Macro-moth families differ in their attraction to light: implications for light-trap monitoring programmes
- Light traps are used to make inferences about local macro-moth communities, but very little is known about the efficiency with which they attract moths from varying distances, and how this may differ among families.
- We released 731 marked individuals, from three of the most common and species-rich macro-moth families, at several distances from low-wattage actinic light traps in open and woodland habitat.
- Logistic regression showed family-specific sampling areas: erebids were attracted from up to 27 m, geometrids from up to 23 m, and noctuids from up to 10 m from the light source, with these distances corresponding to a 5% recapture rate. Sampling size was also family-specific: a maximum of 55% of erebids, 15% of geometrids, and 10% of noctuids were predicted to be trapped when flying near (0–1 m) light traps.
- Our study demonstrates that weak light traps: (i) have remarkably local sampling ranges, resulting in samples that are highly representative of the local habitat, and (ii) attract small, and family-specific proportions of individuals within these ranges.
- We suggest that the local sampling ranges of weak light traps make them excellent tools to monitor nocturnal macro-moth communities. As trap efficiency differs among macro-moth families, care must be taken in relating the abundance of the sample to absolute local abundance. Frequent sampling can provide adequate data on relative temporal change in the local macro-moth fauna, however.