Mechanisms in mutualisms: a chemically mediated thrips pollination strategy in common elder.

MAIN CONCLUSION: This study provides first evidence of a thrips species pollinating Sambucus nigra and describes how interactions are driven by plant biochemical signalling and moderated by temporal changes in floral chemistry. The concept of flower-feeding thrips as pollinating insects in temperate regions is rarely considered as they are more frequently regarded to be destructive florivores feeding on pollen and surrounding plant tissue. Combining laboratory and field-based studies we examined interactions between Sambucus nigra (elderflower) and Thrips major within their native range to ascertain the role of thrips in the pollination of this species and to determine if floral chemicals mediated flower visits. If thrips provide a pollination service to S. nigra, then this will likely manifest in traits that attract the pollinating taxa at temporally critical points in floral development. T. major were highly abundant in inflorescences of S. nigra, entering flowers when stigmas were pollen-receptive and anthers were immature. When thrips were excluded from the inflorescences, fruit-set failed. Linalool was the major component of the inflorescence headspace with peak abundance coinciding with the highest number of adult thrips visiting flowers. Thrips were absent in buds and their numbers declined again in senescing flowers inversely correlating with the concentration of cyanogenic glycosides recorded in the floral tissue. Our data show that S. nigra floral chemistry mediates the behaviour of pollen-feeding thrips by attracting adults in high numbers to the flowers at pre-anthesis stage, while producing deterrent compounds prior to fruit development. Taking an integrative approach to studying thrips behaviour and floral biology we provide a new insight into the previously ambiguously defined pollination strategies of S. nigra and provide evidence suggesting that the relationship between T. major and S. nigra is mutualistic.

Mass trapping designs for organic control of the Japanese beetle, Popillia japonica (Coleoptera: Scarabaeidae).

BACKGROUND: In some regions of North America, damage caused by the Japanese beetle, Popillia japonica, has been increasing as beetle populations continue to become established and expand. This poses a pest management challenge for crop farmers, in particular organic producers. From 2014 to 2016 we evaluated the ability of novel mass trapping systems to capture P. japonica in elderberry and blueberry orchards in Missouri, USA. RESULTS: Across a 3-year period in two locations, the mass trapping systems collected 10.3 million P. japonica adults while season-long adult densities on crop plants were comparatively low (elderberry: 0.5-3.7 per plant; blueberry: 0.01-0.07 per plant). Damage by P. japonica averaged 6.8% per plant in elderberry and 0.12% in blueberry. In 2015 and 2016, large-capacity bins with increased ventilation captured similar beetle numbers as did 1.2-m-long mesh socks (single design used in 2014), and these two trap designs outperformed non-ventilated bins. CONCLUSION: The mass trapping designs captured high numbers of adult P. japonica, while comparatively few adults and little damage to the foliage were recorded on plants. Mass trapping may provide effective alternative management options for P. japonica with less or no insecticides applied to the crop. © 2018 Society of Chemical Industry.

The higher the better? Differences in phenolics and cyanogenic glycosides in Sambucus nigra leaves, flowers and berries from different altitudes.

BACKGROUND: Elderberry (Sambucus nigra L.) possesses high antioxidant activity and has been used to treat numerous medicinal disorders. In addition to their antioxidant properties, elderberry parts accumulate toxic cyanogenic glycosides (CGG). It has been proven that altitude influences the biosynthesis of many secondary metabolites. In the present study we investigated the change of phenolics and CGG in elder leaves, flowers, and berries induced by different altitudes and locations. RESULTS: The data indicate that the accumulation of CGG and phenolics is affected by the altitude of the growing site. An increase of anthocyanin content was recorded in elder berries collected at higher elevations in both locations. Fruit collected at the foothills of location 2 contained 3343 µg g-1 anthocyanins as opposed to fruit from the hilltop, which contained 7729 µg g-1 . Elder berries contained the lowest levels of harmful CGG compared to other analysed plant parts. However, more cyanogenic glycosides were always present in plant parts collected at the hilltop. Accordingly, berries accumulated 0.11 µg g-1 CGG at the foothills and 0.59 µg g-1 CGG at the hilltop. CONCLUSION: Elder berries and flowers collected at the foothill were characterised by the lowest levels of both beneficial (phenolics) and harmful compounds (CGG) and are suitable for moderate consumption. © 2016 Society of Chemical Industry.