Observations on Midgut Structure and Content of <I>Chrysoperla carnea</I> (Neuroptera: Chrysopidae)

Abstract

A study of Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) midgut structures and contents was conducted using scanning and transmission electron microscopy. The larval midgut was enclosed by a peritrophic membrane that seemed to be composed of two layers. Numerous bacteria were found throughout the lumen of the midgut, and because the midgut does not open to the hindgut, we hypothesized that the bacteria may serve to decompose the residues occurring in the midgut lumen. Few yeast cells were present in the larval midgut. The visual observations suggest that the concentration of bacteria were much lower in adult midguts than in larval midguts. However, many yeast cells were observed in the lumen of the adult midgut. No obvious peritrophic membrane was observed in electron micrographs of the adult midgut compared with the larval midgut. The results suggest different modes of food residue disposal.