Daphnia magna were exposed for 21 d to the ecdysteroids, 20-hydroxyecdysone (20-E), the accepted molting hormone, and ponasterone A (PoA), an ecdysteroid found in some crustaceans and many plants. Daphnids were monitored for alterations in molting, fecundity, and survival time. The 20-E elicited no significant effects on molting frequency, and its significant effects on reproduction were only a...

As laying hens age, egg production and quality decreases. Egg producers can impose an induced molt on older hens that results in increased egg productivity and decreased hen mortality compared with non-molted hens of the same age. This review discusses the effect of induced molting by feed removal on immune parameters, Salmonella enterica serovar Enteritidis (SE) invasion and subsequent product...

Molting in insects is regulated by molting hormones (ecdysteroids). The major active hormone, 20-hydroxyecdysone, is formed by ecdysone 20-monooxygenase-catalyzed hydroxylation of ecdysone. During times of decreasing hormone titers, inactivation occurs by several routes including (i) 26-hydroxylation and further oxidation to the 26-oic acid, (ii) formation of various conjugates (e.g. phosphates...

Fitness consequences of ectoparasitism are expressed over the lifetime of their hosts in relation to variation in composition and abundance of the entire ectoparasite community and across all host life history stages. However, most empirical studies have focused on parasite species-specific effects and only during some life history stages. We conducted a systematic, year-long survey of an ectop...

We describe an in vivo screening assay that uses epidermal chitinase activity as the endpoint following a 7-day exposure of Uca pugilator to test chemicals. Chitinase, a chitinolytic enzyme, is the end product of endocrine cascades of a multi-hormonal system for control of crustacean molting. Wherever a molt-interfering agent adversely impacts the Y-organ-ecdysteroid receptor axis, the effect s...

The ultrastructure of follicle cells has been compared to that of developing oocytes in the marine crustacean isopod, Idotea balthica basteri, at different periods of the molting cycle. There was a distinct change in the shape and size of the follicles and in their relation to each other and to the oocytes. During stage 1 of vitellogenesis (molting cycle period C), spaces between the follicles ...

Survival and molting incidence were studied after heat (40 degrees C) and cold (0 degree C) shocks in specimens of Panstrongylus megistus with the aim of establishing its response to temperature stress under laboratory rearing conditions and to understand occasional changes in the biological characteristics of specimens captured in nature. The response to the thermal shocks was found to vary as...

Arthropod growth requires molt-associated changes in softness and stiffness of the cuticle that protects from desiccation, infection and injury. Cuticle hardening in insects depends on the blood-borne hormone, bursicon (Burs), although it has never been determined in hemolymph. Whilst also having Burs, decapod crustaceans reiterate molting many more times during their longer life span and are e...