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In this study, we carried out three bioassays with nine used insecticides in tomato crops to identify their efficiency against tomato leaf miner Tuta absoluta, the physiological selectivity and the activity reduction of insecticides by three rain regimes to predatory wasps Protonectarina sylveirae and Polybia scutellaris. We assessed the mortality caused by the recommended doses of abamectin, beta-cyfluthrin, cartap, chlorfenapyr, etofenprox, methamidophos, permethrin, phenthoate and spinosad to T. absoluta and wasps at the moment of application. In addition, we evaluated the wasp mortality due to the insecticides for 30 days on plants that did not receive rain and on plants that received 4 or 125 mm of rain. Spinosad, cartap, chlorfenapyr, phenthoate, abamectin and methamidophos caused mortality higher than 90% to T. absoluta, whereas the pyrethroids beta-cyfluthrin, etofenprox and permethrin caused mortality between 8.5% and 46.25%. At the moment of application, all the insecticides were highly toxic to the wasps, causing mortality higher than 80%. In the absence of rain, all the insecticides continued to cause high mortality to the wasps for 30 days after the application. The toxicity of spinosad and methamidophos on both wasp species; beta-cyfluthrin on P. sylveirae and chlorfenapyr and abamectin on P. scutellaris, decreased when the plants received 4 mm of rain. In contrast, the other insecticides only showed reduced toxicity on the wasps when the plants received 125 mm of rain.

The mobility of the rice pesticides thiobencarb (S-[(4-chlorophenyl) methyl] diethylcarbamothioate) and fipronil ([5-amino-3-cyano-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]-4-[(trifluoromethyl)sulfinyl]pyrazole) were investigated in the glasshouse under flooded conditions using two Australian rice-growing soils. When using leakage rates of 10 mm day(-1), less than 20% of applied thiobencarb and fipronil remained in the water column after 10 days due to rapid transfer to the soil phase. Up to 70% and 65% of the applied thiobencarb and fipronil, respectively, were recovered from the 0-1 cm layer of soils. Only 5-7% of each pesticide was recovered from the 1-2 cm layer, and less than 2% was recovered from each 1 cm layer in the 2-10 cm region of the soils. Analysis of the water leaking from the base of the soil cores showed between 5-10% of the applied thiobencarb and between 10-20% of the applied fipronil leaching from the soil cores. The high levels of pesticide in the effluent was attributed to preferential flow of pesticide-laden water via soil macropores resulting from the wetting and drying process, worm holes and root channels.

Cartap and cypermethrin, which are among the most widely used pesticides in many countries, are considered safe because of their low mammalian toxicity and their low persistence in the environment. However, recent findings of endocrine-disrupting effects and developmental neurotoxicity have raised concerns about the potential ecological impacts of these pesticides. We evaluated the aquatic toxicity of cartap [S,S'-(2-dimethylaminotrimethylene) bis(thiocarbamate), unspecified hydrochloride] and cypermethrin [(RS)-alpha-cyano-3-phenoxybenzyl-(1RS,3RS,1RS,3SR)-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylate], both individually and combined, on different life stages of the freshwater cladoceran Daphnia magna and a freshwater teleost, Japanese medaka (Oryzias latipes). The 96-hr Daphnia median effective concentrations (EC50s) for cartap and cypermethrin were 91.0 microg/L and 0.00061 microg/L, respectively. Rapid recovery of Daphnia was observed after short-term pulsed exposure to cartap and cypermethrin; there were no adverse effects on reproduction or survival 20 d after a 24 hr exposure to cartap up to 1240 microg/L and cypermethrin up to 1.9 microg/L. Chronic continuous exposure (for 21 d) of 7-d-old Daphnia to cypermethrin significantly reduced the intrinsic population growth rate in a concentration-dependent manner. However, because the intrinsic population growth rates were all above zero, populations did not decrease even at the highest experimental concentration of 200 ng/L. Exposure of Daphnia neonates (< 24 hr old) to cypermethrin for 21 d caused significant, sub-lethal reproduction-related problems, such as increased time to first brood, reduced brood size, and reduced total brood number, at 0.0002, 0.002, and 0.2 ng/L cypermethrin, but the intrinsic population growth rate was not significantly affected. Oryzias latipes was relatively more resistant to both pesticides. In particular, embryos appeared to be more resistant than juveniles or adults, which may be partly due to the protective role of the chorion. The incidence of larval fish deformity was significantly higher after a 96 hr exposure to as low as 250 microg/L of cartap or 40 microg/L of cypermethrin. The mixture of both compounds showed no synergistic toxicity. The extremely high acute-to-chronic ratio suggests that the standard acute lethal toxicity assessment might not reflect the true environmental hazards of these frequently used pesticides. Ecological hazard assessments of long-term low dose or pulsed exposures to cartap and cypermethrin may reveal more realistic consequences of these compounds in surface water.

S-Alkyl thiocarbamates are commercially available and widely used for their herbicidal properties. Despite the numerous methods for synthesizing these compounds, most employ toxic reagents that are harmful to the environment. Within we report a novel efficient one-pot process for the formation of thiobencarb employing readily available reagents. This method makes use of a trichloroacetyl chloride adduct and requires no complex starting materials. Furthermore, this process is efficient, proceeds in high yields, and utilizes several recyclable reagents.

Chronic toxicity studies were conducted with an algae (Nannochloris oculata) and the cladoceran (Daphnia magna) to determine their relative sensitivities to the thiocarbamate herbicide thiobencarb (S-4-chlorobenzyl diethylthiocarbamate). Most of the algal populations were initially affected by exposure to the herbicide. Thiobencarb concentrations higher than 0.5 mg/L significantly reduced algal densities after 24-h exposure. The 24-h static EC50 in D. magna was 3.01 mg/L. The sublethal effects of 0.3, 0.37, 0.5, 0.75, and 1.5 mg/L of thiobencarb concentrations on the survival, reproduction, and growth of D. magna were monitored for 21 days. The parameters used to determined the effect of the herbicide on D. magna were mean total young per female; mean brood size; days to first brood; intrinsic rate of natural increase (r); growth; and survival. Reproduction was significantly reduced at thiobencarb concentrations of 0.30 mg/L and higher while survival was affected after exposure to 0.75 and 1.5 mg/L of the pesticide. The r value decreased with increasing concentrations of thiobencarb. Growth, as measured by body length, was depressed significantly after exposure to all herbicide concentrations tested.

Chronic toxicity tests with Daphnia magna were applied for examination of river water quality. Water was sampled from the Maioka River in Yokohama City on May 14, 20, and 27, 1999, and used for the test after solid-phase extraction. The chronic test was carried out according to the OECD method. The duration was 21 days and the total number of live offspring produced per parent animal was counted. The results of the tests showed, survival rates of 100% using river water sampled on May 14 and 20 and the total numbers of live offspring produced per parent animal did not differ from the control. However, the survival rate of the sample collected on May 27 was 0% and the pesticides, fenitrothion, and thiobencarb were detected in the water. In addition to the river water samples, reconstituted water (Elendt M7) with additions of fenitrothion and thiobencarb was prepared to investigate mortality. When the reconstituted water with thiobencarb was applied to the test, the total number of live offspring produced per parent animal did not differ from the control. In contrast, when reconstituted water with fenitrothion was applied to the test, most parents were alive, but the total number of live offspring produced per parent animal was apparently different. The results of the above tests indicate that D. magna was affected not only by fenitrothion in the river water collected on May 27, but also by other factors that were not clarified in this study.

The acute toxicity of the herbicide thiobencarb (S-4-chlorobenzyl diethylthiocarbamate) was determined for the European eel (Anguilla anguilla). The 24, 48, 72 and 96 hours median lethal concentrations (LC50) were 25.7, 21.7, 17.0 and 13.2 mg/L, respectively. Fish were also exposed to a sublethal thiobencarb concentration (1/60 LC50-96 hr = 0.22 mg/L) during 96 hours in a flow-through system and then an elimination period of 192 hours in clean water was allowed. Eels were removed and blood samples taken out at each exposure time and recovery period in order to evaluate AChE activity. Thiobencarb induced significant inhibitory effects on plasma AChE activity of A. anguilla from the first contact time with the toxicant. This inhibition (under 50% activity) was maintained during the entire exposure period (96 hours) and even those animals transferred to clean water showed plasma AChE activity different from the controls. Differences between total and specific AChE activity were detected during the exposure period. Total AChE activity in the plasma from animals transferred to a medium free of toxicant recovered its normal value while specific AChE activity remained depressed (< 50%) until five days later.

Liver is removed from albino rat and assayed for total adenosine triphosphatase (ATPase) activity following administration with single and repeated doses of larvin and cypermethrin. The data indicate that the total (Na+, K+; Mg2+) dependent ATPase in the liver tissue is significantly inhibited by single and repeated doses of both insecticides. This inhibition is more pronounced by the repeated dose of cypermethrin than that of larvin. The in vitro study revealed that the inhibition encountered by different concentration of both larvin and cypermethrin is of the irreversible non-competitive type. This data indicate that these insecticides can cause biochemical and histopathological changes in the liver ATPase activity which may inhibit several biochemical functions of ATPase system such as: the active transport of metal ions, oxidative phosphorylation of liver cells and generally the muscle contraction.

The in vivo effects of methomyl, thiodicarb and metaldehyde on total soluble proteins, total lipids and glycogen content, in addition, the activity of glutamic oxaloacetic transaminase, (GOT), (GPT) glutamic pyruvic transaminase and catalase (CAT) enzymes of terrestrial E. vermiculata snails was studied. The experimental snails were treated with low concentration of 0.2% brain bait w/w of the pesticides for a period of 1,3,5,7 and 10 days. The results showed that methomyl and thiodicarb lead to significant reduction in total soluble proteins, lipids, and glycogen content, while significant increases in the activity of all enzymes tested were noted. Metaldehyde treatment showed no significant effect on total soluble proteins, lipids and GOT level, whereas a significant increase in GPT and CAT enzymes was observed. Also, metaldehyde resulted a significant reduction in glycogen content of snails.

A single i.p. dose (120 mg/kg) of thiram given to male Sprague-Dawley rats caused a significant increase in the activity of SGOT and SGPT 24 hr post-treatment indicating liver damage. A considerable diminution in the serum cholinesterase activity was also noted in the treated rats as against the control animals. Additional evidence for thiram-induced liver toxicity is provided by the observation that there was approximately 50% inhibition of the activity of hepatic microsomal benzphetamine N-demethylase with a concomitant decrease in the concentration of cytochrome P-450, an important component of the mixed-function oxidase system. Although not significant, hepatic glutathione levels were also depleted by thiram, probably making the liver susceptible to toxic injury.

Two allylthiocarbamate herbicides, diallate and triallate, were evaluated for neurotoxicity by oral and topical dosing studies with mature white leghorn hens. Diallate was tolerated for 90 days at topical doses of 40 mg/kg/day and oral doses of 20 mg/kg/day. Reversible ataxia and narcosis occurred at diallate doses of 80 mg/kg/day and higher by either route of administration. Triallate did not elicit signs of neurotoxicity at 300 mg/kg/day topically or 400 mg/kg/day orally. The oral dose, however, resulted in gastrointestinal irritation and severe weight loss, such that dosing was terminated after 25 days. Triallate was tolerated at oral dosages of 90 mg/kg/day and topical doses up to 330 mg/kg/day.