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Juvenile hormones (JHs) are sesquiterpenoids synthesized by the corpora allata (CA). They play critical roles during insect development and reproduction. The first JH was described in 1934 as a "metamorphosis inhibitory hormone" in Rhodnius prolixus by Sir Vincent B. Wigglesworth. Remarkably, in spite of the importance of R. prolixus as vectors of Chagas disease and model organisms in insect physiology, the original JH that Wigglesworth described for the kissing-bug R. prolixus remained unidentified. We employed liquid chromatography mass spectrometry to search for the JH homologs present in the hemolymph of fourth instar nymphs of R. prolixus. Wigglesworth's original JH is the JH III skipped bisepoxide (JHSB3), a homolog identified in other heteropteran species. Changes in the titer of JHSB3 were studied during the 10-day long molting cycle of 4th instar nymph, between a blood meal and the ecdysis to 5th instar. In addition we measured the changes of mRNA levels in the CA for the 13 enzymes of the JH biosynthetic pathway during the molting cycle of 4th instar. Almost 90 years after the first descriptions of the role of JH in insects, this study finally reveals that the specific JH homolog responsible for Wigglesworth's original observations is JHSB3., Facultad de Ciencias Naturales y Museo, Consejo Nacional de Investigaciones Científicas y Técnicas

Anophelinae mosquitoes are vectors of human malaria, a disease that infects hundreds of millions of people and causes almost 600,000 fatalities annually. Despite their medical importance, laboratory studies on key aspects of Anophelinae reproductive biology have been limited, and in particular, relatively little is known about the role of juvenile hormone (JH) in the control of female reproduction. The study presented here attempts to fill a gap of knowledge in our understanding of the JH control of ovarian development in female Anophelinae mosquitoes, using Anopheles albimanus as a model. Our studies revealed that JH controls the tempo of maturation of primary follicles in An. albimanus in a similar manner to that previously described in Aedes aegypti. At adult eclosion JH hemolymph titer was low, increased in 1-day old sugar-fed insects, and decreased in blood fed individuals. JH titers decreased if An. albimanus females were starved, and were reduced if insects emerged with low teneral reserves, precluding previtellogenic ovarian development. However, absolute hemolymph titers were lower than Ae. aegypti. Decapitation experiments suggested that if teneral reserves are sufficient, factors from the head activate JH synthesis by the corpora allata (CA) during the first 9–12 h after adult emergence. In conclusion, our studies support the hypothesis that JH controls previtellogenic ovarian development in female An. albimanus mosquitoes, in a similar manner that have been described in Culicinae.