Chrysomya megacephala (Fabricius) (Diptera: Calliphoridae) Oviposition Behavior in Previous Oviposition Situation

Behavioral report of Chrysomya rufifacies in response to substrate infestation by Lucilia sericata and Lucilia cuprina using a tetrahedron olfactometer device

Calliphoridae are widespread globally and can inhabit a variety of habitats. In this brief report, we assessed the appeal of Chrysomya rufifacies to resources that were previously inhabited by Lucilia sericata and L. cuprina, both common carrion colonizers. Two hundred adult male and female (1:1) C. rufifacies were released under controlled conditions into clear plastic cages (45 x 45 x 45 cm) with four types of substrates: beef-liver; liver with 100 third-instar larvae of L. cuprina; (III) liver containing 100 third-instar larvae of L. sericata; and liver containing 100 third-instar larvae of C. rufifacies. Each substrate was left in place for 24 hours at the end of a tube connected to the cage, where sticky traps were positioned to capture flies that might have been attracted to a specific substrate. The results indicate variations in the attraction of flies to different types of livers colonized by larvae of various species. It is suggested that flies may have specific preferences depending on the species of larvae present in the substrate. The liver without larvae was the preferred choice, while beef liver with C. rufifacies larvae was the least attractive. Results of statistical tests indicated that there is independence between attractiveness preference and the presence of C. rufifacies flies. Although there is a trend among certain levels of the variables in the correspondence analysis, these relationships are not statistically significant. However, they indicate specific patterns of association between different groups of flies and species of larvae. This study demonstrated that C. rufifacies does not show reduced attraction to any of the resources. A tetrahedron olfactometer device has been used for the first time in a behavioral study of C. rufifacies flies. This may enable future studies to enhance the understanding of fly behavior.

Colonization pattern and thermal needs of immature phases of Sarcophaga argyrostoma (Diptera: Sarcophagidae): Significance for estimating postmortem interval

Members of Sarcophagidae are necrophagous and are commonly found on decaying carcasses; and their developmental forms are important indicators for the approximation of lowest postmortem interval (PMImin). This work describes the biological characteristics of Sarcophaga argyrostoma from Tehran, Iran. Various temperature regimes were applied to estimate the thermal summation constant (k) and thermal requirements for development of S. argyrostoma. Five growth proceedings, containing 1st ecdysis, 2nd ecdysis, wandering, pupariation and eclosion, were investigated under eight fixed temperature regimes (6-30 °C). The effects of fly age, freshness, and availability of oviposition substrate on oviparity and viviparity was studied. At 6 °C, no development occurs, and at 8 °C only the first ecdysis occurs. At temperatures between 10 and 30 °C, all immature stages proceeded to the adult stage, and thus immature development was analyzed at these six remaining temperatures. The development phases needed minimum (Dz ± SE) 5.4(0.4), 8.5(0.26), 5.3(0.44), 3.8(0.1), and 6.6 (0.6)°C to attain one of the succeeding developmental occasion, correspondingly. The approximated K for those five occasions were 15.04 ± 1.12, 12.62 ± 0.65, 140.36 ± 4.35, 14.59 ± 0.6, and 222.8 ± 4.18°-day (DD) accordingly. When the food substrate is available and fresh, the female prefers to lay eggs, no matter how old she is. However, the chance of ovoviviparity increased when no oviposition substrate was available. The truth that S. argyrostoma able to either larviposit or to lay eggs encompasses serious consequences for the precise estimation of the PMImin, as the existence of larvae resulting from eggs laid on the carcass could add hours (based on ambient temperature) to the PMImin.

Chronobiological Effect on the Reproductive Behavior of Chrysomya megacephala (Diptera: Calliphoridae)

The most widely used entomological method of determining the time since death (minimum postmortem interval, mPMI) has been calculating the developmental time of blow flies (Diptera: Calliphoridae) on the deceased body. However, because blow flies are known to be diurnal, nocturnal oviposition has been excluded from standard mPMI calculations. This has been challenged by recent studies demonstrating nocturnal oviposition due to an unknown reason. Therefore, this study investigated the role of chronobiology. We recorded the locomotion amount and pattern of Chrysomya megacephala (Fabricius, 1794) (Diptera: Calliphoridae) under different chronobiological conditions and examined whether Ch. megacephala can oviposit under nighttime conditions in field and laboratory settings. Subjects were found to have a daily activity pattern under normal darkness conditions (12:12 L:D) and under continuous darkness (DD), but they exhibited no pattern under continuous light (LL). Free-running period was approximately 1,341 min/d (22.35 h/d). In the field, no flies were observed during nighttime. Oviposition occurred in the laboratory setting during daytime with no lights and during nighttime with artificial lights. Free-running subjects oviposited in both active and resting periods, with more eggs laid during active than resting periods. The result of this study indicates it is possible to induce oviposition behavior during evening hours on Ch. megacephala. However, this was only observed in the laboratory setting and could only happen during the flies' subjective day.