Landscape level associations between birds, mosquitoes and microclimates: possible consequences for disease transmission?

BACKGROUND

Mosquito-borne diseases are on the rise. While climatic factors have been linked to disease occurrences, they do not explain the non-random spatial distribution in disease outbreaks. Landscape-related factors, such as vegetation structure, likely play a crucial but hitherto unquantified role.

METHODS

We explored how three critically important factors that are associated with mosquito-borne disease outbreaks: microclimate, mosquito abundance and bird communities, vary at the landscape scale. We compared the co-occurrence of these three factors in two contrasting habitat types (forest versus grassland) across five rural locations in the central part of the Netherlands between June and September 2021.

RESULTS

Our results show that forest patches provide a more sheltered microclimate, and a higher overall abundance of birds. When accounting for differences in landscape characteristics, we also observed that the number of mosquitoes was higher in isolated forest patches.

CONCLUSIONS

Our findings indicate that, at the landscape scale, variation in tree cover coincides with suitable microclimate and high Culex pipiens and bird abundance. Overall, these factors can help understand the non-random spatial distribution of mosquito-borne disease outbreaks.

Larvicidal activity of Acacia nilotica extracts against Culex pipiens and their suggested mode of action by molecular simulation docking

Mosquitoes are one of the deadliest and most hazardous animals on Earth, where they transmit several diseases that kill millions of people annually. There is an ongoing search almost everywhere in the world for more effective and contemporary ways to control mosquitoes other than pesticides. Phytochemicals are affordable, biodegradable biological agents that specialize in eliminating pests that represent a risk to public health. The effectiveness of Acacia nilotica methanol and aqueous leaf extracts against 4th instar larvae was evaluated. The results revealed that the methanol extract of A. nilotica had a noticeable influence on the mortality rate of mosquito larvae, especially at high concentrations. Not only did the mortality rate rise significantly, but the hatching of the mosquito eggs was potentially suppressed.Terpenes, fatty acids, esters, glycosides, pyrrolidine alkane, piperazine, and phenols were the most prevalent components in the methanol extract, while the aqueous extract of A. nilotica exclusively showed the presence of fatty acids. The insecticidal susceptibility tests of both aqueous and alcoholic extract of A. nilotica confirmed that the Acacia plant could serves as a secure and efficient substitute for chemical pesticides because of its promising effect on killing larvae and egg hatching delaying addition to their safety as one of the natural pesticides. Molecular docking study was performed using one of the crucial and life-controlling protein targets, fatty acid binding protein (FABP) and the most active ingredients as testing ligands to describe their binding ability. Most of the structurally related compounds to the co-crystallized ligand, OLA, like hexadecanoic acid furnished high binding affinity to the target protein with very strong and stable intermolecular hydrogen bonding and this is quite similar to OLA itself. Some other structural non-related compounds revealed extraordinarily strong binding abilities like Methoxy phenyl piperazine. Most of the binding reactivities of the majortested structures are due to high structure similarity between the positive control, OLA, and tested compounds. Such structure similarity reinforced with the binding abilities of some detected compounds in the A. nilotica extract could present a reasonable interpretation for its insecticidal activity via deactivating the FABP protein. The FABP4 enzyme inhibition activity was assessed for of both methanolic and aqueous of acacia plant extract and the inhibition results of methanol extract depicted noticeable potency if compared to orlistat, with half-maximal inhibitory concentration (IC50) of 0.681, and 0.535 µg/ml, respectively.