Genetic groups of the insect-pathogenic fungus Beauveria bassiana are associated with habitat and thermal growth preferences

Abstract

A persistent paradigm in insect pathology is one that relates the insect host to certain genetic groups of insect-pathogenic fungi. This paradigm assumes that the genotype of an insect-pathogenic fungus coevolves with a certain taxon of insect host that it infects. The insect-pathogenic fungus Beauveria bassiana shows a wide host range and is considered to be a facultative insect pathogen. In this study, a population genetics analysis of B. bassiana from forested and agricultural habitats as well as from the Canadian Arctic showed distinct genetic groups associated with the three different habitats. Within each group, recombining population structures and clonally reproducing lineages were observed. The B. bassiana isolates were also assessed for their abilities to grow at 8, 15, 25 and 37 degrees C and for their tolerances to UV exposure. The genetic groups from the Arctic and from the forested habitats grew at lower temperatures, while the genetic group from the agricultural habitat grew at 37 degrees C and was tolerant to UV exposure. There were no clear associations between the genetic group and the ability to infect coleopteran or lepidopteran insect larvae. There is increasing evidence that such studies represent a significant paradigm shift; habitat selection, not insect host selection, drives the population structure of deuteromycetous insect-pathogenic fungi. We suggest that adaptation to a certain habitat type is an important criterion for identifying insect-pathogenic fungal strains for use in insect biocontrol efforts.

Diversity of entomopathogenic fungi near leaf-cutting ant nests in a neotropical forest, with particular reference to Metarhizium anisopliae var. anisopliae

“…Previously, Metarhizium genotypes have often been found to be associated with either host species (Bridge et al, 1997;Fegan et al, 1993;St. Leger et al, 1992;Tigano-Milani et al, 1995) or habitat (Bidochka et al, 2001(Bidochka et al, , 2002Vänninen, 1996). There was no association with habitat amongst the isolates described in this study, and there was only limited evidence of particular genotypes being associated with particular host ant species.…”

Evaluation of entomopathogenic fungi against the sycamore lace bug, Corythucha ciliata (Say) (Hemiptera: Tingidae)

“…Although there are many studies about fungal biocontrol agents used for the control of C. ciliata, most have been conducted in Italy, and the investigation of local isolates against the target pest was warranted. In addition, entomopathogenic fungi are more likely to have ecological compatibility with pest species, due to their geographical locations and habitat types (Bidochka et al 2001(Bidochka et al , 2002Muro et al 2003;Maurer et al 1997). Therefore, it is suggested that native isolates have a more reduced risk of significant impact on nontarget organisms than exotic isolates.…”

Entomopathogenic Fungi as an Important Natural Regulator of Insect Outbreaks in Forests (Review)

“…The group from forested areas showed ability for growth at low temperatures (at 8°C), while the group from the agricultural areas showed ability for growth at high temperatures (37°C) and resilience to UV exposure. The association of habitat and thermal preferences was also found for B. bassiana (Bidochka et al, 2002). Recently, more sensitive and reliable molecular www.intechopen.com methods also indicate a certain association between B. bassiana isolates and their geographical origins and not between the genetic structure of the fungus and host systematic position (Wang et al, 2005;Fernandes et al, 2009).…”

“…Recently, more sensitive and reliable molecular www.intechopen.com methods also indicate a certain association between B. bassiana isolates and their geographical origins and not between the genetic structure of the fungus and host systematic position (Wang et al, 2005;Fernandes et al, 2009). There is a hypothesis that the saprophytic phase has an evolutionary impact on genetic structure of many species of entomopathogenic fungi including B. bassiana (Bidochka et al, 2002;Ghikas et al, 2010;Ormond et al, 2010;Garrido-Jurado et al, 2011). In studies conducted by Ormond et al (2010) in a conifer forest, molecular analyses (ISSR-PCR) indicate that below-ground and above-ground isolates of B. bassiana are genetically diverse.…”