Interspecific Competition Between <i>Eotetranychus sexmaculatus</i> Riley and <i>Oligonychus biharensis</i> Hirst (Acari: Tetranychidae)
<i>Eotetranychus sexmaculatus</i> has long been recognized as an important spider mite pest of rubber trees. Recently, increasing damage from <i>Oligonychus biharensis</i> has elevated its importance as a key spider mite pest. These two species share highly overlapping ecolog...
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| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-01-01
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| Series: | Insects |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2075-4450/16/1/96 |
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| Summary: | <i>Eotetranychus sexmaculatus</i> has long been recognized as an important spider mite pest of rubber trees. Recently, increasing damage from <i>Oligonychus biharensis</i> has elevated its importance as a key spider mite pest. These two species share highly overlapping ecological niches, with outbreaks strongly associated with high temperatures and drought stresses. However, little is known regarding the potential competition between these spider mite species and the role of temperature in shaping these interactions. This study investigates the development and reproduction of <i>E. sexmaculatus</i> and <i>O. biharensis</i> at varying population densities, and evaluates their dynamics at 27 °C, 30 °C, and 33 °C. Five initial population densities of <i>E. sexmaculatus</i> and <i>O. biharensis</i> were evaluated in mixed populations: 0:30, 10:20, 15:15, 20:10, and 30:0. The results demonstrate both intra- and interspecific competition between <i>E. sexmaculatus</i> and <i>O. biharensis</i>. At all three intraspecific densities, the survival rate and lifespan of both species declined as density increased, with fecundity also decreasing at higher densities. Single-species populations of each mite were larger in number when compared with mixed populations. Across all treatments, the mean and peak values of the intrinsic rate of increase (r<sub>m</sub>) were greater in <i>O. biharensis</i> than in <i>E. sexmaculatus</i>. Additionally, increasing temperatures accelerated the displacement of <i>E. sexmaculatus</i> by <i>O. biharensis</i>, regardless of the initial population density. When the mixed populations of <i>E. sexmaculatus</i> and <i>O. biharensis</i> were at densities of 10:20, the highest interspecific competition coefficients were obtained at 33 °C, with values of 0.6591. In conclusion, <i>O. biharensis</i> consistently outcompeted <i>E. sexmaculatus</i> at all tested temperatures, irrespective of initial densities, providing valuable insights into the competitive dynamics of dominant rubber tree pests. |
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| ISSN: | 2075-4450 |