胡瓜新小绥螨对荔枝叶螨的控制潜力

Predatory Potential of Neoseiulus cucumeris against Oligonychus litchii

荔枝叶螨Oligonychus litchii Lo et Ho是一种重要的农业害螨,寄主范围广,在荔枝产区为害严重。为明确胡瓜新小绥螨Neoseiulus cucumeris Oudemans对荔枝叶螨的潜在控制能力,采用功能反应和数值反应,分析了胡瓜新小绥螨在不同温度下对荔枝叶螨卵和若螨的捕食效应以及胡瓜新小绥螨对荔枝叶螨种群密度效应的影响。结果表明:胡瓜新小绥螨对荔枝叶螨卵和若螨均有较强的嗜食性,但对雌成螨几乎不取食。在20.5~32.5℃时,胡瓜新小绥螨对荔枝叶螨若螨和卵的捕食功能反应均拟合HollingⅡ型方程,20~29℃时,胡瓜新小绥螨对荔枝叶螨卵和若螨的处理时间、瞬间攻击系数随着温度的升高而降低,对卵和若螨的最大日捕食量则随着温度升高而增大。在28~29℃时,胡瓜新小绥螨对荔枝叶螨若螨和卵捕食能力最强、捕食量最大,处理时间最短,但当温度达到32℃以上时捕食量开始减小。另外,胡瓜新小绥螨对荔枝叶螨种群的控制能力,随着益害比的增加,荔枝叶螨种群数量明显下降,当益害比为5:10时荔枝叶螨种群数量在第9 d下降了40.78%。综合分析表明,胡瓜新小绥螨对荔枝叶螨卵和若螨具有一定的捕食作用,捕食的最适温度为28~32℃,在荔枝叶螨种群密度较低时释放胡瓜新小绥螨可起到一定的控害效果。

The litchi spider mite, Oligonychus litchi, is one of the important agricultural mite pests, having a wide host range and causing serious damage to litchi. The predatory functional and numerical response of the predator Neoseiulus cucumeris to egg and nymph of O. litchii was examined at five different temperatures, and N. cucumeris response to density of O. litchii was also investigated. The results showed that N. cucumeris preferred eggs and nymphs but hardly predated female adults of O. litchii. The predatory functional responses to O. litchii eggs and nymphs at 20.5-32.5 ℃well fitted to the Holling Ⅱ equation. At 20-29 ℃, the handling time(Th) and the instant attack rate(a) of N. cucumeris decreased with the increase in temperature, while the maximum predatory number(Na max) of the eggs and nymphs increased with the increase in temperature. However, predation was reduced when the temperature was above 32 ℃. Furthermore, the control of O. litchi population by N. cucumeris responded positively to the ratio of predator to prey. At ratio of 5:10, the prey population was reduced by 40.78% in 9 days in comparison with the blank control(at ratio of 0:10). Therefore, N. cucumeris shows a certain predatory capacity against eggs and nymphs of O. litchii, with an optimal predatory temperature of 28-32 ℃. N. cucumeris released when the prey density is low can control O. litchii population growth to some extent.