Reference

Pymetrozine, a fast-acting and selective inhibitor of aphid feeding

Pymetrozine, a fast-acting and selective inhibitor of aphid feeding. In-situ studies with electronic monitoring of feeding behavior. Harrewijn, Paul; Kayser, Hartmut (IPO-DLO, Wageningen 6700 GW, Neth.). Pesticide Science, 49(2), 130-140 (English) 1997 Wiley. CODEN: PSSCBG. ISSN: 0031-613X. DOCUMENT TYPE: Journal CA Section: 5 (Agrochemical Bioregulators) The aim was to elucidate how and at which step pymetrozine interferes with the mechanisms underlying phloem feeding. The effect of pymetrozine, applied in various ways, on different phases of stylet penetration and feeding activity of individual aphids was studied using the Elec. Penetration Graph technique (EPG). The aphids were Aphis fabae, Macrosiphum euphorbiae, Myzus persicae and A. gossypii. Initial choice expts. indicated that pymetrozine does not have a deterrent or antifeedant action. Topical application (150 ng pymetrozine mg-1 fresh wt.) inhibited stylet insertion into the part. When injected, less than 30 ng mg-1 was sufficient to produce the same effect. When pymetrozine was systemically applied via plant spraying or root uptake, aphids started feeding normally. After some time, however, they withdrew their styles from the phloem and walked around with unaffected locomotion. At low doses, aphids eventually recovered and resumed feeding. High doses, however, irreversibly disrupted feeding and prevented stylet reinsertion. Aphid motility was not affected up to an estd. hemolymph concn. of 1 mM pymetrozine. Aphids which eventually stopped feeding on pymetrozine-treated plants showed EPGs with distorted salivation/ingestion patterns. Pymetrozine does not have a general toxic effect on aphids, but selectively interferes with the nervous regulation of feeding behavior, which consequently results in death due to starvation after a few days.Except for chemicals metioned above, 123312-89-0 is also used. .

The serotonergic system is involved in feeding inhibition by Pymetrozine

The serotonergic system is involved in feeding inhibition by Pymetrozine. Comparative studies on a locust (Locusta migratoria) and an aphid (Myzus persicae). Kaufmann, Liselotte; Schuermann, Franz; Yiallouros, Maria; Harrewijn, Paul; Kayser, Hartmut (Research and Technology, Syngenta Crop Protection AG, Basel CH 4002, Switz.). Comparative Biochemistry and Physiology, Part C: Toxicology & Pharmacology, 138C(4), 469-483 (English) 2004 Elsevier B.V. CODEN: CBPPFK. ISSN: 1532-0456. DOCUMENT TYPE: Journal CA Section: 4 (Toxicology) Pymetrozine inhibits feeding in aphids immediately after application without producing visible neurotoxic effects, as previously reported. In the present work, L. migratoria, though not a plant-sucking insect, was found to respond to Pymetrozine by displaying unique symptoms, which were lifting and stretching of the hind legs, in addn. to inhibition of feeding. In locust, Pymetrozine enhanced spontaneous spike discharge of the metathoracic and subesophageal ganglia in situ at nanomolar concns. Similarly, Pymetrozine increased the spontaneous rhythmic contractions of the isolated foregut with maximal effects also in the nanomolar range.Several substances with their cas registry numbers 123312-89-0 and 50-67-9 may be metioned in this study. The actions of Pymetrozine were counteracted by biogenic amine receptor antagonists and mimicked by serotonin, not by dopamine and octopamine. Moreover, Pymetrozine and serotonin strongly potentiated the effects of each other. Pymetrozine was inactive at all neurotransmitter receptors present on isolated locust neuronal somata, and at all other examd. neuronal sites. In M. persicae, elec. penetration graph expts. revealed that serotonin, like Pymetrozine, inhibited stylet penetration, and strongly enhanced the action of Pymetrozine, comparable to the locust. Amine receptor antagonists were not specifically active in the aphid. Thus, Pymetrozine acts via a novel mechanism that is linked to the signalling pathway of serotonin. .