Biological control of western flower thrips,Frankliniella occidentalis(Pergande) (Thysanoptera: Thripidae), in gerberas, chrysanthemums and roses

Abstract

Frankliniella occidentalis (Pergande), western flower thrips (WFT), is a major worldwide pest of vegetables and ornamental crops. The biology of WFT was examined on gerberas, chrysanthemums and roses in relation to plant stage (flowering and non-flowering), pupation site, soil moisture and plant parts often inhabited by adult and immature thrips. Four foliage thrips predators (Transeius montdorensis (Schicha), Orius armatus (Gross), Mallada signata (Schneider) and Neoseiulus cucumeris (Oudemans)) and three soil predators (Geolaelaps aculeifer (Canestrini), Steinernema feltiae (Filipjev) and Dalotia coriaria (Kraatz)) were studied to determine their ability to reduce the numbers of WFT on gerberas, chrysanthemums and roses. There was no difference in the number of adults that emerged from growing media of high or low moisture content on any host plant. There were also no differences in the total numbers of WFT recaptured from flowering gerberas, chrysanthemums or roses. However, about seven times the number of thrips were collected from flowering chrysanthemums compared with non-flowering chrysanthemums, indicating that the flowering plants were more suitable hosts. Of all thrips recollected, the greatest percentage was immature (larval and pupal) thrips (70%, 71% and 43%) on the flowers for gerberas, chrysanthemums and roses, respectively. The mean percentage of thrips that emerged as adults from the soil was very low (5.3 Ϯ 1.2, 8.5 Ϯ 2.9, 20.5 Ϯ 9.1 and 28.2 Ϯ 5.6%) on gerberas, flowering and non-flowering chrysanthemums, and roses, respectively. Simultaneous release of foliage and soil predators did not reduce the number of thrips beyond that caused by foliage predators alone. Of the foliage predators, T. montdorensis, O. armatus and N. cucumeris performed best, significantly reducing the numbers of adult and immature thrips on flowers and foliage by 30-99%. Further research is required to determine the most cost-effective rates of release in cut flower crops.

Integrated pest management in western flower thrips: past, present and future

“…Hence, combinations of foliar and soil‐dwelling biocontrol agents targeting all WFT life stages have been investigated. Simultaneous treatment of different mites or pirate bugs as foliage predators with the soil predators G. aculeifer , D. coriaria or the nematode S. feltiae did not reduce thrips numbers in ornamentals beyond that caused by foliage predators alone . In contrast, the use of Heterorhabditis nematodes with the foliar‐dwelling mite N. cucumeris provided superior control in green bean compared with individual releases .…”

“…Simultaneous treatment of different mites or pirate bugs as foliage predators with the soil predators G. aculeifer, D. coriaria or the nematode S. feltiae did not reduce thrips numbers in ornamentals beyond that caused by foliage predators alone. 81 In contrast, the use of Heterorhabditis nematodes with the foliar-dwelling mite N. cucumeris provided superior control in green bean compared with individual releases. 82 Combinations of different predatory mites with the nematode S. feltiae achieved good WFT control in cyclamen, while combinations of O. laevigatus with the respective nematodes failed to control thrips.…”

Ecology and Role of the Rove Beetle, <i>Dalotia coriaria</i>, and Insidious Flower Bug, <i>Orius insidiosus</i>, in Greenhouse Biological Control Programs

“…Biological control entails periodic releases of natural enemies or biological control agents, such as parasitoids and predators in order to regulate or maintain insect or mite pest populations below damaging levels [4] [6] [15]. There are natural enemies commercially available for use against fungus gnats and western flower thrips including the following predatory mites: Stratiolaelaps scimitus (Womersley) (formerly = "Hypoaspis miles") (Acari: Laelapidae) [16] [17], Neoseiulus (formerly = Amblyseius) cucumeris Oudemans (Acari: Phytoseiidae) [18] [19] [20], and Amblyseius swirskii AthiasHenriot (Acari: Phytoseiidae) [21] [22]. In addition, two generalist predators commercially available for use in greenhouse production systems are the rove beetle, Dalotia coriaria (Kraatz) (Coleoptera: Staphylinidae), and the insidious flower bug, Orius insidiosus (Say) (Hemiptera: Anthocoridae).…”

Susceptibility of Dalotia coriaria (Kraatz) (Coleoptera: Staphylinidae) to Entomopathogenic Nematodes (Rhabditida: Heterorhabditidae and Steinernematidae)

“…Due to their cryptic behaviors (eggs laid in plant tissue, pupation occurs in the soil, and feeding on developing tissues) and their resistance to many insecticides, biological control has become increasingly important to successful western flower thrips management programs [2,3,4,5]. Both entomopathogenic nematodes and D. coriaria are employed to target the soil-dwelling stage of western flower thrips ( i.e., prepupae and pupae).…”

“…On caged Gerbera jamesonii (Bolus ex Hook) (Asterales: Asteraceae) and Chrysanthemums spp. (Asterales: Asteraceae), D. coriaria did not reduce western flower thrips populations with thrips ranging from 1–1.8 to 6.9–7 on G. jamesonii and Chrysanthemums spp., respectively [5]. In a field experiment with five or 10 adult rove beetles per caged parsley Petroselinum crispum (Mill.)…”