Biology subjects

Nkya, J. D.

Publications and source records attributed to Nkya, J. D..

3 recordsLinked to original sources

bioRxiv2025

Delayed copulation and mating in the malaria vector Anopheles funestus compared to Anopheles arabiensis

Mating is a vital behavior for mosquito reproduction, yet it remains poorly understood under captive conditions. We examined the copulation dynamics of two key malaria vectors, Anopheles funestus, and Anopheles arabiensis, in controlled laboratory settings in Tanzania. We observed how variations in mosquito age and artificial lighting influence mating success for these two mosquito species within cages under controlled conditions. We conducted observations in 24-hour cycles, monitoring copulation events and insemination in females. We used generalized linear mixed models (GLMMs) for statistical analyses to assess how environmental conditions influence mating behavior. We found that Anopheles arabiensis exhibited rapid copulation, with 32.4% of individuals mating by Day 3 post-emergence, while An. funestus showed delayed activity, reaching a similar mating rate by Day 8. The introduction of artificial red light significantly accelerated copulation in An. funestus but did not affect An. arabiensis. Dissection confirmed successful sperm transfer and mating plug delivery in over 92% of copulating pairs for both species. Mating occurred primarily at night, with distinct peaks at 22:00 for An. arabiensis and 23:00 for An. funestus. In conclusion, our findings reveal species-specific differences in reproductive behavior, which could improve the colonization of An. funestus, a species historically challenging to rear in captivity. These insights may also inform the development of new vector control technologies, such as sterile insect techniques and genetic-based approaches, that exploit mosquito mating behaviors.

ecology↗

bioRxiv2022

Common predators and factors influencing their abundance in Anopheles funestus aquatic habitats in rural south-eastern Tanzania

BackgroundThe role that larval predators play in regulating the population of malaria vectors remains relatively unknown. This study aimed to investigate the common predators that co-exist with Anopheles funestus group larvae and evaluate factors that influence their abundance in rural south-eastern Tanzania. MethodsMosquito larvae and predators were sampled concurrently using standard dipper (350 ml) or 10 L bucket in nine villages in southern Tanzania. Predators were identified using standard identification keys. All positive habitats were geo-located and their physical features characterized. Water physicochemical parameters such as dissolved oxygen (DO), pH, electrical conductivity (EC), total dissolved solids (TDS) and temperature were also recorded. ResultsA total of 85 previously identified An. funestus aquatic habitats were sampled for larvae and potential predators. A total of 8,295 predators were sampled. Of these Coenagrionidae 57.7% (n=4785), Corixidae 12.8% (n=1,060), Notonectidae 9.9% (n=822), Aeshnidae 4.9% (n=405), Amphibian 4.5% (n=370), Dytiscidae 3.8% (n=313) were common. A total of 5,260 mosquito larvae were sampled, whereby Anopheles funestus group were 60.3% (n= 3,170), Culex spp. 24.3% (n= 1,279), An. gambie s.l. 8.3% (n= 438) and other anophelines 7.1% (n= 373). Permanent and aquatic habitats larger than 100m2 were positively associated with An. funestus group larvae (P<0.05) and predator abundance (P<0.05). Habitats with submerged vegetation were negative associated with An. funestus group larvae (P<0.05). Only dissolved oxygen (DO) was positively and significantly affect the abundance of An. funestus group larvae (P<0.05). While predators abundance were not impacted by all physicochemical parameters. ConclusionSix potential predator families were common in aquatic habitats of An. funestus larvae group. Additional studies are needed to demonstrate the efficacy of different predators on larval density and adult fitness traits. Interventions leveraging the interaction between mosquitoes and predators can be established to disrupt the transmission potential and survival of the An. funestus mosquitoes.

ecology↗

bioRxiv2022

Challenges of Proper Disposal of Old Long-Lasting Insecticidal Nets and its Alternative Uses in Rural South-Eastern Tanzania

IntroductionInsecticide-treated nets (ITNs) specifically long-lasting insecticidal nets (LLINs) are one of the most commonly used, scalable and cost-effective tools for controlling malaria transmission in sub-Saharan Africa. However, multiple alternative uses of retired LLINs have been observed and are associated with poor disposal practices. Nevertheless, the World Health Organisation (WHO) provided guidelines and recommendations for proper management of worn-out LLINs. This study assessed the existing alternative uses and disposal practices of old LLINs. MethodsAn explanatory sequential mixed-methods approach was used to assess LLINs existing alternative uses, disposal practices, knowledge and perceptions regarding WHO recommendations on proper disposal of old LLINs among stakeholders in Kilombero and Ulanga districts, southe-astern Tanzania. A survey questionnaire was administered to 384 respondents, Focus Group Discussions (FGD) and Key Informant Interviews (KII) were conducted to clarify responses regarding existing disposal practices with associated challenges and alternative uses of the LLINs. Findings from both study components were used to draw inferences. ResultsA total of 384 people surveyed, 97% were not aware of the WHO recommendation on proper disposal of old LLINs. The common methods used to dispose LLINs were burning 30.73%, disposing of into garbage pit 14.84% and alternative uses 12.24 %. Of respondents with LLINs (239); 41% had alternative uses while 59% had no alternative uses. The common alternative uses were ropes for tying or covering items 20.92%, garden fencing 7.53%, chicken coops 5.02% and 7.53% for other minor alternative uses. All key informants reported being unaware of the WHO guideline on the proper disposal of the old LLINs. ConclusionThis study demonstrates that despite participants limited knowledge on WHO guidelines for proper disposal of old LLINs, after presenting these guidelines, majority are willing to comply. Comprehensive efforts are therefore needed to address challenges associated with poor disposal, alternative uses and awareness about WHO guidelines among key stakeholders. Collection strategies should be agreed upon within the community members prior to replacement. Since alternative uses sometimes referred to as repurposing of old nets, proper guidelines should be developed to ensure that repurposing of old LLINs do not cause harm to human health and the environment.

ecology↗