草间小黑蛛雌成蛛对小菜蛾和菜青虫幼虫的捕食效应

Predation of female adults of Erigonidium graminicolum on larvae of Plutella xylostella and Pieris rapae

在实验室条件下,研究了草间小黑蛛(Erigonidium graminicolum)雌成蛛对小菜蛾(Plutella xylostella)和菜青虫(Pieris rapae)幼虫的捕食作用。结果表明,草间小黑蛛对小菜蛾2,3,4龄幼虫及菜青虫1龄至2龄初幼虫的捕食功能反应属于HollingⅡ型。瞬间攻击力a和日最大捕食量1/Th分别为0.7435,0.6571,0.5490,0.5796和47.85,9.93,2.66,4.21头。草间小黑蛛有较强的种内干扰反应,随着捕食者密度的增大,捕食作用率相应降低;对小菜蛾3龄幼虫的捕食作用率(E)与自身密度(P)的函数关系式为E=0.2026P-0.3430。相互干扰会降低草间小黑蛛对小菜蛾3龄幼虫的寻找效应,但对其捕食量影响不大。在小菜蛾和菜青虫幼虫的混合种群中,对草间小黑蛛进行选择性观察,结果表明草间小黑蛛偏嗜小菜蛾。

The predation of female adults of Erigonidium graminicolum to larvae of Plutella xylostella and Pieris rapae was studied in the laboratory. The results showed that all the functional responses for E. graminicolum to the 2nd,3rd,4th instar larvae of P. xylostella and the 1st-2nd instar larvae of P. rapae could be described by the Honing model Ⅱ . And the moment attack‘a＇ and the largest preying amount per day ‘1/Th＇ were 0.7435, 0.6571, 0.5490 and 0.5796, as well as 47.85, 9.93, 2.66 and 4.21, respectively. Intraspecific interference of the spider was found in the experiment. The predation rate of E. graminicolum decreased along with the increase of predator density. The relationship between predation ratio （E） and the spider density （P） was described by equation of E = 0.2026P^-0.3430. Mutual interference in the spiders could reduce the searching efficiency of E. graminicolum, however, had little affection on preying amount. Given the mixed populations of the 3rd instar larvae of P. xylostella and the 1st-2nd instar larvae of P. rapae, the spiders were observed to prefer the former.