Elimination of the Mound-Building Termite, Nasutitermes exitiosus (Isoptera: Termitidae) in South-Eastern Australia Using Bistrifluron Bait

An overview of the development of termite baits in the past 3 decades

Since the commercialization in 1995, termite baits have been introduced in 32 countries, protecting over 3.7 million homes and reducing pesticide use by more than 11,100 metric tons. Over the past 3 decades, advancements have been made to address the limitations of bait systems, including improvements in bait toxicants, bait matrices, and the frequency of required site visits. Termite baits have been applied in both commercial and experimental area-wide projects. This article discusses the factors contributing to the success of these projects and the key elements driving the progress and advancements in termite bait technology.

Revisiting stigmergy in light of multi-functional, biogenic, termite structures as communication channel

Termite mounds are fascinating because of their intriguing composition of numerous geometric shapes and materials. However, little is known about these structures, or of their functionalities. Most research has been on the basic composition of mounds compared with surrounding soils. There has been some targeted research on the thermoregulation and ventilation of the mounds of a few species of fungi-growing termites, which has generated considerable interest from human architecture. Otherwise, research on termite mounds has been scattered, with little work on their explicit properties. This review is focused on how termites design and build functional structures as nest, nursery and food storage; for thermoregulation and climatisation; as defence, shelter and refuge; as a foraging tool or building material; and for colony communication, either as in indirect communication (stigmergy) or as an information channel essential for direct communication through vibrations (biotremology). Our analysis shows that systematic research is required to study the properties of these structures such as porosity and material composition. High resolution computer tomography in combination with nonlinear dynamics and methods from computational intelligence may provide breakthroughs in unveiling the secrets of termite behaviour and their mounds. In particular, the examination of dynamic and wave propagation properties of termite-built structures in combination with a detailed signal analysis of termite activities is required to better understand the interplay between termites and their nest as superorganism. How termite structures serve as defence in the form of disguising acoustic and vibration signals from detection by predators, and what role local and global vibration synchronisation plays for building are open questions that need to be addressed to provide insights into how termites utilise materials to thrive in a world of predators and competitors.

Evaluation of baiting fipronil-loaded silica nanocapsules against termite colonies in fields

Various pesticide nanocarriers have been developed. However, their pest-control applications remain limited in laboratories. Herein, we developed silica nanocapsules encapsulating fipronil (SNC) and their engineered form, poly(ethyleneimine)-coated SNC (SNC-PEI), based on recombinant catalytic modular protein D4S2 and used them against termite colonies Coptotermes lacteus in fields. To achieve this, an integrated biomolecular bioprocess was developed to produce D4S2 for manufacturing SNC containing fipronil with high encapsulation efficiency of approximately 97% at benign reaction conditions and at scales sufficient for the field applications. PEI coating was achieved via electrostatic interactions to yield SNC-PEI with a slower release of fipronil than SNC without coating. As a proof-of-concept, bait toxicants containing varied fipronil concentrations were formulated and exposed to nine termite mounds, aiming to prolong fipronil release hence allowing sufficient time for termites to relocate the baits into and distribute throughout the colony, and to eliminate that colony. Some baits were relocated into the mounds, but colonies were not eliminated due to several reasons. We caution others interested in producing bait toxicants to be aware of the multilevel resistance mechanisms of the Coptotermes spp. "superorganism".

Evaluation of fipronil and imidacloprid as bait active ingredients against fungus-growing termites (Blattodea: Termitidae: Macrotermitinae)

Fungus-growing termites (Macrotermitinae) are important pests in tropical countries. They are difficult to control with existing baiting methods, as chitin synthesis inhibitors are not effectual as active ingredients. We tested two neurotoxins, fipronil and imidacloprid, as potential bait active ingredients against Macrotermes gilvus (Hagen) in Singapore. In laboratory bioassays, M. gilvus showed no preference for doses of 0-64 ppm fipronil, or for doses of 0-250 ppm imidacloprid, indicating no repellence. We tested each insecticide in toilet paper as a bait matrix in a field experiment. After 28 days, termites had eaten 5-13% of the fipronil treated toilet paper, abandoned bait and monitoring stations, contacted no new stations, and repaired poorly their experimentally damaged mounds. Termites ate no imidacloprid treated toilet paper, abandoned bait stations although contacted new stations, and repaired fully their damaged mounds. Termites ate 60-70% of the control toilet paper, remained in bait stations, and fully repaired damaged mounds. After 56 days, all five fipronil colonies were eliminated, whereas all of the imidacloprid and control colonies were healthy. The results suggest that fipronil could be an effective active ingredient in bait systems for fungus-growing termites in tropical countries.

Elimination of Coptotermes lacteus (Froggatt) (Blattodea: Rhinotemitidae) Colonies Using Bistrifluron Bait Applied through In-Ground Bait Stations Surrounding Mounds

The efficacy of bistrifluron termite bait was evaluated using in-ground bait stations placed around Coptotermes lacteus mounds in south-eastern Australia during late summer and autumn (late February to late May 2012). Four in-ground bait stations containing timber billets were placed around each of twenty mounds. Once sufficient numbers of in-ground stations were infested by termites, mounds were assigned to one of four groups (one, two, three or four 120 g bait canisters or 120 to 480 g bait in total per mound) and bait canisters installed. One mound, nominally assigned treatment with two canisters ultimately had no termite interception in any of the four in-ground stations and not treated. Eighteen of the remaining 19 colonies were eliminated by 12 weeks after bait placement, irrespective of bait quantity removed (range 43 to 480 g). Measures of colony decline-mound repair capability and internal core temperature-did not accurately reflect the colony decline, as untreated colonies showed a similar pattern of decline in both repair capability and internal mound core temperature. However, during the ensuing spring-summer period, capacity to repair the mound was restored in untreated colonies and the internal core temperature profile was similar to the previous spring-summer period which indicated that these untreated colonies remained healthy.

Efficacy of Bistrifluron Termite Bait on Coptotermes lacteus (Isoptera: Rhinotermitidae) in Southern Australia

Bistrifluron, a benzoylphenyl urea compound, was evaluated for efficacy against Coptotermes lacteus (Froggatt), a mound-building species in southern Australia. Bistrifluron bait (tradename Xterm) was delivered as containerized pellets inserted into plastic in-ground feeding stations implanted in the sides of mounds. Termites actively tunneled in the gaps between pellets and removed bait from the canisters. Two separate trials were conducted, one commencing on 22 September 2011 and the second commencing on 30 November 2011. In trial 1, all 13 treated colonies (seven single and six double treatments) were eliminated within 19 wk, while all five untreated colonies remained healthy. In trial 2, all four treated colonies were eliminated within 14 wk. In trial 1, bait consumed or removed in treated mounds averaged 105 g for single treatments and 147 g for dual treatments, and overall ranged from 7 to 309 g (70-3,090 mg bistrifluron). In trial 2, the four treated colonies removed an average of 85 g of bait. At the time mounds were dismantled, all showed signs of inattention: external cracking, delamination, and general external weathering. Mound repair and temperature profile data indicate that colony decline commenced much earlier than 19 wk and 14 wk, respectively, for trials 1 and 2, from as early as 4 wk onward. The ability of colonies to repair mound damage was impaired as early as 4 wk in some colonies, and mean internal mound temperatures in treated mounds began declining from 8 wk onward and clearly diverged from mean temperatures of untreated mounds thereafter.