Species of Laboulbeniales fungi parasitic on some common Indian insects: Isolation, visualization and characterization by Scanning Electron Micrographs (SEM)

Abstract

The Laboulbeniales are a group of lesser-known fungi. They occur as ectoparasites on the exoskeleton of various arthropod species, mainly beetles, cockroaches, ants, dipterans and a few millipede genera appearing as hairs/bristles coming out of their cuticle. They are small, non-mycelial fungi forming compact multicellular thalli, starting from a two-celled sheathed ascospore which continues to envelop the mature thallus. The fungi, being obligate, spend their entire life cycle on their insect hosts. The present study attempted to locate the Laboulbeniales fungi in the common insects of India, isolate them and identify them based on morphology. Different species of insects; Carabid beetles - Stenolophus sp., Bembidion sp., Black ants - Camponotus sp., and Earwigs - Labidura riparia; were collected from different habitats of damp garden soil, river banks, light sources and entomological collection museum situated as different sites New Delhi. The insects were scrutinized for the presence of fungi through light and scanning electron microscopy. The morphological features of each fungus were recorded, and the species were characterized. The studies showed the presence of Laboulbenia anaplogenii and L. stenolophi on the legs of Stenolophus sp.; L. egens on Bembidion sp. legs; L. camponoti on the wings of black ants and Dimeromyces anisolabis on the legs of earwigs. The identification was made primarily based on the size, shape and structure of basal foot, receptacles, antheridia and foot of the thallus or it’s remnant scar found on the insect cuticle. This is the first Indian report of conducting scanning imaging of the Laboulbeniales fungi.