A three year study was conducted to determine if testing mosquitoes collected in modified sentinel chicken boxes for West Nile Virus (WNV) or testing sentinel chickens for WNV antibody would detect WNV activity prior to reports of human cases in East Baton Rouge (EBR) Parish, Louisiana. In one year we also compared the effectiveness of CDC light traps, gravid traps, and sentinel chicken box traps for collecting WNV positive mosquitoes. In all three years, we detected WNV activity in mosquito collections from sentinel chicken box traps prior to the onset of human cases, while there were no seroconversions in the chickens prior to human cases. In order to incriminate mosquitoes as vectors of WNV for captive alligators, mosquitoes were collected using Centers for Disease Control (CDC) light traps, gravid traps, backpack aspirators and resting boxes at three commercial Louisiana alligator farms from 2004 to 2006. The bloodmeal origins of 237 field-collected mosquitoes were identified based on cytochrome B (cytb) sequence homology. Alligator blood was detected in 24 mosquitoes representing six species of mosquitoes. This is the first study that identified alligator blood from mosquitoes at Louisiana alligator farms. Mosquitoes also were collected from the commercial Louisiana alligator farms and tested for WNV RNA. A total of 2, 404 mosquito pools were tested using reverse transcriptase polymerase chain reaction. West Nile virus was detected in 41 pools of females of 11 mosquito species. A comprehensive survey for vertical transmission of WNV was conducted. Male mosquitoes and mosquito larvae were collected in EBR Parish, Louisiana, using CDC light traps, gravid traps, backpack aspirators, resting boxes, and from larval habitats. West Nile virus was detected in 15 pools of male Culex specimens (collected as adults). West Nile virus also was detected in 2 pools of Cx. quinquefasciatus nulliparous females, 1 pool of Ae. albopictus nulliparous females and 2 pools of Culex species males. This is the second report of WNV vertical transmission in nature for Cx. quinquefasciatus and the first study that detected WNV from field collected nulliparous Ae. albopictus females.

Aspects of the population ecology of a parasitoid (Pseudacteon tricuspis) of the red imported fire ant (Solenopsis invicta) in Louisiana were studied. The spatio-temporal abundance patterns, dispersal, population spread, aggregation, direct mutual interference and functional response characteristics of this parasitoid were studied to address deficiencies in our knowledge about phorid flies, particularly Pseudacteon parasitoids. This endoparasitoid was discovered to manipulate host ant behavior in ways that benefit its own survival. Laboratory experiments to gain insights into behavioral and functional responses revealed that fly aggregations were density-dependent and interference was not significant when 1-3 females were simultaneously confined with hosts, although per capita oviposition success appeared to decline. Searching efficiency of 2-3 simultaneously ovipositing females was not significantly different than solitary females. Solitary females parasitized a constant proportion of hosts according to a Type 1 functional response. Modelling of the local spatial population structure of P. tricuspis, and relationship of abundances to host social form and pathogen-infected colonies, revealed no significant spatial associations between fly counts and infected host colonies. When fly populations peaked, significant count clusters were associated with polygyne colonies. Fly counts reflected a random spatial and temporal distribution, as count patterns were not stable. Dispersal experiments were conducted to quantify local fly movement. Diffusion rates tended to decline over time after release and most dispersal density-distributions did not conform to a simple diffusion model, implying heterogeneous population dispersal. Long-term population spread was monitored for two expanding populations of P. tricuspis. Range expansion accelerated the first four years post release, contrasting with a linear pattern expected with simple diffusion. Annual rates of spread were low in the first two years, increased rapidly years 3-4, and leveled off years 5-6, peaking at 15-25 km/yr. Finally, daily and seasonal dynamics of P. tricuspis were studied. Findings resulted in a protocol for sampling P. tricuspis populations in Louisiana. In addition to providing essential information about P. tricuspis population ecology, results of this study will be useful in conservation, augmentation, sampling and management of P. tricuspis and other species of Pseudacteon that have been released in the United States.

The rice stink bug (Oebalus pugnax) is the major pest of late-season rice in Louisiana. Prior studies indicate that large populations of mosquitoes are often present in rice fields during the time that rice fields are infested with rice stink bugs. Lambda-cyhalothrin (Karate®) is widely used to control rice stink bugs. The purpose of this study was to determine if application of the insecticide Karate® at a rate of 0.033 kg/ha, for rice stink bug control had an effect on the population of mosquitoes in rice fields. This effect was assessed by monitoring natural populations of mosquitoes before and after applications of Karate® in simulated rice paddies at the LSU AgCenter Rice Research Station (Crowley, Acadia Parish, Louisiana) during the summers of 2003, 2004 and 2005. In 2005, monitoring of native mosquito population was complemented by the use of sentinel cages with Culex quinquefasciatus Say larvae and exposure of Cx. quinquefasciatus larvae to treated rice field water in the laboratory. The number of larvae in Karate® plots decreased after Karate® applications but a significant overall effect was observed only after the first application of 2004 (p=0.034). Mortality of larvae in sentinel cages (p=0.0386) and of larvae exposed to rice field water at 48hrs (p=0.0130) was also observed in some cases. A test conducted in a large rice plot with sentinel cages confirmed the effect of Karate on mosquito larval populations (p=0.0012). An additional effect of foliar Karate residues on adult Cx. quinquefasciatus mosquitoes was observed in the laboratory (2004, 2005). Higher mortality was detected in adults exposed to rice foliage treated with Karate than the untreated control. Another factor that could influence the number of larvae present in rice fields is the oviposition response of mosquitoes to the presence of predatory insects. To test this response, Cx. quinquefasciatus adult mosquitoes were exposed in cages to water conditioned by previous exposure to potential aquatic predators. According to the Oviposition Activity Index (OAI), female mosquitoes preferred to lay eggs in water conditioned water rather than distilled water. The highest OAI was obtained with the Hydrophilidae-conditioned water.

Larval behavior, survivorship, and injury potential of Helicoverpa zea (Boddie), and tobacco budworm, Heliothis virescens (F.), was evaluated on cotton plants genetically engineered to express Bacillus thuringiensis (Bt) insecticidal proteins, Vip3A and Vip3A +Cry 1Ab (VipCot). Larvae (2-d-old) of both species were infested on plant terminals of vegetative or flowering stage cotton plants. Regardless of species, more larvae migrated from the plant terminals of Vip3A and VipCot plants compared to larvae infested on a conventional non-Bt cotton line (Coker 312). Larval (2-d-old) survivorship on VipCot plant structures was generally lower than that on similar structures of the Vip3A cotton line. However, H. virescens survivorship was higher than that for H. zea on similar structures of Vip3A plant. Age-specific (2 d, 4 d, 6 d, and 8 d-old larvae) survivorship was further evaluated on flower buds (cotton squares) of Vip3A and VipCot plants. Cumulative survivorship levels for both species and all larval ages were significantly lower on Vip3A and VipCot squares compared to that for Coker 312. No larvae of either species successfully pupated on VipCot squares. A limited number of H. virescens larvae completed larval development on Vip3A cotton squares. Field trials quantified cotton fruiting form injury on these Bt lines from artificial and native infestations of H. zea or H. virescens. Larvae (L2 stage) of H. zea infested in white flowers injured an average of 8.6, 4.6, and 1.0 fruiting forms per larva on Coker 312, Vip3A, and VipCot plants, respectively. Similarly, H. virescens injured an average of 9.2, 5.9, and 0.9 fruiting forms/larva on Coker 312, Vip3A, and VipCot plants, respectively. Native infestations of both species during 2005-2007 injured fewer fruiting forms on the Bt lines compared to that on Coker 312 plants. Seasonal efficacy patterns showed the VipCot plants to be more durable with less fruiting form injury than that recorded on Coker 312 and Vip3A, especially during periods of peak insect infestations. The combination of two proteins in the VipCot line generally improved efficacy against these pests compared to that of the single protein in the Vip3A line.

ABSTRACT Host utilization patterns of female mosquitoes, and WNV infection rates in male and female mosquitoes, were examined in East Baton Rouge Parish to identify potential vectors of West Nile virus (WNV). A total of 244,374 female mosquitoes were collected between November 2002 and October 2004 and tested by viral isolation. Additionally, 131,896 female mosquitoes were tested by VecTest in 2003, and 167,175 female mosquitoes were tested by RT-PCR in 2004. West Nile virus was isolated from 17 of 36 mosquito species assayed by virus isolation, WNV antigens were detected in 9 of 27 species tested by VecTest, and WNV RNA was detected in 14 of 28 mosquito species tested by RT-PCR. The species with the greatest number of WNV positive pools by all 3 testing methods was Culex quinquefasciatus. The Terminal Restriction Fragment Length Polymorphism assay and direct sequencing were used to determine the host bloodmeal identity in 37 bloodfed Cx. coronator, 67 bloodfed Cx. salinarius, 114 bloodfed Cx. nigripalpus, and 686 bloodfed Cx. quinquefasciatus. The proportions of bloodmeals containing mammalian DNA were 94.6% for Cx. coronator, 82.1% for Cx. salinarius, 66.1% for Cx. nigripalpus, and 40.1% for Cx. quinquefasciatus. The White-tailed Deer was the most common host of Cx. coronator and Cx. salinarius. The most common mammalian host of Cx. nigripalpus and Cx. quinquefasciatus was the Northern Raccoon. Human DNA was detected in 7% of the bloodmeals of Cx. quinquefasciatus and 2.7% of the bloodmeals of Cx. nigripalpus. The Northern Cardinal was the most frequent avian host of Cx. quinquefasciatus and Cx. nigripalpus. There was no seasonal change in the monthly proportion of females of Cx. nigripalpus and Cx. quinquefasciatus feeding on mammals from May through October, in either 2003 or 2004. A total of 45 pools containing 171 males of 12 species were assayed for the presence of WNV by virus isolation, and 148 pools containing 7230 males of 15 mosquito species were tested by RT-PCR. Virus was isolated from single pools of male Cx. salinarius and Oc. triseriatus. Single pools containing male Cx. restuans, Ps. howardii, Oc. triseriatus and An. crucians were positive for WNV RNA.

Wood is important in forest ecology because its large biomass serves as a nutritional substrate and habitat for many organisms, including Coleoptera, and beetles contribute greatly to nutrient recycling in forests. Overlapping complexes of beetles invade dead wood according to the species of tree, ambient conditions, and most importantly, stage of decomposition. Beetle succession was studied in loblolly pines (Pinus taeda L.) and southern red oaks (Quercus falcata Michx.) by documenting beetle arrival and residency in cut, reassembled, and standing bolts. Twelve trees of each species at Feliciana Preserve in West Feliciana parish, LA were felled during October 2004 and April 2005 for a total of 24 trees sampled from October 2004 September 2005. Four 48-inch bolts were cut from each felled tree. Each bolt was further cut into eight six-inch sections, reassembled in proper order, and positioned standing upright. Beetles were aspirated from section interfaces weekly the first month and then monthly for the duration of the study. A total 51,119 specimens from 190 taxa were collected from 3822 samples during 18 sampling events. Species richness and abundance were higher on southern red oak wood (144 taxa, 40874 specimens) than loblolly pine (122 taxa, 10245 specimens); abundance was significantly higher. Colonization and species composition patterns of coleoptera were significantly affected by host tree species, the season in which the tree died, the period of decay, the position or height along the woody substrate and many complex interactions of these effects. Loblolly pine bolts showed a slightly more rapid turnover of taxa than southern red oak bolts. Wood characteristics such as loss of moisture, which caused bark to loosen on pines, and higher quality substrate hardwood in oaks presumably account for the greater number of taxa and specimens collected from southern red oak than loblolly pine. This study has increased the number of species known to inhabit recently dead loblolly pine and southern red oak, two economically important tree species. Studies of this nature supplement investigations into the importance of coarse woody debris in forests by documenting ecological patterns of saproxylic coleoptera.

In November 2004, bluetongue virus (BTV) serotype 1 was detected for the first time in the U.S. from a hunter-killed deer in the marsh area of the Atchafalaya Delta in St. Mary Parish, LA. Subsequent serum surveys of three cattle farms further inland from the area where the deer was shot found bluetongue virus serotype 1 positive cattle on two of the three farms. The purpose of this study was to determine potential BTV vectors in the area where BTV-1 positive animals were detected and compare different trapping techniques for capturing specimens of the genus Culicoides. The study was conducted from January 2006 through November 2007. Seven sites were established in the immediate area (marsh) where the deer was found and miniature CDC light traps were deployed once per month at each site. At each of the three cattle farms, two CDC light traps (one with and one without dry ice) were deployed twice per month. In 2007, New Jersey traps with incandescent bulbs or black light bulbs were compared to CDC traps baited with dry ice. Specimens of 10 different species of Culicoides were captured at the farms and specimens of 7 of these 10 species were caught in the Atchafalaya Delta marsh area. In the entire study, 8,179 ceratopogonids were captured including 5,068 of the genus Culicoides. CDC light traps baited with dry ice caught significantly more flies than traps without dry ice. Infrared reverse transcriptase polymerase chain reaction was performed to screen for BTV in 275 pools representing 2,504 specimens collected at the farms. All positive samples were sequenced for serotype determination. Five pools out of 275 (1.8%) were positive for BTV. Pools of four species of Culicoides were found to be positive: C. crepuscularis, C. debilipalpis (2 pools), C. haematopotus, and C. furens. The amplicons of the positive specimens were sequenced and found to be identical to either BTV-17 or BTV-13. Since we did not detect BTV-1 in any biting midges, future studies will be necessary to establish the epidemiology of bluetongue virus serotype 1 in south Louisiana.

In arid and semi-arid parts of the Old World, Phlebotomus paptasi is a significant biting pest of man and is the primary vector of Leishmania major, the causative agent of zoonotic cutaneous leishmaniasis (ZCL). Phlebotomus papatasi exhibits a close association with the burrowing rodents that serve as the reservoirs of L. major. Rodent burrows are considered to be the primary habitat of immature P. papatasi in ZCL foci, and sand fly larvae have been observed feeding on rodent feces. In laboratory studies, five insecticides (diflubenzuron, novaluron, methoprene, pyriproxyfen, or ivermectin) were incorporated into the diet of Syrian hamsters and evaluated as feed-throughs to control immature sand flies. Feces of hamsters fed a diet containing approximately 10 mg/kg diflubenzuron, novaluron, or pyriproxyfen, or 20 mg/kg ivermectin killed 100% of sand fly larvae that consumed these feces. Feces of hamsters fed a diet containing up to 978.8 mg/kg methoprene caused significant, but not complete, mortality of sand fly larvae. Feces of novaluron-treated hamsters also were held under simulated field conditions for up to 30 d, and all larvae that consumed these feces died before pupation; a significant reduction in treated larval survival relative to control was observed when the feces were aged for up to 150 d. Novaluron also was shown to be effective as a feed-though larvicide when novaluron-treated food made up only a portion of the diet of hamsters. Ivermectin also was evaluated as a systemic insecticide; ivermectin treatment of hamsters was 100% effective against bloodfeeding sand flies for up to 7 d after hamsters were withdrawn from ivermectin-treated diets. In the final study, proof of concept was established for a novel biomarker system using a feed-through fluorescent dye. The value of this method is that it can mark rodents and their feces to establish the consumption of treated-baits, mark adult female sand flies that feed rodents for the duration of persistence of the dye in rodents, and mark adult male and female sand flies that had fed on feces of bait-fed rodents as larvae.

West Nile virus (WNV) infection rates in wild birds and mosquitoes, and the blood-feeding patterns of mosquitoes were examined at two study sites in Baton Rouge, Louisiana to identify the potential avian reservoir hosts and mosquito vectors of West Nile virus (WNV). Blood samples from a total of 2,442 wild birds in the orders Passeriformes, Piciformes and Columbiformes were collected from May 2006 to April 2008 and tested for the presence of WNV RNA using RT-PCR and antibodies to WNV using an epitope-blocking ELISA. WNV was detected in 3.77% of wild bird blood samples and antibodies to WNV were detected in 12.29% of samples. The species with the most historically infected individuals were Northern Cardinal, House Sparrow, American Goldfinch, White-throated Sparrow, Yellow-rumped Warbler, Brown Thrasher, Northern Mockingbird, Carolina Wren, Tufted Titmouse and Mourning Dove. The detection of ELISA positive bird blood samples were correlated with the detection of RT-PCR positive samples. The potential for South-central Louisianas winter resident and migrant passerines to act as long-distant transport agents for West Nile virus was demonstrated. A total of 21,644 female mosquitoes were collected and tested using RT-PCR. WNV was detected in 4.1% of mosquito pools tested with the greatest infection rates in mosquitoes of the genus Culex. The greatest number of positive pools were comprised of Culex quinquefasciatus mosquitoes. Vertebrate hosts of 120 female mosquitoes were successfully identified using PCR amplification and sequencing of the Cytochrome-b gene. Culex quinquefasciatus females host sources were avian (49.4%), mammalian (48.3%) and amphibian (2.2%) with the Northern Cardinal, Brown Thrasher, Blue Jay, Downy Woodpecker and Eastern Bluebird as the most common avian hosts and the domestic dog, Human, Northern Raccoon, White-tailed Deer and domestic cow as the most common mammalian hosts. No seasonal shift in the proportion of Culex quinquefasciatus feeding on avian or mammalian hosts was detected during this study. Stationary point counts and other observations were used to estimate wild bird species diversity and species abundance and at the study sites. Forage ratios in Culex quinquefasciatus were calculated using species abundance estimations and the frequency of bloodmeals identified from those species.

The sugarcane borer, Diatraea saccharalis (F.), is a dominant corn stack boring pest and a major target of Bacillus thuringiensis (Bt)-corn in many areas of the mid-southern region of the United States. A Cry1Ab-resistant strain of D. saccharalis, capable of survival on commercial Bt corn plants, was established using an F2 screening procedure. Larval survival of Cry1Ab-resistant, -susceptible, and -heterozygous genotypes was evaluated on five non-Bt and seven Bt field corn hybrids at two plant stages. During the vegetative stages, all seven Bt corn hybrids were highly efficacious against the three genotypes, while 8-18% of the heterozygous genotype survived on reproductive stage plants for four Bt corn hybrids. Susceptibilities of Cry1Ab-susceptible and -resistant strains were evaluated for four Bt proteins: Cry1Aa, Cry1Ac, Cry1A.105, and Cry2Ab2. LC50 values of the Cry1Ab-resistant strain were >80-, 45-, 4.1-, and -0.5-fold greater than that of the susceptible strain to the four proteins, respectively. Relative fitness on non-toxic diet, diet treated with low concentrations of Cry1Ab toxin, and on conventional corn plants was compared for five genotypes of D. saccharalis. Larvae of Cry1Ab-susceptible and Cry1Ab-resistant strains on both non-toxic diet and non-Bt corn plants developed normally. There were no significant differences between the two strains in all measured biological parameters, suggesting a lack-of-fitness cost of the Cry1Ab resistance in D. saccharalis. Larval development, growth, and survival of the Cry1Ab-susceptible strain were significantly affected on diet treated with low concentrations of Cry1Ab toxin, while the effect to the resistant strains was not/or less significant. Using various genetic crosses, inheritance of Cry1Ab resistance in D. saccharalis was assessed on Bt corn leaf tissue, intact Bt corn plants, and diet containing Cry1Ab toxin. Cry1Ab resistance in D. saccharalis was inherited as a single autosomal gene. The resistance was incompletely or nearly completely recessive on Bt corn leaf tissue and intact Bt corn plants, while the dominance increased as Cry1Ab concentrations decreased when it was tested on Cry1Ab-treated diet. Results generated from this study will provide valuable information in understanding Bt resistance mechanisms and developing effective strategies for managing resistance of D. saccharalis to Bt corn.