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Drosophila suzukii is a pest of soft and stone fruits that is attracted to yeast volatile metabolites. Drosophila suzukii has distinct summer and winter morphs which are found in different habitats. Complex communities of yeasts likely differ between habitats and thus we hypothesized morphs differ in their attraction to yeast volatiles from different species and combinations of species. We presented D. suzukii with yeast species in isolation and in combinations, as either post-culture mixes or co-cultured, and measured activity of the flies in laboratory choice tests with a Locomotor Activity Monitor as a proxy for attraction. Candida zemplinina was more attractive to winter than summer morphs when cultured in both sterile strawberry juice (SSJ) and artificial culture media (YPD). No significant correlations were found between principle component scores derived from single yeast volatile profiles and fly activity. There was also differential attraction of morphs to certain yeast mixes, most notably post SSJ culture mixes of Hanseniaspora uvarum and C. zemplinina were consistently more attractive to winter morphs. Mixtures of Metschnikowia pulcherrima  +  Pichia pijperi  +  H. uvarum in SSJ and M. pulcherrima  +  P. pijperi yeasts in YPD were also preferred by winter morphs, whilst summer morphs were attracted to SSJ co-cultures of M. pulcherrima  +  H. uvarum . However, co-culturing yeasts did not enhance attraction compared to post-culture mixes of constituent yeasts for either morph. Differential attraction of morphs to certain yeasts suggests options for new bait formulations in integrated pest management strategies may be tailored to better target morphs.

Background Sugar feeding is an essential aspect of mosquito biology that may be exploited for mosquito control by adding insecticides to sugar attractants, so-called ‘attractive targeted sugar baits’ (ATSBs). To optimize their effectiveness, ATSB products need to be maximally attractive at both short and long range and induce high levels of feeding. This study aimed to assess the attractiveness and feeding success of Anopheles mosquitoes exposed to attractive sugar baits (ASBs). Method Experiments were conducted in 2 × 5 × 2-m cages constructed within the semi-field systems (SFS) at Ifakara Health Institute, Bagamoyo, Tanzania. Male and female Anopheles gambiae s.s. and An. funestus s.s. mosquitoes were exposed to either 20% sucrose or different ASB station prototypes produced by Westham Co. in either (1) no-choice experiments or (2) choice experiments. Mosquitoes were exposed overnight and assessed for intrinsic or relative olfactory attraction using fluorescent powder markers dusted over the ASB stations and 20% sucrose and for feeding using uranine incorporated within the bait station and food dye in 20% sucrose controls. Results Both male and female An. gambiae and An. funestus mosquitoes were attracted to the ASBs, with no significant difference between the sexes for each of the experiments conducted. Older mosquitoes (3–5 days) were more attracted to the ASBs (OR = 8.3, [95% CI 6.6–10.5] P  < 0.001) than younger mosquitoes (0–1 day). Similarly, older mosquitoes responded more to 20% sucrose (OR = 4.6, [3.7–5.8], P  < 0.001) than newly emerged Anopheles . Of the four prototypes tested, the latest iteration, ASB prototype v1.2.1, showed the highest intrinsic attraction of both Anopheles species, attracting 91.2% [95% CI 87.9–94.5%]. Relative to ATSB v1.1.1, the latest prototype, v.1.2.1, had higher attraction (OR = 1.19 [95% CI 1.07–1.33], P  < 0.001) and higher feeding success (OR = 1.71 [95% CI 1.33–2.18], P  < 0.001). Conclusions Data from these experiments support using ASBs v1.2.1, deployed in large-scale epidemiological trials, as it is the most attractive and shows the highest feeding success of the Westham prototypes tested. The findings indicate that future bioassays to evaluate ATSBs should use mosquitoes of both sexes, aged 3–5 days, include multiple species in the same cage or chamber, and utilize both non-choice and choice tests with a standard comparator.

Pest monitoring is an important tool for successful integrated pest management programmes. Blue sticky traps are important for monitoring western flower thrips, Frankliniella occidentalis , in greenhouses. However, blue sticky traps have three major weak points: (1) efficacy depends on reflection of light, which varies in intensity with fluctuating light conditions (season, diurnal rhythmic pattern), (2) they reflect broad wavelength pattern not optimally matching with maximum sensitivity of WFT photoreceptors, and (3) they offer no olfactory cues which are important for thrips orientation. This study explored the most attractive wavelength range for WFT using broad range of narrow-bandwidth light-emitting diodes (LEDs) in order to improve the attractiveness of blue sticky traps. Subsequently, trapping efficacy of the most attractive blue LED in combination with blue sticky trap and addition of an attractive lure (Lurem-TR) was evaluated in flight cages under greenhouse conditions. Release-capture studies revealed that LEDs with peak emission of 445 nm were clearly more effective than conventional blue sticky traps. In choice experiments, up to 2.7-fold and in no-choice experiment up to 2.1-fold more WFT were captured by LED-blue sticky traps compared to conventional reflecting blue sticky traps. Lurem-TR improved the performance of blue sticky traps and LED-blue sticky traps 2.3-fold and 2.0-fold, respectively, as compared to those without Lurem-TR. The addition of LEDs and kairomone lure to blue sticky traps seems promising for improving WFT trapping, specifically at low population densities especially during early infestation. However, these results should be further validated under more complex, large field conditions.

The florivorous apple blossom weevil, Anthonomus pomorum (Coleoptera: Curculionidae), is the most economically relevant insect pest of European apple orchards in early spring. Neither efficient monitoring nor ecologically sustainable management of this insect pest has yet been implemented. To identify heritable traits of apple trees that might influence the host selection of A. pomorum , we compared the susceptibility of apple tree species using infestation rates of the domesticated apple, Malus domestica (Rosaceae: Pyreae), and the European crab apple, M. sylvestris . We evaluated the suitability of the two apple species for A. pomorum by quantifying the mass of weevil offspring. Because volatile organic compounds (VOCs) emitted from flower buds of the domesticated apple have previously been suggested to mediate female weevil preference via olfactory cues, we conducted bioassay experiments with blossom buds of both apple species to explore the olfactory preference of adult weevils and, furthermore, identified the headspace VOCs of blossom buds of both apple species through GC-MS analysis. The infestation analysis showed that A. pomorum infested the native European crab apple more prevalently than the domesticated apple, which originated from Central Asia. The European crab apple also appeared to be better suited for weevil larval development than the domesticated apple, as weevils emerging from M. sylvestris had a higher body mass than those emerging from M. domestica . These field observations were supported by olfactory bioassays, which showed that A. pomorum significantly preferred the odor of M. sylvestris buds compared to the odor of M. domestica buds. The analysis of headspace VOCs indicated differences in the blossom bud volatiles separating several M. domestica individuals from M. sylvestris individuals. This knowledge might be employed in further studies to repel A. pomorum from M. domestica blossom buds.

Insect herbivores that have more than one generation per year and reproduce on different host plants are confronted with substantial seasonal variation in the volatile blends emitted by their hosts. One way to deal with such variation is to respond to a specific set of compounds common to all host plants. The oriental fruit moth Cydia ( =Grapholita ) molesta is a highly damaging invasive pest. The stone fruit peach ( Prunus persica ) is its primary host, whereas pome fruits such as pear ( Pyrus communis ) are considered secondary hosts. In some parts of their geographic range, moth populations switch from stone to pome fruit orchards during the growing season. Here, we tested whether this temporal switch is facilitated by female responses to plant volatiles. We collected volatiles from peach and pear trees in situ and characterized their seasonal dynamics by gas chromatography–mass spectrometry. We also assessed the effects of the natural volatile blends released by the two plant species on female attraction by using Y-tube olfactometry. Finally, we related variations in volatile emissions to female olfactory responses. Our results indicate that the seasonal host switch from peach to pear is facilitated by the changing olfactory effect of the natural volatile blends being emitted. Peach volatiles were only attractive early and mid season, whereas pear volatiles were attractive from mid to late season. Blends from the various attractive stages shared a common set of five aldehydes, which are suggested to play an essential role in female attraction to host plants. Particular attention should be given to these aldehydes when designing candidate attractants for oriental fruit moth females.

The kudzu bug, Megacopta cribraria (Fabricius), is an invasive pest of soybeans, Glycine max (L.) Merr., that has recently been detected in the United States.This study investigated whether there was a differential attraction of adult bugs to soybean growth stages, and whether the attraction was related to soybean constitutive volatiles. Greenhouse choice assays examined the behavioral orientation preference of adult bugs exposed to four growth stages of whole soybean plants: vegetative (V2), flowering (R1), pod (R3), and seed (R5). Results show that significantly more adults landed on plants in the early reproductive stage R1 than in other stages. Laboratory olfactometer assays also demonstrate that significantly more adult bugs were attracted to R1 plants, with females responding more strongly than males. Both greenhouse and olfactometer assays indicate that the differential attraction of adult bugs to soybean growth stages was mediated by plant constitutive volatiles.These results offer an insight into kudzu bug chemical and behavioral ecology and thus are of great significance for optimizing the timing of field scouting and treatment as well as the development of soybean pest management programs.

Cyclocephaline scarabs are specialised scent-driven pollinators, implicated with the reproductive success of several Neotropical plant taxa. Night-blooming flowers pollinated by these beetles are thermogenic and release intense fragrances synchronized to pollinator activity. However, data on floral scent composition within such mutualistic interactions are scarce, and the identity of behaviorally active compounds involved is largely unknown. We performed GC-MS analyses of floral scents of four species of Annona (magnoliids, Annonaceae) and Caladium bicolor (monocots, Araceae), and demonstrated the chemical basis for the attraction of their effective pollinators. 4-Methyl-5-vinylthiazole, a nitrogen and sulphur-containing heterocyclic compound previously unreported in flowers, was found as a prominent constituent in all studied species. Field biotests confirmed that it is highly attractive to both male and female beetles of three species of the genus Cyclocephala , pollinators of the studied plant taxa. The origin of 4-methyl-5-vinylthiazole in plants might be associated with the metabolism of thiamine (vitamin B1), and we hypothesize that the presence of this compound in unrelated lineages of angiosperms is either linked to selective expression of a plesiomorphic biosynthetic pathway or to parallel evolution.

A 3-chamber in-line olfactometer designed for use with sand flies is described and tested as a high-throughput method to screen honeys for attractiveness to Phlebotomus papatasi (four geographic isolates), P. duboscqi (two geographic isolates), and Lutzomyia longipalpis maintained in colonies at the Walter Reed Army Institute of Research. A diversity of unifloral honey odors were evaluated as a proxy for the natural floral odors that sand flies may use in orientation to floral sugar sources in the field. In the 3-chamber in-line olfactometer, the choice modules come directly off both sides of the release area instead of angling away as in the Y-tube olfactometer. Of the 25 honeys tested, five had a significant attraction for one or more of the sand fly isolates tested. This olfactometer and high-throughput method has utility for evaluating a diversity of natural materials with unknown complex odor blends that can then be down-selected for further evaluation in wind tunnels and/or field scenarios.

Responses of Neoseiulus cucumeris (a predatory mite) and the predatory insect Orius strigicollis to volatiles associated with two different plant species infested with onion thrips, Thrips tabaci, were examined in a Y-tube olfactometer. Both predators species showed a significant preference for volatiles from infested cucumber leaves without T. tabaci over clean air. However, they were not attracted to volatiles from uninfested cucumber leaves, artificially damaged cucumber leaves, or volatiles from T. tabaci plus their visible products collected from cucumber leaves. These results suggest that both predator species are capable of exploiting herbivore-induced volatiles from T. tabaci-infested cucumber leaves as a foraging cue. Neither predator was attracted to volatiles from uninfested spring onion leaves, infested spring onion leaves without T. tabaci, or volatiles from T. tabaci plus their visible products collected from spring onion leaves. Interestingly, they avoided volatiles from artificially damaged spring onion leaves. A possible explanation for the non-significant olfactory responses of the predator species to spring onion plants with infestation damage of T. tabaci is discussed.

Mosquitoes are important vectors of disease and require sources of carbohydrates for reproduction and survival. Unlike host-related behaviors of mosquitoes, comparatively less is understood about the mechanisms involved in nectar-feeding decisions, or how this sensory information is processed in the mosquito brain. Here we show that Aedes spp. mosquitoes, including Aedes aegypti, are effective pollinators of the Platanthera obtusata orchid, and demonstrate this mutualism is mediated by the orchid’s scent and the balance of excitation and inhibition in the mosquito’s antennal lobe (AL). The P. obtusata orchid emits an attractive, nonanal-rich scent, whereas related Platanthera species—not visited by mosquitoes—emit scents dominated by lilac aldehyde. Calcium imaging experiments in the mosquito AL revealed that nonanal and lilac aldehyde each respectively activate the LC2 and AM2 glomerulus, and remarkably, the AM2 glomerulus is also sensitive to N,N-diethylmeta-toluamide (DEET), a mosquito repellent. Lateral inhibition between these 2 glomeruli reflects the level of attraction to the orchid scents. Whereas the enriched nonanal scent of P. obtusata activates the LC2 and suppresses AM2, the high level of lilac aldehyde in the other orchid scents inverts this pattern of glomerular activity, and behavioral attraction is lost. These results demonstrate the ecological importance of mosquitoes beyond operating as disease vectors and open the door toward understanding the neural basis of mosquito nectar-seeking behaviors.