Hybridization in North American bird fleas of the genus Ceratophyllus (Siphonaptera: Ceratophyllidae).

Evidence is presented suggesting hybridization in several species in the genus Ceratophyllus. Suspected interbreeding is reported as follows: C. idius x C. niger; C. celsus x C. scopulorum; C. celsus x C. petrochelidoni. The 1st of these was described as C. niger inflexus (Jordan, 1929). The 2nd was described as C. calderwoodi Holland, 1979, and the 3rd has been considered a dimorphic form of C. celsus (Holland 1985).

Ultrastructure of the eggs of seven flea species (Siphonaptera).

Eggs of seven flea species representing five families, Ctenocephalides felis (Bouché) (Pulicidae), Orchopeas leucopus (Baker) and Aetheca wagneri (Baker) (Ceratophyllidae), Conorhinopsylla stanfordi Stewart and Epitedia faceta (Rothschild) (Hystrichopsyllidae), Sternopsylla distincta texana (C. Fox) (Ischnopsyllidae), and Craneopsylla minerva (Rothschild) (Stephanocircidae), were examined with a scanning electron microscope and are described from the resulting micrographs. In the Pulicidae and Ceratophyllidae the individual outer chorionic cells are not visible; the egg surfaces are covered uniformly with small, nodular tubercles. In contrast, the Hystrichopsyllidae and Ischnopsyllidae have a prominent, raised reticulum, very heavily constructed in the latter, delineating the chorionic cells. The single representative of the Stephanocircidae has only a faintly embossed chorionic reticulum. All of the species examined except E. faceta and C. minerva (both with a single micropylar opening) have multiple micropyles at the posterior end. C. felis, O. leucopus, A. wagneri, and C. stanfordi also have multiple aeropyles at the anterior end (these are lacking in S. d. texana). Lateral aeropyles, consisting of small groups of pores often associated with small mounds in the chorion, are present (maximum of two seen on any one egg) in all species except E. faceta, C. stanfordi, and C. minerva.

A new species of Nearctopsylla Rothschild 1915 (Siphonaptera: Hystrichopsyllidae) from the southern Appalachians.

Nearcyopsylla pfitzeri sp. n. is a parasite of the short-tailed shrew, Blarina brevicauda, in the Great Smoky Mountains. Only two females have been collected, but they are clearly distinct from both the more northern N. genalis and the more southern N. georgiana.

Enzymatic synthesis of esters using an immobilized lipase.

Various esters were synthesized in nearly anhydrous hexane from alcohols and carboxylic acids using a lipase from Candida cylindracea. The enzyme was immobilized on a nylon support and protein loadings as high as 10 mg/g were obtained. The activity of the immobilized enzyme was maximum in a range of temperatures from 25 to 37 degrees C. Ethylpropionate was formed from ethanol and propionic acid at a rate of 0.017 mol/h g immobilized protein. Different esters were formed at comparable rates and equilibrium conversions could generally be approached in less than 10 h in a batch reaction system. The immobilized lipase catalyst was quite stable and retained about one third of the initial activity after repeated experiments during the course of 72 days. A stirred tank continuous flow reactor was used successfully for the continuous production of esters.