8

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

1.6.2

Incompatible Insect Technique (IIT)

The incompatible insect technique (IIT) employs the symbiont-associated (e.g., Wol-

bachia bacteria) reproductive incompatibility as a biopesticide for the control of insect

pests and disease vectors (WHO 2019, Mains et al. 2019). Wolbachia bacteria are obliga-

tory intracellular and maternally inherited bacteria that infect and spread through natural

arthropod populations by inducing male-killing, feminization, parthenogenesis, and, most

commonly, unidirectional and bidirectional cytoplasmic incompatibility (CI). Cytoplasmic

incompatibility can be used to control natural populations of mosquitos, in a way anal-

ogous to the Sterile Insect Technique (SIT). For the successful application of IIT (based

on a unidirectional CI approach) against a target species of mosquitos, it is essential that

only males are released, as the release of females would lead to fertile mating between

the released males and the released females and the establishment of a Wolbachia-carrying

field population. Release of Wolbachia infected male Aedes mosquitos showed a signif-

icant reduction in a natural population of mosquitos (Mains et al. 2019). The combined

SIT and IIT also provided more effective control of dengue vector mosquito populations

in Thailand (Kittayapong et al. 2019).

1.6.3

Sterile Insect Technique (SIT)

The sterile insect technique (SIT) is a method of biological insect control and requires

the release of a large number of sterile insects into the wild. This technique was developed

in the 1940s and 1950s and adopted for Anopheles, Culex, and Aedes mosquito control in

the early 1970s and is now being utilized and accepted by some mosquito control programs.

The released mosquitos are preferably sterile males that compete with wild males to mate

with females of the natural populations. After mating with a sterile male, females produce

no offspring, thus reducing the next generation’s population. This is an environmentally

friendly control method involving mass-rearing and sterilization by radiation and other

methods. The release of sterile male mosquitos requires repeated mass releases over low

population densities to control target populations of mosquitos in certain areas. There are

many reports about the successful mass rearing and release of male Aedes mosquitos ster-

ilized by radiation against dengue vector mosquitos in Malaysia, Brazil, and several other

countries. Recently, the International Atomic Energy Agency (IAEA) and WHO (2020)

published a comprehensive guideline for the testing and application of SIT for control of

Aedes mosquitos and mosquito-borne diseases.

1.6.4

Adult Mosquito Control Traps

Usually mosquito traps, such as New Jersey light trap, CDC light trap, Biogenet (BG)

traps, DynaTraps, and other traps baited with different attractants (UV, LED, regular light,

CO2, octenol, lactic acid, naphtha, human and animal odors, or heat) have been used for the

surveillance of adult mosquito populations. Several new trap designs, have been developed

for control of adult mosquitos through direct killing by electric wires or collecting adult

mosquitos to be killed (Kline 2006). These traps use UV, LED, and regular light plus

different attractants to attract adult mosquitos to the traps and killed by electric shock,

pesticides, sticky pads, and other mechanical methods. The traps usually operated by a