ponsored Research You Can Use Resistant Turfgrasses for Improved Chinch Bug Management University of Nebraska researchers document multiple chinch bug resistance in cool- and warm-season turfgrasses. BY TIFFANY M. HENG-MOSS, F. P. BAXENDALE, R. C. SHEARMAN, AND T. E. EICKHOFF umerous arthropods are important pests of the cool- Nand warm-season turf grasses commonly found on golf courses. Turf- grasses are subject to injury by insect and mite pests, and several are known to have increased susceptibility to certain sap-feeding insects, including chinch bugs. In the United States there are four chinch bug species that are of major economic importance: common chinch bug (Blissus leucopterus leucopterus), southern chinch bug (Blissus insularis), hairy chinch bug (Blissus leucopterus), and western chinch bug (Blissus occiduus).8 Chinch bugs are widely dis- tributed throughout the United States, primarily east of the Rocky Mountains. Individual species often have overlap- Researchers at the University of Nebraska evaluated selected cool- and warm-season turfgrasses for ping geographic distributions. In par- resistance to chinch bugs in the Blissus complex, and documented the presence of multiple chinch bug ticular, the geographic distribution of resistance in these turfgrasses. the western chinch bug, and its pre- ferred host, buffalograss, are such that The hairy chinch bug is distributed has been reported feeding on timothy any of the other chinch bug species throughout the northeastern United grass. could be present in adjacent turfgrasses. States. Its range includes southern The southern chinch bug ranges from Furthermore, all four chinch bug species regions of the eastern Canadian southern North Carolina southward to have extensive documented host ranges. provinces, parts of the Midwest to the Florida Keys and into eastern and The common chinch bug is widely Minnesota, and into the Mid-Atlantic southeastern portions of Texas. This distributed across the east coast and States as far south asVirginia. It is an chinch bug is considered the most de- western plains of the United States and important pest of most cool-season structive pest of St. Augustinegrass. It south in Mexico. The most common turf grasses, including creeping bent- also occasionally infests bahiagrass, ber- hosts of this chinch bug include wheat, grass, Kentucky bluegrass, perennial mudagrass, centipedegrass, and zoysia- sorghum, corn, and several turf grasses ryegrass, and fine-leaf fescues. The hairy grass, and it has been reported feeding (bermudagrass, Kentucky bluegrass, tall chinch bug is also an occasional pest of on crabgrass, guineagrass, pangolagrass, fescue, and zoysiagrass). zoysiagrass and St. Augustinegrass, and it torpedograss, and tropical carpetgrass. JANUARY-FEBRUARY 2006 7 /:~~.- Jrr', ~ ~ ~J:'-~ " :i_/'-~J ~~"""~ .. ':tJ '. ~~)J ~ cello .. ~r;.I' .,,:.-<F ,# .. ~ Chinch bugs are widely distributed throughout the United States, primarily east of the Rocky Mountains. Individual species often have overlapping geographic distributions. Shown, left to right, are the distribution of common chinch bugs, hairy chinch bugs, southern chinch bugs, and western chinch bugs. The distribution of the western provide new information that will with reddish-yellow legs and are about chinch bug includes much of the cen- facilitate improved monitoring and Yto to 116 inch, depending on the sex and tral United States, north into Canada, detection of chinch bug infestations species. Females are typically larger and and south into Mexico. First detected before they build to damaging levels. more robust than males. infesting a heavily damaged buffalograss Increased knowledge of the biology Most chinch bug adults have shiny lawn in Lincoln, Nebraska, in 1989, and host range. of this chinch bug will white wings that extend back over the these chinch bugs have subsequently aid in the development of more abdomen, but wing dimorphism is been found associated with buffalograss efficient management approaches. common, with both macropterous throughout Nebraska and surrounding (long-winged) and brachypterous areas.3 More recently, the western BASIC CHINCH BUG (short-winged) forms present in certain chinch bug has become a pest of BIOLOGY species. Chinch bugs tend to feed in ZOYSlagrass. The immature stages of all chinch bug aggregations and often produce a char- Recent studies at the University of species are similar in appearance. Chinch acteristic odor from scent glands when Nebraska have shown that this chinch bug eggs are elongate, whitish, and disturbed or crushed. Most chinch bug bug has an extensive host range, includ- average < Y25 inch (1.0 mm) in length species have two generations per year ing buffalograss, zoysiagrass, Kentucky when first laid. As the embryo develops, and overwinter as adults. bluegrass, tall fescue, bermudagrass, and the egg takes on an orange-red color, Chinch bugs injure grasses by with- perennial ryegrass.4 Among the turf- with the nymphal chinch bug visible drawing sap from plant tissues in the grasses tested, offspring were produced within the egg before hatching. First crown area. While feeding, they also on buffalograss, fine fescue, perennial instars are tiny « Y25 inch), long, bright- may inj ect a salivary toxin that damages ryegrass, bentgrass, zoysiagrass, Kentucky red insects with a distinctive white band plant tissues and inhibits the transloca- bluegrass, and tall fescue, demonstrating across the abdomen. As nymphs mature tion of water and nutrients. Initially, this that the western chinch bug can repro- through five nymphal stages, their color feeding results in reddish-purple dis- duce on a wide variety of hosts. These gradually changes to orange-brown and coloration of the leaves. In the turf results have profound implications and finally to dark brown. Adults are black stand, damage appears as patchy areas 8 GREEN SECTION RECORD that turn yellow and dry to a straw- pests affecting turfgrasses. One such Turfgrasses with resistance to the brown color as feeding progresses. At approach involves the use of integrated chinch bug species have been identified higher infestation levels, chinch bug pest management (IPM). This strategy in both cool- and warm-season turf- feeding can result in severe thinning or employs all suitable techniques in as grasses. However, few of the recently death of the turfgrass stand. complementary and environmentally released cultivars have been evaluated Damage is usually the heaviest in compatible a manner as possible to for chinch bug resistance, and it remains sunny locations during hot, dry periods maintain pest populations below dam- unclear if turf grasses with resistance to and is often mistaken for drought stress. aging levels. IPM tactics include cultural, one chinch species may also be resistant Chinch bug infestations are less likely mechanical, biological, and chemical to one or more of the other species. to develop in years when spring and controls, and the use of plant resistance The USGA helped to fund a project summer rainfall and temperature are to insects. The development of turf- that focused on evaluating selected near or below normal. This occurs in grasses with resistance to chinch bugs cool- and warm-season turf grasses for part because fungal diseases keep chinch offers an attractive approach for manag- resistance to chinch bugs in the Blissus bugs under control. These diseases are ing insect pests associated with turf- complex, and documenting any inci- much less likely to develop during grasses because it is sustainable and dence of multiple resistance. This infor- periods of drought, and following environmentally responsible. mation is fundamentally important for several dry seasons chinch bug numbers The idea behind plant resistance is to developing chinch bug-resistant turf- can build to damaging levels. exploit natural plant defense systems. grasses through conventional breeding Turfgrasses possess a variety of natural and biotechnological techniques. PLANT defense mechanisms to overcome biotic RESISTANCE stresses such as insect feeding. These RESISTANCE TO THE Historically, insecticides have been defense mechanisms can be based on WESTERN CHINCH BUG employed as the principal method to physical or chemical characteristics of Greenhouse and field screening studies control chinch bugs. However, concern the turfgrass. In some cases, the turf grass were initiated to search for buffalo- for reducing pesticide inputs has under- is able to tolerate insect feeding through grasses, bermudagrasses, and zoysia- scored the need for developing alterna- physiological and biochemical grasses with resistance to the western tive approaches for controlling insect modifications . chinch bug. Forty-eight buffalograss JANUARY-FEBRUARY 2006 9 genotypes from diverse geographical other management approaches. In spite Several zoysiagrasses and bermuda- locations were evaluated in replicated of its advantages, the use of tolerance grasses were also evaluated for resistance studies under greenhouse conditions. for pest management is limited primarily to the western chinch bug. The zoysia- Based on turfgrass damage ratings, because the mechanisms and genetics of grass "Emerald" and bermudagrass 4 were categorized as higWy resistant, plant tolerance remain unknown. "Mini Verde" displayed the highest level 22 were moderately resistant, 19 were Studies are currently underway to of resistance, while the zoysiagrasses moderately susceptible, and 3 were investigate the biochemical and physio- "Myer,"