Seasonal natural history of aphidophagous Syrphidae (Diptera) attacking the balsam twig aphid in balsam fir (Pinaceae) Christmas tree plantations

Abstract

The balsam twig aphid, Mindarus abietinus Koch (Hemiptera: Aphididae), is one of the most important pests of balsam fir (Abies balsamea (Linnaeus) Miller; Pinaceae) grown as Christmas trees in eastern North America. Aphid feeding on the current-year shoots results in needle distortion and shoots stunting, which reduces the aesthetic value of balsam fir trees and can have substantial economic impact. Syrphidae (Diptera) fly predators attacking this aphid are poorly known. We identified four species attacking the balsam twig aphid. Syrphus torvus Osten Sacken (Diptera: Syrphidae) was the most abundant species followed by Eupeodes lapponicus (Zetterstedt) (Diptera: Syrphidae) and Eupeodes americanus (Wiedemann) (Diptera: Syrphidae). We described the seasonal natural history of the two most abundant syrphids feeding on this aphid and we studied their synchrony with their prey. Syrphid larval density on balsam fir shoots increased rapidly and closely followed density of the balsam twig aphid. We also reported heavy parasitism of syrphid pupae by two Hymenoptera on tree foliage but lower parasitism on pupae in the soil under trees. Several cases of multiple parasitism and hyperparasitism were observed in syrphid pupae under trees. Abundance of predaceous syrphid species was higher in untreated balsam fir plantations compared with treated plantations. More research is needed to understand the role and the impact of these predators on balsam twig aphid population dynamics.

Insights into natal origins of migratory Nearctic hover flies (Diptera: Syrphidae): new evidence from stable isotope (δ2H) assignment analyses

“…and frost aster ( Symphyotrichum pilosum ) during September and October 2019 in North Alabama (Limestone County), USA, and areas of southern Alabama in November 2019 (Table 1). Both hover fly species are anthophilous as adults but feed on aphids and other soft‐bodied arthropods as larvae (Noma and Brewer 2008, Berthiaume et al 2016, Arcaya et al 2017) and are common throughout eastern North America (Vockeroth 1992, Skevington and Locke 2019). Female hover flies are believed to be the more migratory sex (Gatter 1976, Dällenbach et al 2018), so these were sought over males when possible (Table 1).…”

Do Nearctic hover flies (Diptera: Syrphidae) engage in long‐distance migration? An assessment of evidence and mechanisms

“…Four North American hover fly species were examined to address the four objectives: Eupeodes americanus (Wiedemann, 1830), Allograpta obliqua (Say, 1823), Syrphus rectus Osten Sacken, 1875, and Syrphus ribesii (Linnaeus 1758) (Figure 1). These four species were selected because they are common throughout much of eastern North America and contribute major biological control services (Arcaya et al, 2017;Berthiaume et al, 2016;Noma & Brewer, 2008;Skevington & Locke, 2019). Eupeodes americanus is even being considered for mass commercial rearing for biocontrol purposes (Bellefeuille et al, 2019(Bellefeuille et al, , 2021.…”

Annual Crops Contribute More Predators than Perennial Habitats during an Aphid Outbreak

“…This species is common in North America, feeds on a variety of plant species (60 reported), and its larvae are generalist aphid predators [59,61]. Eupeodes americanus has been shown to respond numerically to woolly apple aphid, Eriosoma lanigerum (Haussman) [62] and balsam twig aphid, Mindarus abietinus Koch (Hemiptera: Aphididae) abundance [63]. Here, bidirectional movement of E. americanus was higher the second sampling week, coinciding with higher aphid abundance and changes in plant phenology in canola and wheat.…”