Editorial

This special focus issue on “Microbes and insects” features an array of six articles concerning the potential of microorganisms to control insects and symbiotic associations in fungal gardens of leaf-cutting ants. It shows nicely that also with respect to insects, fungi and bacteria are able to undergo specific pathogenic or mutually symbiotic interactions. This is, of course, known for a long time. Nevertheless, the mechanisms of insecticidal interactions, include many different activities. Enzymes expressed within the insect may substantially contribute to this activity, and hence, a lipase is studied from an entomopathogenic fungus, Isaria fumusorosea. The genus Isaria is well known to produce an array of secondary metabolites also useful as antibiotics. However, here specifically enzymatic activity is studied in the fungus–insect interaction. Another article is addressing a microsporidia isolate. This group of Eukarya still is lacking research. It has been discussed whether or not the organisms are early branches within the fungal clade, or rooted outside the true fungi. Here, the impact on insects is investigated. The Bacillus thuringesis insecticidal activity is probably the best known bacteria–insect interaction. Not only is the toxin widely used in plant protection, it also has been cloned into plants which is discussed worldwide with respect to release of genetically manipulated organisms into the wild. Here, an article addresses synergistic activity of two bacteria, with Photorhabdus being naturally carried by an entomopathogenic nematode and released into the insect hemolymph aiding nematode feeding. The Cry protein of B. thuringensis is specifically addressed in another article, where short peptides were screened for insecticidal activity. With the remaining two articles in this special focus, we can address plant interactions as well. The first concerns a streptomycete which does not only carry entomopathogenicity, but at the same time allows for general plant growth promoting and antifungal, plant protection activities. And in the remaining article, finally, the soil surrounding the fungus garden of leaf-cutter ants is addressed. The ants are raising fungal gardens in which they control the fungus helping the nest in providing a rich food source for the ants. The question addressed here was, however, whether the ants’ activity would, at the same time, exert a control over fungal communities within the soil surrounding their nest. Indeed, the authors could show a distinct and species specific impact of the ants on the soil surrounding nests. All in all, with this special focus, the Journal of Basic Microbiology can provide research articles which address important questions associated with interactions between fungal and bacterial interactions with insects.