Should I stay or should I go? Modelling dispersal strategies in saproxylic insects based on pheromone capture and radio telemetry: a case study on the threatened hermit beetle Osmoderma eremita

• To predict how organisms cope with habitat fragmentation we must understand their dispersal biology, which can be notoriously difficult. We used a novel, multi-pronged approach to study dispersal strategies in the endangered saproxylic hermit beetle Osmoderma eremita, exploiting its pheromone system to intercept high numbers of dispersing individuals, which is not possible with other methods. Mark-release-recapture, using unbaited pitfall traps inside oak hollows and pheromone-baited funnel traps suspended from tree branches, was combined with radio telemetry (in females only) to record displacements. Dispersal, modelled as a probability distribution of net displacement, did not differ significantly between sexes (males versus females recaptured), observation methods (females recaptured versus radio-tracked), or sites of first capture (pitfall trap in tree versus pheromone trap – distance from original dispersal point unknown). A model including all observed individuals yielded a mean displacement of 82 m with 1% dispersing1 km. Differences in body length were small between individuals captured in pitfall versus pheromone traps, indicating that dispersal is rarely a condition-dependent response in O. eremita. Individuals captured in pheromone traps were consistently lighter, indicating that most dispersal events occur relatively late in life, which agrees with trap catch data. In addition, most (79%) females captured in pheromone traps were mated, showing that females typically mate before leaving their natal tree. Our data show that integrating odour attractants into insect conservation biology provides a means to target dispersing individuals and could greatly improve our knowledge of dispersal biology in threatened species.

Ämnesord

NATURVETENSKAP  -- Biologi -- Zoologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Zoology (hsv//eng)

NATURVETENSKAP  -- Biologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences (hsv//eng)

NATURVETENSKAP  -- Biologi -- Ekologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Ecology (hsv//eng)

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Environmental Sciences (hsv//eng)

Nyckelord

Dispersal

Mark-release-recapture

Radio tracking

Pheromone traps

Modelling

Oviposition experiments

Conservation

NATURAL SCIENCES

Miljövetenskap

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