Effect of prey stages on numerical response of Nephus arcuatus Kapur

This study examined the effects of prey stages on numerical reponses of Nephus arcuatusat different densities of four different sizes of Nipaecoccus viridis (four different stages including: the 1st, 2nd and 3rd instar nymphs and adult females of N. viridis). The densities of 2, 4, 8, 16, 50, 70, 90, 110 and 130 of 1stinstar nymphs, 2, 4, 6, 10, 20, 30, 40 and 50 of 2nd instar nymphs, 2, 4, 6, 9, 15, 21 27 of 3rd instar nymphs and 1, 3, 5, 7, 9 of adult females of prey were considered as prey and introduced to mated female (10 day- old) during 24h. The results indicated that the number of eggs laid per female were nonlinearly increased with increasing prey density in all four prey stages. Comparisons of means eggs laid by females at highest densities of each prey indicated that females laid the highest number of eggs when exposed to small prey, 1st instar nymph (8.5± 1.2) and lowest eggs on 2nd instar (5.2±0.7), 3rd instar nymphs (5.9±0.8) and as well as adult females (4.7±0.7) with significant differences (P=0.0002). These findings showed that the numerical response of N. arcuatus is affected by different stage of N. viridis.