Predatory Efficiency and Functional Response of the Wolf Spider Pardosa pseudoannulata (Boesenberg and Strand) against the Brown Planthopper Nilaparvata lugens (Stål) under Laboratory Conditions

Abstract

The present study evaluated the predatory efficiency and functional response of the wolf spider Pardosa pseudoannulata against nymphs of the brown planthopper, Nilaparvata lugens, under laboratory conditions. The experiment was conducted using a completely randomised design with six prey-density treatments consisting of 10, 20, 30, 40, 50, and 60 brown planthopper nymphs per arena. A single adult spider was released into each arena, and prey consumption was recorded after 24 hours. Each treatment was replicated three times. The number of prey killed increased with increasing prey density, indicating that prey availability influenced predator feeding. The mean number of nymphs consumed increased from 8.67 at a prey density of 10 nymphs to 23.33 at a prey density of 60 nymphs. In contrast, the proportion of prey killed declined from 0.87 to 0.39 across the same prey-density range, showing reduced proportional consumption at higher prey densities. Functional response analysis based on the relationship between reciprocal prey attacked and the reciprocal prey density-time product indicated a Holling Type II functional response. This pattern was characterised by an increase in prey consumption at lower prey densities, followed by a gradual reduction in consumption efficiency as prey density increased. The findings suggest that P. pseudoannulata can consume brown planthopper nymphs effectively under laboratory conditions and may contribute to the natural regulation of planthopper populations in rice ecosystems. Further field-based studies are required to confirm its practical role in integrated pest management.