Pyridalyl is an insecticide of a novel chemical class (unclassified insecticides). Toxicity of pyridalyl to two insect pest species, Spodoptera litura and Frankliniella occidentalis, an insect predator, Orius stringicollis, and a pollinator, Bombus terrestris, was evaluated in the laboratory. The insecticidal activity of pyridalyl against S. litura was evaluated using the leaf-dipping method. The potency of pyridalyl was highly effective against all development stages (2nd to 6th instar larvae) of S. litura. This compound was also evaluated against F. occidentalis using the direct spray method. For F. occidentalis, toxicity of pyridalyl was almost similar to that of acrinathrin, but greater than acrinathrin for adults. Then the toxicity of this product to the natural enemies, Orius stringicollis and the pollinating insect Bombus terrestris, was evaluated using the body-dipping method or direct spray method. No acute toxicity of this product was observed on these non-target insects. Moreover, the influence of pyridalyl to the nest of Bombus terrestris was evaluated using the direct spray to the inside of the nest. No apparent influence of this compound was observed by 21 days after treatment. The cytotoxicity of pyridalyl to the Sf9 insect cell line and the CHO-K1 mammalian cell line was evaluated using the trypan-blue exclusion method. High toxicity to the insect cell line, but almost no toxicity to the mammalian cell line, was observed. Thus, pyridalyl exhibited high selectivity in cytotoxicity between the insect and mammalian cell line as well as in insecticidal activity among insect species. We infer pyridalyl may be useful for IPM programs of greenhouse cultivation system.
The insecticidal action of pyridalyl at various dosages against S. litura larva was observed. Larvae treated with 100 ng/larva and higher dosages were killed within 6 hr without any conspicuous symptoms. In contrast, larvae treated with 25 ng/larva and lower dosages showed unique symptoms similar to scar burns at the site treated with pyridalyl after molting. Such symptoms caused interference with metamorphosis, suggesting that pyridalyl would suppress populations of S. litura even at lower dose rates. Taking such unique insecticidal symptoms into consideration, it is suspected that pyridalyl has a novel biochemical mode of action.
ABSTRACT-We investigated the effects of histidine on spatial memory deficits induced by the 5-HT1A-receptor agonist, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT). Working memory deficits were elicited by 8-OH-DPAT without affecting reference memory. Histidine improved the working memory deficit induced by 8-OH-DPAT at doses causing a significant increase in brain histamine content. This finding suggests that the histaminergic system regulates 8-OH-DPAT-induced working memory deficit.
The stink bug Leptocorisa chinensis (Hemiptera: Alydidae), which causes pecky rice grains, emits pungent volatiles when disturbed. To study ecological functions of the volatiles, we investigated the responses of adult L. chinensis in a small observation arena. When an undisturbed individual of the same gender was introduced into the arena, the initially occupying L. chinensis did not show any behavioural responses. However, when a disturbed conspecific of the same gender was introduced, the initial occupant was excited immediately and escaped from the arena through the hole, suggesting that the pungent volatiles from a disturbed conspecific caused excitement/ escape behaviour. Chemical analyses using a gas chromatograph-mass spectrometer showed that disturbed adults of both sexes emitted octanal, (E)-2-octenal, octanol, hexyl acetate, (Z)-3-octenyl acetate, octyl acetate and (E)-2-octenyl acetate. (E)-2-Octenal was the major compound. When exposed to (E)-2-octenal and to (E)-2-octenyl acetate, undisturbed females were excited and escaped from the observation arena with a similar proportional response as to disturbed females. Males and females escaped from (E)-2-octenal at ca. 2-10 ppbV in a mesh cage. The possible use of the volatile compounds eliciting excitement/escape behaviour in L. chinensis for control of this species in paddy fields is discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.