Effect of Temperature on the Breeding Black Soldier Fly Larvae in Vitro for Basic Health-oriented Research

Abstract

Article Notes: Received: Sep 20, 2020 Received in revised form: Nov 16, 2020 Accepted: Nov 17, 2020 Available Online: Jan 26, 2021 Background & Aims of the Study: The prevalence of food insecurity in many countries and the challenges emerging to feed more than 9 billion people by 2050 have led the researchers to look for alternative sources of protein in human and animal diets. In this regard, today, the use of insects has attracted a lot of attention since they contain high nutritional value and help to preserve environmental resources. Among the various species of insects, particular attention has been paid to the black soldier fly (BSF) since it can consume from a variety of substrates, including organic waste. Various factors, such as temperature, humidity, density, light, and diet, are involved in the breeding of this insect. It seems that temperature is more effective in the breeding stages of this species than the other factors. Due to the insufficient information on finding the optimal temperature in breeding this species, this study was conducted to determine the mentioned factor in the maximum production and reproduction of black soldier flies to eliminate organic waste and turn it into valuable material in animal food. Materials and Methods: Organic waste, including kitchen fruit and food, was used to feed the larvae. Adult flies were then reared in cotton net cages (404040 cm) and under the temperature range of 25-35°C. Afterward, the eggs were collected by fine needles and transferred to a temperature-controlled incubator during the hatching stage to undergo experiments in the specified temperature range (i.e., 25-35°C). The larvae fed freely from the formulated diet (i.e., chicken feed) until the pre-pupal stage. The produced pupae were monitored for growth and survival in the temperature range of 25-35°C. The emergence of adult BSFs at different temperatures was examined after the completion of the pupal stage under controlled temperature. In this descriptive study after the completion of each insect's development stage, the percentage of insect survival in each stage of measured temperature condition was determined by estimating the proportion of the attribute present in the population. Results: According to the results of this study, the highest hatching percentage (80%) was recorded at 30°C for 4 days, while the slowest growth period was obtained at 30°C for 13 days with a survival rate of 92%. It was also revealed that the highest pre-pupal and pupal survival rates were 82% at 30°C for 10 days and 77% at 30°C for 7 days, respectively. The lifespan of adult flies at 30°C was reported to be 9 days. The statistical population of this consisted of 300 pupae at each temperature. The survival percentage was reported after the survived pupae were counted. Conclusion: The results of this study showed that the growth and reproduction of BSFs were significantly affected by temperature. In this study, the optimum temperature in the breeding of BSFs was obtained as 30°C. Temperature can also affect the insect's biological life cycle, such as immaturity survival and adult lifespan, growth, fertility, gender ratio, and population growth parameters.