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Toxicity and kinetics of methoxyfenozide in greenhouse‐selected Spodoptera exigua (Lepidoptera: Noctuidae)
Author(s) -
Smagghe Guy,
Pineda Samuel,
Carton Bert,
Estal Pedro Del,
Budia Flor,
Viñuela Elisa
Publication year - 2003
Publication title -
pest management science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.296
H-Index - 125
eISSN - 1526-4998
pISSN - 1526-498X
DOI - 10.1002/ps.756
Subject(s) - exigua , noctuidae , beet armyworm , spodoptera , biology , lepidoptera genitalia , instar , excretion , moulting , toxicology , larva , zoology , botany , biochemistry , gene , recombinant dna
Abstract Methoxyfenozide (RH‐2485) was found to be 7.5‐fold less toxic in terms of LD 50 values against last‐instar larvae of a greenhouse‐selected strain of the beet armyworm Spodoptera exigua (Hübner) that was collected in July 2001 in an experimental greenhouse for resistance at Murcia in southern Spain, in comparison with a laboratory susceptible strain. To date, the compound is the newest member of this new group of moulting hormone accelerating IGRs to reach the marketplace against Lepidoptera. To understand this different potency in the greenhouse‐selected S exigua , oxidative metabolism and acetylcholinesterase activities were measured in last‐instar larvae and adults. In addition, we determined, by the use of 14 C‐labelled methoxyfenozide, the pattern of absorption in body tissues and excretion via faeces in last‐instar larvae of the greenhouse‐selected strain and compared the results with those from the laboratory susceptible strain. It was striking that the rate of excretion was about twice as high in the greenhouse‐selected strain, resulting in a more rapid clearance of insecticide amounts from the insect body. Data are discussed in relation to mechanisms of lower toxicities for this new group of IGRs. Copyright © 2003 Society of Chemical Industry