Better insights in plant insect interaction are crucial for the refinement of Economic Injury Levels (EILs) and Economic Thresholds (ETs) in agriculture and form the keystone of any pest management program. Establishing photosynthetic response of potato plants to insects and understanding better the feeding differences between males and females within species are an important step to improving economic decision levels and developing multiple species EILs. However, EILs for defoliating insects are typically based on the number of potential pests without information about intraspecific differences. One potentially important difference which has not been examined for defoliating pests is the individual’s sex. To address this current limit, we compared injury caused by males and females of Colorado potato beetle (Leptionotarsa decemlineata) and examine if this injury would influence the gas exchange parameters of remaining tissue. The experiment was carried out in field conditions on a Fritto Lay proprietary variety at pre-blooming. In 24 h, females ate significantly more tissue than males (t-test, P < 0.05) consuming an average of 3.7 cm2 per individual female compared to 2.1 cm2 per male. The difference in consumption is partially explained by the mass of beetles as females were on average 0.05 grams heavier than males. Despite the difference in leaf tissue removed, plant photosynthetic rates did not differ significantly. Our results show that male and female L. decemlineata differ biological in feeding rate but do not cause differences in plant physiological response. This observation is most important to studies quantifying consumption rates for economically important species.
Species 1: Coleoptera Chrysomelidae Leptinotarsa decemlineata (Colorado potato beetle)
Keywords: defoliation
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