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Insect-plant relationships: insights into biodiversity and new applications

Periodic Reporting for period 2 - FlyHigh (Insect-plant relationships: insights into biodiversity and new applications)

Reporting period: 2017-07-01 to 2018-06-30

Phytophagous and saprophagous hoverflies, blowflies and soldier flies occur worldwide and are diverse and important ecological groups in both natural ecosystems and agricultural environments, as pollinators of plants and as decomposers of organic waste. The phytophagous fly maggots (larvae) develop in living plants while saprophagous maggots utilize a wide range of decaying organic materials (like animal manure or vegetal wastes). Ecological data is available for some European groups of flies due to existing longer research history, while the characteristics of the South African fly fauna remain less explored.
The issues addressed in the FlyHigh project are concerned with filling the gap in ecological and evolutionary knowledge on focal phytophagous and saprophagous South African flies and their host plants (specific bulbous plants such as lilies or aloe succulent plants), and to test if this data could be utilized in artificial rearing protocols of the new industrial-productive sector of flies and other insects.

The FlyHigh project also explores ways to improve controlled rearing protocols for fly mass rearing. The potential benefits being beneficial endproducts for agriculture or ecological farming, including flies being used as bio-agents, providing effective pollination services in natural of greenhouse environments and larvae as effective biodecomposers or organic waste.
The FlyHigh project explored ways to improve controlled rearing protocols for fly mass rearing including optimal ranges for different rearing parameters of e.g. temperature, humidity, diet and density for the Black Soldier Fly and other species also used in artificial rearing like the House Fly (Musca domestica) and the Green Bottle Fly (Lucilia sericata). New larval feeding media were developed and the performance of different strains of flies on these substrates was evaluated. The gained societal importance stems from the enhanced artificial rearing protocols increased maggot activity and produced flies more effectively and sustainably. Despite sharing some COI haplotypes, two industrial level domesticated strains of the BSF showed a significant phenotypic plasticity according to the biological parameters analysed.

The overall objectives of the FlyHigh project is to obtain useful ecological and evolutionary data to be used for research for understanding interrelationships of phytophagous flies and geophyte plants, and, to obtain ecological data to be used for applied research for the increased knowledge on features of ecological processes and also for improving mass rearing protocols. The obtained taxonomic and ecological data was collected for phytophagous hoverfly species distributed in Mediterranean ecosystems of South Africa and Europe, and for some hoverfly species new host plants such as specific bulb plants (e.g. lilies) or aloe succulent plants were recorded. FlyHigh researchers systematically screened selected molecular markers and evaluated the genetic diversity and evolutionary patterns of the flies and their host plants, and these results were published in several scientific publications.
The sampled adult hoverflies were taxonomically described and genetically characterized, and a considerably high number of species new to science of the genus Merodon were identified among the obtained insect materials. Morphological descriptions of the species new to science were done, including digital images of all life stages, and descriptions of new host plants for the genus Merodon. We have obtained a good amount of new information of their distributional patterns in South Africa. A particularly large number of species in the Hyacinthaceae family of bulbous plants occur in southern Africa. The FlyHigh project has demonstrated that some evolutionary lineages in the Hyacinthaceae family that differentiated at an early evolutionary stage first appeared in southern Africa. One genus and many species of Hyacinthaceae new to science were identified and formally described during the project which has resulted in many scientific papers.
The fly larvae rearing trials and exchanging of information between the SMEs and research centers of the consortium was active, and has resulted in the updating and improvement of protocols of artificial rearing and mass-production. New larval media were developed, and comparisons of capacities of different strains of flies (wild, vs “domestic” and comparing different geographic origins) on these rearing substrates were studied. These improvements could have economic impact. All these results were summarized in scientific publications, and presented at scientific meetings.
The progress beyond the state of the art, and the impact of the project is quantified by scientific articles in the five published and two submitted papers. Specific results include updated taxonomy for Merodon hoverflies including descriptions of species new to science, and descriptions of the immature stages and their biology. New taxonomic results for Hyacinthaceae bulbous plant species including occurrence data are also significant contributions. Molecular data was obtained of most sampled hoverfly and bulb plant species and made publicly available GenBank database. The combination of the new and previously available data enabled the analyses of evolutionary patterns among flies and their host plants.

Different commercial strains of three key dipteran species (Hermetia illucens, Musca domestica, Lucilia sericata) reared by Bioflytech and Agriprotein were analyzed. The main abiotic parameters related with the optimal ranges involving the most important rearing parameters e.g. temperature, humidity, light were evaluated. These results are very important as the EU Regulation No 2017/893 authorizes the use of insect proteins from seven different insect species, two of which are the Black Soldier Fly (Hermetia illucens) and the Housefly (Musca domestica), as animal feed (in aquaculture). The text is active from 1st July 2017 and probably will be concern also poultry and other farm animals soon. The use of insect proteins for pets is also allowed. Also significant potential economic impact can be expected due to the improvements of rearing results of the Black Soldier Fly in controlled conditions using a specific artificial light, which allows the mass-rearing under totally controlled conditions and different combinations of larval trophic media and adult densities. A comparison of quality and productivity of different strains of BSF used by Agriprotein and Bioflytech will be published in a scientific journal with wide distribution.
Larvae of Black Soldier Fly feeding on brewers grain.
Damage caused by Merodon larvae feeding on bulbs.
Black Soldier Fly Hermetia illucens
Hover fly species on Merwill natalensis.