Comparison of different pollen substitutes for the feeding of laboratory reared bumble bee (bombus terrestris) colonies

In bumble bee colonies, pollen is the only protein source for larval feeding and its shortage causes a distress in larval development. Adult bumble bees need pollen for the development of glands and the reproductive system. In bumble bee rearing, honey bee collected pollen is used as the main protein source, either as fresh-frozen or dried pellets, and pollen provisioning is the most problematic and expensive aspect of mass rearing. In honey bee breeding, pollen substitutes are used during the period of food shortage or to stimulate colony strength. We tested different protein diets (five commercial pollen substitutes and two natural protein sources) for the maintenance of bumble bee colonies in captivity. We further mixed Feedbee®, one of the substitutes that gave the best results, with different amounts of pollen to evaluate the optimal amount needed for the whole colony development. Although none of the pure protein diets alone were adequate, diets with a 1 to 1 and 1 to 3 ratio of Feedbee to pollen were both suitable for colony development and queen production. The colony consumed between 2 and 4 g per day of the Feedbee mixed diets, corresponding to a protein consumption of 0.75-0.85 g day-1. Nevertheless, the consumption rate of the pure pollen showed that a mean amount of protein between 0.4 and 0.5 g day-1 was enough to allow colony development indicating the suitability of Feedbee mixed diets.Fil: Bortolotti, Laura. Centro di Ricerca Agricoltura e Ambiente; ArgentinaFil: Pošćić, Filip. Institute For Adriatic Crops And Karst Reclamation; CroaciaFil: Bogo, Gherardo. Centro di Ricerca Agricoltura e Ambiente; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentin

Exploring Plant-Pollinator interactions: critical studies for the safeguard of wild Apoidea and spontaneous plant populations

The study of plant-pollinator relationship and the degree of their specialization is among the most lively and debated issues in plant biology and ecology. The fates of plants and bee pollinators are strictly connected: the severe decline lately encountered by wild Apoidea, which in turn results in a lower pollination rate, trigger the so-called “extinction vortex” phenomenon. This study was finalized to improve knowledge on plant-pollinator interactions, in ecological context with conservation needs. Field work on the natural populations of Dictamnus albus allowed us to define practical methods for the joint protection of wild Apoidea and endangered plants applicable in several contexts. In order to define the pollinator importance of single taxa and of the whole pollinator guild of D. albus, an index distinguishing between potential (PPI) and realized (RPI) pollinator importance was created. Moreover, it was assessed the effect of some abiotic and biotic factors on the abundance and activity pattern of flower-visiting insect groups. Laboratory experiments on Gentiana lutea nectar pointed out a gender-specific amino acid solution preference in Bombus terrestris, one of the main pollinator of this plant, and confirm a negative influence of high amino acid concentration diet on insect mortality. The behavioural study showed that β-alanine may affect either positively or negatively bumble bees walking and flying activities depending on its concentration, and that GABA enriched solution greatly increase bumble bee survival time. Studies on B. terrestris colony development and reproductive strategies led to define an inbreeding risk index (IRI) for the colony and highlighted the lack of an inbreeding-avoidance system in this species. Finally, three years of rearing practice allowed to provide new guidance methods for diapause and deposition in bumble bee artificial rearing. In conclusion, this thesis may help to better understand of the complex world of plant-pollinator relationships

Effect of a topical treatment with juvenile hormone analogues on dominance, ovarian development and corpora allata size in Bombus terrestris workers

Juvenile hormone analogues (JHAs) are insecticides that mimic the effect of juvenile hormone (JH), one of the main regulatory hormones in insects. Negative effects of JHAs on preimaginal stages are well known, while little is known of their effects on adults. In this study we assessed the effect of three JHAs on newly emerged workers of Bombus terrestris L. kept in queenless groups. Reproductive dominance status, oocyte length and corpora allata volume were assessed 4 and 7 days after treatment. Contrary to expectations, none of the treatments had a significant stimulating effect on ovarian development in reproductive dominant workers. Conversely, most treatments caused a significant reduction in oocyte size and in corpora allata volumes of seven-day-old reproductive subordinates, indicating a feedback loop of exogenous JHAs on these glands. The study suggests that besides JH, multiple factors influence worker ovarian activity, which makes it difficult to predict the effect of the insecticides in wild colonies.Fil: Bortolotti, Laura. Consiglio Per la Ricerca In Agricoltura E L' Analisi del L' Economía Agraria. Centro de Ricerca Per Le Produzioni Foraggere E Lattier-casearie; ItaliaFil: Bogo, Gherardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Poscic, Filip. Institute For Adriatic Crops And Karst Reclamation; CroaciaFil: Duchateau, Marie José. University of Utrecht; Países Bajo

Wild bees in Southern Italy: impact of landscape management

ItGli impollinatori sono essenziali per il mantenimento degli ecosistemi, e i tre quarti delle principali colture alimentari del mondo necessitano dell'impollinazione animale per la produzione di frutti e semi. Negli ultimi decenni però stiamo assistendo ad un costante declino di questi importantissimi insetti in tutto il mondo, con un conseguente deficit nella produzione agricola. Se da un lato l'agricoltura è strettamente legata agli impollinatori, dall'altro è una delle cause del loro declino. Per questo motivo, in Italia, è nato il progetto "BeeNet", con lo scopo di valutare lo stato di salute degli ecosistemi agricoli italiani attraverso il monitoraggio delle api da miele e delle api selvatiche. In questo studio vengono presentati i dati del primo anno del progetto, 2021, sulle api selvatiche in due regioni meridionali (Campania e Puglia), comparando due ecosistemi agricoli diversi: uno intensivo e l'altro semi-naturale. Una volta al mese, da febbraio a ottobre, in entrambe le regioni ed entrambi gli ecosistemi, abbiamo campionato le api mediante un transetto (200 × 2 metri) percorso alla mattina e al pomeriggio. Inoltre, nelle stesse giornate abbiamo registrato tutte le specie botaniche mellifere presenti sul transetto. Le differenze riscontrate tra i due tipi di ecosistema indicano che l'agro-ecosistema intensivo ha in generale una biodiversità più bassa e una comunità di api più spostata verso specie generaliste. Questo risultato indica che l'uso di pratiche agricole più impattanti e l'omogeneità dell'ambiente influenzano fortemente, e negativamente, questi insetti e le piante spontanee di cui hanno bisogno per sopravvivere. Tuttavia, le differenze tra le ricchezze di specie e le abbondanze di specie tra i due tipi di ecosistema non sono risultate significative, e una possibile ragione di ciò potrebbe risiedere nell'irrigazione degli ecosistemi intensivi, che forse ha ridotto le differenze. È necessario quindi, in questi ambienti, attuare misure per la tutela degli impollinatori come richiesto dalla Comunità Europea, attraverso strategie mirate come ad esempio la nuova PAC 2023-2027.EnIn 2021, in two southern Italian regions (Campania and Puglia) we compared the biodiversity of both Apoidea and plants between intensive and semi-natural agro-ecosystems, aiming to evaluate the impacts of the agro-environment and agricultural practices on wild bees and spontaneous plant communities in southern Italy. Monthly, from February to October, we performed bee samplings (200 × 2 metres fixed transects) and botanical surveys in each site and region. We found no statistical differences between the two environments, probably because the two intensive agro-ecosystems were irrigated that year. However, the semi-natural agro-ecosystem was characterised by a higher biodiversity (bees and plants) and a higher rate of specialised bee species than the intensive agro-ecosystem, indicating that biodiversity benefits of agro-ecological practices and a more heterogeneous landscape

Influence of the brood rearing temperature on honey bee development and susceptibility to intoxication by pesticides

contribution to session IV Test methodolog

Effects of nonprotein amino acids on survival and locomotion of Osmia bicornis

To investigate the effects of two non-protein amino acids (NPAAs), β-alanine and γ-amino butyric acid (GABA), on Osmia bicornis survival and locomotion, two groups of ten caged bees have been fed with a sugar syrup enriched with β-alanine and GABA, respectively. The further control group was fed with the sugar syrup. Five behavioural categories have been chosen in accordance with the principle of parsimony and with their intrinsic unitary consistency from onset to the end. Two states (staying under the paper and staying in the test tubes) and three events (walking on the net, feeding on the flower and flying) have been recorded by scan sampling. Furthermore, we analysed the amino acids content of the haemolymph that was sampled from additional forty-five bees kept under the same diet condition (15 per diet type). Bees fed with ß-alanine had a significant shorter survival than those fed with control and GABA diets. The GABA diet induced a higher locomotion than the β-alanine. The former non-protein amino acid was detected in the haemolymph of only bees fed with GABA. Results suggest that insects consuming NPAAs-reach diets can absorb and transfer these substances into the haemolymph and those NPAAs affect both survival and locomotion. Ecological consequences are discussed in the frame of plant reproductive biology

SOPRAVVIVENZA ALLA DIAPAUSA E AVVIO DELLA COLONIA IN COLONIE DI BOMBO (BOMBUS TERRESTRIS) ALLEVATE ARTIFICIALMENTE

La diapausa delle regine e l’avvio della colonia sono i momenti più critici nel ciclo biologico dei bombi. Il peso delle regine è uno dei principali fattori determinanti nella sopravvivenza all’ibernazione e nel rendimento post-diapausa (Beekman et al., 1998. Entomol Exp Appl, 89: 207-214). Abbiamo misurato la sopravvivenza alla diapausa e il successo di deposizione di 351 regine di Bombus terrestris allevate artificialmente, basandoci sul loro peso pre-diapausa. Come previsto, le regine con il peso minore sopravvivono significativamente meno al regime di diapausa (3 mesi a 5°C). Il peso delle regine non ha invece effetto sul tasso di deposizione, ma quelle con il peso maggiore depongono significativamente più celle di uova. Tra i differenti metodi di avvio della colonia, è spesso consigliato l’utilizzo di una pupa di maschio per la stimolazione della regina (Kwon et al., 2003. Apidologie, 34: 429-437). Abbiamo confrontato l’uso di pupe di maschio (date a 136 regine di bombo) con l’uso di quelle di regina (date a 130 regine). Il numero di regine deponenti non differisce tra i due gruppi, ma il numero di celle di uova e di larve sviluppate è più alto nel gruppo “pupe di regina”. Una possibile spiegazione di questo risultato si può trovare nella dimensione maggiore della pupa di regina e nel comportamento distruttivo dei maschi adulti al momento dello sfarfallamento dalla pupa