**1. Introduction**

Systemic insecticides were first developed in the 1950s, with the introduction of soluble or‐ ganophosphorus (OP) compounds such as dimethoate, demeton-S-methyl, mevinphos and phorate. They were valuable in controlling sucking pests and burrowing larvae in many crops, their main advantage being their translocation to all tissues of the treated plant. Sys‐ temic carbamates followed in the 1960s with aldicarb and carbofuran. Since then, both insec‐ ticidal classes comprise a large number of broad-spectrum insecticides used in agriculture all over the world. Nowadays, OPs are the most common pesticides used in tropical, devel‐ oping countries such as the Philippines and Vietnam, where 22 and 17% of the respective agrochemicals are 'extremely hazardous' [126], i.e. classified as WHO class I. Systemic insect growth regulators were developed during the 1980-90s, and comprise only a handful of compounds, which are more selective than their predecessors. Since 1990 onwards, cartap, fipronil and neonicotinoids are replacing the old hazardous chemicals in most developed and developing countries alike [137].

Through seed coatings and granular applications, systemic insecticides pose minimal risk of pesticide drift or worker exposure in agricultural, nurseries and urban settings. Neonicoti‐ noids and fipronil are also preferred because they appear to be less toxic to fish and terres‐ trial vertebrates. Initially proposed as environmentally friendly agrochemicals [129], their use in Integrated Pest Management (IPM) programs has been questioned by recent research that shows their negative impact on predatory and parasitic agents [221, 258, 299]. New for‐ mulations have been developed to optimize the bioavailability of neonicotinoids, as well as combined formulations with pyrethroids and other insecticides with the aim of broadening the insecticidal spectrum and avoid resistance by pests [83]. Indeed, as with any other chem‐

© 2013 Sánchez-Bayo et al.; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 Sánchez-Bayo et al.; licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

ical used in pest control, resistance to imidacloprid by whitefly (*Bemisia tabaci*), cotton aphids (*Aphis gossypii*) and other pests is rendering ineffective this and other neonicotinoids such as acetamiprid, thiacloprid and nitenpyram [247, 269].

**1.** pollen, nectar, plant tissue, sap or guttation drops contaminated with the active ingredi‐

Impact of Systemic Insecticides on Organisms and Ecosystems

http://dx.doi.org/10.5772/52831

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**2.** prey or hosts that have consumed leaves contaminated with the active ingredient (sec‐

Parasitoids may be indirectly affected because foliar, drench or granular applications may decrease host population to levels that are not enough to sustain them. Furthermore, host quality may be unacceptable for egg laying by parasitoid females [54]. Small insectivorous animals (e.g. amphibians, reptiles, birds, shrews and bats) can also suffer from primary poi‐ soning if the residual insecticide or its metabolites in the prey are still active. It should be noticed that some metabolites of imidacloprid, thiamethoxam, fipronil and 50% of carba‐ mates are as toxic as the parent compounds [29]. Thus, two species of predatory miridbugs were negatively affected by residues and metabolites of fipronil applied to rice crops [159]. However, since systemic insecticides do not bioaccumulate in organisms, there is little risk

Apart from feeding, direct contact exposure may also occur when the systemic insecticides are sprayed on foliage. In these cases, using a silicone adjuvant (Sylgard 309) reduces the contact exposure of honey bees to carbofuran, methomyl and imidacloprid, but increases it for fipronil [184]. In general the susceptibility of bees to a range of insecticides is: wild bees > honey bee > bumble bee [185]. In reality a combination of both contact and feeding exposure

In soil, residues of acephate and methomyl account for most of the cholinesterase inhibition activity found in mixtures of insecticides [233]. Fortunately, repeated applications of these insecticides induces microbial adaptation, which degrade the active compounds faster over time [250]. Degradation of carbamates and OPs in tropical soils or vegetation is also faster than on temperate regions, due mainly to microbial activity [46]. Some neonicotinoids are degraded by soil microbes [172], and the yeast *Rhodotorula mucilaginosa* can degrade acet‐ amiprid but none of the other neonicotinoids [63], which are quite persistent in this media

> **Solubilityin water (mg/L)**

aldicarb C 3.87 4930 1.15 2.52 moderate bendiocarb C 4.6 280 1.72 0.77 low butocarboxim C 10.6 35000 1.1 1.32 low butoxycarboxim C 0.266 209000 -0.81 **4.87** high carbofuran C 0.08 322 1.8 **3.02** high ethiofencarb C 0.5 1900 2.04 **3.58** high methomyl C 0.72 55000 0.09 2.20 marginal oxamyl C 0.051 148100 -0.44 2.36 moderate pirimicarb C 0.43 3100 1.7 2.73 moderate

**Log Kow# GUS**

**index\***

**Leaching potential**

occurs, which is more deadly than either route of exposure alone [152, 218].

ent (primary poisoning);

of secondary poisoning through the food chain.

**Chemical Group Vapour Pressure**

**(mPa, 25oC)**

ondary poisoning).

(Table 2).

This chapter examines the negative impacts that systemic insecticides have on organisms, populations and ecosystems. The efficacy of these products in controlling the target pests is assumed and not dealt with here – only the effects on non-target organisms and communi‐ ties are considered.
