**1.2 Chemical control of termites and colony elimination by insecticidal baiting**

In general, methods to control termites using insecticides are preventive: typically liquid formulations are applied to perimeter or underfloor of a premise or to wooden materials directly. However, their unique characteristics of eusocial nature had been drawn large interests of researchers to control their whole colonies by application of toxic baits. Actually such an approach has been examined for its feasibility for decades and various kinds of insecticide have been evaluated as active ingredients (table 1). Although some insecticides succeeded in reducing population of a colony for the meanwhile, they could seldom bring about elimination of it. In the mid of 1990's benzoylphenylurea (BPU) compounds such as hexaflumuron were proven to be effective as bait toxicants for eliminating rhinotermitid colonies (Su 1994; Su et al., 1997). Since then many studies have documented that BPUs can successfully eliminate subterranean termite colonies in the field (Tsunoda et al., 1998; Peters & Fitzgerald, 1999, 2003; Getty et al., 2000; Sajap et al., 2000; Su et al., 2000; Lee, 2002; Tsunoda et al., 2005; Husseneder et al., 2007; Ripa et al., 2007).


Table 1. Active ingredients that have been evaluated as bait toxicant for termite control in the field

Up to now, only BPUs have been successful as bait toxicants in terms of elimination of subterranean termites' colonies. As BPUs are chitin synthesis inhibitor, it is presumed that their success as bait toxicant should be attributed to 1) their extreme slow action, 2) less dose dependency and 3) less feeding deterrency (Su & Scheffrahn 1993, 1996). However, there have been few reports that tried to examine such properties of BPUs.

## **1.3 Bistrifluron**

348 Pesticides in the Modern World - Risks and Benefits

colonies. Thousands to millions of worker termites are usually deployed in each colony. They are systematically mobilized to attack and feed wooden materials, therefore sometimes give critical damages to wooden structures. Among them, economically the most important group in temperate and tropical regions is Rhinotermitidae which includes genera *Coptotermes* and *Reticulitermes*. Termites belonging to Rhinotermitidae are 'subterranean termites' as they build their nests in the ground. Since they come on underground tunnel and often invade through underfloor space of structures, few people are aware of them until their houses are assaulted. *Coptotermes* and *Reticulitermes* termites widely occur in human habitat and are seriously harmful to structures. *Coptotermes* termites, like *Coptotermes formosanus* Shiraki, *Coptotermes gestroi* (Wasmann), *Coptotermes acinaciformis* (Froggatt) and so on, build huge colonies and

extremely problematic species around the Pacific countries (Fig. 1).

Tsunoda et al., 2005; Husseneder et al., 2007; Ripa et al., 2007).

Juvenile hormone analogue Methoprene e.g., Su et al., (1985)

Metabolic inhibitor A-9248 e.g., Su & Sheffrahn, (1996)

Phenylpyrazol Fipronil e.g., Huang et al., (2006)

Table 1. Active ingredients that have been evaluated as bait toxicant for termite control in

Up to now, only BPUs have been successful as bait toxicants in terms of elimination of subterranean termites' colonies. As BPUs are chitin synthesis inhibitor, it is presumed that their success as bait toxicant should be attributed to 1) their extreme slow action, 2) less dose dependency and 3) less feeding deterrency (Su & Scheffrahn 1993, 1996). However, there

Benzoylphenylurea Hexaflumuron e.g., Su, (1994)

have been few reports that tried to examine such properties of BPUs.

Chemical class or mode

of action

the field

**1.2 Chemical control of termites and colony elimination by insecticidal baiting** 

In general, methods to control termites using insecticides are preventive: typically liquid formulations are applied to perimeter or underfloor of a premise or to wooden materials directly. However, their unique characteristics of eusocial nature had been drawn large interests of researchers to control their whole colonies by application of toxic baits. Actually such an approach has been examined for its feasibility for decades and various kinds of insecticide have been evaluated as active ingredients (table 1). Although some insecticides succeeded in reducing population of a colony for the meanwhile, they could seldom bring about elimination of it. In the mid of 1990's benzoylphenylurea (BPU) compounds such as hexaflumuron were proven to be effective as bait toxicants for eliminating rhinotermitid colonies (Su 1994; Su et al., 1997). Since then many studies have documented that BPUs can successfully eliminate subterranean termite colonies in the field (Tsunoda et al., 1998; Peters & Fitzgerald, 1999, 2003; Getty et al., 2000; Sajap et al., 2000; Su et al., 2000; Lee, 2002;

Active ingredient Source

Fenoxycarb e.g., Jones, (1989)

Sulfluramid e.g., Su & Sheffrahn, (1996) Hydramethylnon e.g., Powson & Gold (1996)

Lufenouron e.g., Haverty et al., (2010) Chlorfluazuron e.g., Peters & Fitzgerald (2003) Noviflumuron e.g., Cabrera & Thoms (2006)

Diflubenzuron e.g., Rojas & Morales-Ramos (2003)

Bistrifluron (Fig. 2) is one of BPUs (Kim et al., 2000), therefore it was expected to show good efficacy in terms of colony elimination of subterranean termites. Author conducted several laboratory studies to evaluate inseciticidal efficacy of the compound against subterranean termites in order to examine how baiting with BPUs bring about colony elimination of termites. *C. formosanus* and *Reticulitermes speratus* (Kolbe) which are the most important pest species in Japan were used for the studies.

Fig. 2. Chemical structure of bistrifluron
