Patch area of macrophyte Stratioites aloides as a critical resource for declining dragonfly Aeshna viridis

: Suhonen J, Suutari E, Kaunisto KM, Krams I

Publisher: SPRINGER

: 2013

: Journal of Insect Conservation

: JOURNAL OF INSECT CONSERVATION

: J INSECT CONSERV

: 2

: 17

: 2

: 393

: 398

: 6

: 1366-638X

DOI: https://doi.org/10.1007/s10841-012-9521-0

Currently, many rare and endangered species occur in fragmented habitats. Habitat patch size is often used as an easily measured surrogate of habitat quality and local population size. We investigated whether habitat patch size affects the presence and density of larvae of the endangered dragonfly Aeshna viridis, which for a large part of their life history depend on the macrophyte Stratiotes aloides rosette. The study was performed in four populations, two from Finland and two from Latvia. Our main result was that density of A. viridis and patch occupation increased with area of S. aloides patch. The results may be due to larvae actively avoiding enemies (higher survival) and/or to the possibility that females laid higher number of eggs in the large S. aloides patches. Our results indicate that local abundance and persistence of A. viridis population may depend on the few, large S. aloides patches rather than several small patches of equal total area.