The order Thysanoptera (Insecta: Paraneoptera), commonly known as thrips, includes organisms that exhibit a wide range of social and feeding behaviors that are of particular interest in evolutionary studies. These studies within thrips have been inhibited by the lack of knowledge of thrips relationships. The recognized classification scheme strives to reflect evolutionary relationships and is based upon morphology. Molecular data is next as morphology alone is not enough to resolve relationships. Few molecular studies have been conducted and all were limited in their taxon sampling and genetic sampling. To provide a foundation of future evolutionary studies, the objectives of this study are to (1) test the monophyly of the suborders Terebrantia and Tubulifera, (2) test the monophyly of the families and decipher their relationships, and (3) test the monophyly of the recognized subfamilies. Phylogenies were reconstructed based upon 5299 bp, from five genetic loci: 18S ribosomal DNA, 28S ribosomal DNA, Histone 3 (H3), Tubulin-alpha (TubA) and cytochrome oxidase c subunit I (COI). 99 thrips species from seven of the nine families, all six subfamilies and 70 genera were sequenced. Maximum Parsimony (MP), Maximum Likelihood (ML) and Bayesian analysis all strongly support a monophyletic Tubulifera and Terebrantia. Phlaeothripidae, Aeolothripidae, Melanthripidae and Thripidae are all monophyletic families. The relationship between Aeolothripidae and Merothripidae to the rest of Terebrantia is equivocal. Morphological and molecular data suggest Aeolothripidae or Merothripidae could be the basal lineage of Terebrantia. Four of the six subfamilies are recovered as monophyletic. The two largest subfamilies, Phlaeothripinae and Thripinae, are paraphyletic and require further study to understand relationships within them.

Rainfastness of insecticides is an understudied aspect of agricultural research. Little is known about the residual of commonly used products for key pests of cotton, as well as their residual after a rainfall event. This project was designed to evaluate the impact of rainfall on the performance of commonly used insecticides for tobacco thrips, Frankliniella fusca (Hinds); tarnished plant bug, Lygus lineolaris (Palisot de Beauvois); and bollworm, Helicoverpa zea (Boddie), management in cotton. Laboratory and field experiments suggest that rainfall occurring within 16 hours after application had a negative impact on the performance of most insecticides. Chemical analyses of leaf tissue using a mass spectrometer confirmed what was observed with field and laboratory experiments. Although direct comparisons between insecticides cannot be made, results from this study suggest that spinosyns and insect growth regulators appeared to have the longest residual after a rainfall event.

There have been many changes in production agriculture over the last 20 years. The use of herbicide resistant crops has become common place in production agriculture. However, the release of crops resistant to auxin herbicides has brought more attention to the pesticide application process regardless of the type of pesticide applied. Moreover, controlling off-target movement of pesticides has become an integral part of the day to day farming tasks. The use of deposition aids when applied with water has been documented; however, the effect of deposition aids on pesticide application is not well understood. Based on these findings, selecting a deposition aid not only can be affected by the pesticide used but also the crop in question. Additionally, label restrictions on auxin herbicide application in auxin tolerant crops brings an additional problem to cotton growers. The use of insecticides in conjuction with herbicide applications has been commonplace for many growers across the cotton belt. However, smaller droplets have been utilized to increase coverage of these insecticides. Data presented in these findings suggest that larger droplets can still have good levels of efficacy and in some instances increase yield. The use of auxin tolerant crops allows for usage of addition POST herbicides to cotton; however, the effect of these tank mix applications on ctrop injury is not well understood. In both EnlistTM and Xtend® Flex cotton levels of injury were increased when glufosinate and S-metolachlor were applied in a tank mix. However, yield was not negatively impacted in either study.

Onion thrips (Thrips tabaci) and Iris Yellow Spot Virus (IYSV) constitute a pest complex of global concern for allium growers. Yield losses due to onion thrips alone can be heavy, and in tandem with IYSV, these losses can be complete. This study was one phase of a multi-phase research project intent on exploring the potential drivers of thrips and virus infestation in onion. Preliminary observations in participating growers’ fields in northern Utah pointed towards a potential link between weedy field borders and thrips/IYSV infestation in onion. Field work was carried out at the Kaysville experiment station examining the possible relationships between thrips and IYSV incidence in onion and the presence of adjacent weed populations. This research was conducted with the intent of guiding growers’ decisions regarding field border management, and to provide additional insights into onion thrips behavior. While implications for growers remain unclear, thrips preferences regarding host plant utilization were identified, as well as preliminary evidence of additional plant species capable of hosting IYSV.

Master of Science / Department of Entomology / Kun Yan Zhu / Raymond A. Cloyd / Protected environments, such as greenhouses and interior plantscapes provide optimal conditions for arthropod (insect and/or mite) pests to survive, develop, and reproduce. Two commonly encountered insect pests in protected environments include the citrus mealybug (CMB), Planococcus citri, and the western flower thrips (WFT), Frankliniella occidentalis. It is difficult to mitigate CMB and WFT populations due to the behavioral characteristics of the insects and few pesticides that are registered for use in protected environments. This research involved two distinctly different studies. The objectives of the first study were to determine the efficacy and residual activity of systemic insecticides registered for use against CMB and to quantify CMB feeding locations. The objectives of the second study were to determine the compatibility and efficacy of commonly used binary pesticide mixtures against the WFT under both laboratory and greenhouse conditions. To determine the efficacy of systemic insecticides against CMB, greenhouse experiments were conducted in which coleus, Solenstemon scutellarioides, plants were artificially infested with CMB. Drench applications of each designated treatment were applied to each plant. Results associated with drench applications of the systemic insecticides against CMB indicated minimal CMB mortality (<30%) for both preventative and curative drench applications of azadirachtin and spirotetramat. Thiamethoxam, a neonicotinoid-based insecticide, at the labeled and twice the labeled rate provided the highest CMB mortality; however, not until 21 days after treatment was this observed, and CMB mortality was <80%. In all cases, significantly more CMB were located on the stem of green coleus plants compared to the leaf top and bottom. Pesticide mixture compatibility was determined using jar tests. In addition, phytotoxicity and efficacy of pesticide mixtures against WFT was determined through a series of laboratory and greenhouse experiments for each individual pesticide, and the mixtures to determine synergism, antagonism, or no effect. Results associated with the jar tests indicated that all the mixtures were compatible. Furthermore, the mixtures were not phytotoxic to the horticultural plant species evaluated. Laboratory results indicated that mixtures containing spinosad + bifenazate were antagonistic against WFT. Greenhouse experiments demonstrated significantly reduced efficacy associated with the abamectin + azadirachtin mixtures; however, each binary mixture provided approximately 80% mortality of WFT.

Peppermint, Mentha piperita 'Black Mitcham' was established as a host for tomato spotted wilt virus-impatiens serotype (TSWV-I). TSWV-I infection of peppermint, initially observed in a research greenhouse (Corvallis, OR), included stunting and downward curling of leaves accompanied by bronzing, and occasionally tip necrosis. Young leaves appeared either symptomless, deformed, or pale even under high nitrogen conditions. Older leaves had sunken, brownish-grey lesions. Bright yellow mottling was observed on newly mature deep green leaves. A begonia isolate of TSWV-I was transmitted to peppermint both mechanically and by western flower thrips, Frankliniella occidentalis (Pergande). Symptoms of TSWV-I infection were similar although only a faint yellow mottling was produced and only under cool temperatures (15°C). ELISA detection of virus distribution throughout the plant indicated infection was systemic. Bulked groups of thrips (5 thrips/sample) also tested positive for TSWV-I using ELISA. Transmission efficiency of 4, 6, 8, and 10 day old thrips adults given acquisition sources during the entire nymphal stage varied from 0-40% for thrips tested in pairs and 0-20% for single thrips (based on a 12 hour access feeding period). Adults 2 days old failed to transmit the virus. Western flower thrips exposed to TSWV-I had reduced survival and reproductive potential and slower development rates than unexposed thrips. Virusexposed thrips were 1.4 times as likely to die than unexposed thrips on a given day. Both individual and population reproductive potentials were significantly lower. Preoviposition period was extended in virus-exposed thrips. Development time from second instar to adult was 15% longer for virus-exposed thrips. This is the first report of altered population parameters in western flower thrips exposed to TSWV-I. / Graduation date: 1992

This thesis investigated new strategies to increase both the control and cost efficiency of the biological control agent, Orius insidiosus Say (Orius), in greenhouse ornamental crops through the identification of an optimal banker plant species, a suitable source of supplemental food, and the identification of an attractive semiochemical lure. Seven plant species/cultivars were evaluated in laboratory and greenhouse bioassays to determine if the plants could provide: an acceptable food source; a location for oviposition; high nymphal survival and rapid development to the adult stage; and a host plant for sustainable population growth. Based on the results obtained overall, the Purple Flash ornamental pepper is the best candidate for use as a banker plant. Greenhouse and laboratory bioassays investigated the suitability of various supplemental food sources. In greenhouse trials, cattail pollen did not sustain a population of Orius on chrysanthemum plants but did significantly increase the population of the target pest, the western flower thrips. The addition of Ephestia kuehniella eggs or honeybee-collected pollen can increase the production of Orius on Purple Flash banker plants. Orius females fed on E. kuehniella eggs or honeybee-collected pollen laid the greatest numbers of eggs and lived significantly longer compared to those fed apple pollen, cattail pollen, corn pollen in laboratory bioassays. In laboratory olfactory assays and greenhouse release experiments, Orius showed the greatest response to olfactory cues associated with a neryl (S)-2-methylbutanoate lure over odours emitted from a methyl salicylate lure, a methyl isonicotinate lures or clean air. / OMAFRA-University of Guelph research partnership, OMAFRA-Highly Qualified Personnel (HQP) Scholarship Program, and MITACS Accelerate.

Diss. (sammanfattning) Alnarp : Sveriges lantbruksuniv. / Härtill 5 uppsatser.

Thesis--Auburn University, 2009. / Abstract. Vita. Includes bibliographical references.

Doctor of Philosophy / Department of Entomology / Raymond A. Cloyd / Western flower thrips, Frankliniella occidentalis, is one of the most destructive insect pests in greenhouse production systems due to direct and indirect plant damage resulting in substantial economic losses. In addition, western flower thrips has developed resistance to many insecticides. Therefore, alternative plant protection strategies are warranted, such as augmentative biological control. This research was designed to evaluate 1) the effect of different absolute numbers of predator (rove beetle, Dalotia coriaria) and prey (western flower thrips) on predation efficacy of rove beetle under laboratory conditions; 2) the effect of western flower thrips pupal stage, predator-prey ratio, predator-prey number, and searchable area on predation efficacy of rove beetle in the laboratory; and 3) the effectiveness and cost of integrating the entomopathogenic fungus, Beauveria bassiana, and the rove beetle, D. coriaria, in suppressing western flower thrips populations under greenhouse conditions. Three laboratory experiments were conducted to assess predation efficacy of rove beetle adults on three western flower thrips pupal stages [prepupa, pupa, and prepupa-pupa combination (50%:50%)]. In each experiment, there were six numbers (0, 1, 2, 3, 4, and 5) of rove beetle adults and four initial numbers (15, 20, 25, and 30) of one western flower thrips pupal stage. This treatment configuration allowed for assessing the effect of predator-prey ratios (1:5, 1:10, and 1:15), accounting for different initial prey numbers, on predation efficacy of the rove beetle. Overall, for each pupal stage, the estimated mean probability of western flower thrips adults captured on yellow sticky cards decreased as the number of rove beetle adults released increased from 1 to 3, although the effect of additional rove beetle adult releases was not apparent. Furthermore, across the pupal stages considered in this study, in general, there was no evidence of any differences due to predator-prey ratios or initial prey numbers within each predator-prey ratio. Two laboratory experiments were conducted to assess the effects of western flower thrips pupal stage, predator-prey ratio, predator-prey number, and searchable area on predation efficacy of rove beetle adults. In experiment 1, there were two western flower thrips pupal stages (prepupa and pupa), three predator-prey ratios (rove beetle:western flower thrips—1:5, 1:10, and 1:15), and three predator-prey numbers (2, 3, and 4 times). Experiment 2 evaluated the latter two factors in combination with searchable area defined by container sizes [15.2 cm (1,834.82 cm3) and 11.5 cm (701.79 cm3)]. The estimated mean probability of western flower thrips adults captured on yellow sticky cards was significantly higher for the 1:5 predator-prey ratio [61.1% (48.5-72.4%)] than 1:10 [39% (28.1-51.2%)] and 1:15 predator-prey ratio [34.7% (24.7-46.3%)]. The estimated mean probability of western flower thrips adults captured on yellow sticky cards for 2 times the predator-prey number [57% (44.3-68.8%)] was significantly higher than 3 [37.2% (26.6-49.3%)] and 4 [40.6% (30-52.3%)] times the predator-prey number. In addition, a significantly higher estimated mean probability of western flower thrips adults was captured on the yellow sticky cards in the 15.2 cm than 11.5 cm containers. Two greenhouse experiments were conducted that evaluated five treatments: combination of insecticides (spinosad, pyridalyl, chlorfenapyr, and abamectin), B. bassiana, D. coriaria, B. bassiana and D. coriaria combination, and a water control. Overall, the estimated mean number of western flower thrips adults captured on yellow sticky cards was significantly lower for the insecticide treatment (mean range: 0, 46) than for the B. bassiana and D. coriaria combination (mean range: 0.3, 105.1) over eight weeks. There were no significant differences in final foliage quality of chrysanthemum, Dendranthema x grandiflorum, plants among the five treatments in experiment 1, but there were significant differences in experiment 2. However, in experiment 2, the chrysanthemum plants across all treatments were not marketable due to substantial feeding damage by western flower thrips. The cost of the insecticide treatment was nearly twice that of the B. bassiana and D. coriaria combination ($963.50 vs. $495.67) and was over twice that of the B. bassiana only treatment ($963.50 vs. $417.04). The D. coriaria only treatment was the least expensive at $78.63. The results of the research provide insight into the predatory behavior of D. coriaria on western flower thrips pupal stages, which may have practical implications for greenhouse production systems. However, predation efficacy of rove beetle adults on western flower thrips is influenced by predator-prey ratio, predator-prey number, and searchable area. Finally, greenhouse producers must initiate insecticide applications or release rove beetle adults early in the production cycle when western flower thrips populations are low to minimize plant damage.