VARIATION IN SELECTION PRESSURES ON THE GOLDENROD GALL FLY AND THE COMPETITIVE INTERACTIONS OF ITS NATURAL ENEMIES
VARIATION IN SELECTION PRESSURES ON THE GOLDENROD GALL FLY AND THE COMPETITIVE INTERACTIONS OF ITS NATURAL ENEMIES
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DOI：
10.1007/bf00378234
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发表时间：
1989-01-01
期刊：
影响因子：
2.7
通讯作者：
WEIS, AE
中科院分区：
文献类型：
--
作者：
ABRAHAMSON, WG;SATTLER, JF;WEIS, AE
高枝黄花（solidagsima Solidago altissima）的茎上长有球状的瘿。生存几率取决于胆的大小；在小虫瘿中，幼虫容易被寄生蜂产卵，而在大虫瘿中的幼虫更容易被鸟类捕食者吃掉。1983年和1984年，对美国宾夕法尼亚州中部20个自然老田蝇种群进行了监测，研究了天敌、拟寄生物巨蜂（Eurytoma gigantea）和钝尾姬蝇（E. obtusiventris）、单色姬蝇（Mordellistena unicolor）和掠食性鸟类短毛树蛾（Dendrocopus pubescens）和非洲小飞禽（Parus atricapillus）的选择强度分布。Mordellistena和obtusiventris能够攻击所有直径的胆囊，而E. gigantea和掠食性鸟类分别优先攻击小直径和大直径的胆囊。在中等大小的瘿中，Eurosta的存活率最高，因此选择具有稳定成分。但是，寄生蜂的攻击比鸟的攻击更频繁，两者并不完全平衡，因此也有方向性成分。虫瘿大小的平均定向选择强度为平均值的0.21标准差，表明更大的虫瘿更受青睐。Eurosta天敌协会的昆虫成员之间的互动是复杂而频繁的。
Larvae of the tephritid fly Eurosta solidaginis induce ball-shaped galls on the stem of tall goldenrod, Solidago altissima. Survival probability depends on gall size; in small galls the larva is vulnerable to parasitoid oviposition, whereas larvae in large galls are more frequently eaten by avian predators. Fly populations from 20 natural old fields in central Pennsylvania [USA] were monitored in 1983 and 1984 to examine the distribution of the selection intensity imposed by natural enemies, the parasitoids Eurytoma gigantea and E. obtusiventris, the inquiline Mordellistena unicolor, and the predatory birds Dendrocopus pubescens and Parus atricapillus. Mordellistena and E. obtusiventris are able to attack galls of all diameters while E. gigantea and the predatory birds preferentially assaulted small and large diameter galls, respectively. Eurosta in intermediate sized galls had the highest survivorship, hence selection had a stabilizing component. However, parasitoid attack was more frequent than bird atack, and the two did not exactly balance, thus there was also a directional component. The mean directional selection intensity on gall size was 0.21 standard deviations of the mean, indicating that larger gall size was favored. Interactions among the insect members of the Eurosta natural enemy guild are complex and frequent.