Bacterial Symbionts of a Devastating Coffee Plant Pest, the Stinkbug Antestiopsis thunbergii (Hemiptera: Pentatomidae)

Abstract

ABSTRACTStinkbugs of the genusAntestiopsis, so-called antestia bugs or variegated coffee bugs, are notorious pests of coffee plants in Africa. We investigated the symbiotic bacteria associated withAntestiopsis thunbergii, a major coffee plant pest in Rwanda. PCR, cloning, sequencing, and phylogenetic analysis of bacterial genes identified four distinct bacterial lineages associated withA. thunbergii: a gammaproteobacterial gut symbiont and symbionts representing the generaSodalis,Spiroplasma, andRickettsia.In situhybridization showed that the gut symbiont densely occupied the lumen of midgut crypts, whereas theSodalissymbiont, theSpiroplasmasymbiont, and theRickettsiasymbiont sparsely and sporadically infected various cells and tissues. Diagnostic PCR survey of 154A. thunbergiiindividuals collected at 8 localities in Rwanda revealed high infection frequencies (100% for the gut symbiont, 51.3% for theSodalissymbiont, 52.6% for theSpiroplasmasymbiont, and 24.0% for theRickettsiasymbiont). These results suggest that the gut symbiont is the primary symbiotic associate of obligate nature forA. thunbergii, whereas theSodalissymbiont, theSpiroplasmasymbiont, and theRickettsiasymbiont are the secondary symbiotic associates of facultative nature. We observed high coinfection frequencies, i.e., 7.8% of individuals with quadruple infection with all the symbionts, 32.5% with triple infections with the gut symbiont and two of the secondary symbionts, and 39.6% with double infections with the gut symbiont and any of the three secondary symbionts, which were statistically not different from the expected coinfection frequencies and probably reflected random associations. The knowledge of symbiotic microbiota inA. thunbergiiwill provide useful background information for controlling this devastating coffee plant pest.