David W. Held

Lethal and Sublethal Effects of Bendiocarb, Halofenozide, and Imidacloprid on Harpalus pennsylvanicus (Coleoptera: Carabidae) Following Different Modes of Exposure in Turfgrass

Abstract Routes by which nontarget predatory insects can be exposed to turfgrass pesticides include topical, residual, and dietary exposure. We used each of these routes to evaluate potential lethal or sublethal effects of two novel turfgrass insecticides, imidacloprid and halofenozide, and a carbamate, bendiocarb, on survival, behavior, and fecundity of the ground beetle Harpalus pennsylvanicus DeGeer. Field-collected carabids were exposed to direct spray applications in turf plots, fed food contaminated by such applications, or exposed to irrigated or nonirrigated residues on turf cores. Halofenozide caused no apparent acute, adverse effects through topical, residual, or dietary exposure. Moreover, the viability of eggs laid by females fed halofenozide-treated food once, or continuously for 30 d, was not reduced. In contrast, topical or dietary exposure of carabids to bendiocarb inevitably was lethal. Exposure to imidacloprid by those routes caused high incidence of sublethal, neurotoxic effects including paralysis, impaired walking, and excessive grooming. Intoxicated beetles usually recovered within a few days in the laboratory, but in the field, they were shown to be highly vulnerable to predation by ants. One-time intoxication by imidacloprid did not reduce females’ fecundity or viability of eggs. There was no apparent behavioral avoidance of insecticide residues, or of insecticide-treated food. Carabids exposed to dry residues on turfgrass cores suffered high mortality from bendiocarb, and some intoxication from imidacloprid, but these effects were greatly reduced by posttreatment irrigation. Implications for predicting hazards of insecticides to beneficial invertebrates in turfgrass are discussed.

Hazards of Insecticides to the Bumble Bees Bombus impatiens (Hymenoptera: Apidae) Foraging on Flowering White Clover in Turf

Abstract Insecticides used on turf are sometimes applied to areas with flowering weeds that attract honey bees and native pollinators. We tested residual effects of such treatments on colony vitality and behavior of the bumble bees Bombus impatiens Cresson foraging on turf containing white clover, Trifolium repens L. Imidacloprid, a systemic chloronicotinyl used for preventive control of root-feeding grubs, was applied as granules, followed by irrigation, or sprayed as a wettable powder, with or without irrigation. Hives were confined on the plots in large field cages after residues had dried and colony vitality (i.e., numbers of brood, workers, and honey pots, and weights of queens, workers, and whole colonies with hives) was evaluated after 28–30 d. Workers’ foraging activity and defensive response to an aggressive stimulus also were evaluated. In another test, weedy turf was sprayed with chlorpyrifos, carbaryl, or cyfluthrin at labeled rates for surface-feeding pests. Bee colonies were confined on the plots after residues had dried, with effects on colony vitality evaluated after 14 d. Finally, foraging activity of wild bumble bees was monitored on open plots to determine if insecticide-treated areas were avoided. Imidacloprid granules, and imidacloprid sprays applied with posttreatment irrigation, had no effect on colony vitality or workers’ behavior, suggesting that such treatments pose little systemic or residual hazard to bumble bees. In contrast, exposure to dry nonirrigated residues of all of the aforementioned insecticides had severe impact on colony vitality. Foraging workers did not avoid insecticide-treated areas. Means by which turf managers can reduce hazards of insecticide applications to pollinators are discussed.

Prospects for Managing Turfgrass Pests with Reduced Chemical Inputs

Turfgrass culture, a multibillion dollar industry in the United States, poses unique challenges for integrated pest management. Why insect control on lawns, golf courses, and sport fields remains insecticide-driven, and how entomological research and extension can best support nascent initiatives in environmental golf and sustainable lawn care are explored. High standards for aesthetics and playability, prevailing business models, risk management-driven control decisions, and difficulty in predicting pest outbreaks fuel present reliance on preventive insecticides. New insights into pest biology, sampling methodology, microbial insecticides, plant resistance, and conservation biological control are reviewed. Those gains, and innovations in reduced-risk insecticides, should make it possible to begin constructing holistic management plans for key turfgrass pests. Nurturing the publics interest in wildlife habitat preservation, including beneficial insects, may be one means to change aesthetic perceptions and gain leeway for implementing integrated pest management practices that lend stability to turfgrass settings.

Androthrips ramachandrai (Thysanoptera: Phlaeothripidae): An Introduced Thrips in the United States

Abstract Androthrips ramachandrai Karny is an exotic thrips, assumed to be predacious, and is associated with gall-inducing thrips. It was first reported in the U.S. from FL, and intercepted in CA from Thailand in 2002. We surveyed Ficus spp. with Gynaikothrips-induced galls in AL, CA, FL, HI, LA, MS, and TX, and document that A. ramachandrai is now established in CA, FL, HI, and TX. It probably has been spread by the ornamental horticulture industry. We outline its biology and compare it to a congener A. flavipes, a documented thrips predator. Androthrips ramachandrai has the potential to be a beneficial biological control agent and a hindrance to weed biological control.

Modified Atmosphere Treatments as a Potential Disinfestation Technique for Arthropod Pests in Greenhouses

Abstract Incidental transport of arthropods on plant material can be a significant mode of pest entry into greenhouses. We evaluated the use of controlled atmosphere treatments as a potential way to eliminate arthropod pests on plant propagules (i.e., cuttings or small rooted plants). Lethal exposures to CO2 or N2 were determined for common greenhouse pests including fungus gnat larvae, Bradysia sp.; green peach aphid, Myzus persicae (Sulzer); sweetpotato whitefly, Bemisia sp.; twospotted spider mite, Tetranychus urticae Koch; and western flower thrips, Frankliniella occidentalis (Pergande). We also studied the effect of pest species, life stage, and presence or absence of plants on efficacy of modified atmosphere treatments. Finally, effects of modified atmospheres on plant quality were evaluated for several bedding plant species including begonia, Begonia semperflorens-cultorum Hort. ‘Cocktail Series’, chrysanthemum, Dendranthema grandiflora Tzvelev., geranium, Pelargonium × hortorum L.H. Bailey, and impatiens, Impatiens wallerana Hook f., and among cultivars of geranium and chrysanthemum. Exposure for 12–18 h to >99% N2 or CO2 caused complete mortality of aphids, mites, thrips, and whiteflies. Fungus gnat larvae were more tolerant of hypoxic conditions. Adult mites and eggs were equally susceptible. For most pests, there was no difference in response to atmospheres modified by CO2 or N2. However, there was variation in response among plant species and cultivars, with effects ranging from delayed flowering to mortality. Despite the possibility of adverse effects on some plants, this work indicates that use of modified atmospheres has potential to eliminate arthropod pests on plant propagules before they are introduced into greenhouses.

Absence of food‐aversion learning by a polyphagous scarab, Popillia japonica, following intoxication by geranium, Pelargonium × hortorum

It is commonly held that food‐aversion learning should be more prevalent in polyphagous herbivores than in specialists. We tested the ability of Popillia japonica, a polyphagous scarab, to learn avoidance of a palatable but illness‐inducing plant. Beetles that feed on flowers of geranium, Pelargonium × hortorum, became paralyzed, although most recovered within 24 h. In choice tests, naive beetles strongly preferred geranium petals over leaves of linden, Tilia cordata, a highly suitable host. Experienced beetles maintained this preference although it resulted in repeated bouts of paralysis. Fecundity was >10 times higher for beetles fed linden foliage for 2 wk than for those fed only geranium. Nevertheless, when a surplus of both foods was provided, the beetles fed mainly on geranium, resulting in greatly reduced fecundity. These results contradict the view that generalists should show propensity for food‐aversion learning. Indeed, in this case, P. japonica continued to prefer the toxic plant, compromising its fitness.

Conophthorin enhances the electroantennogram and field behavioural response of Xylosandrus germanus (Coleoptera: Curculionidae) to ethanol

Ethanol acts as an attractant that aids Xylosandrus germanus (Blandford) in locating living but weakened hosts. Electroantennogram (EAG) and field trapping experiments were conducted with conophthorin and other selected semiochemicals that function as important olfactory cues for various ambrosia beetles to characterize their effect on the attraction of X. germanus to ethanol and to assess whether EAG responses provide an indication of behavioural activity. Thus, semiochemicals hypothesized to enhance (i.e. conophthorin), reduce (i.e. terpinolene, verbenone) or have a negligible (i.e. lineatin, sulcatol, retusol) effect on the attraction of X. germanus to ethanol were selected for comparative purposes. Ethanol plus conophthorin elicited larger EAG amplitudes than binary (1 : 1) mixtures of ethanol plus the remaining semiochemicals at dilutions of 0.001%, 0.01% and 1% per compound. Conophthorin also enhanced the attraction of X. germanus, Euwallacea validus (Eichhoff) and Cyclorhipidion pelliculosum (Eichhoff) to ethanol under field conditions. By contrast, terpinolene and verbenone reduced the attraction of X. germanus and other ambrosia beetles to ethanol. Semiochemicals that enhance (i.e. conophthorin) or reduce (i.e. terpinolene, verbenone) attraction by X. germanus may improve monitoring and/or management tactics. These results also suggest that EAG responses can indicate field behavioural activity and be useful for screening attractants for X. germanus.

Characterizing Toxicity of Pelargonium spp. and Two Other Reputedly Toxic Plant Species to Japanese beetles (Coleoptera: Scarabaeidae)

Abstract The Japanese beetle (Popillia japonica Newman), a polyphagous scarab, feeds on certain palatable plants that are toxic, or reputedly toxic. Paralysis of the beetle after consumption of flowers of zonal geranium (Pelargonium × hortorum L. H. Bailey) has been documented, but factors affecting expression and range of this phenomenon are poorly known. Published anecdotes regarding toxicity of two other hosts, larkspur (Delphinium sp.) and bottlebrush buckeye (Aesculus parviflora Walt.), have not been empirically tested. For zonal geraniums, we compared toxicity with P. japonica of flowers versus leaves, sun-grown and shaded plants, and different-colored flowers. The progression of paralysis and recovery, as well as survival of paralyzed beetles under laboratory and field conditions, also were evaluated. Beetles became paralyzed after feeding on flowers of zonal geranium, but not by consuming leaves, suggesting the active compound is unique to flowers. Shaded or sun-grown flowers, and red-, white-, or salmon-colored flowers, were equally active. Beetles generally became paralyzed within 3 h of the onset of feeding. Most of them recovered when held in the laboratory, but paralyzed beetles placed in the field for 3 h did not recover. Flowers of Pelargonium inquinins (L.) L’Héritier, and Pelargonium zonale (L.) L’Héritier, which are the parental species of P. × hortorum, as well as ivy geranium (Pelargonium peltatum [L.] L’Héritier), another member of the type section Ciconium, all were active. Pelargonium × scarborovia, which belongs to the type section Pelargonium, was the only geranium species that did not cause paralysis. Although the active compounds have not been identified, our results suggest that light-activated flavonoids or anacardic acids probably are not responsible for geranium-induced paralysis. Contrary to published anecdotes, neither flowers nor foliage or larkspur and bottlebrush buckeye were toxic to Japanese beetles.

Leaf biomechanical properties as mechanisms of resistance to black cutworm (Agrotis ipsilon) among Poa species

Biomechanical properties can be important parameters in resistance of plants to herbivorous insects. As plants age, however, there can be dramatic changes in physical defenses that can then influence their susceptibility to insect herbivores. We measured changes in leaf biomechanical properties during ontogeny of Poa species and the relationship of these changes to the development of a generalist herbivore, the black cutworm, Agrotis ipsilon Hufnagel (Lepidoptera: Noctuidae), was investigated. Larvae were reared on two representative age classes, i.e., young (<60 days after planting) and old (>1 year after planting), of foliage in laboratory assays. Foliage generally reaches a peak fracture force between 80 and 109 days after planting depending on grass type. Foliage from old plants was significantly tougher than that of young plants, and black cutworm larvae reared on foliage from young plants gained significantly (ca. four times) more weight than those fed on foliage from old Poa plants. In addition, fracture force has a negative relationship with black cutworm development. Plant fiber, particularly neutral detergent fiber accounted for 65 and 46% of the variation in fracture force and larval development, respectively. These results provide additional insight into how plant ontogeny influences physical defenses to an insect herbivore in a grass system. Likewise, this is seemingly the first study to suggest a mechanism for host plant resistance to black cutworm. Plant fiber may be a useful trait to explore in plant improvement programs in which black cutworm is a primary pest (e.g., managed turfgrass).

Asiatic Garden Beetle Maladera castanea (Coleoptera: Scarabaeidae) Grubs Found in Damaged Turf in Alabama

Root-feeding white grubs (Coleoptera: Scara baeidae) are among the most important group of pests attacking grasses in pastures and land scapes in the United States. Throughout the con tinental United States, about 10 species of grubs and several species in the genus Phyllophaga are reported pests of turfgrass (Vittum et al. 1999). In southeastern states, grubs of Phyllophaga, south ern masked chafer (Cyclocephala lurida), the green June beetle (Cotinus nitidia), and Japanese beetles (Popillia japonica) are traditionally asso ciated with damaged turfgrass. However, recent publications (Buss 2006, 2008) challenge the as sumption that just a few species account for the alleged increase in damage to turfgrass from white grubs in the southeast. Furthermore, intro duced and native species may be expanding their range into or throughout the southeast. This pa per documents the occurrence of white grubs of the Asiatic garden beetle Maladera castanea (Ar row), an exotic species, in damaged turfgrass in Alabama. Asiatic garden beetles, native to China and Ja pan, were first detected in New Jersey in 1921. They have since spread to most of the northeast ern states, west to Indiana, and south to South Carolina (Vittum et al. 1999, NAPIS 2008). Spread of Asiatic garden beetles in the northeast was attributed to natural dispersal of adults as well as movement of infested nursery stock and turfgrass (Hawley & Hallock 1936). All known biological information is based on only a few reports (Hawley 1931; Hawley & Hal lock 1936) of populations in the northeastern United States. Adults are nocturnal, emerging when temperatures are 18.3-21.1?C (65-70?F), and actively fly at temperatures >21.1?C (Hawley & Hallock 1936). Adult flight begins in late Jun and can last into the fall. At night, adults are at tracted to lights and light traps are the suggested means of trapping adults (Hawley & Hallock 1936). Adults feed on foliage or flowers of 100 or more hosts (Hawley & Hallock 1936), and spar ingly on grass blades (Heller 1995). Damage to woody and herbaceous plants from adults can be misdiagnosed since the damage appears over night and adults are rarely observed. Damage to foliage begins from the edges, progressing inward until only the midvein remains. Adults seem to prefer flowers attacking roses, chrysanthemums, dahlia, sunflower, strawflowers, and zinnias (Hawley & Hallock 1936), aster, and goldenrod (Vittum et al. 1999). Even though adult damage can be extensive when present, adults are only considered minor pests of ornamentals (Vittum et al. 1999). In daylight hours, adults are in the soil near host plants or in turf adjacent to these host plants. Females lay eggs in clusters in the soil and seem to prefer weedy patches of turf that are well irrigated (Hawley & Hallock 1936; Heller 1995). Eggs are present in the soil beginning in Jul. Eggs absorb moisture from the soil, swell, and hatch (Hawley & Hallock 1936) similarly to other white grubs. Newly-emerged grubs are 1.4 mm long, and develop to 19 mm when mature. There are 3 instars with mature grubs present in the mid-Oct. Grubs can be found under weedy turf, or in fields of sweetpotato, beans, and other field crops (Haw ley & Hallock 1936). Grubs are distinguished from other scarabs by a distinctive raster pattern and enlarged bulbous stipes on the maxillae (Hawley & Hallock 1936; Ritcher 1966). In the northeastern United States, there is 1 generation per year. On 2-3 Oct, 2008, a stand of weedy turfgrass on the Turfgrass Research Unit in Auburn, AL was sampled for grubs. This stand, 27.2 x 21.9 m (90 x 72 ft), is composed mostly of crabgrass (Digitaria sp.), dichondra, and various sedges and grasses. This stand was established in 1997 on a sandy loam soil and recently has been used for herbicide research, and in 2008, the area was irrigated weekly with about 2.54 cm (1 inch) of supplemen tal water and maintained at 3.8 cm (1.5 inch). The area generally stays moist after rain and wet dur ing the winter months. The grubs collected on both days were mostly southern masked chafer (Cyclocephala lurida), a few billbug larvae, 1 Japanese beetle (Popillia japonica) grub, and 5 unidentified larvae. All grubs were collected into containers along with field soil and transported to the lab. The previ ously unidentified grubs had a raster pattern and swollen stipes characteristic of Asiatic garden beetle. The grubs were preserved in ethanol and the identity later confirmed with the key of Ritcher (1966). Grubs had an average length of 17.1 mm (0.67 inch) and head capsule width of 2.77 mm. These data indicate that the grubs are likely third instars (Hawley & Hallock 1936; Ritcher 1966). This is the southernmost report of Asiatic gar den beetle in the United States. Recent trapping studies in Alabama (Flanders et al. 2000) and, in Florida, Buss (2006) did not detect adult M. casta nea in blaeklight trap samples. The Alabama study, conducted in pastures, was within 50 km of