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Background <p>This study focused on examining the predatory potential of <i>Chrysoperla zastrowi sillemi</i> Esben-Peterson (Neuroptera: Chrysopidae) against different developmental stages of the red spider mite (RSM) <i>Oligonychus coffeae</i> Nietner (Acarina: Tetranychidae) infesting tea crops, under both free-choice and no-choice scenarios at three different temperature gradients: 20&#xa0;°C, 25&#xa0;°C, and 30&#xa0;°C. Additionally, this study aimed to investigate the functional response parameters of the three larval instars of <i>C. z. sillemi</i> at different developmental stages of <i>O. coffeae</i> at varying population densities. </p> Results <p>The predatory potential of <i>C. z. sillemi</i> significantly increased with higher temperatures and predator stages and decreased with the prey stage in both free-choice and no-choice conditions. In both experimental regimes, all three larval instars showed maximum predation at 25 and 30&#xa0;°C. All three instars exhibited a significant preference for <i>O. coffeae</i> eggs compared to other stages. The functional response data also indicated that the first, second, and third instars of <i>C. z. sillemi</i> displayed type II functional responses towards each life stage of <i>O. coffeae</i> when offered individually. They showed significantly different attack rates (<i>a</i>) and handling times (<i>T</i><sub><i>h</i></sub>) for the various life stages of <i>O. coffeae.</i> Eggs were more frequently attacked, with less handling time, by all three predatory stages of <i>C. z. sillemi</i>. Among the three predatory stages, the third instar larvae of <i>C. z. sillemi</i> showed the highest functional response ratio on eggs (FRR = 1173.35), followed by larvae (872.19), nymphs (287.11), and adults (276.57). The theoretical maximum consumption (<i>T/T</i><sub><i>h</i></sub>) of <i>C. z. sillemi</i> also supported the results obtained for <i>a/T</i><sub><i>h</i></sub>, indicating that the predatory efficiency of <i>C. z. sillemi</i> decreased with the advancement of the prey stage.</p> Conclusions <p>In conclusion, third-instar larvae of <i>C. z. sillemi</i> consumed significantly higher amounts of all prey stages of <i>O. coffeae</i> at temperatures between 25 and 30&#xa0;°C in both free- and no-choice conditions. The functional response results suggest that all three larval instars of <i>C. z. sillemi</i> exhibited a type-II response and are efficient regulators of <i>O. coffeae</i> populations. These findings may lead to the development of biocontrol pest management strategies against <i>O. coffeae,</i> by incorporating <i>C. z. sillemi</i> as a potential natural enemy.</p>

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Predatory potential and functional responses of Chrysoperla zastrowi sillemi Esben-Peterson (Neuroptera: Chrysopidae) against the red spider mite, Oligonychus coffeae Nietner (Acarina: Tetranychidae), a major pest of tea

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  • 发表日期：

    2025年6月12日

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  • Nagaraj Santhana Bharathi,
  • Krishnaswamy Sujatha,
  • Thattante Parambil Rabeesh

摘要

Background

This study focused on examining the predatory potential of Chrysoperla zastrowi sillemi Esben-Peterson (Neuroptera: Chrysopidae) against different developmental stages of the red spider mite (RSM) Oligonychus coffeae Nietner (Acarina: Tetranychidae) infesting tea crops, under both free-choice and no-choice scenarios at three different temperature gradients: 20 °C, 25 °C, and 30 °C. Additionally, this study aimed to investigate the functional response parameters of the three larval instars of C. z. sillemi at different developmental stages of O. coffeae at varying population densities.

Results

The predatory potential of C. z. sillemi significantly increased with higher temperatures and predator stages and decreased with the prey stage in both free-choice and no-choice conditions. In both experimental regimes, all three larval instars showed maximum predation at 25 and 30 °C. All three instars exhibited a significant preference for O. coffeae eggs compared to other stages. The functional response data also indicated that the first, second, and third instars of C. z. sillemi displayed type II functional responses towards each life stage of O. coffeae when offered individually. They showed significantly different attack rates (a) and handling times (Th) for the various life stages of O. coffeae. Eggs were more frequently attacked, with less handling time, by all three predatory stages of C. z. sillemi. Among the three predatory stages, the third instar larvae of C. z. sillemi showed the highest functional response ratio on eggs (FRR = 1173.35), followed by larvae (872.19), nymphs (287.11), and adults (276.57). The theoretical maximum consumption (T/Th) of C. z. sillemi also supported the results obtained for a/Th, indicating that the predatory efficiency of C. z. sillemi decreased with the advancement of the prey stage.

Conclusions

In conclusion, third-instar larvae of C. z. sillemi consumed significantly higher amounts of all prey stages of O. coffeae at temperatures between 25 and 30 °C in both free- and no-choice conditions. The functional response results suggest that all three larval instars of C. z. sillemi exhibited a type-II response and are efficient regulators of O. coffeae populations. These findings may lead to the development of biocontrol pest management strategies against O. coffeae, by incorporating C. z. sillemi as a potential natural enemy.