Baits Cockroach control: pesticide applications

Public Health Significance of Urban Pests 69 Sanitation is only a part of a more comprehensive IPM programme to remove preferred cockroach harbourages and resources, and cleaning alone will not reduce cockroach populations. In conjunction with structural repairs and built-in pest control, improved sanitation will stress cockroaches, making them more susceptible to baits and crack-in- crevice treatments.

2.6.2. Cockroach control: pesticide applications

2.6.2.1. Baits

The development of baits has revolutionized cockroach control, especially against the German cockroach Reierson, 1995. This new paradigm has been widely accepted by both the professional pest control community and the public. Nearly 69 of homeowners preferred baits to sprays, and 33.5 thought that baits were the least hazardous method of control Potter Bessin, 1998. Operational factors are also important to the success of baiting programmes Reierson, 1995. Durier Rivault 2003 found that applying numerous discrete droplets of bait were better than one large spot of bait against high densities of German cockroaches; at low densities, a single spot of bait was adequate. Providing many bait stations helped reduce aggression among cockroaches and allowed greater access to bait in their lab study. In addition to greater numbers of bait placements, the location of the bait station may be extremely important. Appel 2004 found that bait consumption decreased if it was pla- ced on surfaces treated with repellents, such as some pyrethroid insecticides. When repel- lents were applied to solid cockroach baits, there was decreased consumption. This did not occur on gel baits. Baiting outdoors often presents special problems, because of rainfall, irrigation and high humidity. Thoms Robinson 1987a reported that hydramethylnon bait molded in high humidity conditions in outdoor bait trials against oriental cockroaches, but still mana- ged 69.3–97.8 reductions in cockroaches. Gel baits that contained fipronil and imida- cloprid provided 96–99 control of American cockroaches in sewers for 6 months or lon- Cockroaches 68 Outdoor IPM programmes have drawn less attention. A checklist of factors that contri- bute to smokybrown cockroach infestations, such as the age of the structure, the presence of woodpiles, railroad ties and tool sheds, and the number of pets, has been developed to identify structures and sites to be treated. By incorporating habitat removal, granular and gel bait treatments, and some spot sprays, greater than 80 reductions were achieved with less total insecticide used, compared with conventional perimeter sprays. In addition, these programmes were able to reduce the number of visits that the pest-management techni- cian made to the structure. Additional research and refinements of IPM programmes indi- cate that baiting consistently provided excellent reductions, and combination treatments that targeted different habitats were especially effective. The application of insecticide to targeted sites is the most cost-effective and environmentally sound approach to control smokybrown cockroach infestations Smith et al., 1998; Appel Smith, 2002. Among the goals of IPM programmes are reducing the amount of insecticide applied and reducing unnecessary treatments. Careful monitoring identifies areas that do not need to be treated. In their two-year control programme based on tenant observations, Rivault Cloarec 1997 estimated that more than 50 of flats were unnecessarily trea- ted. Monitoring of schools with traps revealed that a number of them were unnecessarily treated for German cockroaches Williams et al., 2005. Also, the actual amount applied to control the cockroaches can be reduced. About 6 g of insecticide were applied per unit in the IPM approach, compared with about 140 g in conventional treatments Miller Meek, 2004. Greene Breisch 2002 reported a 93 reduction in the total amount of insecticide applied after the adoption of an IPM programme Table 2.3. Similarly, Williams and colleagues 2005 reported that 99.9 less insecticide was applied in their IPM programmes. In addition to using less insecticide, IPM programmes incorporate alternative strategies. In a pilot project in Toronto, Canada, most tenants showed improved knowledge about IPM concepts and selected non-spray chemical treatments, such as baits, resulting in reductions in the numbers of cockroaches in about 67 of the units Campbell et al., 1999. In Seattle, Washington, a comprehensive project was implemented to improve indoor environmental quality for children with asthma Krieger et al., 2002. To control the cockroaches – in addition to treating with bait – daily cleaning, structural repairs, and the removal of clutter, food and sources of standing water were initiated.

2.6.1. Cockroach control: sanitation practices