Aggregation behavior of the southern chinch bug (Hemiptera: Blissidae)

Authors: Addesso, Karla; MCAUSLANE, H - University Of Florida; CHERRY, R - University Of Florida

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/29/2012
Publication Date: 6/1/2012
Citation: Addesso, K.M., Mcauslane, H.J., Cherry, R. 2012. Aggregation behavior of the southern chinch bug (Hemiptera: Blissidae). Environmental Entomology. 41(4):887-895.

Interpretive Summary: Insects which aggregate in nature often use a combination of visual, physical and chemical cues to form their aggregations. Aggregation behavior can be particularly detrimental in agricultural systems, where high densities of insect herbivores have a dramatic effect on plant vigor. The southern chinch bug is one of a group of chinch bugs which feed on lawn and forage grasses and small grains. The southern chinch bug has a highly aggregative lifestyle which leads to the death of grass where aggregations form. Scientists at CMAVE in Gainesville and the University of Florida conducted laboratory experiments in order to better understand the cues and signals involved in the formation of southern chinch bug aggregations. We discovered that when placed together in an arena, southern chinch bugs will form aggregations without the presence of grass or any other substrate to hide under. The bugs formed aggregations under light and in total darkness and so do not require visual cues to find one another. When artificial ‘shelters’ made from paper were provided, the chinch bugs did not preferentially gather on or under them – suggesting that physical/leaf-like structures are unnecessary for aggregation. When presented with only the odor of a chinch bug aggregation, adult males, females and nymphs walked toward it. Adults and nymphs were also attracted to the odor of adult females. Nymphs were attracted to one another as well, but adults did not respond to the odor of immatures. Adults and nymphs were attracted to the smell of grass but only males preferred the smell of a combination of grass and aggregation over grass alone. The results of these assays suggest that a complex combination of life stage, sex, as well as plant and insect-derived signals influence southern chinch bug aggregation behavior. These results will be useful in seeking out new management technologies for the southern chinch bug as well as forming the basis for future behavioral research on related chinch bug pests.

Technical Abstract: The southern chinch bug, Blissus insularis Barber, forms dense, multigenerational aggregations in St. Augustinegrass lawns leading to grass death from sap feeding. We conducted several bioassays to better understand the signals responsible for the formation and maintenance of southern chinch bug aggregations. In small arenas, chinch bugs demonstrated a stronger aggregation response over time and aggregated more often on or beneath leaf blades, but not on artificial leaf shelters constructed from white or green paper. In Y-tube olfactometer assays, all bugs were attracted to volatiles from mixed-sex chinch bug aggregations and were even more strongly attracted to groups of adult female chinch bugs. Adult males and nymphs were also attracted to adult males. Nymphs were attracted to nymphs and were also more attracted to aggregation volatiles when they could see bugs in the arm of the Y-tube. Adult males were more attracted to short-winged than long-winged adults, while females and nymphs demonstrated no preference. All bugs were attracted to St. Augustinegrass volatiles when presented alone, but only males preferred the odor of grass over odor released from a chinch bug mixed-sex aggregation. When presented with a choice of grass and grass + aggregation volatiles, males preferred the combined treatment. The results of these assays suggest that a complex combination of life stage, sex, as well as plant and insect-derived signals influence chinch bug aggregation behavior.