No abstract

Abstract. Ten predatory mite species, all phytoseiids, were evaluated for control of western flower thrips (WFT), Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), on greenhouse cucumber. This study was done to further improve biological control of thrips on this crop. Neoseiulus cucumeris (Oudemans) is at present used for biological control of thrips in greenhouses. Compared to this species, Typhlodromalus limonicus (Garman & McGregor), Typhlodromips swirskii (Athias-Henriot) and Euseius ovalis (Evans) reached much higher population levels resulting in a significantly better control of thrips. T. limonicus was clearly the best predator of WFT. Also Euseius scutalis (Athias-Henriot) increased to higher populations levels than N. cucumeris, but without controlling the thrips, probably because of an unequal distribution of this predator on the plant. Iphiseius degenerans (Berlese), Neoseiulus barkeri (Hughes), Euseius finlandicus (Oudemans) and Typhlodromus pyri (Scheuten) did not establish better than N. cucumeris. A non-diapausing exotic strain of N. cucumeris did not differ from the North European strain. The best performers in this study were all of subtropical origin. T. limonicus, T. swirskii and E. ovalis have good potentials for controlling not only thrips but also whiteflies. Factors affecting the efficacy of phytoseiids on greenhouse cucumbers are discussed.

No abstract

Spraying suspensions of bee-collected pollens on cucumber plants facilitated the establishment of the predatory mite Amblyseius degelleralls Berlese (Acari: Phytoseiidae), and allowed it to reproduce in the absence of thrips or any other host. Repeated (3x) full crop applications with dosages of 80 and 8 kg/ha produced a predator density respectively 29 and 12 times higher than in control plots, but 0.8 kg/ha had no effect. Isolated predator colonies lasting about a month could be created using 20 adult females and 0.5 g pollen per colony.

No abstract

Entomophthora thripidum sp. nov. is described and illustrated. The species is pathogenic for Thrips tabaci Lind. (Thysanoptera: Thripidae) and caused epizootics in populations of this species in glasshouses in the Netherlands. Entomophthora thripidum is characterized by spores which are broadly ellipsoidal with a pointed apex and truncate base. Infection is restricted to the abdominal parts of the body and primary spores can be discharged from the living hosts. The secondary spores are similar but smaller than the primary ones. Details about the seasonal history and symptoms of the disease are described. The invalidly published name Empusa weberi Lakon (= Entomophthora weberi (Lakon) Batko) is validated by a Latin diagnosis.

The population dynamics of 2 predacious phytoseiid mites as potential biological control agents against thrips were investigated on sweet peppers [Capsicum annuum] in a greenhouse in the Netherlands, where the prey was predominantly a spontaneous outbreak of Thrips tabaci. Amblyseius cucumeris [Neoseiulus cucumeris] established more easily and reached higher population densities than A. mckenziei. Mixed populations of both predators were observed for several generations, but eventually A. mckenziei was superseded by N. cucumeris. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Integrated Pest Management (IPM) is successfully used on a year-round scale on only 15% of the area of roses under glass. Obstacles for further expansion of IPM practices among rose growers are the control of the spidermite Tetranychus urticae and the greenhouse whitefly Trialeurodes vaporariorum. The research stations of Naaldwijk, Aalsmeer and Boskoop have started initiatives in order to enlarge the choice of predator species available for Dutch growers. A series of greenhouse experiments were conducted to select phytoseiid mites suitable for commercial cut roses. Among ten species tested in experimental greenhouses, Euseius ovalis was found to be the most promising control agent of T. vaporariorum. Its efficacy against other pests and its compatibility with chemicals are the subject of further studies. Since E. ovalis is an exotic species formerly not commercially available, efforts are being made to obtain authorization for experimenting with this species in commercial greenhouses in the framework of new fauna protection regulations in The Netherlands.