Abstract Ecological fitness characters of the brown planthopper increased proportionally with
increase in nitrogen content of rice plants they were bred on. The nymphs survived better and
had shorter life spans. Females weighed heavier, laid more eggs and lived longer. In addition,
egg hatchability was sig nificantly increased. Number of insects and dry mass from one pair
of parents were also significantly higher in high nitrogen plants. Relationships between each
of these characters with nitrogen content fitted the linear models well. These characters from
insects reared on four successive generations in low, medium and high nitrogen regimes were
also investigated. There was little between-generation difference in most characters,
except for the population and its dry mass produced by one pairs of insects. This
implies that in areas where nitrogen-rich crops are abundant over long periods, ecological fitness
of the brown planthoppers are potentially higher and if natural biological control is
compromised, the risk of extensive outbreaks are higher. Implications to sudden stoppage of
insecticide use in these areas are also discussed.
Abstract Ecological fitness characters of the brown planthopper increased proportionally with increase in nitrogen content of rice plants they were bred on. The nymphs survived better and had shorter life spans. Females weighed heavier, laid more eggs and lived longer. In addition, egg hatchability was sig nificantly increased. Number of insects and dry mass from one pair of parents were also significantly higher in high nitrogen plants. Relationships between each of these characters with nitrogen content fitted the linear models well. These characters from insects reared on four successive generations in low, medium and high nitrogen regimes were also investigated. There was little between-generation difference in most characters, except for the population and its dry mass produced by one pairs of insects. This implies that in areas where nitrogen-rich crops are abundant over long periods, ecological fitness of the brown planthoppers are potentially higher and if natural biological control is compromised, the risk of extensive outbreaks are higher. Implications to sudden stoppage of insecticide use in these areas are also discussed.
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