Quantitative genetics of juvenile hormone esterase, juvenile hormone binding and general esterase activity in the cricket Gryllus assimilis

Heritabilities and genetic, environmental and phenotypic correlations were estimated for two endocrine traits (juvenile hormone esterase (JHE) and juvenile hormone binding (JHB) activity) and one non-endocrine trait (general esterase activity (GE)) in the cricket Gryllus assimilis. Genetic parameters were estimated in three stages of the last stadium as well as in the entire last stadium. Significant additive genetic heritabilities were observed for each trait for activities pooled over all developmental stages. For JHE and JHB, significant heritabilities were also observed within most developmental stages. This indicates that these endocrine features have sufficient genetic variability during most periods of the last stadium to respond rapidly to selection. Significant phenotypic correlations were observed in eight of nine pairwise comparisons between the three traits in the three stages. Significant additive genetic correlations were observed between JHE and JHB and between JHE and GE for activities pooled over all developmental stages. Nearly all phenotypic and additive genetic correlations between the same trait in different developmental stages were significant. This indicates that these three traits are highly intercorrelated and should evolve in concert. Of particular note is the positive phenotypic and genetic correlation between JHE and JHB which suggests that these two traits may be coordinately regulated and may function in concert to reduce the JH titre. This is, to our knowledge, the first quantitative-genetic analysis of hormonal features of an insect.