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Benefits of Host Plant Specificity in Uroleucon (Homoptera: Aphididae)
Vol. 67, No. 1 (Feb., 1986), pp. 108-115
Published by: Wiley
Stable URL: http://www.jstor.org/stable/1938508
Page Count: 8
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Benefits of host specificity for Uroleucon nigrotibium (Homoptera: Aphididae) include not only improved physiological efficiency but also enhanced success of dispersal and defense tactics. I tested the physiological efficiency hypothesis, which predicts a higher reproductive rate for this specialist that for the generalist U. gravicorne when each is reared on their shared host, Solidago nemoralis. Between-species comparisons of developmental times and fecundities of individuals reared on naturally occurring and potted screenhouse host plants supported this prediction for the spring but not in summer, when most reproduction occurs. Greater physiological efficiency of the specialist is also supported by its greater size, which may aid in dispersing and in escaping enemies by walking. Field colonies of the specialist were found to produce few winged forms and to disperse frequently via apterae walking between hosts; consequently, U. nigrotibium infestations are larger and longer lived and are attacked more by enemies than those of its generalist congener. In experiments using potted host plants, the specialist was better able than the generalists to escape predation by walking to nearby hosts. This strategy of persistence depends on specificity to a long-lived, clumped, bushy host such as S. nemoralis.
Ecology © 1986 Wiley