Effect of pea aphid and bluegreen lucerne aphid (Acyrthosiphon spp.) on coumestrol levels in herbage of lucerne (Medicago sativa)

Abstract

Field and glasshouse studies showed that infestations of pea aphid (Acyrthosiphon pisum Harris) and bluegreen lucerne aphid (A. kondoi Shinji) (BGA) caused increased coumestrol levels in herbage of lucerne (Medicago sativa cv. “Wairau”). Under field conditions log coumestrol concentration (ppm) was linearly related to aphid numbers and a reduction in stem length was associated largely with aphid damage. The coumestrol levels in severely aphid-damaged herbage were high enough to impair ewe fecundity. Glasshouse studies showed that similar levels of coumestrol were found in leaf and stem tissue of aphid damaged plants and that BGA infestations caused higher coumestrol levels than similar population levels of pea aphid.

Keywords:

• Acyrthosiphon species
• aphids
• coumestrol
• phytoestrogens
• Medicago sativa
• bluegreen aphid
• pea aphid