Observation of the infection process of Metarhizium anisopliae on the cuticle of Anoplophora glabripennis larvae with scanning electron microscopy

Abstract

The invasion behavior and infection process of Metarhizium anisopliae on different cuticle areas of Anoplophora glabripennis larvae were observed by scanning electron microscopy. The results indicated that M. anisopliae infected A. glabripennis larvae mainly through the intersegmental membrane where more attaching conidia, faster germination, and higher germination and penetration rates were observed. The secondary invasion area was around the valve. The two areas were vulnerable to infection from M. anisopliae. Twelve hours after vaccination, conidia germinated and bud-shaped protrusions formed on the cuticle of A. glabripennis larvae, then germ tubes and various attaching structures were produced. Conidia penetrated the integument into the hemocoele of A. glabripennis larvae 36–48 h later.