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The efficacy of transgenic cotton genotypes containing Cry1Ac, Cry1F, and Cry1Ac stacked with Cry1F (WideStrike®, Dow Agrosciences, Indianapolis, IN) were investigated during 2001-2003 against the beet armyworm, Spodoptera exigua (Hübner) (=BAW), and the fall armyworm, Spodoptera frugiperda (J. E. Smith) (=FAW), in laboratory bioassays and small experimental field plots. In all experiments, cotton containing Cry1F was more toxic to BAW and FAW larvae compared to cotton containing only Cry1Ac. In the majority of experiments, the addition of Cry1Ac to the Cry1F genotype had no increased effect on efficacy and certain biological parameters against BAW and FAW larvae compared to cotton containing only Cry1F. Furthermore, the presence or absence of an additive, synergistic, or antagonistic effect between Cry1Ac and Cry1F was not observed in these field and laboratory experiments.
Beet armyworm, Spodoptera exigua (Hübner), and fall armyworm, Spodoptera frugiperda (J. E. Smith), are occasional pests of cotton, Gossypium hirsutum (L.), and soybean, Glycine max (L.) Merrill. These insects can be difficult to control due to insecticide resistance and larval behavior on plants. The objectives of these studies were to determine the efficacy of selected insecticides against native infestations of beet armyworm in cotton and soybean and to generate baseline dose-mortality responses for beet armyworm and fall armyworm adults to indoxacarb and pyridalyl in the adult vial test. Indoxacarb, pyridalyl, spinosad, methoxyfenozide, and emamectin benzoate controlled beet armyworm infestations up to 10 d after treatment compared to the non-treated control. Thiodicarb reduced beet armyworm densities up to three d after treatment. The LC50 values of indoxacarb and pyridalyl for beet armyworm and fall armyworm exceeded the highest concentrations tested (100-200 μg/vial) in the adult vial test. Dose-mortality values of indoxacarb and pyridalyl were higher than discriminating concentrations of cypermethrin, methomyl, profenofos, and endosulfan used in the adult vial test for monitoring tobacco budworm, Heliothis virescens (F.), and bollworm, Helicoverpa zea (Boddie), susceptibility in Louisiana and Texas. These results indicate that the adult vial test may not be the most efficient test method for indoxacarb and pyridalyl in insecticide susceptibility monitoring programs.
Fall armyworm is a significant agricultural pest in the United States, affecting most notably sweet corn and turf grass. While infesting much of North America, fall armyworms invading the eastern United States arise from annual migrations of populations wintering in southern Florida. It has long been noted that this seasonal geographical localization represents an opportunity for controlling this pest prior to its annual migration. However, such efforts have been hindered by the presence of two genetically distinct but morphologically identical strains that differ physiologically and behaviorally. The biology of the host strains is poorly understood and this lack of knowledge precludes accurate predictions of fall armyworm population behavior in the field. This paper reviews recent studies examining strain behavior and discusses the potential relevance of these results to the development of effective regional management strategies that can be used proactively to mitigate the economic impact of this pest.
Beet armyworms, Spodoptera exigua (Hübner), were artificially selected in the laboratory for resistance to the insect growth regulator, methoxyfenozide. A field collected beet armyworm colony was separated into three cohorts that were independently selected with three concentrations (0.033 ppm, 0.064 ppm, and 0.125 ppm) of methoxyfenozide incorporated into a meridic diet. These concentrations corresponded closely with the LC10 (0.033 ppm), LC50 (0.072 ppm), and LC90 (0.161 ppm), respectively, for the original colony. After seven generations of continuous exposure to methoxyfenozide, resistance in the colony selected at the low concentration did not increase significantly. In contrast, LC50 values increased 9.7- and 9.4-fold for the colonies selected at the moderate and high concentrations, respectively, over that of the original colony. Crosses between resistant and susceptible individuals indicated that the resistance was heritable. At 4 d after exposure, mortality of offspring from the reciprocal crosses was intermediate between mortality for the offspring from the parental crosses. When rated at 10 d, mortality of offspring from the reciprocal crosses was not different significantly from offspring from the cross between susceptible parents. These data will be important for developing a management program for beet armyworm resistance to methoxyfenozide.
A series of laboratory and field experiments were conducted to compare larval development, feeding behavior, and ovipositional preference of fall armyworm (Spodoptera frugiperda) on a standard host plant, a standard cover crop plant, and two candidate cover crop plants. The results indicate that larvae from different rearing cultures and host strains developed comparably on corn and sorghum-sudangrass, but generally developed poorly on cowpeas and sunnhemp. Larval and ovipositional experiments also suggested a preference for either corn or sorghum-sudangrass. Field plantings of cowpeas and sunnhemp in two locations were ignored by fall armyworm in favor of corn. These studies suggest that cowpeas and sunnhemp have the potential to reduce stepping stone nursery populations of fall armyworm by lengthening developmental time and increasing larval mortality.
Jaime Molina-Ochoa, James E. Carpenter, Roberto Lezama-Gutiérrez, John E. Foster, Martín González-Ramírez, César Andres Angel-Sahagún, Javier Farías-Larios
A survey of parasitoids of fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith), larvae was conducted in six Mexican states during August and September 2000. Thirteen genera of hymenopteran parasitoids were recovered representing the following 3 families, Braconidae: Aleoides, Chelonus, Cotesia, Glyptapanteles, Homolobus, and Meteorus; Ichneumonidae: Campoletis, Eiphosoma, Ophion, and Pristomerus; and Eulophidae: Aprostocetus, Euplectrus, and Horismenus. Out of 5591 FAW larvae collected, 772 produced parasitoids, for a parasitism rate of 13.8%. The highest rate of parasitism from a single collection was 42.2%, representing three species of parasitoids in Michoacán. Chelonus insularis Cresson was the most widely distributed species occurring in 45.3% of the locations. Pristomerus spinator (F.), and Meteorus laphygmae (Viereck), exhibited the highest rates of parasitism for a single collection with 22.2% and 22.1%, in Sinaloa, and Michoacán, respectively. The results supported the hypothesis that natural distribution and rates of parasitism of FAW larvae may be related to more diverse habitats with more forests, orchards, and pastures near to cornfields.
Limited information exists on genetic variation and distribution of Reticulitermes from the south central United States. Focusing on molecular sequence data from the mitochondrial DNA 16S gene, this study records the distribution and genetic variation of Reticulitermes species in Arkansas and updates the current distribution in a neighboring State, Louisiana. Termite samples were collected from the field, subjected to DNA analysis with Polymerase Chain-Reaction (PCR), and sequenced. Reticulitermes sp. sequence data were aligned, genetic distances recorded, and their respective haplotypes were evaluated for possible geographic structure. From 35 Arkansas counties, 59 R. flavipes, 13 R. hageni, and seven R. virginicus were identified. In Arkansas, 11 mitochondrial haplotypes were observed in R. flavipes, three in R. hageni and three in R. virginicus. Among the 12 Louisiana parishes sampled, 13 R. flavipes, three R. virginicus, and one R. tibialis were identified with six, three, and one haplotypes for each species, respectively. Genetic variation among the R. flavipes haplotypes from both States ranged from 0.2 to 0.9%. Reticulitermes flavipes haplotype diversity observed in Arkansas and Louisiana was lower than observed in Texas and Oklahoma.
Males of the oriental fruit fly, Bactrocera dorsalis (Hendel) and the melon fly, B. cucurbitae (Coquillett), are attracted to methyl eugenol (ME) and cue lure (CL), respectively. These lures, when mixed with a toxicant, are widely used to detect and suppress populations of these agricultural pests. The objective of this study was to assess the effectiveness of (1) traps baited with both ME and CL (mixed or presented separately on adjacent wicks), and (2) traps baited with a single lure but placed in the same tree as a trap containing the alternate lure (1 or 3 m apart). Jackson traps were placed in a mixed orchard on Oahu, Hawaii, and the numbers of released (marked) and wild males were recorded. Traps baited with ME and CL (mixed or separate) captured significantly fewer B. dorsalis males than traps baited with ME alone. CL placed 1 m from ME-baited traps in the same tree also reduced the number of B. dorsalis males captured. Conversely, ME appeared to increase capture of B. cucurbitae males, and traps baited with the 2 lures (mixed but not separate) captured significantly more released males than traps baited with CL alone. Also, ME placed 1 m (but not 3 m) from CL-baited traps increased the trap catch of released B. cucurbitae males. Results are discussed from the perspectives of management and evolution of Bactrocera species.
Survival of adult male Caribbean fruit flies, Anastrepha suspense (Loew) fed sucrose and protein in the form of hydrolyzed brewers yeast was studied under greenhouse conditions. Flies fed either a 3:1 mixture of sucrose and protein (optimal) or just sugar from the day of adult eclosion showed no appreciable mortality during the 14-day test period. However, flies fed just protein, or those that were not provided with sugar or protein showed rapid rates of mortality, with 50% mortality occurring at 1.87 and 1.53 days, respectively, and 95% mortality occurring at 2.8 and 2.5 days. Switching flies from the optimal diet to either the protein-only diet or nothing at 7 or 11 days after emergence resulted in values of 50% and 95% mortality, respectively, that were similar to those for flies reared from eclosion on either just protein or nothing. No significant mortality occurred among males maintained on the optimal or sugar-only diets or when flies were shifted from the optimal diet to only sugar at either day 7 or 11 after emergence. These data demonstrate that the flies have an absolute requirement for carbohydrate in the adult diet. Additionally, the results indicate that the flies are incapable of converting of amino acids from protein hydrolysate into precursors useful for generating metabolic energy in sufficient amounts to sustain life.
A sticky trap for fruit flies was developed that is 2.5× more effective than yellow panel traps of equal surface area for capture of Mexican fruit flies (Anastrepha ludens (Loew)). The trap consists of a slightly conical yellow cardboard cylinder coated on the outside surface with trapping adhesive. In trapping efficacy, these stand-alone cylinders were equivalent to plastic Liquibaitor trap tops with similar cylinders fitted over the trap top with the sticky surface facing outward. Liquibaitor trap tops with cylinders mounted on the inside with their sticky surfaces facing inward were ineffective, and Liquibaitor tops with cylinders both inside and outside were not more effective than those with the sticky surface only on the outside. Besides the increased attractiveness of the stand-alone cylinders with the sticky surface outside, advantages of this design are that lures can be suspended from the trap hanger inside the cylinder where they do not contact the sticky surface, sticky cylinders can be changed in the field without disturbing lures that are suspended from the hangers, and traps can be stacked like Dixie cups for storage and transport.
We determined seasonal and nocturnal flight activity of Spodoptera frugiperda (J. E. Smith) males with traps baited with pheromone in the coast of Chiapas, Mexico. A total of 3015, 3065, and 838 males were captured in 2000, 2001, and 2002, respectively. Pheromone trap catches decreased approximately 72% during 2002 with respect to 2000 and 2001. One of five experimental sites caught 90% of the total captured. The pattern of trap captures was quite variable among years and sites. In general, the flight activity of S. frugiperda males was seasonal, with two distinctive peaks in trap captures during the year. Males were caught during all hours of scotophase, however, most males were captured during the first 7 h. Highest peak capture was between 1900-2000 h. Trap captures were positively correlated with wind speed and temperature, and negatively correlated with relative humidity. Significantly more males were captured at wind speeds of 100-200 and >200 m/min than at wind speeds of 0-100 m/min.
Oviposition preference of Homalodisca coagulata (Say) and two of its mymarid egg parasitoids, Gonatocerus ashmeadi Girault and G. triguttatus Girault, for two Citrus limon L. cultivars (‘Eureka’ and ‘Lisbon’) was investigated. In laboratory oviposition choice tests, the number of leaves containing H. coagulata egg masses, the number of H. coagulata egg masses, and the total number of H. coagulata eggs were significantly higher at 187.2%, 204.2%, and 181.7%, respectively, on ‘Eureka’ versus ‘Lisbon’. In the field, there was no significant difference in the number of H. coagulata motiles counted in five-minute searches of foliage on ‘Eureka’ and ‘Lisbon’ trees, and numbers of leaves with old (emerged) and new (unemerged) H. coagulata egg masses were equivalent between field-planted cultivars. In the laboratory, parasitism of H. coagulata egg masses by G. ashmeadi and G. triguttatus was 18.6% and 23.2% higher, respectively, for eggs laid on ‘Eureka’ leaves compared to ‘Lisbon’, but these differences were not significant. Leaf surface morphology and thickness of leaf cell layers of both lemon cultivars were compared with scanning electron microscopy (SEM). SEM demonstrated that total leaf thickness and the thickness of the palisade layer was 19.2% and 38.6% higher, respectively, in ‘Eureka’ leaves compared to ‘Lisbon’, and that H. coagulata egg placement was between the lower epidermis and spongy parenchyma layer for both cultivars. Furthermore, ‘Lisbon’ leaves had a smooth underside, whereas ‘Eureka’ leaves had many small ridges. The thickness and rough surface of ‘Eureka’ leaves may be beneficial for H. coagulata oviposition. However, additional research is required to further investigate whether leaf characteristics or xylem chemistry are responsible for H. coagulata oviposition choice. For mass rearing programs with lemons as host plants, it is recommended that the ‘Eureka’ cultivar be used in preference to ‘Lisbon’ because H. coagulata prefers this cultivar for oviposition and parasitoid foraging is not adversely affected.
Research on biological control of glassy-winged sharpshooter (GWSS) Homalodisca coagulata (Say) started in the 1990s. This sharpshooter, vector of Pierce’s disease bacteria Xylella fastidiosa Wells, expanded its geographical distribution and it has become a very serious pest problem in several crops, especially grapes, in southern California. In 2000, a survey of sharpshooter egg parasitoids was initiated in Argentina. Fourteen species of egg-parasitoids were collected. We report here on laboratory studies of adult longevity, oviposition preference, sex ratio, and development time of Zagella delicata De Santis. Field result of the incidence on its hosts and seasonal occurrence also are provided. Zagella delicata produced one adult per host egg. The overall results indicated that 72.5% of the sharpshooter eggs exposed to Z. delicata were parasitized. Wasps emergence was 43.8%. In host plant searching preference tests, Z. delicata females parasitized 66.7% of host eggs on sugar cane, 57.0% of eggs on corn and 4.5% on citrus leaves. The development time (from oviposition to adult emergence) averaged 23.5 ± 1.2 days. The average adult longevity was 10.3 ± 5.8 days. Females lived longer than males (females: 12.2 ± 5.6 days, males: 6.2 ± 3.7 days). The sex ratio in the laboratory was 1: 2.1 (males/females). In a hyperparasitism test, no adults of Z. delicata emerged from eggs previously exposed to Gonatocerus tuberculifemur. Seasonal sampling carried out in San Miguel de Tucumán showed that Z. delicata occurred from spring to fall, with maximum abundance at the beginning of the spring, where 57.2% out of the 1568 sampled eggs were parasitized. Field and laboratory data suggest that Z. delicata could be a prospective biological control agent against other, exotic, proconiine sharpshooters including H. coagulata. However, the efficiency of Z. delicata is restricted to habitats dominated by grasses.
A survey of tephritid fruit fly species and their parasitoids was conducted in the western portion of Santa Catarina state, Brazil. A total of 9,197 fruits belonging to 46 plant species in 24 families was collected. The parasitoids recovered were Aganaspis pelleranoi (Brèthes), Lopheucoila anastrephae (Rhower) (Figitidae), Doryctobracon areolatus (Szèpligeti), Doryctobracon brasiliensis (Szèpligeti), Odontosema anastrephae Borgmeier, Opius bellus Gahan, Opius sp., Utetes (Bracanastrepha) anastrephae (Viereck) (Braconidae), and Trichopria anastrephae Lima (Diapriidae). Agasnaspis pelleranoi is the most frequent parasitoid species found in the west region of Santa Catarina. We recorded the first occurrence of L. anastrephae in Santa Catarina. Parasitism ranged from 1.2 to 46.9%.
Tropical fish farms provide a prime habitat for the red imported fire ant, Solenopsis invicta Buren, which is an invasive, stinging ant that has spread throughout the southern United States. Stings can be a serious health hazard to hypersensitive individuals, and the presence of large populations can interfere with operational activities. The most efficient method of controlling fire ants is the application of ant bait. However, most fish farmers are reluctant to use baits or other chemical methods of control because of the unknown risk to fish. Baited stations in combination with maps generated by geographical information system software were used to estimate locations of fire ant nests. Maps of estimated fire ant locations encompassed from 10 to 100% of actual fire ant nests surveyed when there was a minimum of a single fire ant within a station. Low percentages of overlap between mapped areas and fire ant nests were associated with low nest densities and when higher ant count thresholds were used to indicate positive stations. Ant bait containing the insect growth regulator methoprene was broadcast between ponds, with some unavoidable bait entry into ponds. Fire ant nest densities declined 57% within 4 months. In contrast, nest densities increased 86% in untreated areas. During the summer, fire ant populations declined an average of 68% and increased 110% for treated and untreated areas, respectively. Fire ant nest densities and populations began to increase by December in both treated and untreated areas. No obvious fish mortality related to the ant baiting was noted during the study.
The life cycle of Dystus puberulus Stål, including all developmental stages, is described and notes on its biology are provided. The association of this rare species of Scutelleridae with several species of Ficus is reported for first time. Nymphs and adults of this species feed on the immature fruits, which resembles them in shape and color. Nymphs and adults are densely setose, with slightly flattened antenna, characteristics that are unusual in Scutelleridae.
Three strains of the entomopathogenic fungus Beauveria bassiana Vuill. were tested for pathogenicity against adults of Metamasius (=Cactophagus) spinolae Gyllenhal. M. spinolae is an important pest of cactus plants (Opuntia ficus indica), which are used as a food crop and to avoid erosion in Mexico. After inoculation in a spray tower, M. spinolae adults were susceptible to B. bassiana at concentrations of 1 × 108 conidia per milliliter. Female mortality was steadily higher than male mortality for all isolates. One of the three isolates caused significantly higher mortality (82%) in females, whereas male mortality was the same for all isolates. These results indicate for the first time the possible use of B. bassiana as biocontrol agent against this insect pest.
A dichotomous key is presented to aid in the identification of the adult stage of the 71 grasshopper species known to occur in Florida. Reflecting recent research one subspecies, Schistocerca alutacea rubiginosa (Scudder), has been elevated to species status Schistocerca rubiginosa (Harris) in this key.
An endemic Cuban tiger beetle, Cicindela (Brasiella) viridicollis Dejean, is reported from Florida, based on a specimen in the Mississippi Entomological Museum. It is the first record of this species in the United States. A description and an illustration of the species are provided.
Caterpillars of Tallula watsoni Barnes & McDunnough regularly occur in the webs of the subsocial spider Anelosimus studiosus (Hentz) in south Florida. The caterpillars have not been found outside of the spider webs. Caterpillars feed on living and dead leaves that are on twigs incorporated into the webs of the spiders. A wide variety of trees and woody shrubs are accepted. In the laboratory caterpillars did not attack spiders or their prey. Spiders did not normally attack the caterpillars in the laboratory, but did so on two occasions. Pupation occurs in the spider web. We speculate that the spider web provides the caterpillars some protection from generalist predators and parasitoids. We suspect that T. watsoni is an obligate inquiline of A. studiosus. Other inquilines in the spider webs include 13 species of spiders and 10 species of insects. Two insects may have close or obligate relationships with A. studiosus: Ranzovius clavicornis (Knight) (Miridae), a scavenger, and Zatypota crassipes Townes (Ichneumonidae), a parasitoid of A. studiosus.
The first North American record for Elachertus scutellatus, a parasitoid of Calpodes ethlius Stoll, occurred August 1999, in Florida. A simple rearing protocol was established to allow the morphology and development of this wasp to be examined. The egg and larval morphology and development of E. scutellatus resemble other Elachertus species. The freshly-ecdysed pupa, on the other hand, is rare among parasitoids in that it secretes a fluid from its anus which, when dry, fastens the pupa to its substrate. The death of the colony after eight months has many possible explanations including a laboratory-induced castration, inappropriate food source(s), and pathogenic infection.
Two new genera and two new species from Irian Jaya and Papua New Guinea are described and illustrated. These taxa are discussed in relation to others in the tribe Colpurini.
Three species of the genus Tanytarsus van der Wulp were captured during a survey of chironomid midges (Diptera: Chironomidae), conducted from September 1997 to October 1999, of all major geographical zones in Egypt. Tanytarsus spadiceonotatus Freeman is recorded from Egypt for the first time, whereas T. itsae sp. nov. is described for the first time from male imagines. Tanytarsus nocticola Kieffer, which had been recorded by Kieffer from Egypt (Aswan) in 1911 (Freeman 1958), was not found at the sampled localities. A key to the male imagines of Tanytarsus in Egypt is presented. New distributional data for the three collected species are provided.
To examine the relationships of geographically isolated paleo-island populations of Pogonomyrmex badius (Latreille 1802) in Florida we generated a phylogeographic hypothesis based on mitochondrial DNA (mtDNA) sequences. We found at least three distinct mtDNA lineages and a positive correlation between genetic and geographic distances. The relationships between nowadays isolated P. badius populations might resemble a long lasting separation due to either restricted gene flow caused by inbreeding, paleo-climatic events or the impact of novel invasive species. The current depletion of the only representative of the ant genus Pogonomyrmex in the south-eastern USA makes a more fine-scaled mapping of the remaining, small P. badius populations necessary to identify evolutionary distinct units for conservation purposes.
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