## 2 Materials and Methods  
### Sources of Insects, Plants and Plant Extracts  
A colony of WFT was maintained on potted moss-roses (also known as portulacas or purslanes in floricultural trade; _Portulaca grandiflora_ Hook., cv. \"Happy Hour\"; Portulacaceae) in a greenhouse at Clemson University's Pee Dee Research and Education Center (PDREC), Florence, SC, USA. The colony was established with WFT dispersing naturally from the surrounding wheat, cotton and soybean fields into the greenhouse through opened side panels. The colony was maintained by both reproduction of the existing population and individuals dispersing from the fields, and it was never treated with insecticide or fungicide once the colony was established. Infested flowers were collected as needed and allowed to desicate in Petri dishes (100 \(\times\) 15 mm) in a laboratory maintained at 21 \(\pm\) 3 \({}^{\circ}\)C, 41 \(\pm\) 5% R.H., and a 10-h photoperiod. Adult WFT emerging from the desiccating flowers were collected with fine paintbrushes and kept in Petri dishes without any plant materials or moisture for 4 h before the experiments. All experiments were conducted on Madagascar periwinkle (commonly known as annual vinca in floricultural trade; _Catharantlus roseus_ ([PERSON], cv. \"Cora Red\"; Apcy-naceae) at PDREC. Periwinkle flowers were chosen for this experiment because of its fully opened and flat petals (which allowed unimpeded observations), as well as its narrow floral tube (which limited refuge for WFT during treatment). Plants were grown from seeds (Parks Wholesale, Greenwood, SC, USA), and germinated in artificial growing media (Sungro Professional; Sun Gro Horticulture, Agawan, MA, USA). Seedlings were grown to about 5 cm in height before they were transplanted into plastic pots (15 cm in diameter, 12 cm in height) filled with growing media. The seedlings were fertilized with 10 g slow-release fertilizer (Osmocote; Scotts Miracle-Gro Company, Marysville, OH, USA) and grown in a greenhouse until they produced flowers and were ready for the experiments. Fully opened flowers excised at the base of pedicels were collected for the laboratory experiments, whereas whole plants were treated and maintained in the greenhouse for the residual toxicity experiment. Eight plant extracts were purchased from Shaanxi Undersun Biomedical Co., Ltd. (Xi'an, China). The products were extracted from _Celastrus angulatus_ Maxim. (Celastraceae; 6% \(v/v\) elangulin according to the supplier's analysis; same for the other extracts), _Cnidium monnieri_ ([PERSON]) [PERSON] (Apiaceae; 10% cnidium lactone), _Derris trifoliata_ [PERSON]. (Fabaceae; 5% rotenone), _Nicotiana tabacum_ L. (Solanaceae; 90% nicotine), _S. flavescens_ (5% matrine), _Stemona japonica_ ([PERSON]) [PERSON] (Stemonaceae; 1% stemonine), _Tanuectum cinerariifolium_ (Trevir.) Sch. [PERSON]. (Asteraceae; 70% pyrethrins), and _Veratrum nigrum_ L. (Melanthiaceae; 1% veratrine). All plant extracts will be identified henceforth by their respective active ingredients. We did not conduct independent analysis of the plant extracts but relied on non-proprietary information provided by the manufacturer. According to the manufacturer, all plant extracts were prepared in 95% ethanol and processed through the steps of extraction, concentration, sedimentation, filtration, and dilution. The active ingredients were identified and quantified by the manufacturer using HPLC, with laboratory-grade active ingredients as the standards for analysis and comparisons. A proprietary surfactant, 4209-A, was added to all products. The products were kept in a refrigerator until dilution. Preliminary two-choice bioassays were conducted to confirm that the extraction solution (ethanol) and the adjuvant used in all bioassays in this study (Tween 20) had no repellency against and caused no mortality in WFT. Ethanol (95%) and Tween 20 (97% polyoxyethylene 20-sorbitan monolaurate) were diluted to 0.05% \(v/v\) of final solution.