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1. Predictions from the Phylogenetic Constraints Hypothesis were tested for the ®rst time in a tropical system using the pasture pest Deois¯avopicta Stal, which oviposits into the ground and not into plant tissues. The prediction that there is no oviposition preference±larval performance linkage was supported. The absence of such a link provides an evolutionary basis for eruptive population dynamics.2. The effects of host species and host plant quality on the preference of ovipositing females of D.¯avopicta and performance of their offspring on the selected host plants were tested at the population level.3. Female oviposition behaviour was affected by the presence of the host plant. Females of D.¯avopicta showed a strong preference to oviposit close to host plants. The number of eggs was higher in pots containing Brachiaria ruziziensis (121.88 6 13.70) than in pots containing only the wet oviposition substrate (5.2 6 1.98) or dry oviposition substrate (0.067 6 0.067). Ovipositing females did not, however, discriminate between plants of Brachiaria decumbens and Axonopus marginatus and did not show a strong oviposition preference in relation to differences in plant quality (protein and ®bre content). They did show oviposition preference for plants under the high watering regime. The mean number of eggs collected from pots with non water-stressed plants was 60% higher than the mean number of eggs collected on pots with water-stressed plants.4. Although females did not show ovipositional preference, spittlebug larval performance, measured as percentage survival and duration of nymphal period, was better on plants of high protein and low ®bre content. These results indicate that there is not a linkage between female oviposition preference and subsequent nymphal performance in relation to differences in protein and ®bre content in the host plants. There was, however, a limited linkage between oviposition preference and nymphal performance in relation to plant water content. Females showed preference for moist sites that have high survival of newly hatched nymphs.5. Evidence indicates that for D.¯avopicta, the in¯uences of natality and female oviposition behaviour in response to plant quality are not the major factors driving population outbreaks, which is in accordance with the Phylogenetic Constraints Hypothesis.

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