Induced host plant resistance: Jasmonic acid effect on soybean loopers, Chrysodeixis includens

Soybean looper, Chrysodeixis includens (Walker),is an important pest of mid-South soybeans.  Soybean looper can colonize over 60 plant species in 28 Families and is an occasional pest in cotton, cowpea, okra, and sweetpotato.  Control can be achieved via insecticides however host plant defensive compounds have been shown to reduce insecticide efficacy.  In order to test this hypothesis, cotton, okra, cowpea and sweetpotato were induced using jasmonic acid.  Plants were sprayed with 1 mM concentration of JA until runoff.  Leaf punches were taken 48 hours after application and fed to soybean looper neonates, one per leaf.  Each replicate consisted of fifty control (water) and treated (JA) leaf punches and neonates.  Mortality was recorded daily and once neonates reached third instar, they were weighed and split into four groups consisting of 20 individuals each; control + diet, JA treated + diet, control + diet with insecticide (methoxyfenozide), and JA treated + diet with insecticide (methoxyfenozide).  Daily mortality was recorded and soybean looper progress was tracked through pupation, where they were then weighed and allowed to emerge.  Leaves treated with JA had significant impacts on third instar larval weight (P < 0.0001) but did not impact pupal weights.