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ABSTRACTInsect pollinators acquire microorganisms when they visit flowers for nutrients. The interactions that occur at the floral interface are complex with three participants – pollinators, plants and microorganisms. The majority of the insect pollinator’s microbiome is shaped by their behaviour, diet and environment. At present the bee (Apidaefamily) microbiome is the best documented and contributes to our understanding of the bi-directional exchange of microbes between pollinators and flowers. The transferred microorganisms may be mutualistic, commensal or pathogenic. We identify a lack of information due to limited studies concerning the diversity of pollinators and a focus on pathogenic microorganisms and their gut microbiome influence on their health. Each candidate, the insect, plant and microbe, makes their own contribution which aids the interaction, but some participants may benefit more than others. The benefits for pollinators include enhanced acquisition of nutritional resources; for microorganisms dispersal and a ‘new’ habitat to colonise and for plants pollination is the outcome. Finally, we explore a novel concept of whether the fruit acts as a potential vector for insect microorganisms to hibernate and extend their lifecycle in the absence of a pollinator host.

The Queensland fruit fly, Bactrocera tryoni(Froggatt) (Diptera: Tephritidae), is a crop pest of global economic importance because of its wide range of hosts and its invasiveness capacities. To develop a novel integrated and sustainable crop protection, we have investigated the insecticidal properties of different varieties of kava (Piper methysticum[Frost]) extracted by two methods and the attractive effects of six plant volatiles identified from B. tryonihost plants to female, mated or not. We did not identify any significant insecticidal effect of the traditional Pacific kava plant at the tested concentrations. Among mated females, ethyl acetate compared to the no odor control elicited the highest attraction (87%, of which 60% for this odor), while ethyl butyrate was preferred compared with ethyl acetate in dual choice assays. Flies’ preferences for specific odors depended on their mating status and the odor landscape they were confronted with. Combination with the commercial ingestion insecticide (Success 4: spinosad, 480 g/l, Dow AgroSciences, Valbonne, France) with the plant volatiles were tested to detect an increase in mortality related to the addition of an attractant. The 2-heptanone slightly showed a tend to increase the attractiveness of mated females within 4-6 h to the food bait, but the results were not statistically significant after 8 h. Further tests should be performed with other concentrations or mixtures of the identified host plant volatiles to develop a strong lure and killstrategy.

Detection of pest infestations in fresh produce traded internationally could offer improved prospects for reducing the movement of unwanted pests. Because immature stages of some pests can be difficult to find visually, other cues such as herbivore-induced volatiles that can potentially be detected at the early stages of infestation are worth investigating. In this study, we artificially infested postharvested apples (Malus × domestica‘Royal Gala’) with two economic apple pests, the specialist codling moth (CM, Cydia pomonellaLinnaeus, Lepidoptera: Tortricidae) and the generalist Queensland fruit fly (QFF, Bactrocera tryoni,Froggatt, Diptera: Tephritidae) and collected volatile organic compounds (VOCs) over time (days 0, 6, and 14–15). In both infestation experiments, we found a strong and significant interaction between time and treatment. Apples infested with the QFF emitted lower total amounts of VOCs than uninfested apples, whereas apples infested with the CM released similar total amounts of VOCs. Apples infested with CM had increases in several hexyl and butyl esters, which were particularly noticeable after 15 d. In contrast, changes in ethyl esters were characteristics of QFF infestation and could be detected from day 6. Our multilevel and multivariate statistical analysis identified specific volatile biomarkers for each species at each sampling time that can be used to design a new tool for remote detection and surveillance of these invasive pests in harvested apples. Nevertheless, other information such as the cultivar as well as the storage condition needs to be taken into consideration to increase accuracy of future odorant-based sensors for pest identification.

Drosophila santomea and Drosophila yakuba are two sister species inhabiting Saõ Tomé island. Previous studies showed that both species display strong reproductive isolation, although they can produce a few viable hybrids. Our study tried to understand the mechanism of this ethological isolation between two allopatric strains. A strong sexual isolation was confirmed, with a marked asymmetry. Comparisons of latency times to either courtship or copulation suggest that males do not discriminate females, whereas D. yakuba females, but not D. santomea females, accept their homospecifics more quickly. Cuticular hydrocarbon compositions of both species and sexes were also established with gas chromatography (GC) and GC/mass spectrometry analysis. All have (Z)-7-tricosene as their major compound. There are several quantitative differences between species for few minor compounds. The largest difference concerns n-heneicosane, which is more abundant in D. santomea than in D. yakuba flies (up to seven times more between males). A similar quantitative difference was also found in a pair of sympatric strains. Furthermore, D. yakuba males artificially perfumed with n-heneicosane were discriminated negatively by D. yakuba females, suggesting a role for this compound in the sexual isolation between these two species.