The tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), is the most important insect pest of cotton, Gossypium hirsutum (L.), in Mississippi. This research project was initiated to gain a better understanding of selected crop production factors that can improve tarnished plant bug integrated pest management. Results suggest that irrigation strategies and varietal pubescence can significantly influence tarnished plant bug management in cotton. Most notably, delaying irrigation for as long as possible and planting hairy varieties can minimize the impact of tarnished plant bug on cotton yields and reduce the number of insecticides needed to manage this pest. Additionally, these results show that tarnished plant bug management is most critical during the first four weeks of flowering. Results from these experiments will be used to improve the current integrated pest management program for tarnished plant bug in cotton and make cotton production more sustainable for Mississippi producers.

No description available.

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.

Cotton (Gossypium hirsutum L.), is cultivated in the United States, primarily in regions characterized by long, hot summers to optimize plant growth. Virginia is the northernmost state where cotton is grown, with approximately 84,000 acres annually. The unique challenges of cultivating cotton in Virginia stems from its relatively short season due to its geographical location, lack of large contiguous acreage, and distinctive issues with pests. A significant pest of this region is the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), which emerged as a major threat to mid-Atlantic cotton during the late 2010s. L. lineolaris utilize a variety of wild and cultivated hosts to survive the winter months. The overwintering success and distribution of diapause survival L. lineolaris was measured on cover crops and weeds common in the Mid-Atlantic. Densities varied between weed and cultivated hosts, with L. lineolaris exhibiting increased survival in legumes compared to grains. Carbohydrate, lipid and protein levels were measured within diapausing and non-diapausing L. lineolaris specimens. Overwintering specimens usually had elevated level of carbohydrates and lipids, while containing decreased concentrations of protein. Nutrient quantification provided an effective tool in selecting for diapause status in L. lineolaris. Through the results from this study, an alternative method to dissection for determining diapause status in L. lineolaris has been identified. In the spring, movement of L. lineolaris throughout the landscape is highly dependent on host senesce. Flight analysis, behavioral assays and nutritional quantification assays on L. lineolaris populations from different weed hosts were performed to assess the flight capacity of specimens fed from different hosts. While weed hosts type provided populations with differing internal nutrient levels, sustained flight was not different between populations. When dispersal of L. lineolaris into cotton occurs, insecticide treatments following scouting are often necessary to prevent economic damage to the plant. Insecticide experiments were conducted aiming to assess the impact of different active ingredients on L. lineolaris, secondary pests, and natural enemy populations. Findings indicated that insecticides used to control L. lineolaris were successful at lowering pest populations and acephate was found to impact natural enemy populations. Plots applied with acephate experienced secondary pest outbreaks, highlighting the crucial role of natural enemies. / Doctor of Philosophy / Cotton is cultivated throughout the southern United States, extending up the east coast and into North Carolina and Virginia. Virginia poses unique challenges for cotton growers due to specific pest issues and need for region-specific research. The tarnished plant bug is a key pest of mid-summer cotton across this region. Overwintering studies were conducted to investigate host preferences on cover crop and weed hosts, as well as diapause survival and termination timing on cover crops. These studies revealed that hairy vetch and deadnettle species may harbor larger populations compared to other weed hosts, and that cover crops such as hairy vetch and crimson clove led to greater overwintering survival compared to grains. During diapause, metabolic changes occur that can lead to increased fat body to aid in overwintering survival. Diapausing and non-diapausing tarnished plant bugs were used in assays to quantify differences in the nutrients commonly found in this fat body. This study successfully found differences in carbohydrates, lipids and proteins levels between the diapausing and non-diapausing populations. This may allow for the identification of reproductive status of tarnished plant bugs based on nutrient levels. Flight capacity, activity levels and nutrient levels in tarnished plant bug populations taken from spring and summer weed hosts were investigated, with the objective to understand the ability of these populations to transition to cotton in the mid-summer. There were some indicators that flight initiation may be influenced by weed host, while all populations had similar flight potentials. Once in cotton, tarnished plant bugs are primarily treated with chemical insecticides which may produce unknown consequences to the system as a whole. Experiments were conducted to assess the impact of insecticides on non-target species within cotton were conducted in the field. Certain insecticides were identified to be harmful to non-target and potentially beneficial insect species, which contributed to outbreaks of other secondary pest species.

The focus of this research was to evaluate commonly used insecticides and plant based scouting practices in cotton, Gossypium hirsutum (L.), prior to bloom for tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), management. As well as determine the influence of ThryvOn technology on these research objectives. Data indicate that imidacloprid may have a limited fit in non-ThryvOn cotton, while the additional mode of action afforded by ThryvOn technology could extend imidacloprid and other insecticide’s effective use prior to bloom. Additionally, sulfoxaflor and acephate remain the best products for pre-bloom management. When evaluating differences between plant based scouting methods prior to bloom used among cotton consultants across the Mid-Southern region, cotton technology and tarnished plant bug control did not cause variability in square retention monitoring methods, while sample date, or cotton growth did. However, based off these results, plant-based extension scouting recommendations do not need altering at this time.

Lygus bug (Lygus Hahn) and predator (Chrysopa carnea Stephens, Geocoris, and Nabis) abundance and spatial distribution in production-managed, drop and furrow-irrigated cotton (Gossypium hirsutum L.) in central Arizona were compared during the early seasons of 1980-1983. Sweep net and drop cloth samples revealed lygus bug populations were established and reached pest status in drip-irrigated cotton 2-3 weeks prior to those in furrow. Several factors combined to make drip cotton more favorable than furrow for Lygus: more dense plant populations, taller plants, lower vapor pressure deficits within the plant canopy, and earlier availability of squares. Within furrow-irrigated cotton, lygus bugs and the percent Lygus-damaged squares were greater in areas of tall, dense plantings, primarily in areas distant from the water source. In drip, damage was significantly greater than in furrow, and comparable in all field ares. Predator populations were not consistently greater under either irrigation system. Under furrow, Geocoris and Nabis populations were greatest in areas of Lygus abundance. Morisita's index and Taylor's power law indicated a higher degree of aggregation in the spatial patterns of Lygus and predator populations in furrow-irrigated cotton than in drip. The two indices agreed in magnitude and trend across the insects studied, but Morisita's index was more frequently significant for contagion. Sweep net samples revealed a higher degree of aggregation than drop cloth. Taylor's coefficients were used to determine optimum sweep net and drop cloth sample sizes to evaluate Lygus populations for pest management. The sweep net requires a greater sample size than the drop cloth to ensure a given level of precision, and more samples are required in furrow-irrigated cotton than in drip. Based on percent damage and the relative variability of damage estimates, the number of squares examined for lygus bug damage should be comparable in all drip field areas, but twice as many should be examined in the furrow head-water as in the middle and tailwater. Extrafloral nectar volumes are greatest in leaves of the middle and top plant regions, and in the blossom and young boll stages of fruiting bodies. Irrigation timing and method affect nectar production. The effects of extrafloral nectar production phenology on insect distribution are discussed.

No description available.

No description available.

The tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), is considered the most economically important pest of midsouth cotton. This study was designed to understand the impact of tarnished plant bug populations in the later weeks of flowering cotton and residual effects of novaluron with subsequent applications. Experiments evaluated dynamic threshold approaches in the later flowering period of midsouth cotton, the impacts of novaluron plus subsequent applications at the 3rd week of square, as well as residual properties in a laboratory experiment. Results suggest that a dynamic late season approach can reduce the amount of insecticide applications targeting tarnished plant bug with no penalty to yield. Populations were observed at lowest densities where applications of novaluron were tank mixed with an adulticide (acephate) at the 3rd week of square. Results of this experiment will be important in refining seasonal management recommendations for tarnished plant bug in midsouth cotton production systems.

The tarnished plant bug (TPB), Lygus lineolaris (Palisot de Beauvois), has been a devastating insect pest in cotton agroecosystems in mid-southern cotton for several decades. Similar to related Heteropteran insect pests, L. lineolaris uses piercing-sucking mouthparts to penetrate harvestable fruiting structures on the cotton plant (i.e., squares, flowers, small bolls) leading to significant reductions in lint yield when infestations are above economic injury levels. Economically damaging infestations of L. lineolaris have occurred in Virginia and North Carolina cotton since 2013. In response, cotton area sprayed with broad-spectrum insecticides for L. lineolaris has increased in these states. As such, this dissertation research sought to answer a variety of questions to address this issue including 1) mapping the spatiotemporal abundance of L. lineolaris across Virginia as well as creating models to predict landscape and climate factors increasing infestation risk, 2) using a systems approach to provide growers with cost-effective and sustainable integrated pest management (IPM) solutions including economic spray thresholds, 3) investigating the incidence and transmission of fungal pathogens by L. lineolaris increasing Fusarium hardlock disease, further impacting yield loss at harvest, and 4) conducting insecticide resistance monitoring of L. lineolaris across the Southeast including biochemical lab assays to determine possible mechanisms of insecticide resistance. These findings will help form compressive IPM and insect resistant management (IRM) plans to equip southeastern cotton growers with practical management tools as well as useful information on "high-risk" areas to invest management resources, increasing economic returns while minimizing environmental impacts of over-spraying foliar insecticides. / Doctor of Philosophy / The tarnished plant bug (Lygus lineolaris) is an important pest in cotton from July through September that causes reduced yields and lower quality of lint and seed. Tarnished plant bugs cost the cotton industry hundreds of millions of dollars in losses annually. However, tarnished plant bug infestations were rare and sporadic in Virginia and North Carolina before 2013. In recent years, tarnished plant bug infestations have nearly doubled in these states, and research is needed to better understand how to manage recent pest outbreaks to avoid substantial economic losses. To address this issue, this dissertation research investigated a variety of questions including 1) the distribution of tarnished plant bugs in this region and the effects of geography and climate on infestation risk, 2) best practices for managing this pest in cotton fields, 3) possible associations between tarnished plant bugs and cotton boll diseases further impacting yield, and 4) whether tarnished plant bugs in this region are resistant to frequently used broad-spectrum insecticides as well as potential mechanisms driving resistance levels. Findings from this research will equip southeastern cotton growers with regionally specific recommendations for managing and monitoring tarnished plant bugs that minimize management costs and increase the quality and quantity of cotton yields.