Patrizia Sacchetti1, Roberta Pastorelli2, Gaia Bigiotti3, Roberto Guidi3, Sara Ruschioni4, Carlo Viti3, Antonio Belcari3. 1. Department of Agriculture, Food, Environment and Forestry (DAGRI), University of Florence, via Maragliano 77, 50144, Florence, Italy. patrizia.sacchetti@unifi.it. 2. Research Centre for Agriculture and Environment, Consiglio per la ricerca in agricoltura e l'analisi dell'economia agraria (CREA-AA), via di Lanciola, 12/A, 50125, Florence, Italy. 3. Department of Agriculture, Food, Environment and Forestry (DAGRI), University of Florence, via Maragliano 77, 50144, Florence, Italy. 4. Department of Agricultural, Food and Environmental Sciences, Polytechnic University of Marche, Via Brecce Bianche 10, 60131, Ancona, Italy.
Abstract
BACKGROUND: The symbiosis between the olive fruit fly, Bactrocera oleae, and Candidatus Erwinia dacicola has been demonstrated as essential for the fly's larval development and adult physiology. The mass rearing of the olive fruit fly has been hindered by several issues, including problems which could be related to the lack of the symbiont, presumably due to preservatives and antibiotics currently used during rearing under laboratory conditions. To better understand the mechanisms underlying symbiont removal or loss during the rearing of lab colonies of the olive fruit fly, we performed experiments that focused on bacterial transfer from wild female flies to their eggs. In this research, eggs laid by wild females were treated with propionic acid solution, which is often used as an antifungal agent, a mixture of sodium hypochlorite and Triton X, or water (as a control). The presence of the bacterial symbiont on eggs was evaluated by real-time PCR and scanning electron microscopy. RESULTS: DGGE analysis showed a clear band with the same migration behavior present in all DGGE profiles but with a decreasing intensity. Molecular analyses performed by real-time PCR showed a significant reduction in Ca. E. dacicola abundance in eggs treated with propionic acid solution or a mixture of sodium hypochlorite and Triton X compared to those treated with water. In addition, the removal of bacteria from the surfaces of treated eggs was highlighted by scanning electron microscopy. CONCLUSIONS: The results clearly indicate how the first phases of the colony-establishment process are important in maintaining the symbiont load in laboratory populations and suggest that the use of products with antimicrobial activity should be avoided. The results also suggest that alternative rearing procedures for the olive fruit fly should be investigated.
BACKGROUND: The symbiosis between the olive fruit fly, Bactrocera oleae, and Candidatus Erwinia dacicola has been demonstrated as essential for the fly's larval development and adult physiology. The mass rearing of the olive fruit fly has been hindered by several issues, including problems which could be related to the lack of the symbiont, presumably due to preservatives and antibiotics currently used during rearing under laboratory conditions. To better understand the mechanisms underlying symbiont removal or loss during the rearing of lab colonies of the olive fruit fly, we performed experiments that focused on bacterial transfer from wild female flies to their eggs. In this research, eggs laid by wild females were treated with propionic acid solution, which is often used as an antifungal agent, a mixture of sodium hypochlorite and Triton X, or water (as a control). The presence of the bacterial symbiont on eggs was evaluated by real-time PCR and scanning electron microscopy. RESULTS: DGGE analysis showed a clear band with the same migration behavior present in all DGGE profiles but with a decreasing intensity. Molecular analyses performed by real-time PCR showed a significant reduction in Ca. E. dacicola abundance in eggs treated with propionic acid solution or a mixture of sodium hypochlorite and Triton X compared to those treated with water. In addition, the removal of bacteria from the surfaces of treated eggs was highlighted by scanning electron microscopy. CONCLUSIONS: The results clearly indicate how the first phases of the colony-establishment process are important in maintaining the symbiont load in laboratory populations and suggest that the use of products with antimicrobial activity should be avoided. The results also suggest that alternative rearing procedures for the olive fruit fly should be investigated.
Authors: Majoline T Tchioffo; Anne Boissière; Thomas S Churcher; Luc Abate; Geoffrey Gimonneau; Sandrine E Nsango; Parfait H Awono-Ambéné; Richard Christen; Antoine Berry; Isabelle Morlais Journal: PLoS One Date: 2013-12-06 Impact factor: 3.240