Donn T. Johnson

Multistate Comparison of Attractants for Monitoring Drosophila suzukii (Diptera: Drosophilidae) in Blueberries and Caneberries

ABSTRACT Drosophila suzukii Matsumara, also referred to as the spotted wing drosophila, has recently expanded its global range with significant consequences for its primary host crops: blueberries, blackberries, raspberries, cherries, and strawberries. D. suzukii populations can increase quickly, and their infestation is difficult to predict and prevent. The development of effective tools to detect D. suzukii presence in new areas, to time the beginning of activity within a crop, to track seasonal activity patterns, and to gauge the effectiveness of management efforts has been a key research goal. We compared the efficiency, selectivity, and relationship to fruit infestation of a range of commonly used homemade baits and a synthetic formulated lure across a wide range of environments in 10 locations throughout the United States. Several homemade baits were more efficient than apple cider vinegar, a commonly used standard, and a commercially formulated lure was, in some configurations and environments, comparable with the most effective homemade attractant as well as potentially more selective. All alternative attractants also captured flies between 1 and 2 wk earlier than apple cider vinegar, and detected the presence of D. suzukii prior to the development of fruit infestation. Over half the Drosophila spp. flies captured in traps baited with any of the attractants were not D. suzukii, which may complicate their adoption by nonexpert users. The alternative D. suzukii attractants tested are improvement on apple cider vinegar and may be useful in the development of future synthetic lures.

Toxicity, Persistence, and Efficacy of Spinosad, Chlorfenapyr, and Thiamethoxam on Eggplant When Applied Against the Eggplant Flea Beetle (Coleoptera: Chrysomelidae)

Abstract A laboratory bioassay was developed for determining the toxicity of spinosad, chlorfenapyr, and thiamethoxam against the eggplant flea beetle, Epitrix fuscula Crotch, on eggplant foliage. Four days after initial exposure, LC50 values were 1.99, 2.50, and 0.88 ppm for spinosad, chlorfenapyr, and thiamethoxam, respectively. By dividing the recommended field rate in ppm by the LC50 value, a field toxicity ratio was determined and ranged from 13.5 for spinosad to 73.9 for thiamethoxam. The high ratios suggest that field rates for all three insecticides could likely be reduced. This was supported by field studies in 2000 in which reduced rates of spinosad and thiamethoxam significantly reduced flea beetle numbers on eggplant. Mortality produced by thiamethoxam occurred more quickly than that for the other tested materials as shown with LT50 values of 1.8, 3.0, and 3.6 and days for thiamethoxam, chlorfenapyr, and spinosad, respectively. Persistence studies indicated that while all three of the tested compounds initially produced high levels of mortality, chlorfenapyr and thiamethoxam produced 50% or greater mortality after 6 d. Our data suggest that future management strategies for E. fuscula on eggplant can be successfully altered to meet the changing needs of the producer. Spinosad was recently registered, is effective against the E. fuscula, and offers a viable alternative to carbamate and pyrethroid insecticides. Thiamethoxam and chlorfenapyr offer high levels of toxicity to E. fuscula and upon registration will offer additional effective tools for management.

(E,Z)-2,13-octadecadien-1-ol acetate. A new pheromone structure for sesiid moths

Abstract (E,Z)-1,13-Octadecadien-1-ol acetate was identified from ovipositor extracts of the grape root borer and was shown to attract males of the species.

Trapping Plum Curculio Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae) in the Southern United States

Abstract A more practical method than limb jarring is needed to monitor the plum curculio, Conotrachelus nenuphar (Herbst), in peach trees. Of 223 orchard visits made in Arkansas, traps captured plum curculio adults on 114 visits, whereas limb jarring did so on only 29 visits. Pyramid traps and jarring tree limbs along the orchard edge began to capture plum curculio adults 1 wk before the start of fruit feeding damage and continued to capture plum curculio adults until after harvest. Pyramid traps located at the edge of the peach orchard caught significantly more adults than did traps placed >30 m into the orchard interior or traps placed along the edge of an adjacent woodlot. Pyramid traps and screen traps captured similar numbers of plum curculio adults in 14 of 17 samples. Only one orchard in Oklahoma and another in Arkansas had smaller circumference tree trunks (<38 cm) than the other orchards resulting in significantly more plum curculio adults captured in pyramid traps than in screen traps. The screen trap was less expensive and sustained environmental conditions better than did the pyramid trap and may be used on trees >38 cm in circumference. The derived economic threshold of 0.045 plum curculio adults per pyramid trap per day equated to 1% new fruit damage. This study suggested that combining trap counts with percentage of new fruit damage should be used to make insecticide application decisions against plum curculio.

Sampling Rice Stink Bug (Hemiptera: Pentatomidae) in and Around Rice Fields

Abstract Several sampling methods were used to determine the number of rice stink bugs, Oebalus pugnax (F.) in rice, Oryza sativa L., fields and grassy margins. Significantly more adult stink bugs were swept in fields of ‘Wells’ than ‘Francis’, ‘Cypress’, or ‘Bengal’. Sweep net sampling in the cooler parts of the day (0900 and 1900 hours CDT) captured significantly more rice stink bugs than in the heat of the day at 1330 hours CDT. In 2002, yellow pyramid traps were set out before rice heading. These traps captured more rice stink bugs from 5 June (before rice heading) to 12 July (75% rice heading) than during rice heading from 12 to 22 July. Significantly more rice stink bugs were visually counted on grass panicles and swept from grassy hosts in margins adjacent to rice fields from 28 June to 12 July than recorded after 12 July. During rice heading, rice stink bugs were dispersing into rice fields as noted by significantly greater counts of rice stink bugs per 10 sweeps in the rice field than at other rice growth periods sampled. After harvest, pyramid trap catches increased in late September to >20 bugs per trap but dropped to below 1 bug per trap after 3 October and to 0 by 1 November. In 2003, counts of rice stink bugs during the preheading, rice heading, and postheading periods from traps, sweep net samples of the field margins, and rice fields were similar to that in 2002. Pest sampling and management options are discussed.

Swimming Behavior of an Aquatic Weevil, Lissorhoptrus Oryzophilus (Coleoptera: Curculionidae)

The swimming behavior of the rice water weevil Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curculionidae) is unique in comparison to that of most other aquatic weevils. Propulsion during swimming is provided only by the mesothoracic legs. The legs are moved synchronously during protraction and retraction. The pro- and metathoracic legs serve as diving planes and provide stability. The average rice water weevil swimming speed was 1.53 (0.15 SE) cm per s with a range of 0.88 to 2.52 cm per s. Weevils averaged 5.67 (0.22 SE) strokes per s. The mode of swimming by L. oryzophilus differs from those described for Phytobious leucogaster (Marsham) (= Litodactylus leucogaster), P. comari (Herbst), Bagous cavifrons LeConte, B. americanus LeConte and B. limosus Gyllenhal. It also differs from descriptions of swimming for other aquatic Coleoptera and Hemiptera. Furthermore, L. oryzophilus swims below the surface and was observed at depths of 18.0 cm in the laboratory. This brings the modes of free swimming (exclusive of skating) to at least 3 by adult aquatic curculionids.

The Seasonal Occurrence of the Grape Root Borer, (Lepidoptera: Sesiidae) in the Eastern United States

The Grape Root Borer, Vitacea polistiformis (Harris), (Lepidoptera: Sesiidae) was trapped during 1985, 1986, and 1987 in seven, nine, and 13 eastern states, respectively, with pure (E,Z)-2,13 octad...

Molecular Diagnostics of Drosophila suzukii (Diptera: Drosophilidae) Using PCR-RFLP

ABSTRACT The invasive spotted wing drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), has become a serious pest in the United States. Identification of immature and poorly preserved specimens can be difficult. A molecular diagnostic method for distinguishing D. suzukii from other Drosophila spp. associated with fruit in the United States was developed. A 709-bp region of the mitochondrial DNA cytochrome oxidase I gene was amplified from D. suzukii collections in the United States and compared with sequences of other Drosophila taxa from GenBank. Based on DNA sequence polymorphisms, a polymerase chain reaction—restriction fragment length polymorphism analysis using the restriction enzyme Msp-I was found to differentiate D. suzukii from other Drosophila spp. in the United States. This technique can identify field-collected specimens from various sources and specimens regardless of life stage. This molecular diagnostic method will be useful for monitoring the spread of this economically important invasive insect.

Ovipositional Preferences of the Japanese Beetle (Coleoptera: Scarabaeidae) Among Warm- and Cool-Season Turfgrass Species

ABSTRACT Japanese beetles, Popillia japonica Newman (Coleoptera: Scarabaeidae), were evaluated for ovipositional preferences among four turfgrasses common in northwestern Arkansas. Choice assays revealed females preferred to oviposit in tall fescue (Festuca arundinacea Schreb.) and zoysiagrass (Zoysia japonica Steud.), and that they avoided oviposition in common bermudagrass (Cynodon dactylon [L.] Pers.) and hybrid bermudagrass (C. dactylon x C. transvaalensis Pers.). Significantly fewer eggs were oviposited in hybrid bermudagrass in a no-choice assay, suggesting that chemical and/or physical plant characteristics deter oviposition in that grass. The percentage of turfgrass cores with evidence of female activity (presence of female or eggs, or signs of female digging) in choice assays revealed no differences among treatments, yet significantly fewer hybrid bermudagrass cores had eggs. These results suggest that many females did not initially reject hybrid bermudagrass based on aboveground plant characteristics, but rather they left without ovipositing. Therefore, resistance in hybrid bermudagrass is likely expressed below ground. Our results suggest that the use of hybrid bermudagrass as a means of cultural control in an integrated pest management program may discourage Japanese beetle oviposition and subsequent grub infestations in lawns, golf courses, or sports fields.

Biology and control of the raspberry crown borer (Lepidoptera: Sesiidae).

Abstract This study explored the biology of raspberry crown borer, Pennisetia marginata (Harris) (Lepidoptera: Sesiidae), in Arkansas and the optimum timing for insecticide and nematode applications. The duration of P. marginata’s life cycle was observed to be 1 yr in Arkansas. Insecticide trials revealed that bifenthrin, chlorpyrifos, imidacloprid, metaflumizone, and metofluthrin efficacy were comparable with that of azinphosmethyl, the only labeled insecticide for P. marginata in brambles until 2005. Applications on 23 October 2003 for plots treated with bifenthrin, chlorpyrifos, and azinphosmethyl resulted in >88% reduction in larvae per crown. Applications on 3 November 2004 of metaflumizone, metofluthrin, and bifenthrin resulted in >89% reduction in larvae per crown. Applications on 7 April 2005 for metofluthrin, imidacloprid, bifenthrin, metaflumizone, and benzoylphenyl urea resulted in >64% reduction in the number of larvae per crown. Applications on 6 May 2004 did not reduce larval numbers. The optimum timing for treatments was found to be between October and early April, before the larvae tunneled into the crowns of plants. Applying bifenthrin with as little as 468 liters water/ha (50 gal/acre) was found to be as effective against larvae as higher volumes of spray. Nematode applications were less successful than insecticides. Nematode applications of Steinernema feltiae, Steinernema carpocapsae, and Heterorhabditis bacteriophora reduced larvae counts per plant by 46, 53, and 33%, respectively.