Environmental Engineering Reference
In-Depth Information
3.6.3 Conclusions of the study
The results of the survey combined with the concentrations of carbofuran and its metabolites (3-keto-
carbofuran and 3-hydroxycarbofuran) detected in water, plant, soil and vulture samples suggests
that carbofuran/Furadan was used extensively in the two study areas (especially in Laikipia). The
environmental distribution and presence of residues in local water sources, which may pose risks
when used for domestic or agricultural purposes (i.e., in drinking water for animals) was particularly
disconcerting. The concentrations in environmental matrices (e.g., water) were elevated and, in our
view, provide suffi cient evidence to support the concern that carbofuran menaces vultures in the
two districts and the current campaign to generate awareness about Furadan use in Kenya. The next
section details the poisoning of what are, in our view, highly underappreciated organisms, namely
non-target, benefi cial insects.
3.7 Repercussions of pesticides (including carbofuran) on nontarget,
benefi cial insects and use of insects in forensic analyses in Kenya
Dino J. Martins
Insect Committee, Nature Kenya, The East Africa Natural History Society
3.7.1 Studies on nontarget insects
Many of the insect species that are not targeted by pesticide applications provide economically
important services, such as pollination and natural pest control. Ecologically speaking, nontar-
get insects also represent a signifi cant food source for birds, particularly during the nesting sea-
son (Moreby, Sotherton and Jepson 1997). In the last 20 years or so, a growing number of studies
have examined the risks that pesticide applications pose to nontarget, benefi cial arthropods, par-
ticularly species termed 'natural enemies', and pollinators, primarily bees (Desreux, Decourtye and
Delphwech 2007). In this regard, a comprehensive series of global case studies on natural enemies
and biological control can be found in Cock, van Lenteren, Brodeur et al. (2009).
In addition to direct mortality (the indicator most frequently used to measure pesticide expo-
sure risk) Desreux, Decourtye and Delphwech (2007) recommended examining sublethal effects
on arthropod physiology and behaviour, for which there are currently no standardised methods of
assessment. Other important factors that can be impacted include: developmental rate, immunology,
fecundity, sex ratio, mobility and navigation, feeding behaviour and detection of food resources
(Desreux, Decourtye and Delphwech 2007).
Pesticide management recommendations (including those from FMC, the manufacturer of
Furadan) have included reducing or mitigating drift into areas on the outer periphery of agri-
cultural zones, which often host a high insect diversity (Moreby, Sotherton and Jepson 1997).
Reducing or restricting the use of certain pesticides known to be harmful (e.g., fenitrothion) is also
suggested (Brittain, Vighi and Bommarco et al. (2010) in Dicks, Showler and Sutherland 2010).
Work on the links between pollinator diversity and crop production (i.e., Martins and Johnson
2009) have demonstrated the link between maintaining biodiversity and agricultural productivity
to bridge the gap between agricultural development and conservation. In addition to protecting
benefi cial insects from exposure to potentially lethal pesticides, such actions will also help ensure
the availability of critical habitat components such as larval host plants, places to oviposit and
wild sources of nectar.
Very few studies have examined pollination by wild insects in the tropics, though their pres-
ence greatly benefi ts crops there (Martins and Johnson 2009). The author's own work on the potential
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