Environmental Acquisition of Gut Symbiotic Bacteria in the Saw-Toothed Stinkbug, Megymenum gracilicorne (Hemiptera: Pentatomoidea: Dinidoridae)

Abstract

Many insects are associated with microbial symbionts, which substantially contribute to physiological, ecological and evolutionary aspects of the host insects (Bourtzis and Miller, 2003; Zchori-Fein and Bourtzis, 2012). Such symbiotic microorganisms are present on the body surface, in the alimentary tract, within the body cavity, or even inside the cells of the host insects (Perlmutter and Bordenstein, 2020; Hosokawa and Fukatsu, 2020). In some cases, the symbiotic microorganisms are indispensable for growth and survival of the host insects, constituting obligatory symbiotic associations and playing important biological roles such as nutrient provisioning (Douglas et al., 2009; Nikoh et al., 2014), food digestion (Brune, 2014; Salem et al., 2017), food production (Vega and Blackwell, 2005; Biedermann and Vega, 2020), etc. In other cases, the symbiotic microorganisms are not essential for survival of the host insects but influential to a variety of host phenotypes in a variety of ways, comprising facultative symbiotic associations and often bringing about beneficial ecological consequences of the host insects such as resistance to parasites and pathogens (Oliver et al., 2003), tolerance to heat stress (Dunbar et al., 2007), resistance to desiccation (Engl et al., 2018), broadening of food plant range (Tsuchida et al., 2004), modifying body color (Tsuchida et al., 2010), affecting reproductive mode (Werren et al., 2008), etc. Hence, understanding the diversity and the biological functions of microbial associates of insects is of fundamental importance.