Improved Flying Abilities in Migrating Insects

Jenn Hoskins
8th December, 2024

Improved Flying Abilities in Migrating Insects

The visual field assessments for the Marmalade hoverfly (Episyrphus balteatus) were validated, showing that estimated size (a) accurately predicts wing length (c) and dry mass (e), while estimated body condition (b), a key determinant of migratory flight performance, strongly correlates with dry mass (f) but not wing length (d).

Image adapted from: Massy et al. / CC BY (Source)

Key Findings

  • Researchers at the University of Exeter found that migratory hoverflies can fly twice as far as non-migratory ones
  • Hoverflies with more energy stores in their bodies can fly almost five times the distance of those with fewer energy stores
  • Flight speed in hoverflies is mainly influenced by their size, not their migratory status or body condition
Seasonal migrations are a fascinating phenomenon observed in many animals, including the marmalade hoverfly, Episyrphus balteatus. These migrations involve long-distance travel and are influenced by various factors such as morphology, physiology, and behavior. A recent study conducted by researchers at the University of Exeter has shed light on the differences in flight characteristics between autumn migratory and summer non-migratory morphs of this species[1]. The study utilized a tethered flight mill to measure the flight performance of the hoverflies. The results revealed that migratory morphs flew twice as far as their non-migratory counterparts. Additionally, the study found that body condition, specifically the quantity of energy stores, played a crucial role in flight performance. Hoverflies with fat abdomens flew almost five times the distance of those with thin abdomens. Interestingly, flight speed was primarily influenced by the size of the hoverflies rather than their migratory status or body condition. These findings highlight the enhanced flight capabilities of migratory morphs and emphasize the importance of body condition for long-distance flight. The ability to accumulate and utilize energy stores is likely a key factor influencing the migration of hoverflies. This study builds on previous research that has explored the migratory behavior and orientation mechanisms of hoverflies. For instance, earlier studies have demonstrated that migratory hoverflies in the Northern Hemisphere move to higher latitudes in the spring and lower latitudes in the autumn[2]. Spring migration has been confirmed through ground observations, showing that hoverflies have an innate northward preference during this season. This northward orientation was observed under sunny conditions and even when the sun was obscured, suggesting a robust navigational mechanism[2]. Moreover, it has been established that the sun is a reliable celestial cue for orientation in daytime migrants. Hoverflies use a time-compensated sun compass to adjust for the changing position of the sun throughout the day[3]. This mechanism was confirmed through flight simulator studies, where hoverflies oriented southwards in autumn when they could see the sun and adjusted their orientation following a shift in their circadian clocks[3]. The current study by the University of Exeter adds to this body of knowledge by elucidating the physical and physiological traits that contribute to the migratory success of hoverflies. The enhanced flight capabilities of migratory morphs and the critical role of body condition underscore the importance of resource availability and feeding behavior in migration. These findings suggest that the ability to accumulate energy stores is a crucial determinant of migratory success in hoverflies. In conclusion, the study provides valuable insights into the factors influencing the migration of Episyrphus balteatus. By comparing the flight characteristics of migratory and non-migratory morphs, it highlights the significance of body condition and energy stores in long-distance flight. This research not only expands our understanding of hoverfly migration but also underscores the importance of resource availability and feeding behavior in the migratory success of these ecologically and economically important insects.

EnvironmentAnimal ScienceEvolution

References

Main Study

1) Enhanced flight performance in hoverfly migrants.

Published 20th December, 2024 (future Journal edition)

https://doi.org/10.1016/j.isci.2024.111345

Related Studies

2) Migratory hoverflies orientate north during spring migration.

https://doi.org/10.1098/rsbl.2022.0318

3) Hoverflies use a time-compensated sun compass to orientate during autumn migration.

https://doi.org/10.1098/rspb.2021.1805


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