Histology and histochemistry of Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) fat body during the post embrionary development

Abstract

Phyllocnistis citrella (Stainton), is one of the most worrying pests in the citrus growing sector. Insects’ fat body is an important tissue where numerous metabolic processes take place; its significance can be clearly seen in its main functions, i.e., assimilation and oxidation of substances so as to obtain energy and generate tissue; beside, it is the main storage source of fats and carbohydrates. The objective of the present work is to analyse its histological and histochemical changes during the post embryonic development of this species. The study material was collected in a lemon growing area free from pesticides. This material was fixed in specific solutions so as to keep proteins, lipids and carbohydrates and was stained with Hematoxylin-Eosin, Schiff Periodic Acid, Nile Blue, Sudan III and Sudan Black. During larval development, the trophocyte cytoplasmatic drops have a lipidic nature. In the prepupa stage, a decrease of lipidic drops and an increase of basophilic granulations and mild PAS positivity in the trophocyte cytoplasm were observed, indicating the beginning of the synthesis and storage of proteins and carbohydrates. Pupa’s fat body accumulates protein granules with low content of glycogen. The lipid content decreases with a predominance of acid lipids. Changes in the fat body chemical composition during the post-embryonic development of Phyllocnistis citrella are related to lysis of larval tissues and the formation of adult structures during metamorphosis.

Keywords

• citrus miner
• larval development
• metamorphosis
• morphology
• trophocytes