LARVAL REARING DENSITY EFFECTS ON LIPID RESERVES AND WING-LOADING IN FAIL ARMYWORM ADULTS (LEPIDOPTERA, NOCTUIDAE)

A laboratory study was conducted to determine if a high larval rearing density produces premigrant traits in the fall armyworm, Spodoptera f rugiperda (J. E. Smith), and if these traits can be used as criteria f or separating non-premigrant from premigrant groups. The putative prem igrant traits of high lipid reserves and low wing-loading were measure d in newly emerged adult fall armyworm. An increase in rearing density significantly increased adult whole-body lipid content, but the incre ase may be due, in part, to enhanced nutrition through cannibalism. Al though larval rearing density did not affect wing-loading, the fall ar myworm as a migrant species showed lower than theoretically expected w ing-loading values. The lack of density-dependent increases in lipid r eserves and the lack of density effects on adult activity, development al time, and size (documented herein and in previous studies) may indi cate that a premigrant phase induced by high larval density does not e xist in the fall armyworm.