tenax are all based on raising larvae in organically polluted water, either via some form of vegetative or fecal matter 9, 10, 29, 30, 31, 32, 33.
Indeed, published techniques for lab rearing of E. tenax larvae, second or third instar, can be identified and harvested from decaying organic matter, such as manure heaps or organically polluted streams 10, 11.
Indeed, in temperate climates they are found in the greatest abundance in the mid to late morning, on calm sunny days, at the end of summer and throughout autumn 26, 27. Conversely in cold temperate climates, Eristalis hibernate over winter and are not found actively behaving in the field from around October through to March 28.įreely flying hoverflies can be collected by netting in the field. In the field, Eristalis can be found at any time of the year in Mediterranean climates 11, but the numbers of active hoverflies are much lower in winter. Indeed, not only the season, and the time of day, but also fluctuations in light intensity, temperature, humidity and wind velocity, affect the activity patterns of hoverflies 26, 27. Hoverflies are not equally active throughout the year, nor throughout the day. For example, the agriculturally important marmalade hoverfly Episyrphus balteatus and the drone fly, Eristalis tenax, which we focus on here, are found across Europe, America and Asia 6, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25. There are about 6000 hoverfly species worldwide 14, 15, with more than 300 species in 75 genera in Sweden 16 and more than 300 species in 69 genera in India 17, 18, 19. Thus, they do not address the need for an easy protocol that provides a consistent supply of healthy robust hoverflies, whilst maintaining the genetic fitness of the population.įollowing bees and bumblebees, hoverflies are one of the most important wild, generalist pollinator groups 12, 13. Indeed, even if the current literature describes methods for breeding the hoverfly Eristalis tenax, many of these are developed for the mass cultivation of hoverflies for crop pollination, bio-degradation of organic waste, or anatomical studies 9, 10, 11. However, as opposed to some other dipteran models, such as Drosophila 8, there are no standardized protocols for lab rearing of hoverflies for use in scientific research. Hoverflies are emerging as useful models for investigating a range of scientific questions, including flight behavior 1, neural mechanisms underlying motion vision 2, pollination efficiency 3, 4, 5, 6 and microbial immunity 7. We furthermore discuss small scale rearing methods and options for optimizing yields and manipulating population demographics. Using these methods, we have significantly increased the health and longevity of captive populations of E. Here, we describe the utilization of an artificial hibernation cycle, in addition to the nutritional and housing requirements, for long term maintenance of Eristalis tenax. Therefore, a method to establish, maintain and refresh a captive research population is required. This is important as commercial captive breeding programs focusing on mass output during peak pollination periods may fail to provide a population that is consistent, stable and robust throughout the year, as is often needed for other research purposes. While large scale commercial breeding for agriculture already occurs, there are no standardized protocols for maintaining captive populations for scientific studies. As the larvae develop in organically polluted water, they are useful models for investigating investment in microbial immunity. However, they are also a useful scientific model to study motion vision and flight dynamics in a controlled laboratory setting. With an estimated 6000 species worldwide, hoverflies are ecologically important as alternative pollinators to domesticated honeybees.