High Exploration Behavior of Termite Propagules Can Enhance Invasiveness

Abstract

Social life is usually associated with enhanced propagule pressure, which increases the chance of introducing several individuals during a single introduction event. Social insects are therefore among the most successful invasive species, benefiting from rapid establishment and increased foundation success in new habitats. In termites, propagule pressure may also be increased by the development of reproductive individuals from a small group of foraging workers. This suggests that enhanced exploration activity may increase propagule pressure through an elevated chance of transporting isolated groups of foragers. Here, we analyzed the exploration behavior of three termite species of the Reticulitermes genus, comparing the invasive species Reticulitermes flavipes (testing both native and introduced populations) to the native species Reticulitermes grassei and Reticulitermes lucifugus. Different features representative of the exploration capacity were measured during 48 h, including: the number of tunnels, the length of tunnels, the number of foragers, and the interindividual distance of foragers in a straight line or through tunnels. Our results show that compared to the native Reticulitermes species, R. flavipes foragers from both populations dug more tunnels with a longer total length, and individuals were more spatially dispersed and covered a larger exploration zone. These findings suggest that the enhanced exploration ability of R. flavipes may have played a role in its invasion success, by increasing its propagule pressure through a higher chance of human-mediated transport. In addition, the absence of differences between the native and introduced populations of R. flavipes suggests that the exploration behaviors facilitating the worldwide invasion of this species originated in its native range.

Comparative genetic study of the colony structure and colony spatial distribution between the higher termiteAmitermes parvulusand the lower, subterranean termiteReticulitermes flavipesin an urban environment

“…Reticulitermes flavipes is a successful invasive species, introduced to many regions worldwide, such as France, Chile, and Uruguay (Clément et al 2001; Austin et al 2005; Su et al 2006; Eyer et al 2021), while A. parvulus has not been reported as introduced outside of its endemic range. The spatially expansive foraging range of A. parvulus is a potential characteristic enhancing invasiveness, as it increases the chance of being inadvertently picked up and transported abroad (Evans et al 2011, 2013; Pailler et al 2022); however, this species was mostly found tunneling in mulch areas but not inhabiting substantial pieces of wood. The absence of dense colony fragments within large pieces of wood may have restricted the opportunity for large fragments of colonies to be transported.…”

“…Some lower termites nest and feed on a single piece of wood (one-piece nesters), while others (both in lower and higher termites) feed on several pieces of wood connected by networks of galleries (multiple-piece nesters), or build large nests separate from their food sources (separate-piece nesters; Abe 1987; Eggleton and Tayasu 2001). Variation in foraging patterns can also be found among species of the same genus (Mizumoto et al 2020; Janowiecki and Vargo 2022; Pailler et al 2022), and sometimes even among colonies within species (Mizumoto and Matsuura 2013). Different tunneling patterns have been reported in subterranean termites of the genus Coptotermes (Mizumoto et al 2020), where colonies of C. formosanus construct a small number of long tunnels, while C. gestroi colonies usually make a large number of short tunnels (Grace et al 2004, Lee et al 2007; Hapukotuwa and Grace 2014).…”