**3.1 Biological and genetic control**

#### *3.1.1 Biological control with bacteria*

An alternative to the use of insecticides is the use of entomopathogenic bacteria, which has been implemented in some countries since the beginning of the century, when, in 1904, Meyer and Neide described the first bacterium, which attacks mosquito larvae, *Bacillus sphaericus* [113]. To date, about 35 strains of this bacterium are known to exist worldwide and are still effective on *Anopheles* [114]. Another bacterium, which has been widely used is *B. thuringiensis var. israelensis*, which is currently considered highly effective [115, 116]. The application of these larvicides although effective in controlling *Anopheles* has financial limitations in addition to the shortage of personnel trained in the ecology and biology of the vectors, the lack of organisational structures, and the predominance of vertical control programmes [117].

Another bacterium, which has recently been evaluated, is *Wolbachia*. It has been tested for the control of *Ae. aegypti*. *Wolbachia* is maternally transmitted intracellular bacteria, which invade insect populations, by manipulating their reproduction and immunity, thus, limiting the spread of numerous human pathogens including *Plasmodium*, but the activity of these bacteria in *Anopheles* control programmes has not been explored. Inhibition of *Plasmodium falciparum* in *Anopheles gambiae* under laboratory conditions has been reported [118] and the same author demonstrated that the native microbiome of *A. gambiae* and *An. stephensi* prevents vertical transmission of *Wolbachia* [119]. On the other hand, there are records of natural infection of this bacterium in wild *Anopheles*, as reported in West Africa where *Wolbachia* was found in *An. gambiae* from the field [120] and in larvae of *An. stephensi* [121]. On the same continent, but in sub-Saharan Africa, *Wolbachia* was found in low densities in species of the gambiae complex (*An. moucheti* and *An. demeilloni*) [122]. Similar reports were recorded in Central Africa by the World Mosquito Program [123]. Reports have also been made in Malaysia where they recorded 17 *Anopheles* species, of which eight species were positive for the natural occurrence of *Wolbachia* [124].

#### *3.1.2 Entomopathogenic fungus*

*Metarhizium anisopliae* and *Beauveria bassiana*, are the two entomopathogenic fungi well recognised in the literature, these can infect mosquitoes early in life and kill them, depending on the exposure dose and fungus isolate, after 3–14 days. In addition, these fungi have shown that interfere with *Plasmodium* parasite development in the *Anopheles* mosquito [125].

The discovery of new mosquitocides from fungal extracts for *Anopheles* species is promising, that is, the extract from *Penicillium toxicarium* has exhibited high toxicity to mosquito larvae and adults on *A. gambiae* [126]. Other studies showed that the fungal extracts of *Trichoderma asperellum* had a larvicidal effect *in vitro* on *Anopheline* larvae [127, 128].

#### *3.1.3 Biological control with nematodes*

The use of Mermithid worms (Nematoda, Mermithidae) for the control of *Anopheles* larvae has been used for several years. The nematode with which the first reported work began was the species *Romanomermis culicivorax*. This is an obligate endoparasite of mosquito larvae and has been recorded in *An. stephensi*, *An. albimanus*, *An. gambiae*, *Culex,* and *Aedes*, the advantage is that it does not affect animals, plants, and humans. In the United States, the nematode has been used to control insects, such as *Anopheles freeborni* and several species of *Culex,* and is classified by the United States Department of Agriculture as a safe and innocuous biological product for mosquito control [129]. In Brazil, in 2000, a bioplant was created in the facilities of the Federal University of the State of Roraima, for rearing *Romanomermis iyengari* as a control strategy in larval breeding sites of *Anopheles* sp. in breeding sites in Boa Vista - Roraima [130]. In Mexico, applications of a dose of 2000–3000 pre-parasitic juvenile *R. iyengari* per square metre produced an infection rate of

#### *Vector Control Strategies DOI: http://dx.doi.org/10.5772/intechopen.105026*

approximately 85–100% in *An. pseudopunctipennis* larvae, thus reducing the risk of malaria transmission to people living nearby breeding sites [131].

New studies have been carried out in recent years, the nematode *R. culicivorax* was used in the North Atlantic Autonomous Region in Nicaragua and showed efficiency in controlling larval densities of *Anopheles albimanus* [132]. In another study, isolated nematodes were subsequently cultured and evaluated their larvicidal potential against the larvae of several mosquitoes. The nematode *Heterohabditis indica* showed 97.33% of mortality against *An. stephensi* [36]. In a recent study in Africa, the nematode *R. iyengari* was mass-produced, and the pre-parasitic stage (J2) was used for laboratory and field experiments. In field experiments, the monthly applications of 3500–5000 pre-parasitic nematodes per m2 eliminated larval mosquito development in *Anopheles* and mixed breeding sites [133]. In Benin, West Africa evaluated coconut coir fibres as a replacement for coarse sand to improve yields in largescale production of *R. iyengari* because this method has the potential for facilitating the wider distribution of this nematode for use against malaria vectors in West Africa [134].

#### *3.1.4 Biological control with kairomones*

Female mosquito vectors use physical and chemical signals to locate their blood food source in vertebrate hosts, such as transpiration of CO2, octenol, lactic acid, and a variety of sweat compounds released in respiration and excretions, producing characteristic odours of substances called kairomones, which are chemicals produced by other organisms different to the insects but which attract them [135]. This is a new area to integrate vector control systems since they are just starting with the first studies conducted in Africa where it incorporated a system of traps with kairomones as attractants as a means of control *An. gambiae*. Thus, the first Kairomone [Methyl mercaptan] has already been identified, which attracts this species of *Anopheles*, which will open the possibility to conduct similar studies in other countries and thus, expand more on this control method [136]. These studies allow to do new research and the search for new strategies of this type in other malarial countries, which can become an alternative control model.

#### *3.1.5 Biological control with pheromones*

The use of pheromones in odour traps for the surveillance and control of mosquito vectors is considered a new and viable component of integrated vector management programmes. Few works have been conducted, by using these substances, due to the difficulty of synthesising them in the laboratory. A study shows pheromone release in the reproductive frenzy of some *Anopheles* species has been reported at the laboratory level in species, such as *An. arabiensis* and *An. gambiae* and five species of importance in the transmission in Africa (*An. gambiae*, *An. coluzzii*, *An. arabiensis*, *An. merus,* and *An. funestus*) in semi-field experiments [137]. It is important to further expand these types of studies, replicate them, and set the foundations for the next generation of attractants and traps to be used in vector-borne disease control programmes.

#### *3.1.6 Sterile insect technique (SIT) in Anopheles*

In recent years, the possibility of using the sterile insect technique (SIT) as part of the programmes against mosquitoes has received increased attention, this is due to the resistance developed by parasites to drugs and vectors to insecticides [138]. The most developed model for SIT is with the species *Anopheles arabiensis* but when considering a mosquito release programme, one of the first issues to be addressed is how to eliminate/separate the hematophagous vector females, several studies have investigated this issue, because sex separation increases the efficiency of an SIT programme [139, 140]. So much progress has been made in these researches that in the study of Kaiser et al., [141] three separate releases were performed within a 2-year period. Approximately 5000–15,000 laboratory-reared male *An. arabiensis* (KWAG) were produced and marked for mark–release–recapture experiments, this study showed that marked males were found in swarms with wild males, indicating that laboratoryreared males are able to locate and participate in mating swarms.

#### **3.2 Chemical and physical control**

Indoor residual spraying (IRS) and the use of long-lasting insecticidal nets (LLINs) have been effective control strategies for malaria vector control, leading to a reduction in cases between 2002 and 2017 [142, 143]. However, there are two major problems—first, the use of these strategies alone or in combination will not eliminate malaria; and second, insecticide resistance of the main malaria vectors is widespread and increasing [142]. According to the literature, few advances have been made in the development of new insecticides for malaria vector control. In this regard, a combination of the neonicotinoid clothianidin and the pyrethroid deltamethrin (Fludora Fusion) was recently developed as a new vector control tool, which has been effective in managing resistance [144].

One study demonstrated in large-cage SFS experiments the autodissemination of PPF by the malaria vector *Anopheles arabiensis*, which provides proof of principle for the autodissemination of PPF to breeding habitats by malaria vectors. Bioassay of water samples from artificial habitats in these experiments resulted in significantly lower emergence rates in treated chambers (0.16 ± 0.23) compared to controls (0.97 ± 0.05) (p < 0.0001) [145]. To this end, Kiware et al., [146] conducted deterministic mathematical models to describe that use only field-measurable input parameters and capture the biological processes that mediate PPF autodissemination.

#### **3.3 Cultural control**

#### *3.3.1 Combi*

The COMBI methodology is a very local and targeted methodology that integrates health education in a language of its own, community mobilisation, and social, anthropological, and biological research, directed in a sharp and intelligent way towards specific and precise health behavioural outcomes [80]. This methodology differs from traditional approaches, achieving generational changes in vector-borne disease control and prevention programmes, but which are subject to political will for their continuity and execution. For example, in Colombia, the COMBI strategy was implemented in several departments (Antioquia, Cauca, Chocó, Córdoba, and Valle del Cauca) articulated with vector-borne disease control programmes, where the behavioural objective was the use of nets [83]. In rural areas of Sudan, a study was conducted where it was assessed the effectiveness of COMBI strategy in enhancing the utilisation of long-lasting insecticidal nets (LLINs) among mothers of underfive

*Vector Control Strategies DOI: http://dx.doi.org/10.5772/intechopen.105026*



