Adulticiding Larviciding Mosquito monitoring

Public Health Significance of Urban Pests Mosquitoes 365 364 cal temephos, biochemical such as Bacillus thuringiensis var. israeliensis and Bacillus sphaericus or IGR such as diflubenzuron and methoprene, depending on compliance with local regulations. Biochemicals and growth regulators have the advantage of being more specific, whereas chemicals are less expensive and easier to use, especially for very large habitats WHO, 1996; Chavasse Yap, 1997.

11.8.3. Adulticiding

Treating adult mosquitoes can reinforce control, if efficacy in treating breeding sites is poor or if larviciding is not pos- sible. To increase control efficiency, in the framework of controlling a vector or urban pest or both, it can be advan- tageous to do a few treatments of this type, limiting both the number of appli- cations and the area covered. Furthermore, such a strategy may avoid large-scale repetitive treatments in a sensitive natural environment that would, otherwise, increase pest control costs. However, adult control, which is usually done by fogging, must be carefully applied, due to its low spe- cificity and to risks such as allergies or damage to vehicle paintwork that may result from the product being used. Such applications are often restricted to critical situations, such as the mass production of adult mosquitoes that have not been or could not be controlled at the aquatic immature stages, or situations that result in a risk to health. Adult mosquitoes can be killed outdoors and indoors, depending on where they rest. When done indoors, it is usually through spraying residual insecticides generally a pyre- Fig. 11.4. Larviciding against northern house mosquitoes in manholes Source: Photo by EID Méditerranée. These efforts are labour intensive, but they lend themselves to community-wide invol- vement, through public education campaigns.

11.8.2. Larviciding

Treatment efficiency and economic and ecological costs influence the final choice of inter- vention methods. The golden rule is to get to the root of the problem: to control larval development Fig. 11.4. This strategy has usually proved effective. To maximize effi- ciency, the actual aquatic habitats should be identified accurately. This often involves the aid of a map, to identify breeding sites that support mosquito production. In Europe, the active ingredients used most frequently in larviciding at present Table 11.2 are chemi- Fig. 11.3. Water-filled uncontrolled containers are potential mosquito breeding sites Note. The photos illustrate potential breeding sites in: a farms and gardens, b terraces and balconies and c next to warehouses and on waste sites. Source: Photos by F. SchaffnerEID Méditerranée. a b c Table 11.2. Active insecticide ingredients available for larvicide treatments Active ingredient AI Dosage AI ha Residual time Formulations Organophosphates Temephos 56–112 g 2–4 weeks EC, G, S Bioinsecticides Bacillus thuringiensis var. 250 g 5–10 days B, G, IG, S, WDP israelensis strain H14 Bacillus sphaericus 250 g 1–3 weeks S, WDP Growth regulators Diflubenzuron 25–100 g 1–4 weeks WDP Methoprene 100–1000 g 4–8 weeks SRS Pyriproxyfen 100 g 4–8 weeks G Surface oils 3–5 litres 2–10 days S Note. B: briquette; EC: emulsifiable concentrate; G: granulate; IG: ice granules; S: solution; SRS: slow release suspension; WDP: water dispersible powder. Source: WHO 1996. Public Health Significance of Urban Pests Mosquitoes 367 366

11.8.4. Use of predators biological control