Laboratory Techniques for Rearing the Fleas (Siphonaptera: Ceratophyllidae and Pulicidae) of California Ground Squirrels (Rodentia: Sciuridae) Using a Novel Nest Box

Abstract

Three species of fleas, Oropsylla montana (Baker), Hoplopsyllus anomalus (Baker), and Echidnophaga gallinacea (Westwood), occur seasonally on the California ground squirrel, Spermophilus beecheyi (Richardson). Few studies have focused on the biology and ecology of these fleas despite their importance in the epidemiology of sylvatic plague. To best duplicate a natural parasite-host relationship in the laboratory, a novel nest box was developed that facilitated housing wild-caught S. beecheyi, was conducive to rearing fleas, and met modern standards for laboratory animal hygiene. This flexible system allowed adult fleas with different feeding strategies to be colonized successfully while providing sufficient flea eggs for both colony maintenance and biological research. The techniques described could be adapted to work with other species of rodents and their fleas.

Laboratory Evaluation of Fipronil and Imidacloprid Topical Insecticides for Control of the Plague VectorOropsylla montana(Siphonaptera: Ceratophyllidae) on California Ground Squirrels (Rodentia: Sciuridae)

“…The techniques for rearing ßeas on wild-caught squirrels in the laboratory are described in detail by Metzger and Rust (2001). Recently emerged adults were used to evaluate the performance of on-animal insecticide treatments.…”

“…Laboratory animal bedding consisting of ground corncobs (0.25-mesh [6.35 mm diameter] Bed-ÕO-Cobs, Andersons Industrial Products Group, Maumee, OH) was selected for use in squirrel enclosures. This bedding is not toxic to ßeas and is ideal in the ßea rearing system developed by Metzger and Rust (2001). In addition, the corncob bedding may be representative of plant material normally used in nests of rodents such as ground squirrels and provide a natural cellulose substrate for determining if insecticide residues are transferred from treated animals to nesting material.…”

“…Ground squirrels were livetrapped on the UC Riverside campus, then individually housed and maintained in the laboratory for at least 1 yr before the experiments (Metzger and Rust 2001). Individual squirrels exhibited unique temperaments, behaviors, grooming abilities, and suitability as ßea hosts.…”

“…Each squirrel was weighed to the nearest gram to calculate an appropriate topical treatment dose in mg/kg. Nest boxes were modiÞed slightly from those used to harvest ßea eggs described by Metzger and Rust (2001). The screen separating the squirrels from the lower collection pan was removed allowing the animals to sleep directly on 2Ð 4 cm of corncob bedding placed in the lower half.…”

An Assemblage of Fleas (Siphonaptera) From Canada, México, and the United States of America, in the Hastriter Collecton (Brigham Young University)

“…Davis (1999) utilized a chitin inhibitor to control populations of Hoplopsyllus anomalus . Metzger and Rust (2001) designed techniques for rearing Hoplopsyllus anomalus and Oropsylla montana in the laboratory. Studies conducted in the mid 1970s at Hunter Ligget and Fort Ord military installations in California by U.S. Army personnel substantiated that the California ground squirrel is the primary reservoir of Y. pestis and that Oropsylla montana and Hoplopsyllus anomalus are the principle vectors in California plague epizootics.…”