Populations of the gall midge Dasineura oxycoccana on cranberry and blueberry produce and respond to different sex pheromones

Population Genetics of the Blueberry Gall Midge, Dasineura oxycoccana (Diptera: Cecidomyiidae), on Blueberry and Cranberry and Testing Invasion Scenarios

We compared the population genetic structure between populations of the blueberry gall midge-Dasineura oxycoccana (Johnson) (Diptera: Cecidomyiidae)-from blueberry and cranberry and determined the genetic relationships among geographical subgroups by genotyping 632 individuals from 31 different populations from their native USA regions (New Jersey, Michigan, and Georgia) and from invaded Korean regions using 12 microsatellite loci. Our population genetic analyses showed a clear separation between the two host-associated D. oxycoccana populations from blueberry and cranberry. Using data from only the blueberry-associated D. oxycoccana populations, we identified five genetically isolated subgroups. An analysis of the approximate Bayesian computation suggests that the invasive D. oxycoccana population from Korea appears to have been introduced from an unsampled source population rather than directly from its native range. Our findings will allow for an easier identification of the source of D. oxycoccana into newly invaded regions, as well as to determine their association with blueberry and cranberry, which based on our results can be considered as two distinct species.

Mini-review: recent advances in the identification and application of sex pheromones of gall midges (Diptera: Cecidomyiidae)

Most gall midges (Diptera: Cecidomyiidae) are cryptic agricultural pests. These tiny insects are prone to lurk in cargoes and spread over long distances. Their larvae feed in plant tissues, so their infestations are imperceptible until crop damage and economic loss appear. The application of sex pheromones is an efficient method with which to monitor and manage gall midges. The present review focuses on recent advances in the accurate identification of gall midge sex pheromones based on rapidly evolving analytical techniques and their use in field trials in integrated pest management. To date, sex pheromones from 19 species of gall midges have been identified and reported, and sex pheromone-based monitoring systems have been developed and commercialized for at least ten gall midge species. All monitoring systems were tested in various experiments with a modicum of success. In addition to further studies of sex pheromones, identification of plant-derived volatiles may offer potentials for the manipulation of behavioral response of gall midges, which can be used in dispensers for surveillance and control purposes. © 2020 Society of Chemical Industry.

Metabolomic Approach for the Authentication of Berry Fruit Juice by Liquid Chromatography Quadrupole Time-of-Flight Mass Spectrometry Coupled to Chemometrics

Berry fruit juice, which is represented by blueberry and cranberry juice, has become increasingly popular due to its reported nutritional and health benefits. However, in markets, adulteration of berry fruit juice with cheaper substitutes is frequent. In the present study, a metabolomic approach for authentication of berry fruit juices by liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) was established. The global characterization of the berry fruit metabolome by information dependent acquisition directed LC-MS/MS coupled to a peak mining workflow by isotope pattern matching was reported. Targeted metabolomics analysis of known juice biomarkers, such as flavonoids, anthocyanins, etc. exhibited a good separation of berry fruit juices from adulterant juices. Moreover, untargeted metabolomics analysis was carried out and subjected to chemometrics analysis. Discrimination of blueberry juice, cranberry juice, and its adulterant apple juice and grape juice was obtained by principal component analysis-discriminant analysis. Eighteen characteristic markers discriminating berry fruit juice and its adulterants were selected by comparison of marker abundances in different juice samples. Identification of characteristic markers was accomplished by elemental formula prediction and online database searches based on accurate MS information. These results suggested that the combination of untargeted and targeted metabolomics approach has great potential for authentication of berry fruit juice.

Physiological integration plays key role in cranberry (Ericales: Ericaceae) for tolerance of damage by Dasineura oxycoccana (Diptera: Cecidomyiidae)

Understanding the mechanisms by which plants tolerate herbivory is important in the study of insect-plant interactions. In cranberry, current season growth has been identified as the main source of photosynthate for the developing fruits. Feeding injury by larvae of cranberry tipworm, Dasineura oxycoccana Johnson, disrupts the apical growth of cranberry shoots or uprights, but does not impact fruit output. To study the effects of experimentally depleting photosynthate available from sources other than the current season growth on fruit output, we girdled tipworm-injured uprights. This technique enabled us to estimate the contribution of current season growth in supplying photosynthate to developing fruits in tipworm-injured uprights. The mean fruit weight declined by >55% in those tipworm-injured uprights that were limited to photosynthate from only the current season growth (girdled uprights). The result was consistent between two phenologically different cultivars of cranberry, one a native selection from wild cranberry stands ('Howes') and the other a hybrid ('Stevens'). In addition, fruit weight was positively correlated to current season leaf area in the girdled uprights only. These results strongly suggest that physiological integration among the different sources of photosynthate plays a key role in the tolerance of tipworm feeding injury for fruit output in cranberry.