Toxicity, repellency, and horizontal transfer of foam insecticides for remedial control of an invasive drywood termite, Cryptotermes brevis (Blattodea: Kalotermitidae)

Abstract

Laboratory tests were conducted to compare imidacloprid and fipronil foams against various criteria to determine the effect of the deposit conditions, exposure method, and exposure time on the toxicity, repellency, and horizontal transfer of selected foam insecticides. Results of toxicity assays showed that imidacloprid and fipronil foams caused significantly higher mortality than control treatments; however, fipronil foam in fresh or old deposits killed Cryptotermes brevis pseudergates more quickly in the short and continuous exposure tests than foam containing imidacloprid. In brief exposure tests, imidacloprid failed to kill all termites when exposed to fresh deposits and delayed total mortality when exposed to dry residues. The mortality of C. brevis pseudergates was also significantly quicker when the fipronil foam was applied topically compared with the imidacloprid foam. In the repellency test, termites were not repelled from the surface treated with fipronil foam, but more than 90% repellency was observed after 24 h of exposure to imidacloprid-treated surfaces. Moreover, the non-repellent mortality of C. brevis with fipronil was significantly higher than imidacloprid in avoidance tests. Results showed that fipronil was effectively transferred to untreated termites from live or dead donors exposed via residual and topical spray.

Potential of Gas-Propelled Aerosol Containing Synergized Pyrethrins for Localized Treatment of Cryptotermes brevis (Kalotermitidae: Blattodea)

“…Termites were collected and maintained in the laboratory as described previously by Hassan et al [ 3 ]. Briefly, C. brevis -infested wood was collected from a building in Maryborough, Queensland.…”

“…A simple bioassay was designed to expose the C. brevis in a gallery-within-wood scenario to evaluate the pyrethrin-containing aerosol treatment in the laboratory as described previously [ 3 ]. Briefly, using a band saw, 20 × 4 × 4 cm hoop pine boards were cut longitudinally in half.…”

“…In a separate experiment, filter paper was used to assess the pyrethrin-containing aerosol’s ability to repel termites, as described by [ 3 , 17 ]. For this purpose, black filter paper discs (9 cm diameter) were cut in half.…”

“…Several research projects were commenced in late 2022 to better equip Queensland’s pest control sector to identify, detect, and manage this pest in the future. An alternative to whole-of-house fumigation can be localized treatments with registered termiticides for drywood termites [ 3 ]. These will provide a cheaper and less disruptive option for a homeowner; however, the success rate of localized treatments with registered insecticides is low.…”

“…One possible impediment to full eradication is the amount of termite frass packed within a gallery that is hindering the delivery of a chemical to the target site. Most of the products registered against C. brevis in Australia are liquids [ 3 ]. Insecticides cannot be distributed evenly due to gravity, and it may be challenging to deliver liquid formulations to the termite colony core, especially during vertical application.…”