Wing shape variations in an invasive moth are related to sexual dimorphism and altitude.

Wing morphology has great importance in a wide variety of aspects of an insect's life. Here, we use a geometric morphometric approach to test the hypothesis that variation, in insect wing morphology patterns, occurs between sexes and along altitudinal gradients for invasive species, despite their recent association to this environment. We explored the variation in wing morphology between 12 invasive populations of the invasive potato pest, Tecia solanivora, at low and high altitude in the central highlands of Ecuador. After characterizing sexual dimorphism in wing shape, we investigated if moths at higher elevations differ in wing morphology from populations at lower altitudes. Results indicate wing shape and size differences between sexes and between altitudinal ranges. Females showed larger, wider wings than males, while high altitude moths showed larger, narrow-shaped wings by comparison to low-altitude moths. GLM analyses confirmed altitude was the only significant determinant of this gradient. Our study confirms a sexual dimorphism in size and wing shape for the potato moth. It also confirms and extends predictions of morphological changes with altitude to an invasive species, suggesting that wing morphology variation is an adapted response contributing to invasion success of the potato moth in mountainous landscapes. Ours is one of the first studies on the morphology of invasive insects and represents a valuable contribution to the study of insect invasions because it both offers empirical support to previous genetic studies on T. solanivora as well as proving broader insight into the mechanisms behind morphological evolution of a recently introduced pest.

Temperature as a key driver of ecological sorting among invasive pest species in the tropical Andes.

Invasive species are a major threat to the sustainable provision of ecosystem products and services, both in natural and agricultural ecosystems. To understand the spatial arrangement of species successively introduced into the same ecosystem, we examined the tolerance to temperature and analyzed the field distribution of three potato tuber moths (PTM, Lepidoptera: Gelechiidae), that were introduced in Ecuador since the 1980s. We studied physiological responses to constant temperatures of the three PTM species under laboratory conditions and modeled consequences for their overall population dynamics. We then compared our predictions to field abundances of PTM adults collected in 42 sites throughout central Ecuador. Results showed that the three PTM species differed with respect to their physiological response to temperature. Symmetrischema tangolias was more cold tolerant while Tecia solanivora had the highest growth rates at warmer temperatures. Phthorimaea operculella showed the poorest physiological performance across the range of tested temperatures. Overall, field distributions agree with predictions based on physiological experiments and life table analyses. At elevations >3000 m, the most cold-tolerant species, S. tangolias, was typically dominant and often the only species present. This species may therefore represent a biological sensor of climate change. At low elevations (<2700 m), T. solanivora was generally the most abundant species, probably due to its high fecundity at high temperatures. At mid elevations, the three species co-occurred, but P. operculella was generally the least abundant species. Consistent with these qualitative results, significant regression analyses found that the best predictors of field abundance were temperature and a species x temperature interaction term. Our results suggest that the climatic diversity in agricultural landscapes can directly affect the community composition following sequential invasions. In the tropical Andes, as in other mountain ecosystems, the wide range of thermal environments found along elevational gradients may be one reason why the risks of invasion by successively introduced pest species could increase in the near future. More data on potential biological risks associated with climatic warming trends in mountain systems are therefore urgently needed, especially in developing nations where such studies are lacking.