Variation in Host Plant Usage and Diet Breadth Predict Sibling Preference and Performance in the Neotropical Tortoise Beetle Chelymorpha alternans (Coleoptera: Chrysomelidae: Cassidinae).

Abstract

Specialized interactions between insects and the plants that they consume are one of the most ubiquitous and consequential ecological associations on the plant. Decades of investigation suggest that a narrow diet favors an individual phytophagous insect's performance relative to a dietary generalist. However, this body of research has tended to approach questions of diet breadth and host usage from the perspective of temperate plant-insect associations. Relationships between diet breadth, host usage, and variation in tropical insect preference and performance remain largely uninvestigated. Here we characterize how variation in diet breadth and host usage affect oviposition preference, development, survival, and gain in mass of a Neotropical tortoise beetle Chelymorpha alternans Boheman 1854 (Coleoptera: Chrysomelidae), using a split-brood, sibling experimental design. Host performance was measured after splitting broods among four no-choice host diets. Groups consuming single hosts varied among themselves in developmental time and survival from larva to adult. Performance did not vary among groups consuming multiple and single hosts. Oviposition preference was measured in choice and no-choice tests. Females displayed preference for the original host in both experiments. Developmental time and survival of offspring sourced from the no-choice experiment was measured for two complete generations to explore correlations with female oviposition preference. Preference for the original host correlated with high survivorship and an intermediate developmental time. Survivorship and time to develop were also high on an alternative host that was less preferred. Departures from predictions of prevailing preference-performance hypotheses suggest that host usage presents C. alternans with fitness trade-offs.