Development Of Resistance In Vectors Research Articles

The effect of entomopathogenic fungi Metarhizium anisopliae var acridum and Beauveria bassiana on the survival of mosquito larvae of Anopheles arabiensis Patton and Culex quinquefasciatus Say

Because of environmental considerations and the development of resistance in vectors, efforts had been directed to microbial control. Immature stages of mosquito are useful components of malaria control program. The entomopathogenic hyphomycetous fungi Metarhizium anisopliaevar acridum and Beauveria bassiana were selected and tested against early (L1-2) and late (L3-4) stages of mosquito larvae (Anopheles arabiensis and Culex quinquefasciatus). Two concentrations of each fungual spores were used to perform the laboratory bioassays and time to death was determined for each mosquito species. Metarhizium anisopliae var acridum and Beauveria bassiana caused high mortality in An. arabiensis and C. quinquefasciatus. However, B. bassiana was less effective compared to M. anisopliae var acridum. Both An. arabiensis and C. quinquefasciatus were susceptible to the two fungi concentrations at the early stage. On the other hand, the older one were less susceptible.This research showed the potentiality of the two fungal species against mosquitoes in the larval stage, and the mortality percentage depends on fungus species itself and larval stage targeted. The increase in fungus concentration did not showed a proportional increase in mortality

Exploitation of Plant Herbs in the Control of Disease Vectors: A Review

Diseases transmitted by vectors have been plaguing man since time immemorial causing millions of deaths annually. The highest occurrence reportedly occurs in tropical and subtropical areas where malaria, the commonest vector-borne disease, is highest. The management of vector-borne diseases has been basically by controlling their vectors using synthetic insecticides: the pyrethroids, organophosphates, organochlorines: carbamates. Reports have shown that these insecticides pollute the environment, result in bio-magnification and affect non-target organisms mostly man thereby raising health concern. Also, there is development of insecticide resistance in the disease vectors, which may hamper the effective use of the insecticides. These negative effects associated with the use of synthetic insecticides emphasize the need for alternative method of control. The control of disease vectors with the use of herbal-based products that have insecticidal properties is promising as it is safe to non-target organisms, eco-friendly, bio-degradable, less expensive and the development of resistance in the vectors is more or less absent. The insecticidal activity of plant herbs is attributed to the presence of complex mixture of bio-active compounds, which act as anti-feedants, oviposition deterrents, repellents, attractants, etc. Using relevant literatures, this paper discussed disease vectors, method of transmission of vector-borne diseases, the need for alternative method of disease vector control and the most common plants employed in the control of disease vectors including their families, products, bio-active compounds, their activity and mode of action. Use of plant herbs and their products can therefore, serve as alternative method for vector control programme.

Evaluation of DawaPlus 3.0 and DawaPlus 4.0, deltamethrin\u2013PBO combination nets against pyrethroid-resistant Anopheles culicifacies in experimental huts in India

BackgroundThe development of resistance in vectors is one of the major impediments for malaria control. Adding synergists to insecticides has proven to be an alternative choice for controlling resistant mosquitoes. DawaPlus 3.0 and DawaPlus 4.0 are new long-lasting insecticidal nets (LLINs) in which deltamethrin and a synergist, piperonyl butoxide (PBO) are added into filaments and their efficacy was tested against resistant malaria vector, Anopheles culicifacies in experimental huts in India.MethodsThe performance of two trial nets in terms of deterrence induced exiting, blood-feeding inhibition and mortality of An. culicifacies was compared with DawaPlus 2.0 and untreated net.ResultsThere was a significant reduction in entry, blood feeding and mortality (p < 0.05) and increase in exit rates of An. culicifacies in the treatment arms compared to untreated arm. But, both candidate LNs washed 20 times could not perform better than the washed reference net (DawaPlus 2.0). Cone bioassay results showed that all the treatment arms (both washed and unwashed) produced < 80% mortality of An. culicifacies before and after hut evaluation.ConclusionsDawaPlus 3.0 and DawaPlus 4.0 with their current specification may not be as effective as required to control the resistant vector, An. culicifacies, in east-central India.