Host plant effects on morphometric characteristics of Liriomyza huidobrensis, L. sativae and L. trifolii (Diptera: Agromyzidae)
Body size of herbivorous insects may be directly related to host plant characteristics (e.g. nutrition, chemical composition) and positively linked to performance of the herbivore and its parasitoids. Differences in adult body size of Liriomyza huidobrensis, L. sativae and L. trifolii reared on Pisum sativum, Phaseolus vulgaris, Vicia faba and Solanum ycopersicum were assessed to determine the effect of host plants on adult size. Furthermore, morphometric wing and hind tibia measurements were used to determine suitability as proxy measures for adult size. Based on canonical and linear discriminant analyses, two distinct Liriomyza morphospecies groups were recognized across all plant species. The first cluster represented L. huidobrensis and the second L. sativae and L. trifolii. The overall degree of correct classification of the three species across all plants tested (correct observation) with cross validation was estimated at 85%. Liriomyza huidobrensis, the largest species, showed no differences in the variables measured when reared on the four plant species. However, different plant species seem to influence wing and hind tibia measurements in L. trifolii to a greater extent than in L. huidobrensis and L. sativae. The first two canonical variates could not separate the populations of L. huidobrensis and L. sativae reared on different plant species, but showed separation of L. trifolii populations into two clusters: firstly, insects reared on V. faba and secondly, insects reared on P. vulgaris and S. lycopersicum. Hind tibia length strongly correlated with wing length. Both can be used to determine adult size of the three Liriomyza species. This study provides some new evidence for the existence of differential preferences by Liriomyza species for the four host plant species. This, therefore, warrants larger scale field studies to test for positive preference- performance of Liriomyza species on these plant species and to determine possible consequences at the third tritrophic level.