Survival and reproductive output of Chironomus tentans (Diptera: Chironomidae) in response to parasitism by larval Unionicola foili (Acari: Unionicolidae).

Parasitic associations between larval Unionicola foili and the dipteran Chironomus tentans were established in the laboratory, and the effects of these water mite larvae on survival and reproduction of C. tentans were determined. Longevity of parasitized insects was not significantly different from those that were unparasitized. Furthermore, there was no significant difference in the onset of oviposition between parasitized and unparasitized female chironomids. However, infected females oviposited significantly more eggs compared to uninfected controls. This study contradicts others indicating that water mite larvae severely reduce the survivorship and reproductive output of insects. The results are consistent with analyses indicating that degree of parasitism is not correlated with either duration of the parasitic phase or longevity of larvae following their parasitic association with chironomids. Larval U. foili apparently secure sufficient nutritional resources to complete their development, yet their hosts still exhibit fitness components expected for unparasitized individuals. Extreme site specificity exhibited by larval U. foili may limit the degree of parasitism on host insects and in doing so preclude larval mites from achieving infection levels that could negatively impact host survival and reproduction.

The effects of azapirones on serotonin1A neurons of the dorsal raphe.

1. The effects of buspirone, gepirone, ipsapirone and tandospirone on spontaneously discharging serotonergic neurons of the dorsal raphe were determined under the same experimental conditions. 2. Buspirone, gepirone, ipsapirone and tandospirone were equally efficacious and acted in a dose-dependent manner to totally inhibit the spontaneous activity of serotonergic neurons. 3. Based on their effects six min after administration (i.p.), their ED50 values were: buspirone, 134 micrograms/kg; ipsapirone, 220 micrograms/kg; gepirone, 225 micrograms/kg; tandospirone, 198 micrograms/kg. 4. The similarity of these ED50 data suggest that they share a similar chemical structure that binds to the 5-HT1A receptor, most likely it is "N-C-C-C-C-N" aliphatic backbone. 5. Buspirone and tandospirone required 4 or more min to totally block the spontaneous activity, while gepirone and ipsapirone blocked it in 3 min. 6. The dose-response curves from buspirone and tandospirone demonstrated enough dissimilarity to the dose-response curves from gepirone and ipsapirone to suggest differences in their rates of absorption, and/or differences in the production of active and inactive metabolites.