Beneficial Diptera

Abstract

The Dipteran insects, commonly known as flies, are a biologically and morphologically diverse group of insects that contribute significantly to vital ecological functions for the maintenance of wildlife species in agrarian and wild ecosystems. Pollinators, predators, parasitoids and decomposers are the most commonly studied functional groups in Diptera, focusing on four ecosystem services, viz. pollination of crops, food provisioning, biological pest control and nutrient recycling in agroecosystems. Based on their food habits, the fly communities are divided into four major groups, i.e. saprophagous/necrophagous, carnivorous, phytophagous and hematophagous. The feeding behaviour of Diptera includes three basic types of carnivory: predation, parasitoidism and parasitism. Most of these predaceous, parasitic and parasitoid Diptera have radiated from ancestors with saprophagous lineages. It is this carnivorous habit, which makes the flies potent biocontrol agents in wild and managed ecosystems. The adult Diptera are predaceous and ectoparasitic, while the larval Diptera are predators, endoparasites and parasitoids. Marked predation is noted in the adults of the family Asilidae, Dolichopodidae, Empididae and Lonchaidae. Larval predators and parasitoids are extensively found in the families Tachnidae, Syrphidae, Bombyliidae, Sciomyzidae, Cecidomyiidae, Dolichopodidae, Ephydridae, Conopidae, Apioceridae, Athericidae, Chamaemyiidae, Chaoboridae, Agromyzidae, Phoridae, Sarcophagidae, Fannidae, Muscidae and Calliphoridae. The Syrphidae, Bombyliidae, Mydidae, Rhagionidae, Scenopinidae, Tabanidae and Therevidae serve the dual purpose of pollination as adults and biocontrol agents in their larval stages. The application of the parasitoid groups of dipteran flies as biocontrol agents depends upon their successful mass production, which again depends on the biology of applied species, especially host range, oviposition strategies and host-parasite interaction as well as the chemical composition of food, time period of application and abiotic factors. Parasitoids can be cultured using both in-vivo and in-vitro techniques. The most successful commercially utilised parasitoid flies belong to the Dipteran families of Tachinidae, Syrphidae and Sarcophagidae and they are the only groups, which can be successfully reared in controlled environments. Adult management, rearing, storage and transport are complicated issues in fly parasitoids. Increasing the use of dipteran parasitoids in applied biocontrol requires improvement of their rearing techniques for mass production. Upcoming research on these issues may deal with species that are recognised as promising biocontrol agents but are not yet exploited due to difficulties encountered in their rearing. Diptera research over the past decade has shown that flies have always served as surrogates for pest control in the natural conservation action plan. It is high time to acknowledge them and conserving them should be prioritised as a pragmatic and responsible approach of environmental biologists on a global scale for achieving our Sustainable Development Goals.