The toxicity of some novel pesticides - synthetic pyrethroids and benzoyl phenylurea chitin synthesis inhibitors - for eggs of Spodoptera littoralis (Boisd.)1

A series of pyrethroids was investigated as to their toxic effect against 0–1-day-old Spodoptera littoralis eggs and their LC50's were determined. Among the pyrethroids Decis was the most active compound, followed by Dowco 417 and Cymbush, and finally Pydrin and Ambush; Cybolt was found to be much less toxic. The benzoyl phenylurea chitin synthesis inhibitors Dimilin and PH 60–44 were more effective at 5 ppm than all the pyrethroids tested, except Decis and Cymbush. Decis was more toxic than Dimilin and PH 60–44 even at 1 ppm. Some further benzoyl phenylureas, such as PH 60–45, Dowco 439 and Dowco 401, had either only low activity or were inactive against S. littoralis eggs. Zusammenfassung Die Giftigkeit einiger neuer Insektizide - synthetische Pyrethroide und Benzoyl-Phenylurea-Chitinsynthese-Hemmer - gegenuber Eiern von Spodoptera littoralis (Boisd.) Es wurden einige Pyrethroide und Chitinsynthese-Hemmer auf ihre toxische Wirkung auf 0–1-Tage alte Eier der agyptischen Baumwolleule, Spodoptera littoralis (Boisd.) untersucht und ihre LC50-Werte bestimmt. Decis war unter den Pyrethroiden die aktivste Verbindung, gefolgt von Dowco 417, Cymbush, Pydrin und Ambush; Cybolt war viel schwacher wirksam. Die Benzoyl-Phenylurea-Chitinsynthese-Hemmer Dimilin und PH 60–40 waren bei 5 ppm wirksamer als alle getesteten Pyrethroide auser Decis and Cymbush, jedoch immer noch weniger giftig als das wirksamste Pyrethroid, Decis, bei 1 ppm. Einige weitere Benzoyl-Phenylurea-Verbindungen, wie z. B. PH 60–45, Dowco 439 and Dowco 401, waren gegen S. littoralis Eier entweder nur schwach aktiv oder unwirksam.