Life history and host‐plant relationships of the rare endemic Arctic aphid Acyrthosiphon calvulus in a changing environment

• Published in: Entomologia Experimentalis et Applicata
• Main Authors: Gillespie, Mark, Hodkinson, Ian D., Cooper, Elisabeth J., Bird, Jeremy M., Jónsdóttir, Ingibjörg S.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2007
• Subjects: Arctic; Norway; Svalbard; Pedicularis hirsuta; Salix polaris; Spitsbergen
• Online Access: http://dx.doi.org/10.1111/j.1570-7458.2007.00547.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1570-7458.2007.00547.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1570-7458.2007.00547.x

Abstract This article examines the abundance, life history, host‐plant relationships, and overwintering biology of Acyrthosiphon calvulus Ossiannilsson (Homoptera: Aphididae) as a precursor to understanding its rarity and potential response to a changing climate. Acyrthosiphon calvulus is restricted to a few scattered localities on the west coast of Spitsbergen, Svalbard, Norway, where it reproduces on Salix polaris WG (Salicaceae) and its taxonomically unrelated root parasite Pedicularis hirsuta L. (Scrophulariaceae) . Acyrthosiphon calvulus overwinters as eggs. Hatching fundatrices give rise directly to males and oviparae, which mate and lay overwintering eggs. The life cycle is closely synchronized with the phenology of S. polaris and appears genetically programmed, lacking summer generations of viviparae. Alate forms are similarly unknown. The progeny sequence of fundatrices resulted in a sex ratio for the sexuales that is strongly female biased (3:1). Eggs hatch coincided with budburst in early June and fundatrices developed on the expanding leaves. Egg production by oviparae corresponded with leaf senescence in July and August. Overwintering egg survival was high, with supercooling points ranging from −29 to −40 °C, lower than the extreme winter minimum temperature recorded (−28 °C). Egg development and hatching occurred at or below 5 °C and sub‐zero temperatures were not required to break diapause. The scarcity and fragmented distribution of A. calvulus is discussed in the context of the ubiquity of its host plants on Spitsbergen.