European Stone Fruit Yellows: A Mark,Release and Recapture Experiment Tracking the Dispersal of its Vector Cacopsylla pruni (Hemiptera: Psyllidae) in a Model Apricot Orchard and Epidemiological Studies in Lower Austria

During the last 15 years, European stone fruit yellows (ESFY) has become a major concern in Austrian fruit production. Therefore, presence and temporal dynamics of its vector Cacopsylla pruni were investigated using a beating tray method and yellow sticky traps on Prunus armeniaca, Prunus domestica, Prunus spinosa and P. cerasifera nigra. Infection rates of C. pruni and Prunus spp. trees were assessed by direct, nested and real‐time PCR. Movement of remigrants in a model apricot orchard was tracked by aid of a mark, release and recapture study. Insects were marked by fluorescent dyes. Movement of the marked insects and presence of naturally occurring insects were monitored by yellow sticky traps. In 2011, remigration of C. pruni to Prunus spp. started in calendar week 10 (8th of March) and in 2012, in calendar week 12 (18th of March). Remigrants were observed until calendar week 20 (middle of May), significant numbers of the springtime generation adults were present until week 26 (end of June). The phytoplasma was ascertained in 0–11.5% of the remigrants and in 0–3.44% of the springtime generation insects. About 9.8–63.3% of the apricot samples, 20–40% of the plum samples and single blackthorn samples were infected. The mark, release and recapture study proved a fast and frequent tree‐to‐tree movement of remigrated C. pruni adults. Insects easily covered distances from row to row or even farther (ca. 13 m) within 24 h after release and were present in a large part of the model orchard after 8 days (up to 24 m from release point).     

Epidemiological and molecular study on ‘Candidatus Phytoplasma prunorum’ in Austria and Hungary

The epidemiology of ‘Candidatus Phytoplasma prunorum’ was studied in Austria and Hungary from 2014 to 2018. Testing of root samples showed average infections rates of 61 and 40% of the Austrian Prunus spinosa and Prunus domestica spp. insititia samples, respectively. In Hungary, on average 21% of the P. spinosa and 13% of the feral Prunus cerasifera samples were infected. The pathogen was found in 18 out of 19 apricot orchards and PCR positive Cacopsylla pruni were observed at 11 out of 17 sampling locations in both countries. In cage experiments with C. pruni remigrants successful pathogen transmission to Prunus armeniaca, P. domestica and P. spinosa seedlings in budding and foliated developmental stages was recorded, an inoculation access period of 4 hr was sufficient for transmission. A field experiment with ungrafted apricot seedlings planted in 2012 and 2014 indicated a prominent role of the insect vectors for disease spread. In 2017, 40 and 28% of the trees planted in 2012 and 2014, respectively, were infected. Molecular characterisation based on the genes aceF and imp allowed the discrimination between 10 phytoplasma types in apricots. Around 70% of the phytoplasma types in apricots were also common in P. spinosa, in P. domestica spp. insititia and in remigrant C. pruni pointing to a possible pathogen exchange by insects between wild and cultivated Prunus spp. For disease control, vector management over the entire flight period of the remigrants seems necessary; when selecting active compounds, the short inoculation access period of not more than 4 hr should be considered.     

Effects of spinosad, spinosad bait, and chloronicotinyl insecticides on mortality and control of adult and larval western cherry fruit fly (Diptera: Tephritidae)

Effects of spinosad, spinosad bait, and the chloronicotinyl insecticides imidacloprid and thiacloprid on mortality of the adults and larvae of western cherry fruit fly, Rhagoletis indifferens Curran (Diptera: Tephritidae), were determined in the laboratory and the field. Spinosad and spinosad bait caused higher adult mortality than imidacloprid, which caused higher mortality than thiacloprid. Only spinosad bait prevented oviposition. All materials were more toxic to adults when ingested than when topically applied. Spinosad bait had the greatest residual toxicity on leaves, killing 100% of adults when aged for 14 d in the field. When materials were sprayed on infested cherries, numbers of live larvae in fruit after 8 d were lower in imidacloprid and thiacloprid than in spinosad and spinosad bait treatments, which did not differ from the control, but all materials reduced larval emergence over 30 d. In the field, spinosad and spinosad bait were as effective in suppressing larval infestations as azinphos-methyl and carbaryl, whereas imidacloprid was effective in most cases and thiacloprid was generally less effective than azinphos-methyl and carbaryl. Overall, results in the laboratory and field show that spinosad and chloronicotinyl insecticides differed significantly in their effectiveness against adults and larvae of R. indifferens but that spinosad, spinosad bait, and imidacloprid seem to be acceptable substitutes for organophosphate and carbamate insecticides for controlling this fruit fly.     

Seasonal infectivity of Cacopsylla pruni, vector of European stone fruit yellows phytoplasma

Epidemiology of European stone fruit yellows was studied by focussing on the life cycle and transmission characteristics of the vector Cacopsyllapruni. The proportion of both phytoplasma positive and inoculative insects was determined for the first C. pruni adults back colonising the stone fruit trees in spring and for the new generations of the vector, hatched at the beginning of summer. We showed that in spring, as soon as the insects moved to stone fruit trees from shelter plants, they were infective. After the vector fed on infected stone fruit trees, the proportion of phytoplasma positive insects increased. The new generation colonising Prunus species also acquired the phytoplasma from their hosts although several of these insects completed the latency period on secondary hosts. Results showed that the risk of natural transmission of European stone fruit yellows-phytoplasma by C. pruni within orchards is high when the vector is present. These results have implications for the control of European stone fruit yellows.     

Knockdown and mortality of adults of eight species of stored-product beetles exposed to four surfaces treated with spinosad

Contact toxicity of a commercial bacterial fermentation insecticide, spinosad, to adults of eight stored-product beetles was evaluated on four different surfaces. Aqueous spinosad suspension was sprayed with an airbrush to 30.5-cm2 surfaces of concrete, galvanized steel, unwaxed floor tile, or waxed floor tile to obtain deposits of 0.05 or 0.1 mg (AI)/cm2. Control surfaces were sprayed with distilled water. Approximately 24 h after distilled water or spinosad application, 30 adult beetles were confined, by species, to each untreated and spinosad-treated surface. Insects on surfaces were exposed for 24 h to assess knockdown at 25 +/- 1 degree C and 50 +/- 10% RH, and then were held on food for an additional 24 h to assess mortality. Knockdown and mortality of each insect species on all four surfaces were significantly greater on spinosad-treated surfaces than on distilled water-treated surfaces. Knockdown and mortality of all species on all surfaces was similar at the two spinosad deposit levels. Except for Tribolium spp., mortality of all other species exposed to spinosad was 99-100%. Tribolium spp. were highly susceptible to spinosad on concrete (98-100% mortality); however, on unwaxed floor tile, steel, and waxed floor tile recovery on food after knockdown resulted in only 72-92% mortality. Our results suggest that spinosad has excellent contact activity against adults of stored-product insects, especially on concrete, and has potential for use as a general surface, spot, or crack/crevice spray to control insects in empty bins, warehouses, food-processing facilities, and retail stores.     

The impact of insecticides applied in apple orchards on the predatory mite Kampimodromus aberrans (Acari: Phytoseiidae)

Kampimodromus aberrans is an effective predatory mite in fruit orchards. The side-effects of insecticides on this species have been little studied. Field and laboratory experiments were conducted to evaluate the effects of insecticides on K. aberrans. Field experiments showed the detrimental effects of etofenprox, tau-fluvalinate and spinosad on predatory mites. Spider mite (Panonychus ulmi) populations reached higher densities on plots treated with etofenprox and tau-fluvalinate than in the other treatments. Single or multiple applications of neonicotinoids caused no detrimental effects on predatory mites. In the laboratory, spinosad and tau-fluvalinate caused 100 % mortality. Etofenprox caused a significant mortality and reduced fecundity. The remaining insecticides did not affect female survival except for imidacloprid. Thiamethoxam, clothianidin, thiacloprid, chlorpyrifos, lufenuron and methoxyfenozide were associated with a significant reduction in fecundity. No effect on fecundity was found for indoxacarb or acetamiprid. Escape rate of K. aberrans in laboratory was relatively high for etofenprox and spinosad, and to a lesser extent thiacloprid. The use of etofenprox, tau-fluvalinate and spinosad was detrimental for K. aberrans and the first two insecticides induced spider mite population increases. The remaining insecticides caused no negative effects on predatory mites in field trials. Some of them (reduced fecundity and repellence) should be considered with caution in integrated pest management programs.     

Evaluation of the insecticidal toxicity of various pesticides for Atractomorpha lata (Orthoptera: Pyrgomorphidae) control

The insecticidal activity of 38 commercialized pesticides against Atractomorpha lata nymphs in Korea was studied. Seven pesticides showed greater than 70% insecticidal activity against A. lata nymphs after 48 h of treatment, and similar results were observed for adult A. lata using the spray method. The insecticidal activity of the seven pesticides, except for thiacloprid, against Oxya sinuosa adults was similar to that against A. lata. Clothianidin, tetraniliprole, and thiacloprid showed higher toxicity when plants and insects were treated together than when insects were treated directly, indicating that pesticides have ingestion toxicity against A. lata. Clothianidin and thiacloprid have been observed to have knockdown effects on both A. lata nymphs and adults. Tetraniliprole showed 86.7% mortality until 7 days after treatment in the residual effect test of pesticide exposure under field conditions. Therefore, this study provides basic data for A. lata control; tetraniliprole was found to be an effective insecticide for the control of A. lata nymphs and adults.     

Floral biology of 'Bulida' apricot trees subjected to postharvest drought stress

Drip irrigated ‘Búlida’ apricot trees (Prunus armeniaca L., on Real Fino apricot rootstock) were submitted to drought stress by withholding irrigation for two different postharvest periods for two consecutive years. The first treatment (T–1) started immediately after harvest, and lasted 11/2 months, while the second treatment (T–2) started when the first treatment finished and lasted 2 months. These stress treatments were compared with a control treatment (T–0), which was irrigated throughout the year so that it received an amount of water equivalent to 100% of the crop evapotranspiration (ETc) demand. Flowers from the three treatments showed similar quality (fresh weight, petal surface area and pistil length) and frequent macrostyle (stigma located above the anthers). A lower percentage of pollen germination was observed in grains from the following year's bloom in plants from the T–1 treatment. The T–1 drought stress also induced a significant decrease in fruit yield, due to an increase in fruitlet drop, which led to significantly lower fruit set. The T–2 treatment did not affect these processes and was not critical as regards apricot yield. The fruits harvested met the required standards of quality in all treatments.     

Field and laboratory tests of new insecticides against the apple maggot, Rhagoletis pomonella (Walsh) (Diptera: Tephritidae)

Laboratory bioassays and field tests were conducted to compare the effectiveness of the new insecticides, imidacloprid, indoxacarb, pyriproxyfen, spinosad, thiacloprid, and thiamethoxam, against apple maggot. The activity ranking of the compounds in reducing oviposition in laboratory bioassays was: imidacloprid, 95% reduction at 11 ppm > thiamethoxam, 91% and thiacloprid, 89% reduction at 100 ppm > spinosad, 98% reduction at 316 ppm > indoxacarb, 80% reduction at 1000 ppm > pyriproxyfen, 0% reduction at 38 ppm. In laboratory bioassays, the only insecticides that were toxic to flies at concentrations equal to or below the recommended field rates were imidacloprid, (50% of flies at 11 ppm), spinosad (90% of flies at rates > 10 ppm), and thiamethoxam (approximately 50% of flies at 32 ppm). In field trials, thiacloprid was the only material that consistently controlled apple maggot fruit infestation that was comparable to standard treatments of organophosphate insecticides. Spinosad applied at weekly intervals, and indoxacarb applied as biweekly sprays provided adequate control of apple maggot damage when infestation levels in the field were low, but were not effective in preventing damage in small plots when apple maggot pressure was high.     

Toxicity of baited spinosad formulations to Ceratitis capitata: from the laboratory to the application

GF‐120, a fruit fly bait designed to attract and kill adult fruit flies, was tested in the laboratory and outdoors to determine effects of pre‐treatment diet and bait aging on mortality of Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae). Two spinosad‐based compounds, GF‐120 and Tracer^® Ultra, had generated two distinctive dose–mortality responds, with LC⁸⁰, LC⁹⁰, and LC⁹⁹ values of 2.4, 2.8, and 4.1 p.p.m., and 255, 479, and 1 143 p.p.m., respectively. The residues of GF‐120 drops, after feeding to the flies, generated 14.3% mortality. The droplet size of the baited spray plays an important role. The toxicity of large drops lasted more than that of small droplets. In the field, exposure to the sun further deteriorates the compound, which lost 50% of its toxicity within 6 days. Disappearance of the compound in the field, due to consumption by various insects, also played a role as 50% of the GF‐120 drops disappeared within 7 days. As mortality was directly related to the amount of insecticide eaten, the effect of GF‐120 depended on the feeding status of the flies: well‐fed flies were almost unaffected compared with starved ones.     

The pattern,rate, and range of within‐patch movement of a stem‐galling fly

1. Information on the movement of insects is critical to understanding the spatial spread, dynamics, and genetic structure of their populations, as well as their interactions with other species. With this in mind, the movement behaviour of the stem‐galling fly Eurosta solidaginis Fitch (Diptera: Tephritidae) was investigated. 2. Fluorescent‐marked adults were released at a single location within pure patches of the host plant, tall goldenrod Solidago altissima, and their distributions censused repeatedly throughout the day. 3. Following their release, male and female flies redistributed themselves in a manner that was well described by a simple‐diffusion model. The diffusion rate was independent of fly density and time since flies were released. 4. Female flies dispersed at a significantly faster rate, and therefore farther on average, than males. Based on the diffusion model, it was estimated that at 2.5–3.0 h post release, males and females had a median dispersal distance of only 2.0 and 2.5 m respectively. Furthermore, 95% of the males were estimated to have dispersed no more than 5.9 m, and females no more than 6.4 m. 5. Post‐release censuses suggested that flies were most active during mid morning, disappeared from the site at a rate of 10–15% per hour (most likely due to mortality), and survived for less than 2 days. Based on the rate of spread, diel activity, and liberal estimates of longevity in the field, 50% of the ovipositing females were predicted to have had a maximum lifetime range of movement within a patch of hosts of ≤ 51 m (95% were expected to have been limited to ≤ 130 m). 6. These data are used to assess whether the absence of a positive correlation between host‐plant preference and offspring performance in this system could be due to the limited scale of dispersal of this species relative to the spatial scale at which its oviposition behaviour has been studied.     

Synergistic effects of heat and diatomaceous earth treatment for the control of Plodia interpunctella (Lepidoptera: Pyralidae)

Plodia interpunctella is a major economic pest that commonly infests most stored and processed agricultural products. Currently, heating at 50–60°C for at least 48 h is applied in facilities for disinfestation. However, this condition requires a great deal of time and expense. To improve the control efficiency of this system, we conducted combined treatments with heating and diatomaceous earth (DE), which is known to be toxic to pest insects. The DE effect was compared to heating at 25°C or 40°C to wandering fifth instar larvae, which is the stage most tolerant to heat. When larvae were brushed with DE powder, mortality was only 15.0–18.3% at 25°C for 10 days, but rapidly increased to 100% at 40°C within 4 h post‐treatment. In addition, when larvae were kept in a plastic cage with DE [4 mg/L (w/v)], their mortality was 100% in 24 h at 40°C post‐treatment; otherwise mortality was only 8.8% without DE. Thus, the control efficiency of heating significantly improved with the combination of DE. These effects increased further at higher temperatures and with longer exposure. Our results clearly showed that DE treatment showed synergistic effects with heating systems for the control of P. interpunctella.     

Impact of feral water buffalo and fire on growth and survival of mature savanna trees: An experimental field study in Kakadu National Park,northern Australia

Abstract The impact of feral Asian water buffalo (Bubalus bubalis) and season of fire on growth and survival of mature trees was monitored over 8 years in the eucalypt savannas of Kakadu National Park. Permanently marked plots were paired on either side of a 25‐km‐long buffalo‐proof fence at three locations on an elevational gradient, from ridge‐top to the edge of a floodplain; buffalo were removed from one side of the fence. All 750 trees ≥ 1.4 m height were permanently marked; survival and diameter of each tree was measured annually; 26 species were grouped into four eco‐taxonomic groups. The buffalo experiment was maintained for 7 years; trees were monitored an additional year. Fires were excluded from all sites the first 3 years, allowed to occur opportunistically for 4 years and excluded for the final year. Fires were of two main types: low‐intensity early dry season and high‐intensity late dry season. Growth rates of trees were size‐specific and positively related to diameters as exponential functions; trees grew slowest on the two ends of the gradient. Eucalypt mortality rates were 1.5 and 3 times lower than those of pantropics and of arborescent monocots, respectively, but the relative advantage was lost with fires or buffalo grazing. Without buffalo grazing, ground level biomass was 5–8 t ha^?1 compared with 2–3 t ha^?1, within 3 years. In buffalo‐absent plots, trees grew significantly slower on the dry ridge and slope, and had higher mortality across the entire gradient, compared with trees in buffalo‐present plots. At the floodplain margin, mortality of small palms was higher in buffalo‐present sites, most likely due to associated heavy infestations of weeds. Low‐intensity fires produced tree growth and mortality values similar to no‐fire, in general, but, like buffalo, provided a ‘fertilization’ effect for Eucalyptus miniata and Eucalyptus tetrodonta, increasing growth in all size classes. High‐intensity fires reduced growth and increased mortality of all functional groups, especially the smallest and largest (>35 cm d.b.h.) trees. When buffalo and fires were excluded in the final year, there were no differences in growth or mortality between paired sites across the environmental gradient. After 8 years, the total numbers of trees in buffalo‐absent plots were only 80% of the number in buffalo‐present plots, due to relatively greater recruitment of new trees in buffalo‐present plots; fire‐sensitive pantropics were particularly disadvantaged. Since the removal of buffalo is disadvantageous, at least over the first years, to savanna tree growth and survival due to a rebound effect of the ground‐level vegetation and subsequent changes in fire‐vegetation interactions, process‐orientated management aimed at reducing fuel loads and competitive pressure may be required in order to return the system to a previous state. The ‘footprint’ of 30 years of heavy grazing by buffalo has implications for the interpretation of previous studies on fire‐vegetation dynamics and for current research on vegetation change in these savannas.     

Zonate Leaf Spot of Prunus mandshurica Caused by Hinomyces pruni in Korea

Zonate leaf spots and severe defoliation were observed on Manchurian apricot (Prunus mandshurica) growing in a humid location in Korea from 2011 through 2013. The main symptoms included greyish green to brownish grey and zonate leaf spots without border lines, which mostly led to premature defoliation. The morphological characteristics of the causal agent were consistent with Hinomyces pruni. Identification was supported by analysing the sequence of the internal transcribed spacer region of ribosomal DNA from an isolate. The pathogenicity of the isolate was confirmed by artificial inoculation. This is the first report of zonate leaf spot caused by H. pruni on Manchurian apricot globally as well as in Korea.     

Integrated control of apple pests in New Zealand

In a study at Appleby Research Orchard, Nelson, examination of the fruit from mature ‘Delicious’ apple trees sprayed with ryania over 5 years showed that less than 10% of 5th‐instar larvae of the codling moth (Laspeyresia pomonella) seeking cocooning sites originated from fruit on the ground. In 1972 and 1973 the survival of such larvae was studied by tagging with cobalt‐58 and releasing them beneath mature trees. In both years about 25 % of the tagged larvae returned to the tree to spin cocoons. Larvae released on bare ground 0–1 m from the tree trunks were more successful than those released in the sward 1–2 m away. Once on the trees, most larvae spun cocoons beneath exfoliating bark on the lower parts of the leaders and the trunk. Fifty‐two percent of the cocoons located were formed on the ground, and overwintering mortality of these was estimated to be near 100%. The pre‐cocooning mortality of larvae released on the ground was similar to that of larvae released on the trees in the same year. It was concluded that larvae from windfalls could be ignored in estimating 5th‐instar larval mortality of codling moth on ‘Delicious’ trees. On the cultivars ‘Dunn's Favourite’ and ‘Cox's Orange Pippin’, however, the higher percentage of larvae in windfalls made their inclusion in mortality estimates essential.     

Comparative selectivity of pesticides used in greenhouses,on the aphid parasitoid Aphidius colemani (Hymenoptera: Braconidae)

A series of bioassays were conducted under laboratory conditions to determine the relative toxicities of various pesticides (acetamiprid, cypermethrin, chlorantraniliprole and emamectin benzoate, Bacillus thuringiensis var. kurstaki and Helicoverpa armigera nucleopolyhedrovirus, copper oxychloride, iprodione, mandipropamid, a mixture of propamocarb?+?fluopicolide and mixture of fludioxonil?+?cyprodinil) on Aphidius colemani adults and mummies, as well as sublethal effects on female fecundity. Cypermethrin was highly toxic to pupa of A. colemani within host mummies. Acetamiprid, cypermethrin, emamectin benzoate, a mixture of propamocarb?+?fluopicolide and mixture of fludioxonil?+?cyprodinil were also highly toxic to A. colemani adults (92–100% mortality at 48?h post treatment). Mandipropamid, iprodione and copper oxycloride treatments significantly reduced fecundity of the female parasitoids. In contrast B. thuringiensis var. kurstaki, H. armigera nucleopolyhedrovirus and chlorantraniliprole were harmless (<30% mortality) to the parasitoid species tested according to International Organisation for Biological Control toxicity classification and are likely to be compatible with integrated pest management programmes.     

Post-alighting responses of Mexican fruit flies (Dipt., Tephritidae) to different insecticides in paint on attractive spheres

Abstract: Two new, comparatively safe insecticides (spinosad and imidacloprid) were compared with dimethoate (each at 1.5% active ingredient) for behavioural and mortality effects on Mexican fruit flies, Anastrepha ludens . Insecticide was mixed with sugar (as a feeding stimulant) and yellow latex paint (as an extending agent) applied to the surface of fruit-mimicking biodegradable 7 cm spheres made of sugar, flour and glycerin. Flies feeding on spinosad-treated spheres did not differ from flies feeding on untreated spheres in post-feeding intra-tree flight capability, amount of oviposition or mortality. Flies that fed on imidacloprid- or dimethoate-treated spheres for as little as 30 s experienced both high reduction in oviposition and high mortality compared with flies that fed on untreated spheres, and the flies from imidacloprid-treated spheres also showed a much reduced intra-tree flight capability. If baited with attractive odour, biodegradable yellow spheres treated with a surface coating of imidacloprid in latex paint and sugar could have potential for suppressing Mexican fruit flies on host trees.     

Limited protection of the parasitoid Pachycrepoideus vindemiae from Drosophila suzukii host‐directed spinosad suppression

Laboratory trials were conducted to determine whether the spotted wing drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), puparium can provide an effective physical barrier to protect immature stages of the pupal parasitoid Pachycrepoideus vindemiae (Rondani) (Hymenoptera: Pteromalidae) from spinosad treatments. Spinosad insecticides are currently an important suppression strategy for D. suzukii in organically managed fruit orchards although they are well known to cause mortality in hymenopteran parasitoids. High adult P. vindemiae female mortality (83%) occurred within 24 h of exposure to D. suzukii pupae treated with 10 mg a.i. l^?1 spinosad and female parasitoids did not avoid the pupae treated with similar low levels of spinosad in choice tests that included untreated pupae. Pachycrepoideus vindemiae develops as an idiobiont ectoparasitoid on host fly pupa within the sclerotized host puparium. Significant P. vindemiae survival and emergence was recorded when parasitized D. suzukii puparia were exposed to field treatment levels of spinosad; however, the parasitoid survival was dependent on the time of the spinosad treatment of the host post‐parasitization. Significant parasitoid survival occurred when the host puparia were treated at 2 weeks when the parasitoid was in the pupal stage but did not occur when the host puparia were treated at 1 week post‐parasitization, when the parasitoids were still in a larval stage. The parasitoid adults consumed or otherwise came in contact with residual degrading spinosad when they exited the treated host, and consequently high and low adult parasitoid mortality occurred when the adults emerged from puparia treated at 2 and 1 week(s), respectively. Our study indicates that generally the integration of P. vindemiae parasitism into a sustainable D. suzukii management program is not compatible with spinosad treatments, although P. vindemiae in the pupal stage inside sclerotized host puparia appear to be minimally impacted by spinosad treatments, provided that the spinosad degrades before parasitoid emergence.     

Host preference of the plum curculio

We assessed host preference of adult plum curculio, Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae), based on the total number of mark‐released and wild adults recovered and the total distance moved by mark‐released adults in an orchard whose layout was designed to specifically allow foraging plum curculios to choose among host tree species. Host trees included apple, Malus domestica Borkh.; pear, Pyrus communis (L.); peach, Prunus persica (L.) Batsch; apricot, Prunus armeniaca L.; tart cherry, Prunus cerasus L.; sweet cherry, Prunus avium (L.); European plum, Prunus domestica L.; and Japanese plum, Prunus salicina Lindl. (all Rosaceae). We released 2900 marked adults and recovered 17.7%. We used screen traps to provide a measure of the number of adults that arrived at and climbed up particular host trees and found that significantly greater numbers of marked adults and the greatest number of wild adults were recovered from screen traps attached to Japanese plum. We sampled host tree canopies by tapping limbs to provide a measure of the number of adults within a tree canopy at a particular moment. Again, significantly greater numbers of marked and wild adults were recovered from plum species, with no difference between Japanese and European plum cultivars for marked individuals, but with significantly greater numbers of wild individuals recovered from Japanese plum. The preference index (PI) for Japanese plum based on total distances moved by all marked adults recovered on Japanese plum divided by the total distance moved by marked adults recovered on other host trees indicated that Japanese plum was the most highly preferred host, followed by European plum, peach, sweet cherry, tart cherry, apricot, apple, and pear, respectively.     

Field evaluations of systemic insecticides for control of Anoplophora glabripennis (Coleoptera: Cerambycidae) in China

Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae), a pest native to China and Korea, was discovered in North America in 1996. Currently, the only reliable strategy available for eradication and control is to cut and chip all infested trees. We evaluated various doses of the systemic insecticides azadirachtin, emamectin benzoate, imidacloprid, and thiacloprid for control of A. glabripennis in naturally infested elms (Ulmus spp.), poplars (Populus spp.), and willows (Salix spp. ) in China between 2000 and 2002. Significantly more dead A. glabripennis adults were found beneath elm and poplar trees treated with imidacloprid (in 2000 and 2001) or thiacloprid (in 2001) and beneath willow trees injected with imidacloprid or thiacloprid (in 2002) compared with control trees. In 2000, 4 mo after injection, the density of live A. glabripennis was significantly reduced in poplar trees treated with imidacloprid (90%) and in willow trees treated with imidacloprid (83%) or emamectin benzoate (71%) compared with controls. In 2001, 9 mo after injection, the density of live A. glabripennis was significantly reduced in poplar (76%) and willow (45%) trees treated with imidacloprid compared with control trees. Similarly, percentage mortality of all life stages of A. glabripennis feeding within trees was significantly higher on poplar trees 4 mo after injection with imidacloprid (64%) in 2000 and on elms (55%) and poplars (63%) 9 mo after injection with imidacloprid in 2001 compared with control trees. Imidacloprid residue levels in leaves and twigs collected at various times from 1 d to 9 mo after injection ranged from 0.27 to 0.46 ppm. Injecting A. glabripennis-infested trees with imidacloprid can result in significant mortality of adults during maturation feeding on leaves and twigs and of all life stages feeding within infested trees. Imidacloprid is translocated rapidly in infested trees and is persistent at lethal levels for several months. Although, injection with imidacloprid does not provide complete control of A. glabripennis, systemic insecticides may prove useful as part of an integrated eradication or management program.