The Indian livestock population is huge. Most (99%) of the livestock owners still follow traditional animal husbandry practices and graze their livestock, especially small ruminants, on natural pastures where no pesticides are used. In order to feed the ever-increasing livestock population, efforts are being made to increase quality fodder productivity from limited land resources. In such situations, pesticides play an important role by minimizing the loss of green fodder due to disease and pest attack. In countries such as Canada, Israel, the UK, and other European countries, pesticides have been registered for forage crops; in India, however, although pesticides have been registered for cultivable grain, horticultural and cash crops, etc., there are no registration guidelines or authenticated information regarding pesticide use with regard to forage crops. Hence, there is a need to take necessary steps in this direction, keeping in view the importance of fodder and livestock in the country. In this review, detailed aspects of the status and use of pesticides in forage crops in India are discussed.

The action mechanism of cyclopyrimorate, a novel herbicide for weed control in rice fields, was investigated. Cyclopyrimorate caused bleaching symptoms in Arabidopsis thaliana similar to those caused by existing carotenoid biosynthesis inhibitors, mesotrione and norflurazon. However, cyclopyrimorate treatment resulted in significant accumulation of homogentisate and a reduction in the level of plastoquinone. A metabolite of cyclopyrimorate, des-morpholinocarbonyl cyclopyrimorate (DMC), was detected in plants. These data suggested that cyclopyrimorate and/or DMC inhibit homogentisate solanesyltransferase (HST), a downstream enzyme of 4-hydroxyphenylpyruvate dioxygenase in the plastoquinone biosynthesis pathway. In vitro assays showed that A. thaliana HST was strongly inhibited by DMC and weakly by cyclopyrimorate, whereas other commercial bleaching herbicides did not inhibit HST. DMC derivatives showed a positive correlation between HST inhibition and in vivo bleaching activities. These results indicate that the target site of cyclopyrimorate and DMC is HST, a novel target site of commercial herbicides.

The defense allomones of two haplodesmid millipedes, Eutrichodesmus elegans and E. armatus (Polydesmida: Haplodesmidae), are known as a mixture of the following three nitro compounds: (2-nitroethyl)benzene and (Z)- and (E)-(2-nitroethenyl)benzenes. Administrations of a mixture of ²H-labeled (Z)- and (E)-phenylacetaldoximes and of ²H-labeled phenylacetonitrile as precursors resulted in the same production of three ²H-labeled nitro compounds, [2′-nitroethyl][2,3,4,5,6-²H₅]benzene and [(Z)- and (E)-2′-nitroethenyl][2,3,4,5,6-²H₅]benzenes, in both species. Oxime administration at an appropriate dose resulted in the production of three nitro compounds with similar natural ratios more effectively than nitrile administration. Conversion from oximes to nitrile and vice versa was evidenced during administration. Occurrences of three precursors (Z- and E-oximes and nitrile) were detected sporadically in millipede extracts by selected ion chromatography.

We cultivated Brassica rapa var. perviridis in soil mixed with four pesticides (fenobucarb, procymidone, flutolanil, and tolclofos-methyl) at different temperatures, day lengths, and soil water contents. We compared plants’ uptake and translocation abilities of the pesticides as affected by growth conditions. The root concentration factor (RCF) of pesticides tended to increase with rising temperature; however, but the influence of temperature on the transpiration stream concentration factor (TSCF) differed for each pesticide. The RCFs and TSCFs of pesticides were high for short days. The soil water content had little or no effect on the uptake and translocation of pesticides. These results showed that it is necessary to consider growth conditions, especially the temperature and day length in plant uptake models for these pesticides.

Ipfencarbazone exhibits excellent herbicidal activity against Echinochloa spp. and is safe for transplanted rice at a dose of 250 g a.i./ha. However, the effect of various environmental factors on its activity has not been verified. The present study evaluated the factors affecting the herbicidal activity of ipfencarbazone against Echinochloa spp. and its phytotoxicity to transplanted rice. The herbicidal activity and phytotoxicity of ipfencarbazone were barely affected by temperature, soil texture, water leakage, or flooding water depth. When an overflow was conducted artificially 6 hr after application, the herbicidal activity was stable. Furthermore, ipfencarbazone completely inhibited the emergence of Echinochloa spp. for 56 days regardless of the soil texture, water leakage and overflow conditions. When the period between application and reflooding was within 24 hr of herbicide application, the phytotoxicity of ipfencarbazone on transplanted rice was slight. These results suggest that ipfencarbazone shows stable efficacy in practical use.

A plant growth regulating agent “Fuji-one” has been used to control non-parasitic damping-off (Murenae disease) of rice seedlings. Its active ingredient, isoprothiolane (diisopropyl 1,3-dithiolan-2-ylidenemalonate, IPT), enhances root elongation of rice and Arabidopsis. To understand the mechanisms of IPT’s effect on root development, its effect on Arabidopsis root cells was investigated histologically. IPT at a lower concentration (12.5 µg/mL) had no effect on root cell elongation, whereas it enhanced cell division in the root meristem. Histological analysis using phytohormone-related mutants indicated that jasmonic acid and ethylene were involved in the enhanced cell division. In contrast, IPT at a higher concentration (75 µg/mL) suppressed both cell elongation and cell division, in which jasmonic acid and ethylene were not involved. In addition, root hair formation was suppressed by treatment with IPT. These analyses demonstrated that IPT (12.5 µg/mL) enhanced root elongation by activating cell division in a jasmonic acid- and ethylene-dependent manner.

We previously reported the strong insecticidal activity of a microbial secondary metabolite, pyripyropene A (PP-A), against aphids. Pyripyropenes (PPs) have been known to show weak feeding inhibition against lepidopteran pests, but their strong aphicidal activities were first reported in our former study. Here we investigated the details of the insecticidal property of PP-A. Our biological evaluation of PP-A found that it shows high insecticidal activities against some sucking pests, such as whiteflies, as well as aphids, and preferable biological profiles as agricultural insecticides. Furthermore, PP-A controlled aphids well under field conditions.

The flower thrips Frankliniella intonsa strain showing resistance to spinosad was established in the laboratory. The resistant strain showed an LC₅₀ value of 1398.7 mg/L in a leaf dipping/contact assay. The LC₅₀ value was ca. 280 times higher than that of the most susceptible strain. An insecticidal assay using synergists suggested no involvement of degradation enzymes, such as cytochrome P450, glutathione S-transferase, and carboxyl esterase, in the resistance. Glycine at amino acid position 275 of the nicotinic acetylcholine receptor (nAChR) α6 subunit was mutated to valine in the resistant strain. These results suggest that spinosad resistance in F. intonsa is conferred by the reduced sensitivity of nAChR.

We compared the soil sorption coefficient (K_d) measured by batch and centrifugation methods using a Japanese andosol and ten pesticides. Although the K_d values measured by both methods increased with time, those obtained via the batch method tended to be higher during the test period. The difference in K_d values between the two methods affected pesticide concentrations estimated in the soil solution, and the results estimated using K_d values obtained via the batch method underestimated the observed trends.

Three peptaibols, trichorzins HA II (1), HA V (2), and HA VI (3), were isolated from okara fermented with Trichoderma harzianum HK-61 as anti-plant viral agents. Their structures were confirmed by spectroscopic and chemical methods. At micro molar concentrations, the trichorzins inhibited infections by Cucumber mosaic virus in the cowpea plant Vigna sesquipedalis.

We compared the risk of reselecting melanin biosynthesis dehydratase inhibitor (MBI-D)-resistant Pyricularia oryzae isolates between two treatment programs, a nursery box application of diclocymet and a rotational program in which nursery boxes received a non-MBI-D fungicide application and then later, in the field, a foliar application of a diclocymet and ferimzone mixture. Both were effective against panicle blast. However, the latter prevented the reselection of MBI-D-resistant isolates more effectively than the former.

To investigate root uptake and translocation of heptachlor and its degradates (cis-heptachlor epoxide and 1-hydroxychlordene) in soil, zucchini and tomato seedlings were transplanted to soil approximately four months after treatment with ¹⁴C-heptachlor. The results indicated that a relation between the root concentration factor and the log P_ow did not follow Briggs’ theory, probably due to the contribution of plant metabolism. It also appeared that a compound with a lower log P_ow tends to show higher mobility from root to shoot.

To clarify the properties of pesticide transformation products (TPs) for which the risk to aquatic organisms should be evaluated, I monitored the concentrations of paddy pesticides and their TPs in the Sakura River, Japan, during the rice-growing season in 2007–2010. I also conducted algal growth inhibition tests of herbicides and their TPs using a diatom and a green alga and acute toxicity tests of insecticides and their TPs using a caddisfly and a daphnid. Moreover, on the basis of the results of pesticide monitoring and toxicity tests, I attempted to evaluate the risk of these compounds to the riverine organisms as well as the risk of mixtures of insecticides and their TPs for caddisflies and cladocerans. The TPs were detected in the river water depending on the half-lives of the parent compounds and of the TPs in water and soil. The toxicities of the parent compound and its TPs may be related to their hydrophobicities and chemical structures. Some toxic and persistent TPs that formed rapidly in water and soil posed a risk to the organisms over a long period. The physicochemical properties and chemical structures of a parent compound and its TPs can be key factors in evaluating the pesticide TP risk to aquatic organisms in rivers.

We often encounter difficulties in analyzing pesticide residues in food, since the residue level to be measured is infinitesimal but the food samples may contain a variety of matrices, including interferences, for chromatographic analysis. Thus it is important to find out the key points to be checked in the extraction, purification, and determination steps of analysis. We have attempted to develop practical technologies for the analysis of pesticide residues in raw agricultural commodities based on the following studies: The effect of processing and cooking on pesticide residue levels in several crop samples (rice, wheat, soybean, and sesame) was investigated. The processing factor is useful to estimate the amount of exposure to each pesticide residue for risk assessment and is helpful in setting the maximum residue limits of processed foods. In addition, residue levels in the peel and pulp of watermelon, melon, and kiwi fruit samples were examined to confirm the differences in the distribution of residues. As a basic study, the effect of water-soaking pretreatment of powdered dry cereal on extraction efficiency was examined, and an optimal time for water-soaking was found. A recent study examined the ability of several new types of solid-phase extraction columns to remove matrices in brown rice samples and verified the effective purification method for each sample.

An aerobic dieldrin-degrading fungus, Mucor racemosus strain DDF, and two aerobic endosulfan-degrading fungal strains, Mortierella sp. strains W8 and Cm1-45, were isolated from soil contaminated with organochlorine pesticides. Strain DDF degraded more than 90% dieldrin during 10-days of incubation at 25°C and showed the production of a small amount of aldrin trans-diol. Moreover, strain DDF reduced levels of aldrin trans-diol while producing unknown metabolites that were determined to be aldrin trans-diol exo- and endo-phosphates. On the other hand, Mortierella sp. strains W8 and Cm1-45 degraded more than 70% and 50% of α and β-endosulfan, respectively, over 28 days at 25°C, in liquid cultures containing initial concentrations of 8.2 µM of each substance. Only a small amount of endosulfan sulfate, a persistent metabolite, was detected in the both cultures, while these strains could not degrade endosulfan sulfate when this compound was provided as the initial substrate. Both strains generate endosulfan diol as a first step in the degradation of endosulfan, then undergo further conversion to endosulfan lactone.