Efficacy of Soil-Applied Neonicotinoid Insecticides for Long-term Protection Against Emerald Ash Borer (Coleoptera: Buprestidae).

Protection of green ash trees (Fraxinus pennsylvanica Marshall) from the emerald ash borer (EAB), Agrilus planipennis Fairmaire, by soil applications of neonicotinoids (imidacloprid, clothianidin, and dinotefuran) was tested at five locations between 2005 and 2013. Application rate and spring versus fall application dates were evaluated in tests with neighborhood street trees and in one plantation of 65 ash trees. Insecticide treatments of ash trees at all five sites were initiated as the leading edge of the EAB invasion began to kill the first ash trees at each location. Trees were treated and evaluated at each site for 4 to 7 yr. Spring applications of imidacloprid were more efficacious than fall applications. Application rates of 0.8 g a.i./cm dbh or greater per year gave a higher level of protection and were more consistent than rates of 0.56 g a.i./cm dbh per year or less. The number of years between the first observation of canopy loss due to EAB and death of most of the control trees varied from three to seven years among test sites, depending on how many non-treated ash trees were nearby.

Interspecific variation in resistance to emerald ash borer (Coleoptera: Buprestidae) among North American and Asian ash (Fraxinus spp.).

We conducted a 3-yr study to compare the susceptibility of selected North American ash and an Asian ash species to emerald ash borer, Agrilus planipennis Fairmaire, an invasive wood-boring beetle introduced to North America from Asia. Because of a coevolutionary relationship between Asian ashes and emerald ash borer, we hypothesized an Asian ash species, Manchurian ash, is more resistant to the beetle than its North American congeners. Consistent with our hypothesis, Manchurian ash experienced far less mortality and yielded far fewer adult beetles than several cultivars of North American green and white ash. Surprisingly, a black ash (North American) x Manchurian ash hybrid was highly susceptible to emerald ash borer, indicating this cultivar did not inherit emerald ash borer resistance from its Asian parent. A corollary study investigated the efficacy of soil-applied imidacloprid, a systemic, neonicotinoid insecticide, for controlling emerald ash borer in each of the five cultivars. Imidacloprid had no effect on emerald ash borer colonization of Manchurian ash, which was low in untreated and treated trees. In contrast, imidacloprid did enhance survival of the North American and hybrid cultivars and significantly reduced the number of emerald ash borer adults emerging from green and white ash cultivars. We identify a possible mechanism of resistance of Manchurian ash to emerald ash borer, which may prove useful for screening, selecting, and breeding emerald ash borer-resistant ash trees.

Distribution and adult activity of Popillia quadriguttata (Coleoptera: Scarabaeidae) on golf courses in Korea.

Japanese beetle traps baited with the Popillia japonica Newman (Coleoptera: Scarabaeidae) pheromone lure and a eugenol feeding attractant were placed at five golf courses in Korea to determine how well they work for detecting activity of a closely related species, Popillia quadriguttata (F.) (Coleoptera: Scarabaeidae), a turf pest in Korea. The traps also were used to determine the time of day and time of year that P. quadriguttata is most active. Nineteen scarab species of 13 genera were attracted to the Japanese beetle traps with P. quadriguttata clearly being the most abundant (383 beetles per trap), followed by Adoretus tenuimaculatus Waterhouse (10 per trap), Popilliaflavosellata Fairmaire (seven per trap), Exomala orientalis Waterhouse (four per trap), and Maladera japonica (two per trap). Other scarab species were trapped at a rate of <1.0 per trap. Popillia quadriguttata adults were active over a 5-wk period in late June and early July. At Yongwon Golf Club in 2002, peak adult activity was during the last week of June in visual counts and approximately 1 wk later in the Japanese beetle traps. In Korea, P. quadriguttata adults are most active between 12:00 p.m. and 4:00 p.m. This information should be helpful to golf course superintendents in Korea and to entomologists interested in finding natural enemies of P. quadriguttata to evaluate as potential biocontrol organisms for the very closely related species, the Japanese beetle.

Revision of the genus Stictospora and description of Stictospora villani, n. sp. (Apicomplexa: Eugregarinida: Actinocephalidae) from larvae of the Japanese beetle, Popillia japonica (Coleoptera: Scarabaeidae), in Michigan.

Stictospora villani n. sp. is described from larvae of the Japanese beetle Popillia japonica (Coleoptera: Scarabaeidae) from southern Michigan. Stictospora villani is distinguished from known species of the genus by differences in gamont size and by structural details of the epimerite. In general, S. villani is smaller than other known species of the genus and possesses an epimerite with a margin of 20-24 sympetalous, pendulate, narrowly to very narrowly elliptoid lamina. Previously described species are characterized by epimerites with notably fewer marginal lamina. A heretofore unrecognized protistan is diagnosed from the coelomic fat bodies and tentatively placed within the Neogregarinorida. We conclude that previous workers have mistaken this neogregarine for the gametocyst and oocyst of Stictospora, which are described in this study for the first time. The generic diagnosis of Stictospora is revised to encompass the epimeritic variation of its constituent species and to correctly reflect the morphology of the oocyst.

How the use of chlorothalonil on golf courses impacts Paenibacillus sp., a pathogen of Ataenius spretulus (Coleoptera: Scarabaeidae).

One of the most frequently used fungicides on golf courses, chlorothalonil, was applied to field plots at four different golf courses to determine how Ataenius spretulus Haldeman, Aphodius granarius L., carabids, staphylinids, formicids and Paenibacillus sp. were affected. Chlorothalonil had no influence on the incidence of Paenibacillus sp. infection of A. spretulus larvae in golf course fairways. The incidence of Paenibacillus sp. infection of A. spretulus larvae was much greater in the rough (47.4%) compared with the fairway (26.4%) at Cattails Golf Club despite a more dense population (fourfold) of larvae in the fairway. Chlorothalonil treatment of turf plots had no influence on the number of staphylinids, carabids, formicids, or A. spretulus adults caught in pitfall traps. It also did not affect the density of A. spretulus larvae. Data from this study suggest that the widespread use of chlorothalonil on fairways is not likely to cause outbreaks of A. spretulus on golf courses.

Comparison of tall fescue (Cyperales: Gramineae) to other cool-season turfgrasses for tolerance to European chafer (Coleoptera: Scarabaeidae).

Three cultivars of tall fescue, Festuca arundinacea Schreb., were compared with three cultivars each of fine fescue (Festuca spp.), Kentucky bluegrass (Poa pratensis L.), and perennial ryegrass (Lolium perenne L.) to evaluate tolerance to root-feeding by European chafer grubs, Rhizotrogus majalis (Razoumowsky). Potted turfgrasses were infested with initial densities equivalent to 33 or 66 grubs per 0.1 m2 on 19 August 2000. More grubs were added in late September and October, bringing the total to 66 or 143 grubs per 0.1 m2. Plant growth, root loss, weight gain, and survival of grubs were measured. The experiment was repeated in fall of 2001 with an initial density of 66 grubs per 0.1 m2. The proportion of root mass lost as a result of grub feeding was a function of turf species, root growth, grub survival, and grub growth during the test. Grubs gained the most weight and consumed the most roots when feeding on fine fescue. Fine fescue suffered the greatest percentage of root loss in 2000, despite having the most rapid root growth and largest mass in control pots. Cultivars of tall fescue appeared to be the most tolerant of grub feeding, having the smallest reduction in root mass in both years. Data from fine fescue, Kentucky bluegrass, and perennial ryegrass cultivars were not as consistent as tall fescue, because for some cultivars root growth and grub survival were different between years. We also found that grubs increased in mass by 20% when the mass of available roots was doubled.

Laboratory and field evaluation of Korean entomopathogenic nematode isolates against the oriental beetle Exomala orientalis (Coleoptera: Scarabaeidae).

The oriental beetle Exomala (Anomala) orientalis (Waterhouse) is an important pest of turfgrass in Korean golf courses, and although a few chemical insecticides are registered for insect pest control, they are not very effective against scarab larvae. There is also a growing concern in Korea about the run-off of insecticides into sensitive habitats and the potential for groundwater contamination. A safe and environmentally sound alternative is needed to conventional insecticides. We therefore evaluated six Korean entomopathogenic nematode isolates: S. carpocapsae Pocheon, S. glaseri Dongrae, S. glaseri Mungyeong, S. longicaudum Gongju, S. longicaudum Nonsan, and Heterorhabditis sp. Gyeongsan for their potential as bioinsecticides for control of E. orientalis. In addition, we evaluated a reduced chemical insecticide approach that combined chlorpyrifos-methyl with nematodes. In laboratory tests Heterorhabditis sp. Gyeongsan was the most efficacious, causing 100% mortality of the second and 38% of the third instars. All other nematode isolates caused 50-80% mortality of the second and 15-30% of the third instars. E. orientalis pupae were highly susceptible to all the Korean entomopathogenic nematode isolates except S. carpocapsae. In artificially infested field plots, all Korean nematode isolates cause 50-70% mortality of the third instar. A combination of a one-half rate of Heterorhabditis sp. and a one-half rate chlorpyrifos-methyl was synergistic, causing 91% mortality compared with 69% for the full rate of Heterorhabditis sp. or 22% for the full rate of chlorpyrifos-methyl. In a second field trial, a natural infestation of preoverwintering third instar was treated. In this trial a one-half rate of S. longicaudum Nonsan plus a one-half rate of chlorpyrifos-methyl caused 96.8% mortality, much more than a full rate of S. longicaudum Nonsan (45.9% mortality) or a full rate of chlorpyrifos-methyl (28.7% mortality). The interactions of Heterorhabditis sp. and S. longicaudum Nonsan with chlorpyrifos-methyl in our field trials appear to be synergistic.

Life history and spatial distribution of Oriental beetle (Coleoptera: Scarabaeidae) in golf courses in Korea.

Larval and adult activity of the oriental beetle Exomala orientalis (Waterhouse), a pest of turfgrass in Korea, was investigated at four golf clubs in Pusan, Korea, from 1995 to 1999. Adult emergence was first observed on the greens in late May with peak activity occurring 2 wk later. During the day, E. orientalis adults were most active between 1800 and 2200 hours. First instars were found mostly in early July, second instars mostly in late July, and third instars from August to April. The density of larvae in fixed plots decreased steadily from the time of egg laying to pupation: 667/m3 on 26 July, 267/m3 on 29 August, and 122/m3 on 2 October 1997. All the observed E. orientalis completed one generation per year. Adult females were observed feeding on flowers of a late-blooming variety of Japanese chestnut (Castanea crenata Sieb & Zucc). E. orientalis larval densities were higher in greens with Japanese chestnut nearby, and where magpie, Pica pica sericea (Gould), feeding was observed. More E. orientalis adults emerged from the right, left, and back of greens than from the front or middle. The intensity of emergence was inversely proportional to the amount of golfer traffic on various parts of the green. Counting emergence holes may be a way that golf course superintendents can predict which greens and tees are most likely to be damaged from E. orientalis larvae without destructive sampling.

Association of Ovavesicula popilliae (Microsporida: Ovavesiculidae) with winter mortality of larvae and reduced fecundity of female Japanese beetles (Coleoptera: Scarabaeidae).

Populations of Japanese beetle at sites in Michigan where Ovavesicula popilliae (Andreadis) was introduced in 1999 and 2000 were compared with nearby control sites from fall of 2005 through spring of 2008. Percent infection by O. popilliae and winter mortality of Japanese beetle were determined by sampling larvae in October and April from 12 golf holes on six courses in southeast Michigan and eight holes on four courses in southwest Michigan. Adult Japanese beetles were also collected from these golf courses in July and August of 2007 to determine the impact of O. popilliae-infection on egg development in females. In southeast Michigan, O. popilliae appeared to spread rapidly from the 100 m(2) plots where it was previously introduced to surrounding golf course holes between 2000 and 2006. However, data from southwest Michigan suggests that O. popilliae had already been introduced into the area. Regression analysis of data from all 20 golf course holes gives a significant relationship between percent infection of larvae with O. popilliae and winter mortality of Japanese beetle. Mean winter mortality of larvae around golf course holes where <10% were infected with O. popilliae was 24.7% compared with 41.7% mortality where 10-30% were infected, and 72.0% mortality where >30% were infected. Females infected with O. popilliae contained 50% fewer mature eggs than uninfected females. In addition, females from golf courses where all of the fairways and roughs were treated annually with imidacloprid contained 48% fewer mature eggs than females from golf courses where insecticides were only used on the fairways or not at all.