Agricultural chemicals: life changer for mosquito vectors in agricultural landscapes?

Abstract

BackgroundAlthough many mosquito species develop within agricultural landscapes where they are potentially exposed to agricultural chemicals (fertilizers and pesticides), the effects of these chemicals on mosquito biology remain poorly understood. This study investigated the effects of sublethal concentrations of four agricultural chemicals on the life history traits of Anopheles arabiensis and Culex quinquefasciatus mosquitoes.MethodsField and laboratory experiments were conducted to examine how sublethal concentrations of four agricultural chemicals: an insecticide (cypermethrin), a herbicide (glyphosate), and two nitrogenous fertilizers (ammonium sulfate and diammonium phosphate) alter oviposition site selection, emergence rates, development time, adult body size, and longevity of An. arabiensis and Cx. quinquefasciatus.ResultsBoth mosquito species had preference to oviposit in fertilizer treatments relative to pesticide treatments. Emergence rates for An. arabiensis were significantly higher in the control and ammonium sulfate treatments compared to cypermethrin treatment, while emergence rates for Cx. quinquefasciatus were significantly higher in the diammonium phosphate treatment compared to glyphosate and cypermethrin treatments. For both mosquito species, individuals from the ammonium sulfate and diammonium phosphate treatments took significantly longer time to develop compared to those from cypermethrin and glyphosate treatments. Although not always significant, males and females of both mosquito species tended to be smaller in the ammonium sulfate and diammonium phosphate treatments compared to cypermethrin and glyphosate treatments. There was no significant effect of the agrochemical treatments on the longevity of either mosquito species.ConclusionsThese results demonstrate that the widespread use of agricultural chemicals to enhance crop production can have unexpected effects on the spatial distribution and abundance of mosquito vectors of malaria and lymphatic filariasis.

Effects of inorganic fertilizer on larval development, adult longevity and insecticide susceptibility in the malaria vector Anopheles arabiensis (Diptera: Culicidae)

“…A study that attempted to examine the effects of agrochemicals on An. arabiensis reported that nitrate concentration in water bodies has been reported to be over 100 mg L −1 and phosphate over 9.45 mg L −1 . The concentrations used in this study were much lower, yet demonstrate biological effects on mosquitoes.…”

“…arabiensis . The runoff of fertilizers and other agrochemicals, particularly those of an inorganic nature, is known to pollute water bodies surrounding crops, creating attractive and nutrient‐rich pools for mosquitoes to breed in . This can lead to increased vector abundance, as has consistently been observed in Kenya for An.…”

Pesticides as risk factors for head and neck cancer: A review

“…However, these chemicals also cause adverse biological effects on non‐target organisms such as humans, who may be exposed occupationally, as in the case of farmers and pesticide industry workers, and non‐occupationally, through contact with pesticide residues in food, air, and drinking water . Currently, it is estimated that each year 2.4 million tons of pesticides and 180.1 million tons of fertilizers are used worldwide to improve agricultural production …”

“…1 Currently, it is estimated that each year 2.4 million tons of pesticides and 180.1 million tons of fertilizers are used worldwide to improve agricultural production. 2 Global data show that pesticides may be responsible for 350 000-440 000 deaths each year, with 99% of poisonings occurring in developing countries. 3 Systematic reviews of the literature have shown that human exposure to pesticides may be associated with chronic, non-cancer effects, including dermatologic, neurologic, reproductive, and genotoxic effects 4 ; and carcinogenic effects, such as lung, breast, pancreatic, brain, prostate, stomach, ovarian, and kidney cancers, as well as non-Hodgkin lymphoma, and leukemia.…”

Patch size influences perceived patch quality for colonising Culex mosquitoes

“…Though patch size surely plays a role in detection, and larger patches have a greater probability of encounter, patch quality is the primary factor in habitat selection (Fretwell & Lucas, 1970;Wiens, 1976). Resource density (Binckley & Resetarits, 2008;Blaustein & Kotler, 1993), disease (Robertson & Hamilton, 2012), predator presence/absence (Resetarits & Wilbur, 1989;Vonesh & Blaustein, 2010;Vonesh, Kraus, Rosenberg, & Chase, 2009), canopy cover (Binckley & Resetarits, 2007, 2009), productivity (Binckley & Resetarits, 2007) and pesticides (Bentley & Day, 1989;Kibuthu et al, 2016;Takahashi, 2007;Vonesh & Buck, 2007) may all influence perceived patch quality. However, patch quality and patch size are seldom independent, and changes in patch size often affect patch quality, confounding the two, especially when limiting resources are correlated with habitat area (see reviews in Haynes & Cronin, 2004;Krauss, Steffan-Dewenter, M€ uller, & Tscharntke, 2005;Rabasa, Guti errez, & Escudero, 2008).…”