Interactions between Metisa plana, its hyperparasitoids and primary parasitoids from good agriculture practices (GAP) and non-gap oil palm plantations

The bagworm species, Metisa plana (Lepidoptera: Psychidae), is a major oil palm pest. The existence of M. plana parasitoids is reliant on the presence of the host (M. plana) and food supplies. However, no detailed information on their food web has been studied as a model system for community ecology, specifically in the oil palm ecosystem. Therefore, in this study, we have listed two main objectives: (1) to determine the diversity of M. plana parasitoids from Good Agriculture Practices (GAP) and non-GAP plantations and (2) to investigate the relationships between hyperparasitism and primary parasitism. The parasitoid samplings were conducted at six oil palm plantations throughout Peninsular Malaysia. A total of 1199 hymenopteran parasitoid specimens belonging to 16 species under 8 families were successfully collected by using malaise traps for 12 months. Based on the Shannon-Wiener diversity index (H'), the diversity of the parasitoids was significantly higher (t = 3.840, p < 0.05) in the GAP plantations compared to the non-GAP plantations. The ratio for hyperparasitoids to primary parasitoids is as follows: 32.19%: 67.81%. Interestingly, the analysis indicated a strong negative correlation between the hyperparasitoids and the primary parasitoids (R = - 0.807, R-2 = 0.6509, p < 0.05) collected from the GAP plantations. For the non-GAP, intensive insecticide application for pest control was assumed to be the main reason for the weak correlations. These findings contribute the latest information on the diversity of M. plana parasitoids towards Integrated Pest Management (IPM) strategies and towards successful parasitoid rearing programs.

Automated summary

This study investigated the diversity of Metisa plana parasitoids and found that their diversity was significantly higher in Good Agriculture Practices (GAP) plantations compared to non-GAP plantations. The study also revealed a negative correlation between hyperparasitoids and primary parasitoids.