Interactions between two aphid natural enemies, the entomopathogenic fungus Erynia neoaphidis Remaudiere & Hennebert (Zygomycetes: Entomophthorales) and the predatory beetle Coccinella septempunctata L. (Coleoptera: Coccinellidae)
1997
Pell, J.K. | Pluke, R. | Clark, S.J. | Kenward, M.G. | Alderson, P.G.
Interactions between the pea aphid, Acyrthosiphon pisum, and two of its natural enemies, the ladybird Coccinella septempunctata and the fungus Erynia neoaphidis, were examined in the laboratory. Adult C. septempunctata starved for 48 or 24 hr or nonstarved were presented with aphid prey items at different stages of infection with E. neoaphidis and their feeding behaviors monitored. This demonstrated that, under laboratory conditions, C. septempunctata adults, particularly when starved for 48 hr, perceived A. pisum infected with E. neoaphidis as acceptable food sources. This is a potentially antagonistic interaction as inoculum necessary for further transmission and the development of epizootics would be removed from aphid populations. However, less time was spent feeding, except by 48-hr-starved individuals, on infected than on uninfected aphids and the number of "feeding" versus "ignore" mouthpart encounters was greater for uninfected than infected aphids, thus limiting the severity of this antagonism. In addition, under laboratory conditions, C. septempunctata adults were able to passively vector infective conidia of E. neoaphidis to susceptible aphids and initiate infection in 10-11% of the population. Ladybird foraging on E. neoaphidis-infected aphids and their ability to vector infective conidia to susceptible aphid populations is discussed in relation to the epizootiology of the fungus and its implications for the manipulation of natural enemies in integrated management strategies.
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