Effect of petroleum-derived substances on life history traits of bird cherry-oat aphid (Rhopalosiphum padi L.) and on the growth and chemical composition of winter wheat

The aim of the study was to determine the effects of various petroleum-derived substances (PDSs), namely petrol, diesel fuel, and spent engine oil, on life history traits of the bird cherry-oat aphid Rhopalosiphum padi L., and on the growth and chemical composition of its host plant-winter wheat Triticum aestivum L. Each substance was tested separately, using two concentrations (9 and 18 g kg(-1)). Plants were cultivated in both control and contaminated soils. In early October 2013, soil was contaminated and after 1 week, winter wheat seeds, 'Batuta' cultivar, were sown. In early June 2014, observations of the effect of petroleum-derived substances on traits of three successive generations of aphids were conducted. Aphids were inoculated separately on leaves using cylindrical cages hermetically closed on both sides. Contamination of aphid occurred through its host plant. Results showed that all of the applied petroleum-derived substances have a generally adverse effect on the developmental parameters in aphids, resulting in the decrease of its fecundity, shortening its average life span, and most often lowering of the population intrinsic growth rate. PDSs caused the limitation of growth in wheat plants; whereas, changes in nutrient contents and heavy metals depended on the part of the plant analysed, the substance applied, and on its dose. The negative relationships between the contents of both some macro-elements (Ca, K, P) and heavy metals (Mn, Cd, Cu, and Zn) and the developmental parameters of particular generations of R. padi were observed. The high susceptibility of R. padi to the presence of PDSs in the substrate for the host plant should be emphasised-the clear-cut changes in the life span and fecundity, with relatively small changes in the chemical composition of the plant, constitute an evident indication that the developmental parameters of aphids have the potential for the use as bio-indicator to evaluate the state of the environment contaminated by PDSs.