Invasive Species Compendium

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Abstract

Multi-modal oviposition model of overwintered Unaspis yanonensis (Hemiptera: Diaspididae) females and its field validation.

Abstract

A multi-modal oviposition model of overwintered Unaspis yanonensis (Kuwana) (Hemiptera: Diaspididae) was developed to predict the population of crawlers in citrus orchards for future incorporation into a population model of U. yanonensis. Three temperature-dependent components, namely, temperature-dependent total fecundity (TDF), age-specific cumulative oviposition rate (ACO), and age-specific survival rate (ASR) functions, were incorporated into the oviposition model. Overwintered U. yanonensis females showed cyclic oviposition activity. Thus, we assumed that the oviposition curve of U. yanonensis consisted of three independent oviposition cycles, and therefore estimated both TDF and ACO curves. The ASR curve, however, was not separated into three cycles. The chronological age of U. yanonensis was converted into a normalized age by the summation of pre-oviposition completion rates (1/pre-oviposition time in days). The estimated models of TDF, ACO, and ASR were successfully integrated to construct the multi-modal oviposition model. The model outputs accurately reflected the actual temporal abundances of U. yanonensis crawlers, displaying characteristic bimodality in the field. The peak time predictability of the model was largely robust. The mean discrepancies were no more than 3 days in all cases as indicated by one-tailed one sample t-test. Also, the Chi-square test showed no significant difference between observed and predicted peak dates. Furthermore, the model showed high robustness, as the Pearson's correlation coefficients between actual observations and model outputs indicated significantly positive values and were mostly high values >0.80. Consequently, the developed oviposition model should be useful for timing control action targeting on the crawler population in citrus orchards.