The importance of nitrogen fertilization as a factor in plant-insect interactions has been recognized for many years. Nutritional ecologists have provided many examples which demonstrate the importance of host plant nutrition to herbivore fitness (see reviews by Onuf 1978 and Scriber 1981). In cotton, this relation was apparent to many early pest management workers. McGarr (1942, 1943) and Isley (1946) reported positive correlations between high nitrogen (N) fertilization and increases in numbers of cotton aphid, Aphis gossypii. Higher levels of Heliothis spp. larval infestation in well fertilized cotton also has been reported by several workers (Adkisson 1958, Beckman 1970, and Jackson et al. 1973)

Because natural populations were monitored in those studies with Heliothis spp., adult ovipositional preferences and establishment of young larvae were confounded within the experimental designs. With that "choice" component, data from these studies are unsuitable for accurately relating larval establishment to plant N status. To construct models of this relationship, the additional factor of ovipositional behavior must be removed. This may be accomplished by examining the relationship in terms of equal size cohorts on host plants grown over a range of fertilizer treatments, and by using artificial infestation techniques. Such studies were carried out in the field in 1983 and 1984 at Texas A&M University (TAMU). These were designed to provide quantitative and qualitative biological data describing Heliothis virescens (F.) larval establishment and survival in relation to N fertilization.