Absence of Insect Juvenile Hormones in the American Dog Tick, Dermacentor veriabilis (Say) (Acari: Ixodidae), and in Ornithodoros parkeri Cooley (Acari: Argasidae)

Synganglia, salivary gland, midgut, ovary, fat body and muscle alone and in combination from the ixodid tick, Dennacentor variabilis (Say), or the argasid tick, Omithodoros parkeri Cooley, were incubated in vitro in separate experiments with L-[methyl-3H]methionine and farnesoic acid or with [1-14C]acetate. Life stages examined in D. variabilis were 3-72 hold (after eclosion) unfed nymphs, partially fed nymphs (18-72 h after attachment to the host), fully engorged nymphs (2 dafter detachment from host), 3-72 hold (after eclosion) unfed females, partially fed unmated females (12-168 h after attachment to host) and replete, mated females (2 d after detachment from the host). Those from 0. parkeri were last stadium nymphs and female 0. parkeri, all 1-2 h after detachment Corpora allata from Diploptera punctata, Periplaneta americana and Gromphadorina portentosa were used as positive controls in these experiments. No farnesol, methyl farnesoate, JH I, JH II, JH Ill, or JHIII bisepoxide was detected by radio HPLC from any tick analysis while JH Ill, methyl farnesoate, and farnesol were detected in the positive controls. To examine further for the presence of a tick, insect-juvenilizing agent, Galleria pupal-cuticle bioassays were conducted on lipid extracts from 10 and 15 d old eggs, unfed larvae, unfed nymphs, and partially fed, unmated female D. variabilis adults. Whole body extracts of fourth stadium D. punctata and JH Ill standard were used as positive controls. No juvenilizing activity in any of the tick extracts could be detected. Electron impact gas chromatography-mass spectrometry of hemolymph extracts from fed, virgin and replete female D. variabilis and fully engorged female 0. parkeri also failed to identify any of the known insect juvenile hormones in these ticks. The same procedures were successful in the identification of JH Ill in hemolymph of fourth stadium D. punctata. Last stadium nymphal 0. parkeri implanted with synganglia from next to last nymphal instars underwent normal ecdysis to the adult The above studies in toto suggest that D. variabilis and 0. parkeri do not have the ability to make the common insect juvenile hormones, and