Temperature effects on the survival and oviposition of an invasive blow fly Chrysomya rufifacies Macquart (Diptera: Calliphoridae)

Authors: Rusch, Travis; SAWYER, SAMANTHA - Texas A&M University; ORR, ABIGAIL - Texas A&M University; RICHTER, NICHOLAS - Texas A&M University; SOHN, DAVID - Texas A&M University; SMITH, ALEXANDRIA - Texas A&M University; TOMBERLIN, JEFFERY - Texas A&M University; TARONE, AARON - Texas A&M University

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/10/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary: The hairy maggot blow fly (Chrysomya rufifacies) is an invasive species in North America that can outcompete and displace multiple native blow fly species. However, their survival and reproduction are largely limited by environmental temperature. Through two laboratory experiments, we investigated the effects of temperature on the reproduction and survival. High survival (= 90%) was observed from 10-40°C, with moderate mortality at 42.5°C (29.2%) and high mortality at 43.5°C (75.4%). All flies died when exposed to 44.5 or 45.0°C for 24-h. Oviposition occurred from 22.5 – 42.5°C, with the greatest occurrences (100%) at 30 and 35°C, and the greatest number of eggs (2035) occurring at 30°C. Although egg laying occurred from 22.5-42.5°C, egg viability was only observed from 22.5-37.5°C, with the greatest viabilities (100%) at 30 and 35°C. Exposing females to a heat shock of 44.0°C before breeding started laying eggs sooner (37.5% decrease), more frequently (33.3% increase), and produced more eggs (73.3% increase) than female flies not exposed to a high temperature. The combined results potentially provides the hairy maggot blow fly a competitive advantage over native species in warm environments. These data are important in determining when and where this invasive blow fly can be active and reproducing, which will help determine its potential impact on native blow fly species. Additionally, forensic entomologists can use these data in death investigations to help determine time of colonization, which can ultimately help determine the postmortem time interval (i.e., time of death).

Technical Abstract: The increased severity and frequency of elevated temperatures due to climate change are altering native species geographic distributions and local abundances, while also increasing the invasion of new areas by exotic species. These distributional shifts have led to the displacement and extinction of several native species. Through two experiments, we investigated the effects of temperature on the survival and oviposition of the hairy maggot blow fly Chrysomya rufifacies (Macquart), a highly competitive and predatory invasive blow fly of ecological, economic, and forensic importance. In our first experiment, we exposed mixed sex colonies of C. rufifacies to a given temperature (10 – 45.0°C) for 24-h. High survival (= 90%) was observed from 10-40°C, with moderate mortality at 42.5°C (29.2%) and high mortality at 43.5°C (75.4%). All flies died when exposed to 44.5 or 45.0°C for 24-h. Oviposition occurred from 22.5 – 42.5°C, with the greatest occurrences (100%) at 30 and 35°C, and the greatest number of eggs (2035) occurring at 30°C. Although oviposition occurred from 22.5-42.5°C, egg viability was only observed from 22.5-37.5°C, with the greatest viabilities (100%) at 30 and 35°C. Thus, C. rufifacies has distinct thermal limits for survival and oviposition, and may exhibit a bet-hedging strategy in response to temperature exposure. In our second experiment, we assessed the effects of an acute heat shock on C. rufifacies oviposition performance. Adult virgins (males and females) were exposed to 25.0°C, 42.0°C, or 44.0°C for 1-h, and then maintained at ~25°C in mixed-sex colonies for 14-d. Pre-breeding heat exposure had no effect on male or female reproductive success, except for females exposed to 44.0°C. Females exposed to this temperature before breeding oviposited sooner (2.5 ± 0.0 days, 37.5% decrease), more frequently (0.52 ± 0.4, 33.3% increase), and produced more eggs (10,772.9 ± 2258.6 eggs, 73.3% increase) than female flies exposed to 25°C. The combined results that C. rufifacies survives exposures up to 43.5°C, successfully oviposits up to 37.5°C, and accelerates both oviposition timing and intensity following brief exposure to near upper lethal temperatures (44.0°C), potentially provides C. rufifacies a competitive advantage over native calliphorids in warming environments.