ABSTRACT
The predatory coccinellid Harmonia axyridis is a polyphagous species, efficient at controlling certain aphid species and already commercialized in Europe for that purpose. The complete development of this predator can be accomplished using the aphid Acyrthosiphon pisum or Ephestia kuehniella eggs as substitution prey. Biochemical analyses were conducted on the proteins, lipids, and carbohydrates of these two different prey species. E. kuehniella eggs were 2 times richer in amino acids than A. pisum adults (12% of the fresh weight vs. 6%). E. kuehniella eggs were 3 times richer in lipids than the aphids but, on the contrary, the aphids were 1.5 times richer in glycogen. The impact of these two kinds of food on the body composition of the coccinellid was evaluated to appreciate the degree of nutritional plasticity of the coccinellid. The composition of the coccinellids feeding either on E. kuehniella eggs or on aphids was compared for amino acid, fatty acid and glycogen contents, revealing a good capability of H. axyridis to develop on foods that are very different in their biochemical composition. Nevertheless, when fed on aphids, the crude protein content of the predator was reduced and the lipid content decreased by a factor of two, with a change in amino and fatty acid patterns. Some biological parameters, such as larval mortality, adult weight, and fecundity, were modified according to the food eaten.
Subject(s)
Animal Nutritional Physiological Phenomena , Coleoptera/physiology , Predatory Behavior , Adaptation, Physiological , Amino Acids/metabolism , Animals , Aphids , Coleoptera/metabolism , Female , Fertility , Glycogen/metabolism , Lipid Metabolism , Molting , Moths , Ovum , Species SpecificityABSTRACT
The stylet secretions produced by plant parasitic root-knot nematodes are thought to be pathogenicity factors involved in the invasion of the root tissue and in the induction and maintenance of feeding cells. A new procedure was established that allowed the direct qualitative analysis of proteins secreted by Meloidogyne incognita infective juveniles. Purified proteins whose isoelectric point (pI) ranged from 5.0 to 7.5 were separated by two-dimensional (2D) electrophoresis and the seven most abundant proteins were identified by micro-sequencing. A calreticulin (CRT) was isolated and transcription of its gene in infective juveniles and adults was demonstrated. Moreover, evidence for expression of the CRT in the subventral oesophageal glands of infective juveniles was obtained. The potential roles of this secreted protein in pathogenesis and the advantages of developing this strategy to obtain new insights into plant-nematode interactions are discussed.
