Post‐embryonic development of Chrysomya putoria (Diptera: Calliphoridae) in swine and bovine tissues in South America: implications for forensic entomology

Abstract

AbstractNecrophagous diptera are used in forensic entomology to measure the post‐mortem interval (PMI) of cadavers. PMI estimates based on fly larvae, however, can be inaccurate when larval development is retarded, or accelerated, by the nutritional composition of the cadaveric tissue. We compared the post‐embryonic development of Chrysomya putoria (Wiedemann, 1830) on different tissues of pigs and cows. Forty newly hatched fly larvae per treatment were placed on 60 g of the following swine tissues: liver (T1), swine lung (T2), swine heart (T3), swine muscle (T4), bovine heart (T5), bovine lung (T6) and bovine muscle (T7). There were four replicates/treatment. Experiments were conducted in controlled conditions (28°C day/26°C night, RH 70% ± 10% and 12 h of photophase). Fly larvae reared on swine liver took longer to develop (5.2 days) than flies reared on other substrates (from 3.5 to 4.5 days), and this difference was statistically significant. The total duration of development on swine liver (T1) was significantly slower (8.7 days) when compared to the other treatments. Larvae reared on swine lungs (T2) were significantly heavier in the third instar ( = 61.2 mg) than larvae reared on swine liver (T1), swine muscle (T4), bovine lung (T6) and bovine muscle (T7). Total larval survival was high (above 76%) in all treatments except for T1 (66%). There was no deviation from the expected adult sex ratio, and the percentage of abnormalities remained within the expected range. These results reinforce the idea that, to achieve greater accuracy in PMI estimates, the type of tissue on which the larvae develops needs to be taken into account.