title: 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).
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.
authors.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.
authors.forename: Aiming
authors.initials: A
authors.lastname: Zhou
authors.affiliation: Red Imported Fire Ant Research Center, South China Agricultural University, Guangzhou 510642, China.
authors.forename: Beiqing
authors.initials: B
authors.lastname: Kuang
authors.affiliation: Red Imported Fire Ant Research Center, South China Agricultural University, Guangzhou 510642, China.
authors.forename: Yingrui
authors.initials: Y
authors.lastname: Gao
authors.affiliation: Red Imported Fire Ant Research Center, South China Agricultural University, Guangzhou 510642, China.
authors.forename: Guangwen
authors.initials: G
authors.lastname: Liang
mesh_terms: D000818:Animals; D001000:Ants; D006430:Hemiptera; D011156:Population Density; D013559:Symbiosis / Q000502:physiology*