Influence of environmental factors on predation rate for Bactrocera dorsalis on a tropical island.

Abstract

In tropical environments, insect prey face high predation rates due to the diverse interspecific interactions driven by various environmental factors. However, a detailed understanding of how these factors interact to influence predation rate remains limited. This complexity increases with the presence of both native and nonnative predators, yet no comprehensive assessment has been conducted. In this study, we used the pupae of the widely distributed fruit fly Bactrocera dorsalis to examine how 8 tropical environmental factors affect its predation rate. Principal component analysis identified 3 principal components (PCs) that collectively explain 78.86% of the variance in the influence of these environmental factors: PC1 accounted for 49.62%, PC2 for 15.59%, and PC3 for 12.65%. PC1 was strongly influenced by patch density (loading: 0.87) and altitude (loading: -0.90), with communalities of 77.8% and 82.3%, respectively. PC2 was primarily driven by native predator diversity (loading: 0.90), with the highest communality (84.1%). PC3 was characterized by temperature (loading: 0.65) and humidity (loading: 0.70), with communalities of 81.2% and 81.8%, respectively. Although no individual PC had a significant effect on predation rate, the interaction between PC1 and PC2 was highly significant, indicating a strong combined effect. This interaction likely results from the way altitude and human disturbance contribute to habitat fragmentation, which in turn affects native predator diversity and alters the predation rate for B. dorsalis. These findings offer valuable insights into the interaction between B. dorsalis and its predators, as well as into the effectiveness of potential control strategies involving predators.