Abstract: Predation of the brown planthopper (BPH), Nilaparvata lugens (Stål) by its predators is particularly important in rice field ecosystem, but its studying is rather difficult. In this study, PCR cross-amplification was initially conducted on DNA extracted from 66 species of arthropods commonly found in rice fields. Only Lug-F1a/Lug-R1 was specific and efficient enough to detect species-specific DNA of N. lugens in the gut of wolf spider Pardosa pseudoannulata. Then, we assessed how digestion time, temperature, feeding amount of predators and the sex of predators can influence the effectiveness of detecting BPHs in spider guts using Lug-F1a/Lug-R1. The results indicated that digestion time, temperature and feeding amount significantly affected the detection of the primers, while the sex of predators had no significant influence. The detection was significantly and negatively correlated with digestion time and temperature, but positively with the feeding amount. Thus the species-specific primers of N. lugens had been successfully identified, which could be effectively used in rice fields. These primers under the conditions tested here provide a new detection tool efficient for studying the relationship between N. lugens and its predators.

Key words: Nilaparvata lugens, Pardosa pseudoannulata, molecular identification, species-specific primers, predation detection, environmental conditions