Cyrtobagous salviniae is widely used for biological control of Salvinia molesta. Despite success in tropical and subtropical regions, the effectiveness of C. salviniae on S. molesta is inconsistent in temperate regions, indicating the need for a better understanding of the thermal biology of this agent. The objectives of this study were to compare cold tolerance of C. salviniae populations from the temperate native range and Louisiana, and characterize the overwintering physiology and population dynamics of C. salviniae in Louisiana. Surveys of the Lower Paraná-Uruguay Delta resulted in the first record of C. salviniae in Uruguay, and revealed the most southern distribution of this species in Argentina and Uruguay. Survival at 0°C was 1.5-times greater, chill coma recovery time was 1.8-times faster, and SCP was 1.2-times lower in the Argentine population compared to the Louisiana population. These findings show that the Argentine provenance should be considered for managing S. molesta in temperate regions. Besides host range tests, cross breeding between the Louisiana and Argentine populations should be investigated to determine the life histories of any possible hybrid. Laboratory assays demonstrated phenotypic plasticity in the cold tolerance of populations from central and southern Louisiana when acclimated to winter conditions. Survival at 0°C was 1.8- and 1.7-times greater, critical thermal minimum was 1.2- and 1.3-times lower, and chill coma recovery time was 2.7- and 1.5-times faster in the winter treatments compared to summer treatments, for both populations (central and south, respectively). Seasonal changes in reproductive status, fat body, and water content were evident from the field study, and are speculated to contribute to the overwintering success of adults at both sites. Adult and larval densities showed that populations were most vulnerable in the late winter/early spring, presumably when water temperatures and host plant quality have not yet recovered. Seasonal monitoring of the physiological status and population dynamics should be conducted to improve the timing of releases and predicting the success of S. molesta control. In conclusion, the management of S. molesta in northern Louisiana should incorporate releases of cold tolerant populations, and seasonal monitoring of physiology and population dynamics of C. salviniae.

Evolution of resistance in target pest populations is a major threat to the sustainability of transgenic crops expressing Bacillus thuringiensis (Bt) proteins. Fall armyworm, Spodoptera frugiperda (J.E. Smith), is a cross-crop target pest of Bt corn, Bt cotton, and Bt soybean. This pest, thus far, is the only target pest species that has developed field resistance to Bt crops in multiple areas across countries. Cry2Ab2 is a common Bt protein expressed in transgenic corn and cotton targeting lepidopteran pests including S. frugiperda. The objective of this study was to characterize fitness costs and inheritance of Cry2Ab2 resistance in S. frugiperda. In the fitness cost test, performance of the Cry2Ab2-resistant, -susceptible, and two reciprocal F1 colonies of S. frugiperda was assayed on non-toxic diet and non-Bt corn leaf tissue. Biological parameters measured were 7-day larval weight, neonate-to-pupa development time, neonate-to-pupa survivorship, pupal weight, sex ratio, and egg production. In the inheritance study, larval mortalities of the resistant- and susceptible parents, and eight other cross-strains were assayed using diet-incorporated and leaf tissue bioassays with Cry2Ab2. Maternal effects were examined by comparing the larval mortalities between the two F1 strains. Dominance levels of resistance were measured by comparing the larval mortalities of resistant, susceptible, and F1 heterozygous strains. Number of genes associated with the resistance was estimated by fitting the observed mortalities of F2 and backcross strains with the Mendelian monogenic inheritance model. There were no significant differences among the four insect strains for all the fitness parameters measured with few exceptions, suggesting that the resistance was not associated with fitness costs. The Cry2Ab2 resistance in S. frugiperda was likely inherited as a single, autosomal, recessive gene. Information generated from this study should be useful in assessing resistance risk and developing management strategies for the sustainable use of Bt crop technology.

<p> Grain sorghum is a drought tolerant crop used in the Mid-south region in rotation with corn, cotton, soybeans, and corn. In 2015 and 2016, research was conducted to determine the influence of insecticide treatment, planting date, planting population, hybrid, and environmental temperatures on sugarcane aphid, <i>Melanaphis sacchari</i> (Zehntner), populations and yield in grain sorghum, <i>Sorghum bicolor</i> (L.) Moench. In general, cooler temperatures had a negative effect on sugarcane aphid control with sulfoxaflor and flupyradifurone. Additionally, there was a negative relationship between grain sorghum plant population and sugarcane aphid densities per plant. These data suggest management of sugarcane aphid with insecticide seed treatments and foliar sprays is critical for maximizing grain sorghum yields. Additionally, growers should wait for warmer temperatures to ensure optimum control.</p>

<p> Soybean accounts from more than half of the acres dedicated to row crop production in the mid-south, leading to a wide planting window from late-March through mid-July. Studies were conducted in 2013 and 2014 evaluating seven planting dates of soybean, and their impact on agronomics. As planting was delayed, plant heights significantly increased, increasing the potential for lodging. Canopy closure significantly decreased as planting was delayed, leaving soybean more vulnerable to caterpillar pests. Yield potential also significantly decreased as planting was delayed. Season long surveys of insect pests and their arthropod natural enemies were conducted from 2013 to 2014 in small plot studies, and in large plot studies from 2015 to 2016 across multiple planting dates. The most common insect pests encountered in both studies were bean leaf beetles, the stink bug complex, and soybean looper. The most common natural enemies encountered were lady beetles, spiders, and the assassin bug complex. In general, insect pests densities increased as planting was delayed, whereas natural enemies were higher in earlier plantings or had no change throughout the planting windows. With the increased difficulty of controlling some caterpillar pests such as soybean looper, new control tactics need to be evaluated. A simulated Bt treatment was evaluated against a threshold, bug only, and untreated control across multiple plantings in 2013 and 2014. The simulated Bt treatment yielded significantly higher than the untreated control at plantings from early-June through mid-July. These were the only plantings that reached action threshold for soybean looper. The simulated Bt and threshold treatments were not significantly different from one another. In 2015 and 2016, a simulated Bt treatment plus threshold was evaluated in a late planting situation. The simulated Bt plus threshold treatment yielded significantly higher than the untreated control at the early-June and early-July plantings. Also in 2015 and 2016, the simulated Bt treatment was evaluated against a grower check on producer fields at 23 locations. The simulated Bt treatment resulted in significantly higher soybean yields than the grower check.</p>

Phylogenetic studies suggest that historically all paper wasps (Vespidae: Polistinae) in North America have tropical origins. However, paper wasps have adapted to thrive in temperate conditions. Subtropical and temperate climates allow for a study of adaptive traits which can be retained or lost within populations, and ultimately help elucidate the process of social wasp evolution. Additionally, species occurrence patterns can help us to understand partitioning and resource use within populations. We investigated the occurrence and phenology of each Polistine species found at four sites in southern Louisiana around Baton Rouge, and also examined the occurrence and behavior of a closely associated brood parasite, Chalcoela iphitalis. Based on nest height analysis we found two statistically different groupings: lower nesting species (Mischocyttarus mexicanus, Polistes dorsalis, P. metricus) and higher nesting species (P. exclamans, P. fuscatus, P. bellicosus). Patterns of occurrence in wasp nest attachment substrate also were found, with 32% of all nests occurring on Sabal palmetto or Sabal minor. Two periods of nest initiation were observed: spring nests in March-May and late season or fall nests in July-September. Late season nests made up roughly 40% of all nests observed and were represented by all species. Late season nests of P. dorsalis, P. bellicosus, P. metricus, and M. mexicanus demonstrated a significantly shorter colony duration than did spring nests, however the highest number of adults recorded at the nest was significantly less only in P. bellicosus. Results suggest niche portioning between species in relation to nest site usage, as well as a possible bivoltine colony cycle in some paper wasp species of southern Louisiana.

The crapemyrtle bark scale, Acanthococcus lagerstroemiae (Kuwana) (Hemiptera: Eriococcidae), is an exotic pest on crapemyrtles, Lagerstroemia spp. (Myrtales: Lythraceae). Because of its recent arrival in the US, little is known about its biology and ecology. The purpose of my thesis was to improve the knowledge about A. lagerstroemiae in four aspects involving its thermal tolerance, physiological adaptations to cold temperatures, temperature-dependent development and host range. Thermal tolerance was determined to understand how temperature extremes constrain the distribution of A. lagerstroemiae in the US. Results suggested that A. lagerstroemiae can tolerant high heat, but its potential distribution to the northern US may be limited by cold temperatures. Based on laboratory experiments and local temperatures from reported infestations, A. lagerstroemiae can establish in areas south of 43 °N, which is similar to the northern distribution limit of crapemyrtles. Therefore, the temperature extremes cannot limit its distribution on crapemyrtles in the US. To adapt to winter, cold tolerance of A. lagerstroemiae nymphs was observed to increase since November. The mechanisms of this increase were investigated by measuring seasonal changes of biochemical variables. From November to February, A. lagerstroemiae had 20% less water and higher energy reserves, which could have contributed to the increased cold tolerance. A restructuring of fatty acid composition in the body fat of overwintering nymphs was reported indicating accumulation of fatty acids in shorter chains (C6:0, C8:0 and C10:0), resulting in lower melting points that can help maintain lipid fluidity for energy conversion. The development and host range of A. lagerstroemiae were also studied. Developmental time and survival of A. lagerstroemiae eggs and nymphs were assessed under different temperatures, and results can help IPM practitioners improve field sampling strategies and timing of control measures. Callicarpa americana L. (Lamiales: Lamiaceae), Heimia salicifolia Link, Lawsonia inermis L., Lythrum alatum Pursh, and Punica granatum L. (Myrtales: Lythraceae) supported life cycle development and reproduction of A. lagerstroemiae and thus determined as suitable hosts other than Lagerstroemia spp. Scouting is recommended on these host species, following immediate responses to avoid additional spread, economic loss, and ecological disturbance of this pest.

Honey bees are crucial pollinators for many economically important fruit crops. The recent honey bee colony decline in the United States and other regions of the world has caused concern among commercial beekeepers, research groups, the government, and the general public. The role of pesticides in recent honey bee declines has not been fully determined. In Louisiana, it is a common practice to spray truck based ultra-low volume mosquito adulticides in Integrated Mosquito Management Programs to control mosquitoes and minimize the risk of vector borne viruses such as West Nile, chikungunya, and Zika. This study measured the effects of truck based ultra-low volume (ULV) mosquito adulticides on honey bees in a real world scenario. We looked at mortality, colony health (number of adult bees, brood quantity and quality), and detoxification enzymes (esterase and glutathione S-transferase) on honey bees from sentinel bee hives in Baton Rouge, Louisiana over a seven week period. The mosquito adulticides used by mosquito control programs during this study were Scourge, Duet and Deltagard. We did not find significant differences in honey bee mortality, colony health (frames of bees and brood quality) or detoxification enzymes among our control and treatment sites over the seven weeks. We found differences in brood quantity between control and treatment; however only two colonies at one of our treatment sites skewed the result in brood quantity. Although the findings of this study suggests that there is no effect of truck based ultra-low volume mosquito adulticides on bee mortality, colony health, and detoxification enzymes on honey bees, there might be deleterious effects if mosquito adulticides are used inappropriately.

Twospotted spider mites, Tetranychus urticae, is an important agricultural pest of many field crops worldwide. This study investigated the impacts of imidacloprid seed treatments on populations of twospotted spider mites while also investigating if exogenous applications of jasmonic acid can offset any hormone modulating effects caused by seed treatments. Imidacloprid seed treatments significantly increased cumulative adult mite days in 2013 but not 2015 or 2016 in the field. Applications of 10 millimolar jasmonic acid did not reduce mite severity or injury in all field trials. Imidacloprid seed treatments significantly increased all spider mite life stages in the laboratory while applications of jasmonic acid significantly reduced all mite life stages on neonicotinoid treated and non-treated cotton. Seed treatments do not affect the host preference of twospotted spider mites compared to non-treated however, jasmonic acid applications reduced the host suitability of seedling cotton to only adult mites. Additionally, leaf dip bioassays were conducted to evaluate resistance levels to abamectin in 12 populations of T. urticae collected from the Midsouth. Louisiana populations were highly resistant with corresponding LC50 values of 0.082 and 0.184 ppm and resistance ratios of 630 and 1415-fold. One population from Mississippi was slightly resistant with an LC50 value of 0.0021 ppm and a resistance ratio of 11.1 compared with a susceptible control population. Finally, greenhouse and field applied foliar spray tests and leaf dip bioassays were conducted to examine the susceptibility of T. urticae to glufosinate ammonium in cotton. Leaf dip bioassay results indicated that T. urticae were highly susceptible to concentrations of formulated glufosinate ammonium. The LC50 value was determined to be 10.31 ppm. Field applied glufosinate ammonium at 1.61 and 3.14 L ha−1 provided 48.86 and 80.22 percent control while fenpyroximate provided 89.62 percent control 5 days after application in 2015. Greenhouse applications resulted in 55.43 percent control 14 days after application with 0.73 L ha−1 while 1.61 L ha−1 resulted in 72.86 percent control and 3.14 L ha−1 resulted in 91.85 percent control of T. urticae populations. Data generated from these studies provide useful information on integrated pest management of twospotted spider mites in Midsouth cotton.

Mosquito control districts in Louisiana focus their efforts on Culex quinquefasciatus, the primary vector of West Nile virus in the southern United States, with rigorous larvicide treatments. However, the development of resistant populations of Cx. quinquefasciatus in response to extensive insecticide application has been demonstrated repeatedly. Examining changes in insecticide susceptibility and larvicide efficacy in real world scenarios can help inform mosquito control districts as to whether or not their treatments are killing mosquitoes. We hypothesized that frequent larvicide applications for the control of mosquitoes in East Baton Rouge Parish had lowered susceptibility of wild Cx. quinquefasciatus to insecticides, and that treatment in real-world septic water conditions negatively impacts larvicide efficacy. Larvicide susceptibility and efficacy in septic-water were measured using the larvicides Bacillus sphaericus, spinosad, and temephos. Culex quinquefasciatus populations were sampled from sites in three Parishes where frequencies of insecticide applications varied, and frequencies of resistance and efficacy were measured relative to a susceptible reference colony. Five-fold resistance to the organophosphate temephos was detected at one site in East Baton Rouge Parish in the spring of 2016, which increased to ten-fold resistance by the end of the mosquito season. Activities of esterases were found to be elevated in wild, temephos-resistant mosquitoes, indicating the potential role of these enzymes as a mechanism of resistance. Water quality did not appear to play a significant role in the efficacy of the larvicides used in this study. The results of this study provide a baseline of comparison for future measurements of susceptibility in Cx. quinquefasciatus in Louisiana, and may help inform local mosquito control districts as to the effectiveness and sustainability of their insecticide programs.

<p> The Environmental Protection Agency recently registered seed blend refuges for two of the transgenic Bt corn products targeting the western corn rootworm (WCR), <i>Diabrotica virgifera virgifera</i> LeConte. Larval movement between Bt and isoline plants can be detrimental to resistance management for high dose Bt products because the insect larvae will potentially be exposed to sublethal amounts of the Bt, however, the effect of this movement on low to moderate dose products is unknown. All current rootworm products are low dose. The main criteria for whether movement by WCR larvae between isoline and Bt corn plants will influence the development of resistance is whether or not selection for resistance is taking place. We found that movement between isoline and SmartStax^&reg; hybrid plants did occur in seed blend scenarios in our field study. The majority of plant damage to the SmartStax plants occurred when the larvae moved from surrounding infested isoline plants moved late in their development. These older, larger larvae are all able to tolerate the Bt in the plants, therefore resistance will likely not develop in these larvae. In a similar experiment, movement also occurred between Agrisure^&reg; Duracade&trade; and isoline plants in seed blend scenarios, however the damage was low for all treatments. With isoline plants being mixed with Bt plants in seed blend refuges, host recognition behavior of the western corn rootworm on Bt and isoline plants is also important to understand. There were no differences between the host recognition behavior of WCR larvae after exposure to mCry3A, Cry3Bb1, Cry34/35Ab1, or their isoline corn hybrids, therefore all hybrids were perceived as hosts by WCR larvae. With all the hybrids on the currently registered being pyramided by different companies to control rootworms, the potential for cross resistance between these hybrids was evaluated using field resistant and susceptible populations. Based on the data from laboratory and greenhouse assays, the potential for cross resistance between mCry3A and Cry3Bb1 might be likely, but not between these hybrids and Cry34/35Ab1. Information gathered in this study provides important behavioral information on western corn rootworms that will aid in making decisions involving Bt corn hybrids.</p><p>