Insecticides for Mosquito Control: Improving and Validating Methods to Strengthen the Evidence Base

Lees, Rosemary Susan; Fornadel, Christen; Snetselaar, Janneke; Wagman, Joseph; Spiers, Angus

doi:10.3390/insects14020116

Cited by 10 publications

(9 citation statements)

References 33 publications

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“…In addition to the standard parameters such as mortality and blood feeding, sublethal exposure effect could provide complementary valuable information to better appreciate the performance of vector control strategies. It may be regarded as reductions in longevity, development rates, feeding, oviposition, fertility, fecundity, changes in sex ratio or changes in behaviour (49). Several studies have shown that insecticide resistance mechanisms can negatively affect the reproductive tness and longevity of Anopheles mosquitoes (50)(51)(52).…”

Section: Discussionmentioning

confidence: 99%

Efficacy of Interceptor G2, Royal Guard and PermaNet 3.0 against pyrethroid- resistant Anopheles gambiae s.l. from Za-Kpota, Southern Benin: an experimental hut trial

Sovegnon,

Akoton,

Stopard

et al. 2024

Preprint

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Background Widespread use of insecticide-treated nets (ITNs) has made a major contribution to the dramatic decline in malaria cases and deaths seen across Africa in the 21st century. Unfortunately, this control strategy is threatened by the rapid spread of resistance to pyrethroid insecticides in malaria vectors. Dual-active-ingredient insecticidal nets are available to mitigate the impact of pyrethroid resistance and data is needed on the efficacy of these different nets against local mosquito populations to make evidence based decisions regarding product selection in specific use settings. Methods Two experimental Hut Trials were performed in Za-Kpota Southern Benin in 2021 to evaluate the performance of Interceptor G2 (BASF), Royal Guard (DCT) and PermaNet 3.0, (Vestergaard) compared to untreated or standard pyrethroid ITNs, against free-flying wild Anopheles gambiae mosquitoes. Both unwashed nets and those that had been in use for up to 2 years were assessed. Mosquitoes collected in the hut were followed up after exposure to assess the sublethal effects of treatments on certain life-history traits. Results The predominant species in the study site was Anopheles. gambiae s.s. Both Anopheles coluzzii and Anopheles gambiae s.s. were resistant to pyrethroids (deltamethrin susceptibility was restored by PBO pre-exposure). In experimental hut trials Royal Guard induced the highest blood-feeding inhibition (OR = 0.05; CI = 0.01–0.6; p < 0.001) relative to PermaNet 2.0. Interceptor G2 induced the highest 72 hour mortality rate (OR = 5.9; CI = 2.7–12.6; p < 0.001) compared to PermaNet 2.0. The highest risk of death in An. gambiae s.l. was observed with Interceptor G2 (HR = 6.5; CI = 5.7–7.6; p < 0.001) and PermaNet 3.0 (HR = 4.4; CI = 3.4–5.7; p < 0.001) compared to Untreated net. Lower mortality was recorded with Interceptor G2 aged compared to new Interceptor G2. Oviposition rates were low in mosquitoes collected from huts containing ITNs compared to untreated controls. No mosquitoes oviposited from huts with Royal Guad nets. Conclusion All of the dual active ingredient nets showed superior reductions in the survival of pyrethroid resistant An. gambiae s.s. compared to standard pyrethroid only ITNs.

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Section: Discussionmentioning

confidence: 99%

Efficacy of Interceptor G2, Royal Guard and PermaNet 3.0 against pyrethroid- resistant Anopheles gambiae s.l. from Za-Kpota, Southern Benin: an experimental hut trial

Sovegnon,

Akoton,

Stopard

et al. 2024

Preprint

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“…Effective mosquito abatement and disease prevention strategies employ integrated approaches, and include at least seven components: (1) mosquito surveillance, in which the use of various types of traps are useful for cataloguing the vector species that are present in a geographic region; (2) physical mosquito control or source reductions focused on eliminating mosquito land and aquatic breeding sites; (3) mosquito larval control measures using chemical or biological control; (4) adult mosquito control (aduticiding) using chemical pesticides that target the stage that transmits viral and parasitic agents of human and animal disease; (5) insect resistance monitoring using cage trials and bioassays—a component that cannot be ignored as mosquitoes are extremely adaptable and can have multiple generations in a single transmission season; (6) public education on measures that can be taken to reduce or eliminate potential mosquito breeding sites, how to avoid mosquito bites, and clinical symptoms associated with vector-borne diseases; and (7) accurate record keeping to establish year-to-year trends and breeding sites, and for regulatory compliance [ 55 , 56 , 57 , 58 ]. It should be noted that synthetic repellents, such as DEET, icaridin, and permethrin, and natural oils from cedar, cinnamon, catnip, neem, and citronella, can be applied directly to skin and clothing to prevent mosquitoes from biting and foraging [ 59 , 60 , 61 , 62 , 63 ], but apart from preventing transmission when used appropriately, these personal practices have no measurable impact on the proliferation of mosquitoes in nature.…”

Section: Integrated Pest Management Programs (Ipmps) For Mosquito Con...mentioning

confidence: 99%

The Perpetual Vector Mosquito Threat and Its Eco-Friendly Nemeses

Miranda,

Rudd,

Mena

et al. 2024

Biology

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Mosquitoes are the most notorious arthropod vectors of viral and parasitic diseases for which approximately half the world’s population, ~4,000,000,000, is at risk. Integrated pest management programs (IPMPs) have achieved some success in mitigating the regional transmission and persistence of these diseases. However, as many vector-borne diseases remain pervasive, it is obvious that IPMP successes have not been absolute in eradicating the threat imposed by mosquitoes. Moreover, the expanding mosquito geographic ranges caused by factors related to climate change and globalization (travel, trade, and migration), and the evolution of resistance to synthetic pesticides, present ongoing challenges to reducing or eliminating the local and global burden of these diseases, especially in economically and medically disadvantaged societies. Abatement strategies include the control of vector populations with synthetic pesticides and eco-friendly technologies. These “green” technologies include SIT, IIT, RIDL, CRISPR/Cas9 gene drive, and biological control that specifically targets the aquatic larval stages of mosquitoes. Regarding the latter, the most effective continues to be the widespread use of Lysinibacillus sphaericus (Ls) and Bacillus thuringiensis subsp. israelensis (Bti). Here, we present a review of the health issues elicited by vector mosquitoes, control strategies, and lastly, focus on the biology of Ls and Bti, with an emphasis on the latter, to which no resistance has been observed in the field.

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“…Despite the availability of a standard procedure for testing Anopheles susceptibility to chlorfenapyr, it remains vital to explore supplementary techniques that may best reflect the toxicity mechanism of the active ingredient and improve our understanding of the potential selection pressures which could drive resistance (11). Chlorfenapyr's mode of action differs remarkably from that of neurotoxic insecticides used for malaria vector control (12).…”

Section: Introductionmentioning

confidence: 99%

TestingAnopheleslarvae and adults using standard bioassays reveals susceptibility to chlorfenapyr (pyrrole) while highlighting variability between species

Bouaka,

Ambadiang,

Ashu

et al. 2024

Preprint

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A standard test is available for assessing the susceptibility of adult Anopheles mosquitoes to chlorfenapyr, a new active ingredient in insecticide-treated nets. However, for a new insecticide with a unique mode of action, testing both larvae and adults using different routes of exposure is crucial to a comprehensive evaluation of susceptibility and to identifying potential selection pressures that may drive resistance. We followed WHO guidelines to assess the lethal toxicity of chlorfenapyr and monitor Anopheles susceptibility. Based on the median lethal concentration (LC50), larvae of the pyrethroid-susceptible colonized strain An. coluzzii Ngousso were 16-fold more susceptible to chlorfenapyr than immature stages of another susceptible colony: An. gambiae Kisumu. Larval bioassays indicated 99.63 +- 0.2% mortality after 24 h at a discriminating concentration of 100 ng/ml in Anopheles gambiae and An. coluzzii larvae collected from seven locations in urban and rural areas of Yaounde, Cameroon. By contrast, exposing emerging female adults from these populations to the recommended discriminating concentration (100 ug Active Ingredient (AI)/bottle) in bottle bioassays revealed variable mortality after 72 h, with values below the threshold of susceptibility (98%) in several tests. Anopheles coluzzii larvae and adults were fully susceptible, but mortality rates were slightly lower in An. gambiae adults compared to larvae (94 +- 1.5% vs 100%, Fisher exact test, p < 0.001). Piperonyl butoxide antagonized the activity of chlorphenapyr in An. gambiae adults. 100 ng/ml provides sufficient discriminative power for assessing the susceptibility of An. gambiae and An. coluzzii larvae to chlorfenapyr. Testing An. gambiae adults with 100 ug AI/bottle is likely to reveal inconsistent mortality values making it difficult to detect any emergence of resistance. Exploring different tests and accounting for variability between species are key to a reliable monitoring of Anopheles susceptibility to chlorfenapyr.

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Insecticides for Mosquito Control: Improving and Validating Methods to Strengthen the Evidence Base

Abstract: Efforts to eliminate vector-borne diseases, for example malaria which caused an estimated 619,000 deaths in 2021 [...]

Cited by 10 publications

References 33 publications

Efficacy of Interceptor G2, Royal Guard and PermaNet 3.0 against pyrethroid- resistant Anopheles gambiae s.l. from Za-Kpota, Southern Benin: an experimental hut trial

Efficacy of Interceptor G2, Royal Guard and PermaNet 3.0 against pyrethroid- resistant Anopheles gambiae s.l. from Za-Kpota, Southern Benin: an experimental hut trial

The Perpetual Vector Mosquito Threat and Its Eco-Friendly Nemeses

TestingAnopheleslarvae and adults using standard bioassays reveals susceptibility to chlorfenapyr (pyrrole) while highlighting variability between species

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