BIOLOGY AND CONTROL OF THE APPLE MEALYBUG PHENACOCCUS ACERIS (SIGNORET) IN BELGIUM.

Although in general very rare, some outbreaks of the apple mealybug Phenococcus aceris (Signoret) (Hemiptera: Pseudococcidae) were reported in the Belgian fruit growing area recently. This insect is known to be geographically widespread, to have a broad host range and to infest apple trees. Damage at harvest is considerable when sooty molds, a consequence of the pest's honeydew production, cover the fruits. Indirect damage of an infection is caused in cherry cultivation through transmission of the Little cherry virus (LChV2). Efficacy trials were executed in infested apple orchards in the Belgian fruit growing area and the life cycle of the pest on apple was studied more into detail. Apple mealybugs are univoltine, overwinter as 2nd instar nymphs inside a white cocoon on the tree (under the bark, in crevices) and leave their overwintering site in early spring (mid March). On sunny days the nymphs become active, move around and attach to start feeding (mid April). After a final moult into the adult form, females lay eggs in a cocoon-like white structure (from flowering on). Following hatching (end May), massive numbers of young nymphs spread out on the underside of the leaves (mid June) where they feed through suction. In order to manage this pest the efficacy of several plant protection products was tested in two infested apple orchards. Results indicated that mortality was high after an application of compounds belonging to the neonicotinoid insecticides. Different application timings and control strategies are possible, with active nymphs being the most vulnerable life stage. The observed degree of parasitation in our trial orchards also indicates a biological control contribution of parasitic wasps that should be taken into account. A decent IPM-strategy based on our results solved the problem in both apple orchards.

Preliminary results on the ability of pentatomidae to transfer fire blight Erwinia amylovora under controlled conditions.

With their piercing-sucking mouthparts stink bugs (Heteroptera: Pentatomidae), a major pest in especially organic orchards, create wounds in fruit of pear trees. As Erwinia amylovora (Burrill, Winslow et al.), a wide spread bacterial disease affecting many rosaceous plants including pome fruit trees and hawthorn, enters through openings in flowers, leaves, shoots and fruit, feeding punctures caused by these bugs might be inoculated with Erwinia bacteria. In order to investigate the ability of the bugs Pentotoma rufipes L. and Polomena prasina L. to transmit fire blight, insects were caught in an organically managed orchard without fire blight, brought into contact with artificially inoculated immature pear fruit/slices and transferred to healthy, mechanically wounded pear fruit/slices. After an incubation period potential transmission of bacteria was examined by evaluation of symptom expression (necrosis, ooze production). To assess the presence of bacteria on the exoskeleton of the tested bugs, all bugs were forced to walk on a semiselective nutrient agar medium. In another experiment the viability of Ea on the exoskeleton was tested -after previous contact with ooze- through washing and plating of the wash water. All experiments were conducted under optimal climatological conditions and according to quarantine standards. Results demonstrated the ability of stink bugs to transfer E. amylovora to fruit and the viability of bacteria on stink bugs externally - both under lab conditions.

Life cycle and control of the forest bug Pentatoma rufipes L. in organically managed pear orchards.

In Belgian pear production growers may encounter major economic problems when fruit becomes damaged by bugs. One of the major pests belongs to the stink bugs, Pentatoma rufipes L. (Heteroptera, Pentatomidae) which feeds by piercing into buds, flowers and fruit. To study the population dynamics of this species it was monitored in organic pear orchards by the beating tray method. Results revealed their univoltine life cycle and their presence within the orchard during the entire year. They overwinter in the second nymphal stage and become active in March/April. After 3 moultings adulthood is reached during May/June. In summer mating takes place and eggs are laid at the underside of the leaves of the fruit trees. By the end of August the eggs hatch and the first young nymphs appear. At first they aggregate but when they have moulted into the next stage dispersal takes place (September) and by October they search for hiding places on the trees to hibernate. As damage is done before and after blossom the application of an insecticide has to be well defined and timed. Therefore the efficacy of spinosad and natural pyrethrum, applied once or twice before and/or after bloom, was compared in a field trial. Data indicated that a single application of spinosad after bloom and a double application of spinosad or pyrethrum (before and after bloom) reduced the number of bugs with 83.3%. Damage to the crop was the lowest (4.5%) when spinosad was applied twice but no statistical difference with both other applications was found.

Earwig management tool: an IPM decision aid system for augmentation of European earwig populations (Dermaptera: Forficulidae) in pip fruit orchards.

A key element of integrated pest management (IPM) is the suppression of potential pest outbreaks by beneficial arthropods. The European earwig, Forficula auricularia L., is an important natural enemy of a wide range of insect pests in pip fruit orchards. However, earwig population sizes vary greatly from location to location, illustrating their sensitivity to biotic and abiotic factors, especially human interventions relating to orchard management. In order to help growers sparing and augmenting earwig populations in their pip fruit orchards, we developed a software tool that integrates a sophisticated earwig phenology model with management recommendations. The program is based on a day degree model for earwigs which is fed by temperature data collected by the pcfruit research centre. In addition, a pesticide database with known side effects of a wide range of products on the different life stages of earwigs is integrated in the system. The output gives the current status of the earwig population and management recommendations for activities critical for their survival. Hence, by consultation of this user-friendly software fruit growers can predict the earwig development in the field at any time, and organize the timing of orchard management actions taking into account the presence of (sensitive) life stages of the earwig life cycle. Doing so, negative effects specific orchard management actions, such as badly timed spray applications and soil tillage, can be avoided.

Integrated management of phytoplasma diseases in pome fruit: an overview of efficacy results of IPM insecticides against pear Psylla (Cacopsylla pyri).

Phytoplasmas are plant pathogenic mollicutes that cause devastating diseases in various crops worldwide. The closely related pome fruit tree phytoplasmas Candidatus Phytoplasma mali and Candidatus Phytoplasma pyri are the causal agents of apple proliferation and pear decline, respectively. They can be transmitted from tree to tree by Psyllidae. As pear suckers (Cacopsylla pyri) are widely considered to be the most important pest in pear orchards, a good control of this insect vector is a key element for limiting the natural spread of pear decline. Efficient control relies on a perfect tuning of treatment schedules, taking into account efficacies of (at preferably) low-impact insecticides and side-(repellent)-effects of alternative products (e.g. kaolin, mineral oils and fungicides), the optimal positioning of these crop protection agents, and the best possible presence of beneficial predators. The department of Zoology of the pcfruit vzw research institute (Belgium) has a long tradition of executing insecticide field trials according to EPPO guidelines. Here, we present an overview of the results of a selection of IPM-compatible insecticides (abamectin, spirotetramat, thiacloprid, spinosad, spirodiclofen), tested in efficacy trials against pear Psylla on different life stages during the last decade. Based on these results and monitoring data of pest and beneficial biology, we additionally propose optimal pear Psylla control schedules which allow to reduce the number of (phytoplasma harbouring) psyllids in integrated systems to a minimum.

Side effects of plant protection products and biological interactions on the European earwig Forficula auricularia L.

Plant protection products are designed to control pests but can have negative side effects on non-target arthropods thus disturbing the important population of natural enemies required for biological control. Although the European earwig, Forficula auricularia L, (Dermaptera: Forficulidae) is not considered to be a key beneficial in pome fruit, it is an important predator of several pests, e.g. woolly apple aphid and pear sucker. The impact of non-selective plant protection products at crucial moments in their (univoltine) life cycle can be of significant relevance compared to insects with numerous generations. Foliar applications in spring when nymphs are migrating into the trees can reduce the number of adults in summer and subsequently affect the population size next year. Multiple and/or combined spraying during summer on adults may have a cumulative effect resulting in less over wintering females which possibly exhibit poor reproductive performance. Previous residual contact bioassays already revealed the harmful side effect of several formulated products on adults. Insects showing sub lethal symptoms recovered partially or died eventually. As spinosad caused significant toxicological effects it was subsequently tested in 3 different dose rates on adults and N4-nymphs. We noticed not only a clear dose-response relationship but N4-nymphs proved to be more susceptible than adults; even a dilution of 1/9-th of the registered dose rate still caused a mortality of 45.5 % after 20 days. Understanding the earwig's population dynamics is essential for efficient practical biocontrol. It proves difficult to increase population levels to sufficient high numbers for optimal pest control. Local biological factors might be limiting. Therefore, we tested two hypotheses that pertain to population limitation: 1. Bird predation during summer, 2. Small mammal nest predation during winter. Enclosure experiments showed no negative bird effect on earwig densities unless large bird flocks inhabited the area. Small mammals did not actively predate the over wintering nests, although other predatory arthropods may be important.

Parasitation of the parasitic wasp Ephedrus Persicae(Frogatt) on the rosy apple aphid Dysaphis Plantaginea (Passerini).

The rosy apple aphid Dysaphis plantaginea is one of the most important leaf sucking pests in pome fruit. As damage, caused by an infestation of a relatively small number of fundatrices in spring, easily exceeds the economic threshold level, pest management is crucial. Besides the use of IPM-compatible pesticides, natural enemies (ladybird beetles, parasitic wasps, saw flies...) can play an additional role in controlling aphids. In Europe, the solitary endoparasitoid Ephedrus persicae (Hymenoptera: Braconidae, Aphidiinae) is the dominant parasitic wasp attacking rosy apple aphid. As this parasitoid develops later than its host, control is determined by the population density and the parasitising efficiency of the wasp. The population increase within a season is determined by generation turnover and parasitizing capacity, a factor poorly understood in E. persicae. To be able to estimate the number of wasps required for successful control the parasitic behaviour was studied in semi-field circumstances. Artificially infested colonies of rosy apple aphid on apple trees grown in a greenhouse, were covered with cages of gauze in which young, mated female parasitic wasps were released. The number of aphids (alatae, apterae and mummies) as well as the number of adult parasitic wasps were recorded weekly until the end of infestation or parasitation. This test method allowed a comparison of the parasitizing efficacy of Ephedrus with that of the well-studied parasitoid Aphelinus mali (Haldeman), that efficiently controls the woolly aphid Eriosoma lanigerum (Hausmann).

The Stroke Unit Discharge Guideline, a prognostic framework for the discharge outcome from the hospital stroke unit. A prospective cohort study.

OBJECTIVE: To investigate which factors during the subacute phase post stroke have predictive value for the discharge outcome from the hospital stroke unit. METHODS: In a prospective cohort of 338 patients admitted to a hospital stroke unit 26 potentially prognostic factors, arranged in clinical and social subdomains, were scored and analysed by binary logistic regression analysis. The outcome of the research consisted of the various discharge destinations. RESULTS: The overall predictive value of the discharge model is high (91%). Factors predictive of a poor discharge outcome are a low Barthel Index score (odds ratio (OR) 0.78 per point increase; p < 0.001), a poor sitting balance (OR 5.96; p < 0.001), a depression (OR 7.23; p < 0.001), poststroke cognitive disability (OR 3.51; p = 0.007) and older age (OR 1.05 per point increase; p = 0.008). If present, a personality disorder, premorbid cognitive disability and premorbid functional disability all show a tendency towards poor discharge outcome, but these factors did not reach statistical significance in this study, possibly due to their low prevalence. Readiness of the family circle to provide support was only significant in the univariate analysis. CONCLUSIONS: Somatic, biological and psychological factors predict the discharge outcome. Functional and cognitive factors play a decisive role in the future ability to live independently after a stroke. The prognostic importance of social factors could not be demonstrated. Urinary incontinence did not emerge as a prognostic factor. This is in contrast to scientific findings till now, but in accordance with clinical experience.