Does Soil Treated with Conidial Formulations of Trichoderma spp. Attract or Repel Subterranean Termites?

Abstract

Previous studies showed that many wood-rotting fungi were attractive to termites; however, little attention has been paid to the relationship between termites and soil fungus. In the present study, different designs of two-choice tests were conducted to investigate the behaviors of two subterranean termites, Coptotermes formosanus Shiraki (wood-feeding lower termites) and Odontotermes formosanus (Shiraki) (fungus-growing higher termites), in response to soil (or sand) treated with the commercial conidial formulations of Trichoderma harzianum Rifai (BioWorks) and Trichoderma viride Pers. ex Fries (Shuiguxin). The short-term (1 d) choice tests showed no significant difference in termite aggregation (C. formosanus and O. formosanus) between treated and untreated soil, regardless of Trichoderma species and concentrations. However, in the long-term choice tests, C. formosanus consumed significantly more wood in the chambers containing soil treated with the conidial formulation of T. viride (1 × 108 conidia/g) than that containing untreated soil. The tunneling choice tests showed that sand treated with T. viride (1 × 106 or 1 × 108 conidia/g) or T. harzianum (1 × 106 conidia/g) significantly increased the tunneling activities of C. formosanus. However, sand treated with T. viride (1 × 106 or 1 × 108 conidia/g) had a repellent effect on O. formosanus. Our study showed that the two subterranean termites behaved differently when responding to the conidial formulations of Trichoderma.

The Effects of Trichoderma Fungi on the Tunneling, Aggregation, and Colony-Initiation Preferences of Black-Winged Subterranean Termites, Odontotermes formosanus (Blattodea: Termitidae)

“…In general, Trichoderma fungi inhibited the tunneling activities of the fungus-growing higher termite, Odontotermes formosanus (as shown in the present study), and they are antagonistic to the Termitomyces cultured by fungus-growing termites [24]. On the contrary, Trichoderma fungi attract the wood-feeding lower termite, Coptotermes formosanus [29], and benefit this termite by antagonizing the entomopathogenic fungi and cellulose-competition fungi [50,51].…”

“…Although Trichoderma fungi are not pathogenic to termites, they antagonize Termitomyces cultured by the fungus-growing higher termites. Our previous work showed that commercially formulated conidia of T. viride repelled tunneling behavior of O. formosanus [29]. In the present study, we found that unformulated conidia of six Trichoderma fungi significantly decreased the tunneling behaviors of O. formosanus ( Table 2), indicating that O. formosanus showed general avoidance behaviors in response to different fungal species in the genus Trichoderma.…”

“…Previous studies showed that many Trichoderma fungi can be isolated from bodies of C. formosanus [50,51] and Reticulitermes flavipes (Kollar) [52]. Our previous studies showed that C. formosanus built more tunnels in sand treated with conidia of T. viride or T. harzianum compared with untreated sand [29]. The positive associations and tunneling preferences may be due to the beneficial effects of Trichoderma fungi on the lower termites.…”

“…In an earlier study, we showed that O. formosanus workers made significantly shorter tunnels in the sand containing commercially formulated conidia of Trichoderma viride Pers. ex Fries than in untreated sand [29], which provided the first evidence of "spatial avoidance" performed by fungus-growing higher termites responding to an antagonistic fungus against Termitomyces. However, two questions remained: (1) Do different species in the genus Trichoderma exert general repellent effects against O. formosanus?…”

Super Absorbent Polymers Buried within Dry Soil Attract Formosan Subterranean Termites (Blattodea: Rhinotermitidae)

“…Suran and Rust [22] reported that 3% xylose in the food (paper discs) significantly increased the intake and horizontal transfer of hexaflumuron among individuals of Reticulitermes hesperus Banks, and caused significantly higher termite mortality than that of hexaflumuron alone. Other reported termite attractants include wood-rotting and soil fungi [23][24][25][26][27], decayed wood extract [28], carbon dioxide [29,30], clay materials [11,31,32], and even some sport drinks [33].…”