Seasonal insect migrations: massive, influential, and overlooked

Abstract

During seasonal changes around the globe, trillions of insects are on the move. Many insect populations, including butterflies, moths, hoverflies, and dragonflies, make repeated seasonal migrations each year. It is only during the past century that biologists have come to accept the concept of insect migration, and new research using radar, citizen science, and stable isotopes has revealed unexpected insights about this phenomenon. Drawing on these findings, we demonstrate how seasonal insect movements are both massive and ecologically influential, with consequences for food webs, nutrient transport, pollination, and infectious disease. Responding to environmental changes, some mobile insect populations are declining or shifting the timing and extent of their journeys. We suggest research and policy priorities for investigating and protecting insect migrations. Outcomes from such work could transform strategies for agricultural pest control and wildlife conservation, and could help preserve the ecological functions performed by migratory insects.

Climatic drivers of (changes in) bat migration phenology at Bracken Cave (USA)

“…Unfortunately, very little is known about the drivers and mechanisms influencing migratory behaviour (e.g. timing) of insects in general (Satterfield et al., 2020), and even less so for autumn migration specifically (Krauel et al., 2015). Increased insect abundance is, however, often linked to higher precipitation levels (Krauel et al., 2018), and migration theory predicts the optimal time for bat migration to be determined by (changes in) insect abundance (Hedenström, 2009; Krauel & McCracken, 2013).…”

A Review of Insect Monitoring Approaches with Special Reference to Radar Techniques

“…All mentioned direction of recent research on insect radar is especially significant in light of concerns regarding the insect abundance decline [ 132 ]. Satterfield et al [ 133 ] suggested further research and policy priorities to investigate and protect insect migrations concerning the mobile insect population decline and behavioral shift. Similar concerns motivated Stepanian et al [ 104 ] for their work on the aquatic insect abundance decline in North America using radar “at scales that have been previously impossible.” Moreover, radar confirmed that the pest migration is under the severe impact of climate change [ 134 ].…”

Seasonal Migrations of Pantala flavescens (Odonata: Libellulidae) in Middle Asia and Understanding of the Migration Model in the Afro-Asian Region Using Stable Isotopes of Hydrogen

“…This seems to support the thesis that the ecological success of migratory insects depends largely on summer reproduction in high-latitude regions [ 49 ]. The significance of long-distance migrations of dragonflies as a part of the global phenomenon of insect mass migrations should be also emphasized, as the importance and scale of this phenomenon remain largely underestimated [ 50 ].…”