ABSTRACT
(1) Monitoring of Drosophila suzukii is based on the use of effective traps and baits. The current baits are insufficient to provide efficient monitoring. The use of bacteria as bio-catalyzers to produce bioactive volatiles may improve flies' attraction. Thus, we conducted this work to improve Droskidrink® bait's attractiveness using lactic acid bacteria. (2) Different baits that were based on the use of Droskidrink® were assessed for flies' attraction in a Droso-Trap® in a vineyard. Oenococcus oeni, Pediococcus spp., and Lactobacillus spp. were used. The performance of the most attractive species, O. oeni, inoculated into Droskidrink® was assessed in laboratory tests. The responses of female flies to volatiles produced by Droskidrink® with O. oeni strains were recorded by electroantennography. (3) Preliminary field assessment of baits recorded O. oeni as the most attractive species. Three strain groups showed adaptation to test conditions. Volatiles extracted by the headspace of baits inoculated with O. oeni, elicited electroantennographic responses from fly antennae. (4) Droskidrink® inoculated with O. oeni is a highly attractive bait for monitoring. These findings will be useful for improving the attractiveness of D. suzukii commercial baits based on the utilization of LAB volatiles in a strain-dependent manner.
ABSTRACT
: Lactic acid bacteria (LAB) are an important group of honeybee gut microbiota. These bacteria are involved in food digestion, stimulate the immune system, and may antagonize undesirable microorganisms in the gastrointestinal tract. Lactobacillus kunkeei is a fructophilic lactic acid bacterium (FLAB) most frequently found in the gastrointestinal tracts of honeybees. Ascosphaera apis is an important pathogenic fungus of honeybee larvae; it can colonize the intestine, especially in conditions of nutritional or environmental stress that cause microbial dysbiosis. In this work, some functional properties of nine selected L. kunkeei strains were evaluated. The study focused on the antifungal activity of these strains against A. apis DSM 3116, using different matrices: cell lysate, broth culture, cell-free supernatant, and cell pellet. The cell lysate showed the highest antifungal activity. Moreover, the strains were shown to possess good cell-surface properties (hydrophobicity, auto-aggregation, and biofilm production) and a good resistance to high sugar concentrations. These L. kunkeei strains were demonstrated to be functional for use in "probiotic syrup", useful to restore the symbiotic communities of the intestine in case of dysbiosis and to exert a prophylactic action against A. apis.
ABSTRACT
The meadow spittlebug, Philaenus spumarius, is a highly polyphagous widespread species, playing a major role in the transmission of the bacterium Xylella fastidiosa subspecies pauca, the agent of the "Olive Quick Decline Syndrome". Essential oils (EOs) are an important source of bio-active volatile compounds that could interfere with basic metabolic, biochemical, physiological, and behavioural functions of insects. Here, we report the electrophysiological and behavioural responses of adult P. spumarius towards some EOs and related plants. Electroantennographic tests demonstrated that the peripheral olfactory system of P. spumarius females and males perceives volatile organic compounds present in the EOs of Pelargonium graveolens, Cymbopogon nardus and Lavandula officinalis in a dose-dependent manner. In behavioral bioassays, evaluating the adult responses towards EOs and related plants, both at close (Y-tube) and long range (wind tunnel), males and females responded differently to the same odorant. Using EOs, a clear attraction was noted only for males towards lavender EO. Conversely, plants elicited responses that varied upon the plant species, testing device and adult sex. Both lavender and geranium repelled females at any distance range. On the contrary, males were attracted by geranium and repelled by citronella. Finally, at close distance, lavender and citronella were repellent for females and males, respectively. Our results contribute to the development of innovative tools and approaches, alternative to the use of synthetic pesticides, for the sustainable control of P. spumarius aiming to contrasting the expansion of X. fastidiosa.
