Juvenile hormone and locust phase

Juvenile hormone (JH) is directly and indirectly involved in the determination of many phase characteristics of locusts. Temporal differences in JH titer and the biosynthetic capacity of excised corpora allata of solitary nymphs are correlated to some extent with the effects on them of treatment with JH or JH analogs. Juvenile hormone modulates cuticular melanization and the rate of reproductive maturation - specifically regulating vitellogenesis at the transcriptional level, and nonspecifically stimulating the translational capacity of the locust fat body. Juvenile hormone does not appear to be involved in behavioral phase transition of locusts. Long-term treatment of crowded nymphs with the JH analog methoprene does not lessen their gregarious behavior, and does not reduce hemolymph lipids or carbohydrates. Reducing endogenous JH levels of solitary nymphs by chemical allatectomy with precocene III does not induce gregarious behavior. However, methoprene does affect nymphal coloration. The relevance of these results to locust control is discussed.