Development and evaluation of granule and emulsifiable concentrate formulations containing Derris elliptica extract for crop pest control.
Derris elliptica Benth. extracts containing rotenone have long been used as natural insecticides, but time-consuming preparation processes and the short shelf life of the extract limit their use in pest control. In this study, stable water-dispersible granules and emulsifiable concentrate liquids containing Derris extract (equivalent to 5% w/w of rotenone) were developed with simple techniques. Accelerated degradation kinetics of rotenone in the Derris extract, and in both formulations, indicated that its degradation followed first-order kinetics. The predicted half-life (t(1/2)) and shelf life (t(90%)) at 30 degrees C of rotenone in Derris extract were 520 and 79 days, respectively. Derris granules and emulsifiable concentrate clearly prolong the stability of rotenone 8-fold (t(90%) = 633 days) and 1.4-fold (t(90%) = 110 days), respectively. The study of rotenone degradation after application onto plants indicated that both formulations would be effective for up to 3 days after spraying. Preliminary efficacy testing indicated that the Derris emulsifiable concentrate was clearly more effective than Derris water-dispersible granules in controlling Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae).
Wiwattanapatapee
Ruedeekorn
R
Department of Pharmaceutical Technology, Faculty of Pharmaceutical Sciences, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand. wruedeek@pharmacy.psu.ac.th
Sae-Yun
Attawadee
A
Petcharat
Jiraporn
J
Ovatlarnporn
Chitchamai
C
Itharat
Arunporn
A
D000818:Animals; D002626:Chemistry, Pharmaceutical / Q000379:methods*; D018556:Crops, Agricultural / Q000469:parasitology*; D029866:Derris / Q000737:chemistry*; D004304:Dosage Forms; D004655:Emulsions / Q000737:chemistry; D007306:Insecticides / Q000737:chemistry* / Q000494:pharmacology; D007700:Kinetics; D010571:Pest Control; D004364:Pharmaceutical Preparations / Q000737:chemistry*; D010935:Plant Diseases / Q000469:parasitology; D010936:Plant Extracts / Q000737:chemistry* / Q000494:pharmacology; D012402:Rotenone / Q000737:chemistry / Q000494:pharmacology; D018411:Spodoptera / Q000187:drug effects
D004304:Dosage Forms; D004655:Emulsions; D007306:Insecticides; D004364:Pharmaceutical Preparations; D010936:Plant Extracts; D012402:Rotenone