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Density-dependent benefits in ant-hemipteran mutualism? The case of the ghost ant Tapinoma melanocephalum (Hymenoptera: Formicidae) and the invasive mealybug Phenacoccus solenopsis (Hemiptera: Pseudococcidae).

Zhou A, Kuang B, Gao Y, Liang G - PLoS ONE (2015)

Bottom Line: Although density-dependent benefits to hemipterans from ant tending have been measured many times, few studies have focused on integrated effects such as interactions between ant tending, natural enemy density, and hemipteran density.Our results showed that mealybug colony growth rate and percentage parasitism were significantly affected by ant tending, parasitoid presence, and initial mealybug density separately.These results suggest that benefits to mealybugs are density-independent and are affected by ant tending level.

View Article: PubMed Central - PubMed

Affiliation: Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, People's Republic of China; Red Imported Fire Ant Research Center, South China Agricultural University, Guangzhou 510642, China.

ABSTRACT
Although density-dependent benefits to hemipterans from ant tending have been measured many times, few studies have focused on integrated effects such as interactions between ant tending, natural enemy density, and hemipteran density. In this study, we tested whether the invasive mealybug Phenacoccus solenopsis is affected by tending by ghost ants (Tapinoma melanocephalum), the presence of parasitoids, mealybug density, parasitoid density and interactions among these factors. Our results showed that mealybug colony growth rate and percentage parasitism were significantly affected by ant tending, parasitoid presence, and initial mealybug density separately. However, there were no interactions among the independent factors. There were also no significant interactions between ant tending and parasitoid density on either mealybug colony growth rate or percentage parasitism. Mealybug colony growth rate showed a negative linear relationship with initial mealybug density but a positive linear relationship with the level of ant tending. These results suggest that benefits to mealybugs are density-independent and are affected by ant tending level.

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Relationship between percentage of parasitism and ant tending level.* above bars indicates statistically significant differences between the two treatments ( P<0.05), different letters above bars indicate significant differences among the treatments (P<0.05).
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pone.0123885.g006: Relationship between percentage of parasitism and ant tending level.* above bars indicates statistically significant differences between the two treatments ( P<0.05), different letters above bars indicate significant differences among the treatments (P<0.05).

Mentions: The colony growth rate of mealybugs showed a negative linear relationship with the initial mealybug density both in the presence and in the absence of ants (Fig 5A, Ants present: Y = -0.033X+6.979, R2 = 0.679, P<0.001; Ants absent: Y = -0.007X+3.009, R2 = 0.377, P = 0.004; and S3 Dataset), and there was a significant difference in the slopes of those two lines (F = 19.323, df = 1, P<0.001). When the mealybug density was greater than approximately 150 individuals per plant, the growth rate of the mealybug colony on ant-tended plants was less than that on untended plants (Fig 5A). In contrast, there was a positive linear relationship between the level of ant tending and the colony growth rate of mealybugs (Fig 5B: Y = 20.911X+1.545, R2 = 0.515, P<0.001, and S3 Dataset). There was a negative linear relationship between the percentage of parasitism and the level of ant tending (Fig 6: Y = -1.198X+0.359, R2 = 0.619, P<0.001, and S3 Dataset).


Density-dependent benefits in ant-hemipteran mutualism? The case of the ghost ant Tapinoma melanocephalum (Hymenoptera: Formicidae) and the invasive mealybug Phenacoccus solenopsis (Hemiptera: Pseudococcidae).

Zhou A, Kuang B, Gao Y, Liang G - PLoS ONE (2015)

Relationship between percentage of parasitism and ant tending level.* above bars indicates statistically significant differences between the two treatments ( P<0.05), different letters above bars indicate significant differences among the treatments (P<0.05).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4401700&req=5

pone.0123885.g006: Relationship between percentage of parasitism and ant tending level.* above bars indicates statistically significant differences between the two treatments ( P<0.05), different letters above bars indicate significant differences among the treatments (P<0.05).
Mentions: The colony growth rate of mealybugs showed a negative linear relationship with the initial mealybug density both in the presence and in the absence of ants (Fig 5A, Ants present: Y = -0.033X+6.979, R2 = 0.679, P<0.001; Ants absent: Y = -0.007X+3.009, R2 = 0.377, P = 0.004; and S3 Dataset), and there was a significant difference in the slopes of those two lines (F = 19.323, df = 1, P<0.001). When the mealybug density was greater than approximately 150 individuals per plant, the growth rate of the mealybug colony on ant-tended plants was less than that on untended plants (Fig 5A). In contrast, there was a positive linear relationship between the level of ant tending and the colony growth rate of mealybugs (Fig 5B: Y = 20.911X+1.545, R2 = 0.515, P<0.001, and S3 Dataset). There was a negative linear relationship between the percentage of parasitism and the level of ant tending (Fig 6: Y = -1.198X+0.359, R2 = 0.619, P<0.001, and S3 Dataset).

Bottom Line: Although density-dependent benefits to hemipterans from ant tending have been measured many times, few studies have focused on integrated effects such as interactions between ant tending, natural enemy density, and hemipteran density.Our results showed that mealybug colony growth rate and percentage parasitism were significantly affected by ant tending, parasitoid presence, and initial mealybug density separately.These results suggest that benefits to mealybugs are density-independent and are affected by ant tending level.

View Article: PubMed Central - PubMed

Affiliation: Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, People's Republic of China; Red Imported Fire Ant Research Center, South China Agricultural University, Guangzhou 510642, China.

ABSTRACT
Although density-dependent benefits to hemipterans from ant tending have been measured many times, few studies have focused on integrated effects such as interactions between ant tending, natural enemy density, and hemipteran density. In this study, we tested whether the invasive mealybug Phenacoccus solenopsis is affected by tending by ghost ants (Tapinoma melanocephalum), the presence of parasitoids, mealybug density, parasitoid density and interactions among these factors. Our results showed that mealybug colony growth rate and percentage parasitism were significantly affected by ant tending, parasitoid presence, and initial mealybug density separately. However, there were no interactions among the independent factors. There were also no significant interactions between ant tending and parasitoid density on either mealybug colony growth rate or percentage parasitism. Mealybug colony growth rate showed a negative linear relationship with initial mealybug density but a positive linear relationship with the level of ant tending. These results suggest that benefits to mealybugs are density-independent and are affected by ant tending level.

Show MeSH