Technique for Repeated Hemolymph Sampling From the Madagascar Hissing Cockroach (Gromphadorhina portentosa)
Despite the increasing attention paid to invertebrates as veterinary patients, guidelines for biomaterial sampling from arthropods remain limited.1-3 To evaluate roaches as a reliable pharmaceutic vehicle for exotic vertebrates, a safe, simple, and replicable technique for manual restraint and repeated hemolymph sampling from the Madagascar hissing cockroach (Gromphadorhina portentosa) was developed.
Adult cockroaches (n=24) were group housed in plastic containers of four animals each with bark substrate under standard temperature, lighting, and dietary conditions for their species. Before sampling, each animal was weighed to estimate overall hemolymph volume at 10% of their body weight. To collect hemolymph, roaches were restrained manually between two foam sponges, one of which contained an access window overlying the sampling site. Using an insulin needle, the optimal location for hemolymph collection was determined by collection at two locations: the base of the metathoracic (hind) leg and the dorsal sinus.
Repeated hemolymph collection was performed with each tank of roaches serving as a single time point twice so that each collection site could be assessed. Extracted sample volumes were targeted at 1% of body weight for total volume of both time points. Excessive hemolymph leakage was controlled by external seal with surgical glue. While few roaches died or were euthanized during the procedure due to injury, freshly presented individuals were examined to assess hemolymph sampling techniques. After the second sampling, roaches were provided an equal volume of 0.9% saline to replace hemolymph removed.4
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