundance of P. laevicollis across treatments (F = 0.081, p > 0.05), and correlation analysis showed no significant relationship between pest and predator populations. These findings suggest that insecticide application did not consistently enhance pest suppression under field conditions and may be associated with increased variability in pest population dynamics. The absence of a significant response from natural enemy populations indicates limited evidence of biological control interaction within the observed system. This study is limited to entomological observations and does not include yield or economic data; therefore, conclusions regarding economic efficiency or cost-effectiveness cannot be drawn. However, the results highlight the need for further investigation into ecological mechanisms underlying pest dynamics and support the importance of integrated pest management approaches that consider both chemical and biological factors in oil palm systems.