Bragantia (2005) 64, 233-239

Alexandre de Almeida e Silva, Elenice Mouro Varanda and Ana Cândida Primavesi (2005)
Effect of the inherent variation in the mineral concentration of alfalfa cultivars on aphid populations
Bragantia 64 (2), 233-239
Abstract: Plants have inherent variability of mineral content which affects their physiology and consequently the herbivorous insects feeding on them. Besides, insects need considerable amounts of potassium, phosphorus and magnesium in their diets, whereas little calcium, sodium and chloride are required. In this study, the inherent variation on mineral (Ca, S, Mg, N, P, K and also C:N ratio) concentrations and aphid (Acyrthosiphon spp., Therioaphis maculata, Aphis craccivora) populations on three alfalfa (Medicago sativa) cultivars (P3; Crioula, the most widely cultivated in Brazil, and CUF 101, an aphid-resistant) were studied between September/1997 and August/1998. A significant variation on mineral concentrations and aphid populations was observed among different sampling times and cultivars. The correlations between C:N ratio, Mg, N, P and S concentrations and aphid density variation suggest that the mineral status affects aphid population dynamics under field conditions.
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Research topic(s) for pests/diseases/weeds:
resistance/tolerance/defence of host

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Acyrthosiphon pisum	Alfalfa/lucerne (Medicago sativa)	Brazil (south)
	Aphis craccivora	Alfalfa/lucerne (Medicago sativa)	Brazil (south)
	Acyrthosiphon kondoi	Alfalfa/lucerne (Medicago sativa)	Brazil (south)
	Therioaphis trifolii	Alfalfa/lucerne (Medicago sativa)	Brazil (south)