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An Extraordinary Host-Specific Sex Ratio in an Avian Louse (Phthiraptera: Insecta)--Chemical Distortion?
1Institute of Marine Science, University of Alaska, Fairbanks, AK 99775. Current address: Science Department, College of Rural and Community Development, Kuskokwim Campus, University of Alaska, Bethel, AK 99559. hector.douglas@alaska.edu.
Environmental Entomology
|August 28, 2015
Summary
Naturally occurring chemicals from seabirds can skew insect sex ratios. Male lice are more susceptible to the crested auklet's citrus-like secretions, leading to a highly female-biased sex ratio in this louse species.
Area of Science:
- Ecology
- Chemical Ecology
- Entomology
Background:
- Synthetic chemicals are known to distort sex ratios in insects, but evidence for naturally occurring compounds is limited.
- Vertebrate chemical secretions may influence ectoparasitic insect sex ratios due to differential susceptibility between sexes.
- Female ectoparasitic lice are often larger than males, potentially making males more vulnerable to chemical effects.
Purpose of the Study:
- To investigate if naturally occurring chemical secretions from seabirds affect the sex ratios of their ectoparasitic lice.
- To compare sex ratios of lice on seabird species with and without specific chemical secretions.
Main Methods:
- Studied sex ratios of lice on two sympatric seabird species: crested auklets (Aethia cristatella) and least auklets (Aethia pusilla).
- Crested auklets produce a citrus-like odorant (aldehydes), while least auklets lack these compounds.
- Examined sex ratios of lice, specifically Quadraceps aethereus, shared by both auklet species.
Main Results:
- The sex ratio of Quadraceps aethereus was highly skewed towards females (1:69 males:females) on crested auklets.
- In contrast, the sex ratio of Quadraceps aethereus on least auklets was close to unity (1:0.97 males:females).
Conclusions:
- Host-specific chemical secretions, such as the crested auklet's odorant, likely contribute to skewed louse sex ratios.
- This suggests a role for natural chemical cues in influencing insect population dynamics and sexual selection.
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