Three insect growth regulators (IGR), the chitin synthesis inhibitors (CSI) teflubenzuron and hexaflumuron and the juvenile hormone mimic (JHM) pyriproxyfen, as well as the organophosphate (OP) pirimiphos-methyl, were evaluated for their activity against the cowpea weevil, Callosobruchus maculatus (F), in cowpea seeds stored for up to 8 months post-treatment. The initial activity data showed that, based on LC50 level, teflubenzuron had strong ovicidal activity (LC50 = 0.056 mg kg(-1)) followed by pirimiphos-methyl (1.82 mg kg(-1)) and pyriproxyfen (91.9 mg kg(-1)). The residual activity data showed that none of the IGRs tested had strong activity when applied at 200 mg kg(-1) in reducing the oviposition rates of C maculatus at various storage intervals up to 8 months post-treatment. However, teflubenzuron reduced adult emergence (F1 progeny), achieving control ranging from 96.2% at 1 month to 94.3% at 8 months. Hexaflumuron showed a similar trend in its residual activity, ranging between 93.8% control at 1 month to 88.2% control at 8 months post-treatment. However, pyriproxyfen was more active than the CSIs tested and caused complete suppression (100% control) of adult emergence at all storage intervals. Unlike the IGRs tested, pirimiphos-methyl applied at 25 mg kg(-1) was more effective in reducing oviposition rates of C maculatus up to 8 months post-treatment. A strong reduction of adult emergence was also observed at various bimonthly intervals (98.6% control at 1 month to 91.6% control at 8 months post-treatment). The persistence of hexaflumuron and pirimiphos-methyl in cowpea seeds was also studied over a period of 8 months. The loss of hexaflumuron residue in treated cowpeas (200 mg kg(-1)) was very slow during the first month post-treatment (4.43%). At the end of 8 months, the residue level had declined significantly to 46.4% of the initial applied rate. The loss of pirimiphos-methyl residue in treated cowpeas (25 mg kg(-1)) was relatively high during the first month post-treatment (36.7%) and increased to 81.6% after 8 months.

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The activity of 2 benzoylphenyl ureas, Diflubenzuron and Triflumuron alone in addition to the joint action for 5 of their binary combinations at different mixing ratios, was assayed through continuous exposure of the green cabbage aphid Brevicoryne brassicae (L.) 3rd instar larvae to treated cabbage leaves. Combinations of both IGRs at different mixing ratios were more active and revealed, in general, accumulated mortality percentages during immature and adult stages much higher than that of each IGR alone at the same testing level of 0.1 or 0.05 ppm. Also, different experimental combinations disrupted aphid development much more than within each IGR alone and resulted in less number of individuals that succeeded to develope as adults. Likewise, the reproductive potentiality of the produced adults as well as survival of their resulting off‐spring was adversely affected, relatively more within different combinations than with each IGR alone. However, in particular, Diflubenzuron/Triflumuron at mixing ratio of 4:1 exhibited the maximum bioactivity in this respect. Zusammenfassung Zur Wirkungssteigerung zweier Wirkstoffe der Benzoyl‐phenyl‐Harnstoffgruppe beim Einsatz gegen die Mehlige Kohlblattlaus, Brevicoryne brassicae (L.) Die Wirkung von zwei Harnstoffderivaten, Diflubenzuron und Triflumuron, wurden gegen Brevicoryne brassicae einzeln und in 5 verschiedenen Kombinationen getestet. Läuse des dritten Stadiums wurden durchgehend auf behandelten Kohlblättern gezüchtet. Die Kombination der beiden Wirkstoffe waren in den verschiedenen Mischungsverhältnissen wirksamer, d.h. das akkumulierte Mortalitätsprozent während des Larven‐ und Imaginalstadiums war höher als bei Einzelapplikation der beiden Wirkstoffe. Es wurden jeweils die Konzentrationen 0,1 ppm und 0,05 ppm getestet. Auch traten bei den Kombinationen häufiger Entwicklungsstörungen auf, so daß sich weniger Larven zu Imagines entwickelten als bei Behandlung mit nur einem der Wirkstoffe. Ebenso war die Kombination hinsichtlich der Reduktion der Reproduktion und der Lebensdauer der Nachkommen wirksamer. Eine Mischung von 4 Teilen Diflubenzuron und 1 Teil Triflumuron zeigte die höchste Bioaktivität bezüglich der hier untersuchten Reaktionen.

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Pesticides are known to interfere with the biochemical processes of plants, lowering their food quality. Therefor, this study was designed to evaluate persistence of Lambda-cyhalothrin in / on fresh orange fruits and investigate its effect on fruit quality. The insecticide residues were determined using GC-ECD system. Also, the biochemical parameters were determined using spectrophotometric techniques. The results showed that a waiting period of 7days after application on orange is enough to reduce the Lambda-cyhalothrin residues to below the maximum residue limits (MRL). Lambda-cyhalothrin rapidly disappeared with half-life (t ½) of 1.6 days on orange fruits. Furthermore, the ascorbic acid content and dry matter percentage were significantly reduced however, total protein content, acidity (%), moisture(%) and total soluble solids (T.S.S,%) were significantly increased in Lambda-cyhalothrin treated compared to untreated orange fruits.