Effect of gut symbiont Caballeronia insecticola on life history and behavioral traits of male host Riptortus pedestris (Hemiptera: Alydidae)

Abstract

Symbiotic microorganisms can affect physiological conditions of host insects, subsequently altering life history and behavioral traits of their host insects. The bean bug, Riptortus pedestris, is a polyphagous insect pest which established an insect-microbe symbiosis with the bacterial genus Caballeronia. To understand how Caballeronia bacteria could affect life history and behavioral traits of host R. pedestris, we evaluated morphometric charac-teristics, feeding behavior, dispersal behavior, and survivorship of symbiotic and apo-symbiotic adult male R. pedestris. From morphometric character evaluation, symbiotic male displayed significantly greater body weight and larger body size than apo-symbiotic males. Moreover, symbiotic males had significantly larger hind legs utilized as a weapon in male-male competition for R. pedestris. From feeding behavior evaluation, symbiotic male consumed greater amount of food with lesser feeding attempt, resulting in significantly enhanced feeding efficiency. Dispersal behavior evaluation revealed that symbiotic male displayed significantly enhanced move-ment and flight capacity compared to apo-symbiotic male. In particular, flight capacity of symbiotic male increased ca. 170 times compared to apo-symbiotic males, yielding 1.39 km flight distance an average. There was no significant difference in survivorship between symbiotic and apo-symbiotic male R. pedestris, yielding 97 % and 90 % of survivorship over 60 days evaluation, respectively. However, titer of Caballeronia symbiont in male R. pedestris gradually decreased during the adult period evaluated. Our results demonstrated how gut microbe could affect the fitness-related and dispersal ability of male host insect.