Growth performance of the black soldier fly (Hermetia illucens) on by-products from brewing production

Hermetia illucens (Diptera: Stratiomyidae), also known as the black soldier fly, is considered an interesting candidate as alternative source of protein for livestock. Larvae of this species are able to efficiently bio-convert organic waste material into insect biomass. In addition, larvae can consume twice of their weight per day of waste, accumulating high amounts of protein and fat. The choice of the correct rearing substrate is essential in order to contribute to the disposal of waste or by-products obtained from the various stages of the industrial food production, that could hardly find other utilization, and to maximize the production of black soldier fly prepupae. Moreover, it is important to identify a lowcost diet with no competition with animal or human consumption. Among numerous by-products of vegetal origin, in this study black soldier fly larvae were reared on the following substrates originating from the brewing production: brewer\u2019s spent grain, trub, and a mix of the two by-products (50 and 50%). The influence of the rearing substrates of the different life-history traits was observed. In particular, we considered the survivorship of the different developmental stages, the larval final weight, the duration of the larval period and the emergence of adults. Larvae could complete their development on the three substrates tested. Nevertheless, some differences were observed on the different parameters. In particular, the mixture of the two by-products resulted in a faster growth of the larvae that took less days to reach prepupal stage than the ones grown on the single by-product. The same trend was noticed on the final larval weight. The mortality of the larvae was significantly higher on those grown on brewer\u2019s spent grain, while no differences were noticed among the other substrates. This study showed the possibility to rear the black soldier fly on different byproducts coming from the brewing production industry, that can therefore represent an interesting rearing substrate for the insect. More research is needed to optimize the diet for a possible use in mass rearing system

Flower selection of Xylocopa violacea: aromatic and ornamental plants as resources in a botanic garden

We assessed the interactions between aromatic and ornamentals plants and local pollinators in a botanic garden. We focused our attention on a frequent solitary bee, Xylocopa violacea, that thanks to its large size and its feeding preferences can visit many types of flowers. By conducting linear walking transects, we recorded all flower visits by bees, highlighting those of X. violacea. We analysed bee preferences in terms of plant family, plant origin or flower morphology. We also identified plant species that were visited by X. violacea together with other foraging bees. Results indicated that X. violacea selectively visits flowering plant species at the botanic garden, preferring Lamiaceae and bilabiate flower types on which legitimate or illegitimate visits can be performed. Other bee species do concurrently visit the same plants, and in the future studies on competition, resource exploitation and pollination success will be addressed

Influence of the liquid fraction on Hermetia illucens (L.) reared on vegetables

Introduction: Hermetia illucens. Methods: The main scope of this study was to determine if the presence of a drainage can affect the preimaginal development of BSF reared on vegetable waste. Different tests were conducted in presence and in absence of a good drainage filter in climatic chamber. Results/Conclusion: No significant differences were observed on the larval and pupal final weight and on the mortality of the larvae. However, the presence of a drainage filter has influenced the length of larval development: in the experiment with the drainage larvae took 33 days to reach their maximum weight, while on the other 42 days. The time to pupation of all the specimens was shorter and much synchronized in the presence of the net; finally, the pupae mortality was significantly higher in the experiment without drainage. These data need to be deepened, but have to be taken in consideration in the case of BSF mass rearing

Exotic and native plant species and their role attracting native pollinators

Facing continuous losses of natural habitats, botanical gardens seem to pop up as important centre to sustain insect communities. Actually, what distinguishes many of these areas is the fact that the preserved plants are often exotic and that, in the case of Angiosperms, there is a wide variability of flower anthesis and morphology in a restricted area. The role of exotic plant species in attracting floral visitors in such environments, is little known yet. We addressed the question of how successful native and exotic plant species within the same environment were in attracting insects. In summer 2016 and 2017 we performed pollinator surveys at all flowering plants species at the Ghirardi\u2019s botanical garden at Garda Lake (N 45\ub038\u2019 21,61\u2019\u2019, E 10\ub0 36\u2019 40,33\u2019\u2019), Brescia, Italy. Network analysis of plants and native pollinators were performed by distinguishing the origin of plants in two groups, native and exotic. Thus, we assigned the role of each plant group in attracting the bee community. Furthermore, we grouped all bees by functional traits (tongue size) to address the question if bee-plant interactions were driven by plant origin (native/exotic) or by compatibility between tongue size and floral traits. Our results added a novel paradigm in bee-plant interactions in urban areas where, according to our results, exotic species seem to play an important role in network interactions

Can sublethal pesticides exposure in honeybee colonies with subclinical infections by Paenibacillus larvae favour the development of American foulbrood in clinical form?

Stress factors may interact with additive or synergic effects and a multi-stress condition is the most probable cause for honeybee decline. We evaluated how the combination of different stresses (sublethal dose of pesticides, and electromagnetism) affect survival and make bee susceptible to Varroa attack and viral diseases. Experimental hives, from the same origin and health status, were equally and randomly placed on 5 April 2017 in 2 exposure sites (ES1-2) and in 1 control site (CS) The ESs were inside an experimental farm where chemical treatments are applied in orchards (ES1 sublethal exposures to pesticides), and where there is also a high-voltage electric line (ES2 chemicals as in 1 plus electromagnetism). The CS was far from agricultural fields and from human settlements. Clinical inspections and debris collection from the hives for mite checkup were weekly performed. Monthly, sugar treatments have been also made to check the mite infestation level. During a routine check in mid-June, unexpectedly, one case of American foulbrood (AFB) caused by P. larvae genotype ERIC II was diagnosed in ES1. In the following days AFB was diagnosed again in 1 colony in ES1 and in 2 colonies in ES2. No hive in CS resulted affected. After the diagnosis of AFB, sugar and debris previously harvested and stored have been examined for P. larvae detection (culture method). The sugar collected at the end of May in ES ranged from 174,000 to 5,000,000 CFU/g in diseased colonies and from 60 to 17,000 CFU/g in the asymptomatic ones. In CS it was <20 CFU/g (detection limit). The debris of three diseased colonies collected on 28 April showed already a high number of CFU. Since the bacteriological examination always underestimates the number of spores, we hypotheses that low contamination was present at the beginning of the trial in all the colonies. The presence of stressors in ES1-2 has probably favoured the development of the infection by sporadically giving rise to the AFB disease

Using Hermetia illucena to bioconvert the waste from insect farming

The European pet food market is the second largest in the world with an estimated value of US$21.5 billion. Approximately 8.59 million reptile and amphibian pets are kept across Europe and a thriving and well established industry rears the live feeder insects for insectivorous species. Two popular groups of feeder insects are locusts and crickets, and substantial quantities of organic waste are generated in their production consisting of frass, exuviae and uneaten food. Here we investigated the use of a saprophagous fly species, Hermetia illucens (Diptera: Stratiomyidae), the black soldier fly (BSF), as a bioaccumulator to recapture the nutrients in this waste with potential applications in the pet food, animal feed, or biofuel industries. BSF larvae were reared on four experimental diets consisting of the waste from either cricket farming, or locust farming. These were used either unmodified or finely chopped, and the Gainsville diet was used as a control giving five conditions. Trial substrates were given to young handling larvae ad libitum and maintained in a climate chamber. The suitability of these diets for rearing BSF was demonstrated by a low mortality rate, not significantly affected by diet, and the successful emergence of adults from all conditions. BSF larvae reared on cricket waste reached a significantly higher weight than those reared on the locust and control diets. Diet did not significantly affect time taken to reach the prepupal stage, except in chopped locust condition which took more days. We conclude that the waste from farming locusts and crickets represents a suitable substrate for rearing H. illucens, potentially establish a circular nutrient economy in the rearing of insects for the live pet food market

Multi-stress approach for the assessment of decline causes for honeybee

Honeybee decline is a problem of high concern since a complex pathology (Colony Collapse Disorder) brought to worldwide events of colony losses. Many adversities may be responsible of this decline: recrudescence of old and new pathologies, contamination from pesticides and emerging contaminants (e.g. nanoparticles) and environmental stresses. Stress factors may interact among them with additive or synergic effects and, currently, a multi-stress condition is accepted as the most probable decline cause for honeybees. Experimental hives were placed in two experimental sites in Northern Italy: an exposure site ES and a control site CS (14 km far from ES, agricultural field and significant human settlements). ES is located inside an experimental farm where a high-voltage electric line is present together with a complex and controlled pesticide application schedule for orchards. In the ES, two experimental area were set up (one just below the electric line, with the combined presence of electromagnetic fields and sublethal pesticide exposure SPE, and one exposed only to SPE). Honeybees were sampled from April to October 2017 weekly for health status (mites, virus, bacteria spores and fungi), and population parameters (queen and brood status and food stokes, together with daily mortality), and monthly for biomarker analyses (acetylcholinesterase, catalase, glutathione S-transferase and alkaline phosphatase activity, amount of reactive oxygen species, lipid peroxidation, and DNA fragmentation). Preliminary analysis revealed that population parameters and biomarkers were both affected by stresses. Effects on biomarkers were registered in relation to pesticide applications. Multi-stress position showed the most severe effects, leading to colonies death. Colony losses were related to the development of different pathologies. Reduced immunity defences and social disorders by frequent queen replacement seem to be the main effects related to the multi-stress condition

Utilizzo di Hermetia illucens per la produzione di proteine da substrati vegetali

Il costante aumento della richiesta di proteine animali per l\u2019alimentazione e la produzione di mangimi, ha determinato un crescente interesse nei confronti degli insetti in quanto presentano un\u2019elevata efficienza di conversione dei substrati alimentari in massa corporea e possono costituire una fonte proteica con elevato valore nutrizionale. Le larve di Hermetia illucens L. (Diptera: Stratiomyidae), un dittero saprofago, sono ritenute ottimi biotrasformatori per la loro capacit\ue0 di crescere su diversi substrati in decomposizione, sia di origine animale che vegetale. Quantitativi rilevanti di frutta e verdura sono smaltiti quotidianamente dalla grande distribuzione e attualmente vengono utilizzati prevalentemente per la produzione di compost. Essi potrebbero invece rappresentare un interessante substrato per l\u2019allevamento di H. illucens al fine di produrre farine da utilizzare nell\u2019industria mangimistica. Poco \ue8 noto sullo sviluppo, le caratteristiche morfofunzionali ed il profilo proteico della farina ottenuta delle larve di H. illucens allevate su substrati vegetali. Questa mancanza di conoscenze rappresenta una forte limitazione all\u2019utilizzo di questo insetto come fonte di proteine poich\ue9 la composizione del substrato di allevamento influenza sia l\u2019efficienza di conversione che il profilo e la qualit\ue0 nutrizionale della farina. La nostra ricerca si \ue8 indirizzata alla valutazione e all\u2019ottimizzazione dell\u2019allevamento di H. illucens su frutta e verdura. Lo sviluppo e le performance di esemplari alimentati ad libitum su questo substrato sono stati confrontati con quelli di individui alimentati con una dieta standard per ditteri. A tale scopo sono state valutate le curve di crescita, i tempi di sviluppo, il tasso di mortalit\ue0 oltre che alcuni parametri dimensionali e le performance degli adulti (dimensioni e peso, sex ratio, peso e numero di uova nelle ovature). I dati ottenuti evidenziano come H. illucens sia in grado di compiere l\u2019intero ciclo di sviluppo anche quando le larve sono allevate su frutta e verdura, raggiungendo dimensioni equiparabili a quelle del gruppo controllo, seppur in tempi pi\uf9 lunghi. Inoltre gli insetti adulti dei due gruppi presentano performace analoghe. Le farine ottenute da larve allevate sui diversi substrati sono state sottoposte ad analisi centesimale per valutare eventuali variazioni nella loro composizione. Infine sono state eseguite analisi di parametri morfo-funzionali (valutazione delle caratteristiche morfologiche e ultrastrutturali dell\u2019intestino medio larvale e misurazioni dell\u2019attivit\ue0 di enzimi coinvolti nella digestione di proteine e zuccheri) al fine di individuare dei marcatori che consentano di monitorare la crescita delle larve sui due diversi substrati

The Mexican Salvia blepharophylla and S. greggii in an ecological context : scents, biotic interactions and exudates

Strategies adopted by plants to interact with other organisms are very sophisticated and the study of these relationships are full of charm for researchers and extremely important to understand evolutionary perspectives. Our work arises in this framework. We focused our attention on two Mexican Salvia species (Lamiaceae) preserved at the Ghirardi Botanic Garden of the University of Milan: Salvia blepharophylla Brandegee ex Epling and Salvia greggii A. Gray. Both species show nice red flowers, of the kind usually pollinated by hummingbirds. We explored the phytochemical characterization related to the productivity in volatile organic compounds (VOCs) from both flowers and leaves, and the epicuticular depositions, in concert with the biotic interactions established by the target species. We evaluated the biodiversity of insect pollinators visiting the flowers and of the microorganisms inhabiting the phyllosphere. Moreover, we performed a micro-morphological investigation on the glandular trichomes. Our aim is giving a first attempt to sketch a link of the plant productivity in secondary metabolites to observed biotic relationships concurrently occurring at the botanic garden. Phytochemical survey revealed that sesquiterpene hydrocarbons were the most abundant chemical class of volatiles in the leaf of both species (42.34% in S. greggii and 54.97% in S. blepharophylla), while monoterpenes dominated the flower emission profiles. As a whole, different emission profiles characterized the two species thanks to exclusive compounds: the floral bouquets are dominated by limonene and \u3b2-pinene in S. greggii, and by 1,8-cineole in S. blepharophylla. On the other hand, common principal compounds occurring in high relative percentages in flowers are \u3b2-caryophyllene and germacrene D, both also detected in the leaf emission profile. Slight differences were found for the composition of the secondary metabolites present in the leaf exudates, with isopimaric acid and a compound structurally related to the cloredane diterpenes blepharolide A and B prevailing in S. greggii and S. blepharophylla, respectively. Biological surveys were equally interesting. Although the relatively high biodiversity of pollinators recorded at the botanic garden, the target species attracted only two functional pollinator groups: small (Lasioglossum morphotypes) and large bees (Xylocopa violacea L.). These insects applied different but interesting handling strategies to reach flower resources: the described strategies are significant from an evolutionary point of view, considering the probable link of the Mexican Salvia with bird pollinators. The microbiological analysis revealed that S. greggii harbours a more abundant and diverse phyllospheric bacterial community than S. blepharophylla did, although a considerable variability between the replicates was observed within each species. Our data can be linked to existent literature concerning chemical compounds and biotic responses. With regards to VOCs, an attractive role towards bees is documented only for limonene, \u3b2-pinene and 1,8-cineole [1-3]. Conversely, \u3b2-caryophyllene and germacrene D are common deterrents [4]. Our data, as existent literature [5], sustain the hypothesis that local bees do adapt to novel food sources. The chemical compounds we found may moreover allow to infer that bees are able to recognise the chemical signals emitted by the target-species and possibly use them to locate the plants. In this view, also chemicals produced by leaves may be used by bees: more data are needed to investigate this potential role of leaf chemistry. Compounds in leaves are so far known to exert defensive functions [6]. Finally, our is the first report on the microflora inhabiting the phyllosphere of the two Salvia species and represents an initial step towards the understanding of the adaptive mechanisms between microorganisms and leaf exudates