California at Davis supplied western flower thrips. This research was made possible by a grant from the UIUC Campus Research Board (RES BRD CLOYD R 1-2-68037) awarded to Raymond A. Cloyd and Daniel F. Warnock. We also thank Jack Juvik, Department of Natural
primary pest. Western flower thrips are extremely polyphagous, feeding on a wide range of greenhouse-grown horticultural crops ( Gerin et al., 1994 ; Lewis, 1997 ; Tommasini and Maini, 1995 ). Western flower thrips populations are a major concern of
Western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), is an important insect pest of greenhouse-grown horticultural crops worldwide ( Cloyd, 2009 ; Kirk, 2002 ; Lewis, 1997a ; Reitz, 2009 ; Robb and Parrella
Western flower thrips are the most destructive insect pest of greenhouses worldwide, causing both direct and indirect damage to a wide range of horticultural crops ( Brodsgaard, 1989 ; Gerin et al., 1994 ; Helyer et al., 1995 ; Tommasini and
Western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), is an insect pest of horticultural crops worldwide ( Cloyd, 2009 ; Kirk, 2002 ; Mouden et al., 2017 ; Reitz, 2009 ; Robb and Parrella, 1995 ). Western
Western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) are one of the most destructive insect pests of horticultural crops ( Helyer and Brobyn, 1992 ; Jensen, 2000 ; Kirk, 2002 ; Kirk and Terry, 2003 ). The
Western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), and fungus gnats Bradysia spp. (Diptera: Sciaridae) are major insect pests of greenhouse production systems ( Cloyd, 2008 , 2009 ; Hamlen and Mead, 1979
Control failures of many insecticides used against the western flower thrips (WFT), Frankiniella occidentalis (Pergande), have been reported from several locations by greenhouse operators. To document resistance, thrips were bioassayed by placing them in vials coated with doses of diazinon, methomyl, bendiocarb, dimethoate, azinphosmethyl and cypermethrin at (100, 50, 10, 5, 1, 0.5 and 0.1 g/vial). Adult female WFT were collected from a colony exhibiting control failures using organophosphate, carbamate and pyrethroid insecticides. A colony showing no resistance was used as a control. The LC50's of the resistant and susceptible strains were diazinon 49.3 and 4.6 g/vial, cypermethrin no mortality and 3.7 g/vial, and azinphosmethyl 20.2 and 2.l g/vial respectively. Results show resistance is present as well as cross resistance to diazinon and cypermethrin because the resistant population was never exposed to these compounds.
Western flower thrips (WFT) [Frankliniella occidentalis (Pergande)] are an ever-present problem in greenhouse floricultural crops. To determine if host plant resistance varied in impatiens [Impatiens wallerana Hook. f.] nine genotypes were evaluated for resistance to WFT feeding damage. Individual insect-free plants of each genotype were inoculated with ≈30 laboratory-reared WFT. Thrips were allowed to feed on individual plants for a 4-week period during which visual evaluations were conducted every 2 weeks to estimate feeding damage. Feeding damage varied among genotypes and increased with time. At 4 weeks after inoculation, `Cajun Carmine' and `Super Elfin Lavender' had significantly less feeding damage than all other genotypes. The San Vito Wild-type germplasm was determined to be highly susceptible to thrips feeding damage based on visual evaluations. Because WFT feeding damage varied among genotypes, the potential for improving impatiens resistance to WFT exists within commercially available germplasm.
A greenhouse study was conducted to confirm the availability of resistance in pepper (Capsicum annuum L.) to western flower thrips [Frankliniella occidentalis Pergande)]. Host plant resistance ratings confirmed earlier observations that there is a considerable amount of variability within pepper germplasm for reaction to F. doccidentalis. Plants of `California Wonder', `Keystone Resistant Giant', `Mississippi Nemaheart', `Sweet Banana' and `Yolo Wonder L' were resistant to the insect and exhibited only mild injury. Plants of `Bohemian Chili', `Carolina Cayenne', and `Santaka', however, exhibited the symptoms of severe thrips injury, i.e., poorly expanded, deformed and distorted leaves, greatly shortened internodes, and severe chlorosis. The resistance in pepper to F. occidentalis appears to be due to tolerance mechanisms, not nonpreference or antibiosis mechanisms. The levels of resistance identified in this study are sufficiently high to justify the initiation of breeding efforts to transfer F. doccidentalis resistance into susceptible pepper cultivars.