The long-term objective of this research is to understand more about productive mechanisms and their evolution in acarines (mites and ticks) and other ectoparasites vectors of public health importance which exhibit different parasitic habits and ticks Dermacentor variabilis, Amblyomma americanum, and Ixodes scapularis (all vectors of several pathogens to man and other animals; D. variabilis is the major vector of Rocky Mountain Spotted Fever; A. americanum has been reported to transmit laboratory vector of Lyme disease although its role in nature is unknown), Amblyomma rotundatum which is parthenogenetic, the argasid ornithodoros parkeri (vector of Borrelia parkeri) and the chicken mite Dermanyssus gallinae. Specific objectives are nutritional and reproductive stages, and attempt experimental alterations of the NSC by tissue transplants, injections, and topical applications of exogenous insect hormones and selected pharmacologically active compounds known to be present in experiments via in vitro synganglia preparations; (2) partition and define the role of feeding in spermatogenesis and spermiogenesis; (3) determine the stimuli for egg production which is initiated by mating (except in A. rotundatum and other parthenogenetic species). These experiments involve spermatid proteins, catecholamines, prostaglandins from males and Egg Development Stimulation Factor (EDSF), juvenile hormone-like factor (JH-F) and ecdysteroids; (4) identify the descriptive and experimental approaches to elucidate critical gaps in knowledge of reproductive biology of medically important disease vectors and parasites. Acarine reproduction, especially its hormonal regulation, is poorly understood. Techniques will include organ cultures, autoradiography, RCA, RIA, TLC, HPLC, GC/M Galleria bioassay, labeling and scintillation counting, SEM, histochemical and immunofluorescent tissue sections, organ transplants, chromosomal analyses, PAGE and immunoblotting.