The Formosan subterranean termite, Coptotermes formosanus Shiraki, an invasive species from southern China, is one of the most destructive wood pests in the United States. Presently, termites are managed through chemical control. However, some synthetic chemicals cause serious environmental problems due to their persistence and toxicity. There is growing interest in using natural compounds with low toxicity to mammals to control termites. Trans-caryophyllene is a component of essential oil found in many flowering plants. It is especially abundant in clove oil. It has also been found to be released from the roots of maize damaged by insects. I investigated caryophyllene as a potential control agent for Formosan subterranean termites. I evaluated caryophyllene topical toxicity, consumption of treated filter paper in choice and no choice tests, and effect on Formosan termite tunneling behavior. Caryophyllene was moderately toxic to Formosan subterranean termites (LD50 =40.19 ug/insect; 95% CL 28.36-53.74 ug/insect). In no choice consumption tests, termite feeding was negatively correlated with dose of caryophyllene. In multiple choice bioassays, greater consumption occurred on untreated filter paper, suggesting caryophyllene is not a feeding stimulant, but may in fact act as a repellent. Equal tunnel volumes were recorded in chambers with or without caryophyllene but loctaion of tunneling suggested an effect on tunnel orientation behavior and attraction to caryophyllene. However, tunnel volume increased significantly toward the center of areas where caryophyllene droplets were placed, but in untreated chamber, tunnel volume increased mainly along the edges of the chamber. These results indicate that while caryophyllene shows moderate acute toxicity to Formosan subterranean termites and paper treated with this sesquiterpene is a feeding deterrent, termites will tunnel toward caryophyllene droplets. Further studies are needed to evaluate caryophyllenes effectiveness when used against termites.

The tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), is a primary pest of cotton in the mid-southern United States. Chemical control strategies are the primary integrated pest management tool used to manage this pest in cotton. A better understanding of tarnished plant bug behavior and distribution on cotton plants is needed to improve the scouting and monitoring protocols used to estimate population and crop injury levels needed to initiate treatments. This pest frequently re-infests fields after insecticide treatments. Sampling protocols should consider the sub-lethal effects of insecticides on migrating populations or on survivors that remain on insecticide-treated plants. Studies were performed during 2007-2008 to evaluate the effects of acephate on tarnished plant bug nymph age-classes, preference for selected fruiting structures, and vertical distribution within the cotton canopy. The test sites included flowering stage cotton plants that were infested with native populations of nymphs (>1 insect / row ft). Non-treated and acephate-treated (Orthene 90SP 0.8 lb AI/acre) cotton plants were evaluated at 0 (pre-treatment) to 120 hours after treatment (HAT). Numbers of small (1st ¨C 3rd instars) nymphs were significantly greater than large (¡Ý4th instars) on non-treated plants, but no differences between age-classes were detected on acephate-treated plants. Regardless of insecticide treatment, nymphs were significantly greater on flower buds (squares) compared to bolls or white flowers. Nymphs were greater on sympodial branches of plant main stem nodes 1-5 (top five) and 6-10 compared to those on main stem nodes 11-15 for both treatments. On non-treated plants, the numbers of nymphs found on nodes 1-5 compared to those on 6-10 were not significantly different. However, on acephate-treated plants from 24 to 72 HAT, more nymphs were found on sympodial branches 6-10 compared to sympodial branches 1-5. The results of this study showed that acephate influenced tarnished plant bug nymph age-class, short-term vertical distribution on cotton plants, but did not change the preference for squares. Whole-plant sampling protocols that measure infestations throughout a cotton plant¡¯s entire profile or examination of squares for injury should provide the best estimate of tarnished plant bugs on non-treated and insecticide (acephate)-treated cotton plants.

The tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), is one of the most yield- limiting insect pests attacking cotton in the Mid-Southern region of the U.S. This pest is almost exclusively managed with chemical control strategies. The organophosphate insecticide, acephate, has been one of the most important insecticides recommended to control tarnished plant bugs. In recent years, reports of unsatisfactory acephate performance have become common and actual field rates have been increased to improve control. The objective of this study was to survey acephate susceptibility in Louisiana populations of tarnished plant bug using laboratory bioassays and evaluate acephate efficacy in field trials. Insecticide residual on glass (vial tests) bioassays were used to estimate acephate dose mortality responses (LC50s) for five, nine, and six populations during 2007, 2008, and 2009, respectively. The LC50s for these collections ranged from 1.63-32.36 µg/vial. Resistance ratios (RR) were calculated relative to a susceptible standard population (LC50 = 3.1 µg/vial) and ranged from 0.52-10.44 among populations. Field control failures with acephate are likely when RRs >3.0 and when persistent infestations exceed the action threshold for foliar sprays. Twenty field trials were conducted during 2007-2009 to determine acephate performance against native infestations. Five treatments (0[control], and acephate at 0.54, 0.82, 1.1, 1.34 kg AI/ha) were arranged in a Latin square design and were placed in commercial production fields and on LSU AgCenter Research Stations. Acephate efficacy was collected five to seven days after treatment using a one meter black shake sheet. The lowest acephate rate (0.54 kg AI/ha) significantly reduced tarnished plant bugs compared to that in the non-treated plots at 17 locations. However, this rate only reduced numbers below the action threshold in the 2007 trials. During 2008 and 2009, acephate rates of 0.82-1.34 kg AI/ha were needed to adequately control infestations. These results indicate that acephate susceptibility in Louisiana populations of tarnished plant bug is shifting and field performance is decreasing.

The Formosan subterranean termite, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), is considered one of the most destructive structural pests in the world, especially in warm and humid areas. Insecticide application is an effective strategy in termite control. In recent years, non-repellent insecticides have become popular for their high efficacy due to delayed toxicity and horizontal transfer. Fipronil (registered name Termidor®) and imidacloprid (registered name Premise®) have been applied to the perimeter of millions of houses in the United States. Fipronil and imidacloprid have different modes of action which may produce a synergistic effect when combined. There have been no studies on the toxicity interaction of fipronil and imidacloprid against termites including the Formosan subterranean termite. The original objective of the research was to determine whether combinations of the termiticides lead to enhanced toxicity against Formosan subterranean termites. Combinations of the non-repellent insecticides were treated on filter paper and sand for evaluation. After timed exposures, any living termites were transferred to untreated Petri dishes. Mortality of termites was recorded before and after the transfer. Lower mortality was observed when imidacloprid was mixed with fipronil compared to fipronil alone. Mortality was increased by the mixture over imidacloprid alone. To validate these results, more combinations were introduced in the second and third set of experiments. Besides the recording of mortality, the number of excavation holes made by termites in sand was also counted to determine whether excavation activity was related to mortality effects. A second objective was to seek a threshold level whereby the efficacy of fipronil becomes negatively impacted by imidacloprid presence. A threshold of between 15 and 25 ppm imidacloprid added to 100 ppm fipronil reduced the efficacy of fipronil. An increase in the number of excavation holes was significantly associated with a rising mortality, indicating imidacloprid affected the uptake of fipronil by reducing termite excavation behavior of treated soil. In practical terms and of potential concern for homeowners, the studies suggest that the efficacy of Termidor® applied around the perimeters of houses may be negatively affected by the presence of Premise®.

The sugarcane borer, Diatraea saccharalis, is a major target pest of transgenic corn expressing Bacillus thuringiensis (Bt) proteins in many areas of the U.S. mid-southern region. A Cry1Ab-resistant (Cry1Ab-RR) strain of D. saccharalis has been developed from a single two-parent family-line. To examine the molecular mechanisms of the Cry1Ab resistance in this insect strain, cDNAs of five types of potential candidate genes related to Bt resistance were sequenced using reverse transcriptase polymerase chain reaction (RT-PCR) and 5 rapid amplification of cDNA end (5 RACE). The Bt resistance candidate genes examined included three trypsins (DsTRYs), three chymotrypsins (DsCHYs), three aminopeptidases N (DsAPNs), one cadherin (DsCAD1), and three alkaline phosphatases (DsALPs). cDNA sequence of each gene and its expression levels were compared between a Cry1Ab-susceptible strain (Cry1Ab-SS) and the Cry1Ab-RR at different larval growth stages. The cDNA sequences of these genes were identical between Cry1Ab-SS and -RR strains. Gene expression levels of the trypsins, chymotrypsins, and alkaline phosphatases were similar between the two strains. There were also no significant differences in total enzymatic activity of trypsins, chymotrypsins, and alkaline phosphatases between Cry1Ab-SS and -RR. However, the gene expression levels of the three DsAPNs and the DsCAD1 in Cry1Ab-RR were significantly lower than those of the Cry1Ab-SS. RNA interference (RNAi) was employed to knock-down the three DsAPNs and the DsCAD1 in the Cry1Ab-SS strain by oral droplet feeding to neonates. Down-regulations of the expressions of these four genes by RNAi were correlated with the decrease in susceptibility to Cry1Ab toxin. Silencing each of the three DsAPNs in D. saccharalis in vivo by RNAi resulted in a decrease of total APN activity. In addition, the total specific APN activities from Cry1Ab-RR larvae were significantly lower than those of the Cry1Ab-SS strain. These results suggest that reduction in expression of the three DsAPNs and DsCAD1 is functionally associated with the Cry1Ab resistance in D. saccharalis.

Insecticide, greenhouse and varietal resistance experiments were conducted in Texas to develop management tactics for the Mexican rice borer, Eoreuma loftini (Dyar), sugarcane. A 3-treatment, large plot aerial application study was set up in 5 commercial sugarcane fields (35-84 acres) to evaluate the utilization of pheromone traps to improve chemical control strategies for E. loftini during 2009 and 2010 growing seasons. A threshold of 20-25 moths/trap/wk was used as an indicator to initiate monitoring for E. loftini larval infestations. Larval infestations were directly related to the no. of moths/trap/wk (R2=0.71). Reductions in borer injury and adult emergence (60% and 40% for novaluron and â-cyfluthrin, respectively) were detected when a threshold of 5% of stalks with treatable larvae was used for timing an insecticide application. Data revealed novaluron treatments increased sugar production by 14%. A greenhouse study assessed the establishment and behavior of E. loftini neonates on two phenological stages of stalkborer resistant (HoCP 85-845) and susceptible (HoCP 00-950) cultivars. Approximately half (55%) of neonates on HoCP 00-950 and 28% on HoCP 85-845 tunneled inside the leaf mid-ribs within 1d of eclosion. Duration of neonate exposure ranged from 3.5 - 6.4 d. This research shows a short window of vulnerability of E. loftini to insecticide applications, and demonstrates the potential to use pheromone traps and new chemistries for enhancing chemical control. A 5-replication field test evaluated stalkborer resistance in 25 sugarcane cultivars. Differences were detected between cultivars in E. loftini injury which ranged from 1.0-20.3% bored. The resistant standard HoCP 85-845 and a South African cultivar, N-21, were the most resistant. HoCP 96-540, which represents the majority of sugarcane acreage in Louisiana, was among the most susceptible. Assessment of stalkborer resistance in sugarcane cultivars is needed as host plant resistance will continue to be important to E. loftini IPM.

The sugarcane borer, Diatraea saccharalis, is a major target pest of transgenic corn expressing Bacillus thuringiensis (Bt) proteins in many areas of the U.S. mid-southern region. A Cry1Ab-resistant (Cry1Ab-RR) strain of D. saccharalis has been developed from a single two-parent family-line. To examine the molecular mechanisms of the Cry1Ab resistance in this insect strain, cDNAs of five types of potential candidate genes related to Bt resistance were sequenced using reverse transcriptase polymerase chain reaction (RT-PCR) and 5 rapid amplification of cDNA end (5 RACE). The Bt resistance candidate genes examined included three trypsins (DsTRYs), three chymotrypsins (DsCHYs), three aminopeptidases N (DsAPNs), one cadherin (DsCAD1), and three alkaline phosphatases (DsALPs). cDNA sequence of each gene and its expression levels were compared between a Cry1Ab-susceptible strain (Cry1Ab-SS) and the Cry1Ab-RR at different larval growth stages. The cDNA sequences of these genes were identical between Cry1Ab-SS and -RR strains. Gene expression levels of the trypsins, chymotrypsins, and alkaline phosphatases were similar between the two strains. There were also no significant differences in total enzymatic activity of trypsins, chymotrypsins, and alkaline phosphatases between Cry1Ab-SS and -RR. However, the gene expression levels of the three DsAPNs and the DsCAD1 in Cry1Ab-RR were significantly lower than those of the Cry1Ab-SS. RNA interference (RNAi) was employed to knock-down the three DsAPNs and the DsCAD1 in the Cry1Ab-SS strain by oral droplet feeding to neonates. Down-regulations of the expressions of these four genes by RNAi were correlated with the decrease in susceptibility to Cry1Ab toxin. Silencing each of the three DsAPNs in D. saccharalis in vivo by RNAi resulted in a decrease of total APN activity. In addition, the total specific APN activities from Cry1Ab-RR larvae were significantly lower than those of the Cry1Ab-SS strain. These results suggest that reduction in expression of the three DsAPNs and DsCAD1 is functionally associated with the Cry1Ab resistance in D. saccharalis.

The purpose of the first study was to evaluate the effectiveness of the use of a mid-season avermectin pour-on to cattle for managing OP resistance in horn fly populations at the Rosepine Louisiana Agricultural Research Station. During an eight year study, ivermectin treatments were made three times (when the treatment threshold of less than five weeks of control was reached), and in the following years, the number of weeks of control increased to 9 to 10 weeks each time. The purpose of the second study was to test a two-year OP/one-year pyrethroid rotation strategy as a strategy for maintaining susceptibility in horn fly populations to both pyrethroids and organophosphates. A seven-year study was conducted at the Agricultural Research Stations at Iberia and Hill Farm, Louisiana. At Iberia, 6, 10 and 7 weeks of control were recorded when pyrethroid ear tags were used every third year. When OP tags were used, horn fly control was maintained at 9 to 7 weeks throughout the 4 years of use. At Hill Farm, when pyrethroid ear tags were used, weeks of control reduced from 11 to 6 to 2 weeks of control. When OP ear tags were used, weeks of control reduced from 12 to 3 in the 4 years of use. The objective of the third study was to determine the rate of change in kdr and skdr allele ratios and genotype proportions in horn fly populations in the absence of pyrethroid pressure at the Louisiana Agricultural Research Stations in Winnsboro and St. Joseph. Allele ratios decreased about every 45 days from July to September by an average 20% for skdr and 10% for kdr. The number of skdr homozygous susceptible horn flies increased significantly and the number homozygous resistant horn flies increased significantly. We showed for the first time that the allele ratio changes were related primarily to the RR kdr and skdr genotypes and that the heterozygote likely had no biotic fitness costs.

<i>Diatraea saccharalis</i> (F.) and <i>Eoreuma loftini</i> (Dyar) are stem boring pests of sugarcane (<i>Saccharum</i> spp.) and rice (<i>Oryza sativa</i> L.) crops in the Gulf Coast region. Studies were conducted to determine the role of agroecological factors, including predator disruptions, alternate hosts, and crop phenological conditions, on stem borer populations.<br> The year after Hurricane Rita storm surge flooded sugarcane in Louisiana, a 71% reduction in the predaceous <i>Solenopsis invicta</i> Buren was recorded. Even with a 2.4-fold increase in the number of insecticide applications used for <i>D. saccharalis</i> management in flooded fields, growers still incurred higher injury.<br> In two field experiments, October sampling showed that sugarcane planted in early August harbored 4.7 to 19.0-fold greater <i>D. saccharalis</i> infestations than September plantings. Although there is a potential for increased <i>D. saccharalis</i> overwintering populations in early plantings, differences in infestations were not recorded during the spring.<br> Sentinel plant experiments confirmed that a number of non-crop grasses are stem borer hosts. Subsequently, sampling along transects every 6-8 wk compared stem borer infestations in non-crop grasses adjacent to rice fields. While <i>D. saccharalis</i> densities were relatively low, <i>E. loftini</i> average densities were 0.3 to 5.7 immatures/m2 throughout a 2-yr period. A greenhouse study showed that rice is more preferred for <i>E. loftini</i> oviposition than the primary non-crop hosts johnsongrass [<i>Sorghum halepense</i> (L.) Pers.] and Vaseys grass (<i>Paspalum urvillei</i> Steud.). In addition, <i>E. loftini</i> larval development duration in degree-days above a threshold temperature is 1.7-fold greater on johnsongrass and Vaseys grass than on rice.<br> A 2-yr rice study showed that a lower than traditional harvest cutting height (20 vs. 40 cm) reduced <i>E. loftini</i> infestations by 70 to 81% whereas <i>D. saccharalis</i> infestations were not changed. Furthermore, rice stubble under favorable conditions represents an overwintering habitat in addition to non-crop hosts.<br> This research showed that predator disruptions, sugarcane planting dates, non-crop hosts, and rice stubble management impact stem borer populations when they are traditionally left unmanaged. Thus, the evaluation of a stem borer management strategy that targets infestations in late season sugarcane and rice, but also in non-crop hosts, is warranted.

The southern pine beetle guild (Coleoptera: Curculionidae: Scolytinae) is arguably the most destructive group of forest pests in the Southeastern United States. Laboratory assays suggest that larvae of wood borer associates from the genus Monochamus (Coleoptera: Cerambycidae) may be facultative intraguild predators of southern pine beetle guild. In this study the dynamics of the subcortical interactions between M. titillator (F.) and members of the southern pine beetle guild were examined using PCR-based molecular gut content analyses. Species-specific PCR primer sets were developed to work under multiplex PCR conditions to detect DNA of members of southern pine beetle guild in the gut contents of M. titillator larvae. The molecular half-life of the bark beetle Ips grandicollis (Eichhoff) was calculated as 6.89 hours post-consumption in the gut contents of M. titillator larvae under laboratory conditions. Comparison of the proportion of M. titillator larvae testing positive for each bark beetle species at 6.9 hours post-consumption showed that the proportion fed Dendroctonus terebrans (Olivier) differed significantly. A field study was performed to determine the detection frequencies of southern pine beetle guild DNA in the gut contents of M. titillator larvae under semi-natural conditions. A total of 271 M. titillator larvae were collected from experimental boles in the field. Twenty-six (9.6%) of the field-collected M. titillator larvae tested positive for DNA of members of the southern pine beetle guild. Of these larvae, 25 (96.2%), 1 (3.8%), 0 (0%), and 0 (0%) tested positive for I. grandicollis, I. calligraphus (Germar), D. terebrans, and D. frontalis (Zimmerman) DNA respectively. The species compositions of the southern pine beetle guild within the gut contents of the field-caught M. titillator larvae reflected those within the host, suggesting random predation. Results from this study support the hypothesis that Monochamus species may be facultative intraguild predators of bark beetle larvae in the field. Additionally, this study demonstrates the capabilities of PCR in elucidating the predator-prey interactions of cryptic forest insects and provides a powerful tool to better understand mechanisms driving southern pine beetle guild population fluctuations.