This study clarified the difference in sensitivity of lepidopteran host larvae parasitized by a gregarious endoparasitoid Cotesia kariyai and a solitary endoparasitoid Meteorus pulchricornis to four insecticides, fenitrothion, cypermethrin, pyriproxyfen and pyridalyl, along with the growth and development of each parasitoid. It is well known that the physiological state of the host is regulated by endoparasitoid after parasitization. It was predicted from our previous report that the detoxification ability of the parasitized hosts was changed by parasitization. The effect of four insecticides on the growth and development of two parasitoids was examined with LD₅₀ or LD₉₅ values of unparasitized hosts. Fenitrothion and cypermethrin had an effect on the growth and development of host larvae parasitized by C. kariyai, but in M. pulchricornis caused low mortality on day 3 and later after parasitization. Pyriproxyfen had no effect on the growth and development of C. kariyai, but inhibited the adult eclosion of M. pulchricornis even when the parasitized hosts were treated with 50 ppm (less than LD₁₀ to unparasitized hosts). Paraffin sections revealed developmental malformations in the abdomen during the pupal stage of M. pulchricornis endoparasitoid. Pyridalyl had a strong effect on larval emergence of C. kariyai from the host during early stages (until day 7 postparasitization), because parasitoid larvae did not grow as lepidopteran larvae became motionless after pyridalyl treatment and could not eat. On the other hand, pyridalyl at LD₅₀ has a little effect on larval emergence and adult eclosion of M. pulchricornis. Gregarious and solitary endoparasitoids showed different sensitivity to four individual insecticides.

View full abstract

Pyribencarb, methyl {2-chloro-5-[(E)-1-(6-methyl-2-pyridylmethoxyimino)ethyl]benzyl}carbamate, is a novel fungicide having excellent activity against a wide range of plant pathogenic fungi, especially gray mold diseases caused by Botrytis cinerea. Pyribencarb exhibited not only a preventive effect but also a curative effect. When spraying was performed 48 hr after inoculation (after visible symptoms appeared), pyribencarb also showed strong inhibitory activity against lesion development by cucumber gray mold that was significantly superior to its preventive activity. Experiments in the greenhouse demonstrated good translaminar, rain fastness and residual activities, resulting in pyribencarb's high performance in the field. Pyribencarb was effective to control eggplant gray mold and kidney bean gray mold at 100–200 μg/ml in field trials.

View full abstract

In the course of an agrochemical random screening test of 1-alkylpyrazole-4-carboxamide analogs showing herbicidal activity, it was discovered that some 1-alkyl-3-sulfonyloxypyrazole-4-carboxamides exhibited high insecticidal activity. These derivatives were readily synthesized through the reaction of various amines with mixed anhydrides of pyrazole-4-carboxylic acids. All pyrazole-4-carboxamides synthesized were evaluated for insecticidal activity and their structure–activity relationships are discussed. It was found that introduction of a methyl or an ethyl group at the 1-position of the pyrazole ring increased insecticidal activity, in particular, introduction of a methylsulfonyloxy group on the pyrazole ring at the 3-position induced potent activity. The level of activity varied with N-substituents of the carbamoyl group at the 4-position of the pyrazole ring. An α-branched alkyl group, such as an isopropyl or a sec-butyl group on the amide nitrogen atom, demonstrated the highest level of activity. Among the compounds evaluated, N-sec-butyl-1-methyl-3-methylsulfonyloxypyrazole-4-carboxamide showed the highest activity against Nephotettix cincticeps, and exhibited moderate activity against both adults and eggs of Tetranychus urticae. Interestingly, substitution of a cyano group induced a higher level of acaricidal activity, while N-(3-cyanopentan-3-yl)-1-methyl-3-methylsulfonyloxypyrazole-4-carboxamide gave excellent activity against T. urticae as well as N. cincticeps.

View full abstract

In the search for new control methods for the fall armyworm (FAW), Spodoptera frugiperda (Lepidoptera: Noctuidae), we present the inhibition of the electroantennographic (EAG) response to the pheromone by 3-octylthio-1,1,1-trifluoropropan-2-one (OTFP). As a member of the trifluoromethyl ketones, OTFP is a potent inhibitor of serine esterases, particularly those of insect antennae. Exposure of antennal receptors to OTFP vapors resulted in a decreased amplitude and 2/3 repolarization time (2/3 RT) of the EAG response to the pheromone. The effect was reversible, with the amplitude and repolarization time being recovered upon suppression of the treatment. The non-fluorinated analogue 3-octhylthiopropan-2-one (OTP) did not affect either the amplitude or the 2/3 RT of the EAG response to the pheromone, confirming the key role played by fluorine atoms in this type of chemical. These results may be the basis for new behavioral studies with the aim of considering OTFP in future management strategies of the FAW.

View full abstract

Culex quinquefasciatus is a domestic mosquito known as a primary vector of lymphatic filariasis. We report the development of insecticide resistance in four populations of C. quinquefasciatus Say, 1823 in Jodhpur (JD), Bikaner (BKN), Jamnagar (JMN) and Bathinda (BTH) in India in comparison to a susceptible laboratory population against larvicides such as temephos, fenthion, Bacillus thuringiensis var. israelensis and Neemarin (azadirachtin), and adulticides such as cypermethrin, alpha cypermethrin and lambda cyhalothrin. The resistance ratio (RR) at LC₅₀ between field and laboratory populations was used for resistance expression. JD strain showed 10.8-, 6.94-, 5.29- and 2.82-fold resistance to temephos, fenthion, Neemarin and cypermethrin, respectively. BTH strain showed resistance to temephos, fenthion, lambda cyhalothrin, alpha cypermethrin and cypermethrin (9.06-, 2.06-, 3.33-, 4.96- and 3.19-fold, respectively). RR of BKN strain to temephos, fenthion, Neemarin and alpha cypermethrin was 5.17-, 4.12-, 4.33- and 3.04-fold, respectively; however RR was least in the JMN strain against most insecticides except alpha cypermethrin and fenthion. This study suggests that B. thuringiensis var israelensis and Neemarin may be efficient for larval control as an alternative to fenthion- and temephos-resistant strains of C. quinquefasciatus while lambda cyhalothrin and cypermethrin may be used effectively as an adulticide of this mosquito.

View full abstract

Twelve novel compounds of 1-substitutedphenyl-3-(5-halobenzimidazol-2-yl) acylurea were synthesized by the reaction of 5-halobenzimidazol-2-yl acylisocyanate with substituted anilines in yields of 62.4–76.1%. The structures of the title compounds were characterized by IR, ¹H NMR spectra and elemental analysis. Antifungal activities against Botrytis cinerea and Sclerotinia sclerotiorum were also evaluated by the mycelium growth rate method in the lab. The results indicated that most of the title compounds exhibited excellent antifungal activities against Sclerotinia sclerotiorum, and their activities were higher than that of thiophanate-methyl.

View full abstract

Insecticide bromfenvinphos of 94–96% purity is manufactured in the Institute of Industrial Organic Chemistry. Besides the main component (bromfenvinphos), more than ten impurities are observed. Two new impurities: 2-bromo-1-ethoxy-(2′,4′-dichloro)styrene (as a mixture of geometric isomers) and 2,2-dibromo-1-ethoxy-(2′,4′-dichloro)styrene were identified by means of mass spectrometry (MS) analysis. Both impurities were independently synthesized using 2,4-dichloroacetophenone as the starting material. The synthesized compounds were characterized spectroscopically and were found identical to the impurities which had been previously identified in bromfenvinphos.

View full abstract

[in Japanese]

View full abstract