Trophic transfer and bioaccumulation of lead along soil-plant-aphid-ladybird food chain

Lead (Pb) contamination of agroecosystems is a serious issue as Pb is a persistent pollutant that is retained in soil for long, causing toxicities to organisms. This study examines biotransfer of Pb from soils treated with different concentrations of Pb through a broad bean (Vicia faba L.)–aphid (Aphis fabae Scop.)–ladybird (Coccinella transversalis Fabricius) food chain and its consequent inference for natural biological control, the ladybird. The soil was amended with Pb at the rates of 0, 25, 50, 75 and 100 mg kg−1 (w/w). The amount of Pb in plant, aphid and ladybird increased in a dose-dependent manner to Pb contents in the soil. The results showed that Pb biomagnified from soil to root with transfer coefficient always > 1. Biominimization of Pb occurred at the second trophic level in aphids and at the third trophic level in ladybirds as their respective transfer coefficients from shoot to aphid and aphid to ladybird were always