Ted E. Cottrell

Factors influencing dispersal of larval Coleomegilla maculata from the weed Acalypha ostryaefolia to sweet corn

The polyphagous predator, Coleomegilla maculata (DeGeer) (Coleoptera: Coccinellidae), commonly oviposits on the native weed, Acalypha ostryaefolia Riddell (Euphorbiaceae), in and around Kentucky sweet corn fields. Cannibalism of eggs by C. maculata adults and larvae is drastically lower on A. ostryaefolia than on nearby sweet corn plants. We examined ovipositional preference of C. maculata for A. ostryaefolia plants or sweet corn plants, dispersal of larvae from A. ostryaefolia plants, capability for dispersal of larvae across bare soil (e.g., to nearby plants), ability of larvae to climb from ground level up A. ostryaefolia plants or sweet corn plants, and effect of A. ostryaefolia borders adjacent to sweet corn plots on C. maculata population density in sweet corn. The ovipositional preference study revealed that C. maculata laid more eggs on A. ostryaefolia than on corn. First‐instar C. maculata that hatched from egg clusters on A. ostryaefolia dispersed predominantly by falling, rather than crawling, to the ground. Glandular trichomes on A. ostryaefolia petioles and stems apparently inhibited intraplant movement of first instars, resulting in those larvae falling directly from leaves to the ground. Some first instars were capable of moving at least 8 m across bare soil in 24 h. From the ground, significantly more first instars climbed sweet corn plants than climbed A. ostryaefolia plants. Significantly more larvae were present in sweet corn plots bordered by A. ostryaefolia plants than in sweet corn plots without an A. ostryaefolia border. These findings show that physical attributes of companion plants can significantly influence natural enemy populations on crop plants by affecting interplant dispersal of natural enemies.

Hosts of Plum Curculio, Conotrachelus nenuphar (Coleoptera: Curculionidae), in Central Georgia

Abstract Potential host plants for the larvae of plum curculio, Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae), in central Georgia’s peach producing region were surveyed. This fruit-attacking curculionid is reported to have a broad host range, including many plants in the Rosaceae and other families. However, our collections indicated that in this region plum curculio largely is limited to peach (Prunus persica) and plum (P. angustifolia and P. umbellata). Abandoned peach orchards and wild plum thickets are important hosts for the spring generation of plum curculio and are sources of subsequent infestations of managed peach orchards. However, only abandoned peach orchards were available to the summer generation of plum curculio. May haw, Crataegus aestivalis, was also a host, but other species of Crataegus were not used. Although the plum curculio was reported to be a significant pest of blueberries (Vaccinium spp.) in North Carolina, New Jersey, and Delaware, they were only rarely used as a host in central Georgia. Apple (Malus domestica) and Asian pear (Pyrus pyrifolia), when available, were ovipositional hosts of plum curculio in central Georgia; however, no larvae emerged from these hosts. We report the first records of plum curculio developing in Vaccinium stamineum and Vitis rotundifolia. Our results are compared with a previous survey conducted in the northeastern United States, as well as to data reported in the literature.

INVERTEBRATE PREDATORS AND PARASITOIDS OF PLUM CURCULIO, CONOTRACHELUS NENUPHAR (COLEOPTERA: CURCULIONIDAE) IN GEORGIA AND FLORIDA

Abstract The extent of predation and parasitism on larvae of the plum curculio, Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae), was measured independently with several different experimental designs at sites in northern Florida and central Georgia. Experimental manipulation in Monticello, FL, and in Byron, GA, demonstrated equivocal impacts by predation. However, direct observations in Byron, GA, revealed that ants are the dominant invertebrate predators of plum curculio larvae, causing up to 62% mortality. Primary ant predators included Solenopsis invicta (Buren) (Hymenoptera: Formicidae) and Dorymyrmex bureni (Trager) (Hymenoptera: Formicidae). Predation may be more important later in the season when infested fruit does not abscise and plum curculio larvae must drop to the ground from the trees and spend a considerable time burrowing into the soil. This contrasts with the early season when infested fruit abscise and larvae crawl from the fruit directly into the soil, reducing their exposure to predators. Recorded parasites included Nealiolus curculionis (Fitch) (Hymenoptera: Braconidae) and Cholomyia inaequipes Bigot (Diptera: Tachinidae). Parasitism, particularly by N. curculionis, was common in northern Florida but rare in middle Georgia.

Efficacy of Entomopathogenic Fungi in Suppressing Pecan Weevil, Curculio caryae (Coleoptera: Curculionidae), in Commercial Pecan Orchards

Abstract. The pecan weevil, Curculio caryae (Horn), is a key pest of pecans, Carya illinoinensis (Wangenh.) K. Koch. The entomopathogenic fungi Beauveria bassiana (Balsamo) Vuillemin and Metarhizium anisopliae (Metschnikoff) Sorokin are pathogenic to and are being developed as microbial control agents for pecan weevil. One approach to suppressing pest populations and the resultant damage might be to apply entomopathogenic fungi when adult pecan weevils are emerging from the soil. Here we report the efficacy of B. bassiana (GHA strain) and M. anisopliae (F52 strain) applied to trees in orchards at three locations: Byron, GA, Fort Valley, GA, and Comanche, TX. At Fort Valley, treatments included B. bassiana as an oil-based spray with a UV-protective screen applied to the trunk, M. anisopliae applied as an impregnated fiber band stapled onto the trunk, and a nontreated check. At Byron, GA, we compared the B. bassiana trunk treatment to a nontreated check. Treatments at the Texas location were the B. bassiana trunk application, M. anisopliae applied as a trunk band and as a soil drench, and a nontreated check. At each location, weevils were trapped and transported to the laboratory for 15 to 17 days post-treatment to record mortality and mycosis. At both Georgia locations, B. bassiana caused ≥80% mortality and mycosis, which was significantly greater than mortality observed in the check (≤33%); mortality and mycosis in the M. anisopliae treatment at Fort Valley did not differ from that observed in the check. In Texas, due to insufficient replication in plots, statistical comparison among treatments was not possible. However, mean percentages of mortality of pecan weevils after 7 and 14 days were 38 and 55% in the check, 75 and 88% in the B. bassiana-treated plots, and 57 and 75% in the M. anisopliaetreated plots. These results indicate potential for B. bassiana trunk sprays to suppress adult pecan weevil. Future research is needed to determine if the approach contributes to economic levels of crop protection.

First Report of Seasonal Trap Capture for Halyomorpha halys (Hemiptera: Pentatomidae) and Native Stink Bugs in Central Georgia

The brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), is native to China, Taiwan, Korea, and Japan. Unfortunately, this invasive insect pest has spread to the United States, Canada, Switzerland, and Europe (Lee et al. 2013, Environ. Entomol. 42: 627–641). It is both an urban nuisance, due to its propensity for overwintering in structures (Inkley 2012, J. Entomol. Sci. 47: 125–130), and a serious economic pest of orchard crops, including apples and peaches, row crops such as field corn and soybeans, and vegetable crops including sweet corn, peppers, eggplant, and tomatoes (Leskey et al. 2012a, Psyche. DOI: 10.1155/2012/535062; Leskey et al. 2012b, Outlooks on Pest Manage. 23: 218–226; Rice et al. 2014, J. Integr. Pest Manag. 5: 1–13). The first known H. halys populations in the United States were reported in 1996 from Allentown, PA. To date, H. halys is present in 43 states and four Canadian providences (StopBMSB 2017, Stopbmsb.org). In Georgia, urban pest management professionals began reporting overwintering H. halys aggregations in the metropolitan Atlanta area in 2011. In late August 2014, H. halys adults and 2nd through 5th instars were collected from a Euschistus spp. pheromone-baited stink bug trap at the University of Georgia Horticulture Farm near Watkinsville, GA (P.G.T. unpubl. data). When the immediate area was searched, H. halys nymphs and adults were found on catalpa, pecan, and ornamental hibiscus. In the summer of 2015, H. halys was collected feeding and

A DNA Marker to Track Conotrachelus nenuphar (Coleoptera: Curculionidae) Dispersal

Plum curculio, Conotrachelus nenuphar (Herbst), is indigenous east of the Rocky Mountains and north of latitude 50°N in the United States (Amis and Snow. 1985, Handbook of Insect Rearing, Vol. 1) with a population in Utah (Hallman 1998, USDA-ARS Report, Weslaco, TX, USA). It is a phytophagous, true weevil and a pest of pome and stone fruit, i.e., apples, plums, cherries, and peaches (Shapiro-llan et al. 2002, J. Nematology 34: 246-349). In Georgia and South Carolina, the peach (Prunus persica [L.]) is a major stone fruit commodity. Plum curculio is the most destructive pest of the commodity (Brannon 1927, J. Elisha Mitchell Scientific Soc. 43: 79-83; Leskey and Wright. 2004, Environ. Entomol. 33: 389-396) on which they feed and into which they oviposit. Commercial fruit orchards also have historically been unable to rely on trap monitoring systems to accurately time insecticide applications (Prokopy et al. 2000, J. Entomol. Sci. 35: 411-420; Leskey et al. 2012, http://digitalcommons.unl.edu/usdaarsfacpub/1108). Thus, in 1994 Mexico halted importation of peaches from Georgia and South Carolina due to concerns of importing plum curculio with the peaches. But, in 2008 the U.S. Department of Agriculture Animal and Plant Health Inspection Service (APHIS) revisited the plum curculio issue on behalf of the peach growers in Georgia and South Carolina. An agreement was reached in 2011 between the U. S. and Mexico which required that specific procedures be in place to insure that peaches shipped to Mexico from Georgia and South Carolina are free of plum curculio. These procedures included field surveys, trapping, packinghouse inspections, fruit-cutting, and post-entry inspections. A DNA verification system designed specifically to track dispersal of plum curculio from Georgia is also needed to track and/or verify infestations, particularly if post-entry

Assays of Orchard-Applied Insecticides on the Brown Stink Bug (Hemiptera: Pentatomidae) Feeding on Pecan

Abstract  The brown stink bug, Euschistus servus (Say) (Hemiptera: Pentatomidae), is an economic pest of pecan, Carya illinoinensis (Wangenh.) K. Koch (Juglandaceae), and other agronomic crops across the southeastern United States. The efficacy of many insecticides against E. servus attacking pecan is not well documented even though the label for many of these insecticides may indicate one or more stink bug species as targets. Thus, we assayed various insecticides, labeled for application to pecan, to determine efficacy against E. servus. Insecticides were applied to pecan limb terminals with nut clusters in orchards in Georgia and Texas during 2009 and 2010. Treated limb terminals were cut from the tree and taken to the laboratory 1, 4, and 7 d after treatment. Treated nuts or limb terminals (i.e., nuts and foliage) were placed individually in cups or cylinder cages, respectively, and adult E. servus then placed into these containers. Mortality and moribundity of E. servus were recorded at 24, 48, or 72 h in addition to rating feces production at 72 h in some trials. Results consistently indicate that bifenthrin provided greater control of adult E. servus for a longer time after application than other products, including the organophosphate chlorpyrifos. Aside from bifenthrin also affecting the feces rating, the only other treatment that reduced feces production compared with untreated nuts was λ-cyhalothrin + thiamethoxam.