HAWKMOTHS OF EAGLENEST WILDLIFE SANCTUARY
For my doctoral work, moths, which are known to be phototropic, were chosen as one of the two study taxa due
to the relative ease of their sampling at ultraviolet light screens. As one of the principal herbivores of an ecosystem (De Vos et al. 2006), and with species-specific food plant, the changes in their population may be expected to reflect those in the plant community. This
would make them excellent faunal targets for population monitoring programs under climate change studies. As important pollinators and agricultural pests, they have served as model organisms from the viewpoint of economics as well (Haber & Frankie 1989;
Moulds 1981, 1984; Kitching & Cadiou 2000 and references therein).
Hawkmoths are easy to distinguish from species of other moth families even on a screen thereby reducing sampling effort in the field. The ability to identify the family at a glance meant that none of the other thousand moths on the screen had to be examined or
processed, and we had an immediate count of the sampling success for each day. Sphingids have been the targets of considerable taxonomic studies and we have a better knowledge of their geographical distributions, compared to other families, largely through
the on-going efforts of Ian Kitching and his team of collaborators (Kitching 2017). Ironically, the lower species richness of hawkmoths compared to most other macrolepidopteran families – 1500 extant hawkmoth species, contra ~23,000 Geometridae (Scoble and Hausmann 2007) or ~35,000 Noctuidae (Quimbayo et al. 2010) – is an advantage in diversity studies. The rate limiting step in studies of tropical insect
diversity is specimen identification (Brehm et al. 2003; Brehm et al. 2016), which may not even be possible at the level of species without DNA-based identifications for many groups and may lead to erroneous measures of diversity (Brehm et al. 2016). Our study is part of a much larger biodiversity project in EWS to investigate patterns in distribution of many other taxa (ongoing projects on other moth families, frogs and ants).
‘Species’ is the fundamental unit of data collected for most community ecology studies. However, recognizing, naming and identifying species, especially for hyper-diverse invertebrates, is not easy, requiring some degree of expertise and experience (Krell 2003).
Due to a persistent decline of human resources in taxonomy (e.g. Hopkins & Freckleton 2002), ‘morpho-species’ sorting – i.e. taxa readily separable by morphological differences that are obvious to individuals without extensive taxonomic training – with minimum or no involvement of taxonomists has become a widely used strategy in conservation biology and species diversity-based ecology (Krell 2003; Brehm et al. 2003). To quote Oliver & Beattie (1993) “Ninety percent agreement has been found between morpho-species
classification by non-specialists and specialist taxonomists.” Oliver (1994) showed that morpho-species provided accurate estimates of species richness of ants, spiders and beetles. They suggest the use of morpho-species as surrogates for species when
comparing richness of sites over time or space. More recently, Brehm et al. (2016) compared analyses using morpho-species and DNA-barcodes to confirm that incomplete species delineation does not necessarily conceal trends of biodiversity along a gradient,
but it might underestimate the true magnitude of diversity (a case study on Geometridae). We were able to assign individuals to taxonomic species in most cases because Sphingidae identification is relatively easy due to the large amount of available literature
and type-specimen inventories. Where we were not confident of our identifications, we assigned individuals to morpho-species. Nevertheless, we only use the assigned taxonomic name as a label for an OTU; i.e. we only claim that individuals which share a
name belong to the same (morpho-) species, but they may not be the one named, but a similar looking sister species. For instance, most of the individuals that we have listed as Ambulyx tobii are all very likely to belong to the same species, but that species may not be A. tobii. We relied chiefly on the following reference material for identification:
1. Moths of Thailand Vol. 2 Sphingidae, H. Inoue, R.D. Kennett & I.J.Kitching (MOT)
2. Moths of Borneo J.D. Holloway (MOB)
3. Sphingidae Taxonomic Inventory http://sphingidae.myspecies.info (STI)
4. Sphingidae of the eastern Palaearctic http://tpittaway.tripod.com/china/ (SOTEP)
5. Sphingidae of Southeast- Asia https://www.sphin-sea.unibas.ch/ (SSA)
The species names assigned to our morpho-types are only meant to be name handles, and not actual species identifications, though many of them may be the correct identification. For the purpose of this thesis the actual specific identification is not essential.