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■Bio-mathematics, Statistics and Nano-Technologies: Mosquito Control Strategies

to have a specific fogging machine to deliver the insecticides in oil formulation and are

mostly used during the day. Thermal fogging machines are available in trucked-mounted,

hand-held, or backpack form. The droplets generated by fogging are very small and can

be used to treat heavily vegetated areas. Several products included pyrethroid insecticides,

permethrin, deltamethrin, and sumithrin are available on the market.

1.3.3

Barrier Spray

This method has been used since the 1960s and recently has been given more atten-

tion (Stoops et al. 2018). Barrier spraying uses a long residual formulation of insecticides

sprayed on vegetation and materials to control adult mosquitos when they contact the sur-

face treated by an insecticide. In some instances, the effectiveness of barrier spraying could

last for a few weeks. The most popular insecticides used in barrier spraying include bifen-

thrin, lambda-cyhalothrin, and deltamethrin. The commercial product called Talstar (7%

bifenthrin) is currently available on the market.

1.4

INDOOR RESIDUAL SPRAYING (IRS)

Indoor residual spray (IRS) is an application method of insecticide for the control of

adult mosquitos that enter and rest indoors, and requires the use of long residual active

ingredients. Adult mosquitos are killed by contacting the long residual insecticides on the

walls and other materials indoors. The IRS has been recommended and used as a success-

ful malaria vector control by the World Health Organization (WHO, 2006) for many years.

The most successful insecticide for IRS is DDT, an old and effective organochlorine in-

secticide, which has been banned in many countries, and currently, is only used for IRS in

a handful of countries for malaria mosquito control. Other common insecticides used for

IRS are pyrethroids (deltamethrin, alpha-cypermethrin, cyfluthrin, etofenprox, bifenthrin,

lambda-cyhalothrin, and permethrin), and organophosphates (malathion and fenitrothion),

and carbamates (propoxur and bendiocarb). Detailed instructions for the selection and ap-

plication of insecticides for IRS have been published by the WHO (2006) and also de-

scribed and reviewed by Najera & Zaim (2002) and Pluess et al. (2010).

1.5

INSECTICIDE-TREATED BED NETS (ITN)

Insecticide-treated nets (ITNs) and long-last insecticide treated nets (LLINs) use dif-

ferent materials treated by insecticides or a long residual formulations of insecticides. ITNs

and LLINs are designed to kill adult mosquitos as they contact the treated bed nets and ma-

terials. ITN and LLIN have been recommended by the WHO (2008, 2019) for control of

malaria vector mosquitos in communities, and the mass application of the LLIN in many

countries have aided in successfully reducing the incidence of malaria. The materials used

for bed nets are usually cotton and polyesters, and the control efficacy varies based on the

specific materials and insecticidal formulations used. The most common insecticides for

ITN and LLIN are permethrin, deltamethrin, alpha-cypermethrin, and Lambda-cyhalothrin.

Recent reports have shown the development of resistance to these control techniques. This

issue is being overcome by mixing active ingredients with the insect growth regulator,

pyriproxyfen, and attractive toxic sugar baits, ivermectin and BTi, to overcome the re-