Characterization of the Insect Assemblage and Associated Floral Volatiles of Black Cherry (Prunus serotina)

Abstract

Black cherry is an ecologically important high-value wood. A decline of its regeneration has been reported in the USA, which could be associated with a lack of pollination. This study was conducted to identify insects visiting black cherry flowers, to determine whether insects captured on the flowers carry black cherry pollen and to identify the volatile organic compounds (VOCs) emitted by flowers of black cherry. A two-year insect survey was conducted before, during and after the black cherry bloom. A total of 9533 insects were captured in traps and Diptera was the most abundant (64.1%). Significantly more insects in Diptera, Lepidoptera and Thysanoptera were captured in the traps installed in the canopy than those on the ground, and Anthalia bulbosa (Diptera: Hybotidae) was the dominant species. Electron microscopy analyses demonstrated that insects captured in the canopy indeed carried black cherry pollen. Black cherry flowers emitted a VOC blend that is composed of 34 compounds and dominated by β-ocimene and several phenylpropanoids/benzenoids. This floral VOC profile is similar to that of other pollinator-dependent Prunus species. This study reports pollinator insects and associated VOCs, for the first time, that could play a significant role in the pollination and regeneration of black cherry.

Effects of Forest Management on the Insect Assemblage of Black Cherry (Prunus serotina) in the Allegheny National Forest

“…Our study also revealed that the canopy traps captured significantly more insects (~60% of all insects captured in this study) than the ground traps ( Table 1 , Figure 3 ). In line with our previous study [ 12 ] two specific insect orders (i.e., Lepidoptera and Thysanoptera) were found to be significantly more abundant in the canopy of black cherry, indicating that these insects might be utilizing flowers and thus contributing to the pollination of black cherry. Likewise, the number of Diptera captured in the canopy of black cherry trees was higher than that on the ground ( Table 1 ), however, in contrast to our previous study [ 12 ], the difference in Diptera captured in the two trap positions was not significant ( p = 0.123) in the current study ( Figure 3 ).…”

“…In line with our previous study [ 12 ] two specific insect orders (i.e., Lepidoptera and Thysanoptera) were found to be significantly more abundant in the canopy of black cherry, indicating that these insects might be utilizing flowers and thus contributing to the pollination of black cherry. Likewise, the number of Diptera captured in the canopy of black cherry trees was higher than that on the ground ( Table 1 ), however, in contrast to our previous study [ 12 ], the difference in Diptera captured in the two trap positions was not significant ( p = 0.123) in the current study ( Figure 3 ). Remarkably, the species diversity of all the insect species and that of Diptera in the removal treatment were significantly higher in the ground traps than in canopy traps ( Figure 5 ), suggesting that the resources (i.e., nectar and pollen) in the removal stands were less abundant in the canopy than on the ground.…”

“…Many insects collected in this study are known to feed on pollen or are associated with flowers. Our previous study [ 12 ] via electron microscopy analysis demonstrated that insects collected in the canopy traps, representing 12 different families in three major orders (Coleoptera, Diptera, and Hymenoptera), carried pollen grains of black cherry on their bodies, legs, and antennae. These insects included Antocha sp.…”

“…These are important pests economically due to their feeding habits on flowers (florivore) and their ability to transmit viruses [ 19 ]. Our previous study [ 12 ] found that some of the volatile organic compounds (VOCs) emitted by the flowers of black cherry match VOCs that have been demonstrated to be attractive to F. occidentalis [ 20 ]. Prunus necrotic ringspot virus (PNRSV), and prune dwarf virus (PDV) can be transmitted through pollen found on the bodies of thrips and can cause up to 50% yield loss in sweet cherry and 100% yield loss in peach [ 21 , 22 ].…”

“…Surveys conducted in a non-forest stand [ 10 ] and forest edge [ 11 ] reported that Hymenoptera (bees and wasps) and Diptera (true flies) are the most prevalent insect groups visiting black cherry flowers. Our previous study conducted in unmanaged black cherry stands [ 12 ] showed that the most abundant insects that visited black cherry canopies were insects belonging to the order Diptera followed by Coleoptera (beetles) and Hymenoptera. In addition, the study also found that insects, in particular dipterans, are attracted to the canopy of black cherry trees when flowers are present and thus likely contribute to pollination, and black cherry flowers emit a volatile blend that is similar to that of other pollinator-dependent Prunus species.…”