The method of application of the antibiotic tylosin (Tylan) for control of oxytetracycline-resistant American foulbrood (Paenibacillus larvae White) was tested in honeybee (Apis mellifera L.) colonies. A powdered sugar mixture with tylosin, applied as a dust, was efficacious in eliminating American foulbrood symptoms at a rate of 200-mg Tylan per 20 g of powdered sugar, applied at weekly intervals for 3 weeks. A second method of treatment consisting of Tylan mixed with granulated sugar and vegetable shortening and applied once as a patty, at an equivalent total dose as the dust method, to diseased colonies also effectively eliminated symptoms of disease. In all colonies treated with patties, however, small hive beetle (Aethina tumida Murray) populations significantly increased, compared with the powder sugar method or untreated controls. Bee populations in patty-treated colonies also were significantly reduced, most likely the result of the invasion and proliferation of adult and larval small hive beetles. Such reduction in colony strength was not seen in dust-treated colonies. Because of the obvious damaging populations of small hive beetles, concerns about development of disease resistance, unknown risks of residues, and lack of support by regulatory agencies for the use of the patty method, the use of the dust method of tylosin is greatly favored over the patty method.

In northeast Spain, the most common predators found in tomato fields and greenhouses are the mirids Macrolophus caliginosus Wagner and Dicyphus tamaninii Wagner. Natural colonization occurs during the growing season and both species prey on whiteflies. Because D. tamaninii can damage tomato fruits during periods of prey scarcity, a semifield experiment was carried out to evaluate whether the presence of M. caliginosus affects damage produced by D. tamaninii. In a tomato greenhouse, 60 plants were individually caged and distinct predator treatments were introduced: D. tamaninii, D. tamaninii eggs of Ephestia kuehniella Zeller, D. tamaninii M. caliginosus, M. caliginosus alone, and a control without any insect. Damage to tomato fruits was recorded (>25% of the fruit) in all the treatments with D. tamaninii, whereas no significant damage was detected with M. caliginosus alone. Finally, no intraguild predation was detected between both mirid species.

We evaluated wheat stem sawfly, Cephus cinctus Norton, parasitism, infestation, and sawfly-cut stems in wheat fields bordering intensely tilled (no visible stubble residue), minimally tilled (>75% stubble residue visible), and untilled (chemical fallow, herbicide fallow management) summer fallow fields in north-central and south-central Montana. No difference in sawfly parasitism or sawfly-cut stems was found between fields bordering minimally tilled and fields bordering untilled summer fallow. Sawfly parasitism in fields bordering untilled summer fallow was greater than in fields bordering intensely tilled summer fallow at six of the eight sites examined. Sawfly-cut stems were greater in the field bordering intensely tilled fallow at four sites, with no difference in sawfly-cut stems between the intensely tilled and untilled field at the other four sites. Although it has never been reported, we have observed that many sawfly stubs are completely buried. Therefore, we measured the depth of sawfly stubs in four untilled fields in Broadwater County, MT. Two-thirds of the stubs were completely buried (206 of 300) with an average depth of 6 mm. Intensive tillage, which results in soil-covered stubble, is not an effective sawfly control practice, because sawflies typically overwinter below ground and upon emergence must dig to reach the soil surface. However, Bracon cephi (Gahan) and Bracon lissogaster Muesebeck overwinter above ground in stems and might be unable to dig to the soil surface if buried. The elimination of intensive tillage in favor of chemical fallow should result in greater sawfly parasitism over time. Producers replacing minimal tillage with chemical fallow should see no effect on sawfly parasitism.

The predatory mite Neoseiulus fallacis (Garman) was evaluated as a biological control agent of herbivorous mites on outdoor-grown ornamental landscape plants. To elucidate factors that may affect predator efficiency, replicated tests were conducted on 30 ornamental plant cultivars that varied in relationship to their generalized morphology (e.g., conifers, shade trees, evergreen shrubs, deciduous shrubs, and herbaceous perennials), production method (potted or field grown), canopy density, and the prey species present on each. Plant morphological grouping and foliar density appeared to be the most influential factors in predicting successful biological control. Among plant morphological groups, N. fallacis was most effective on shrubs and herbaceous perennials and less effective on conifers and shade trees. N. fallacis was equally effective at controlling spider mites on containerized (potted) and field grown plants, and there was no difference in control of mites on plants with Tetranychus spp. versus those with Oligonychus or Schizotetranychus spp. Moderate to unsuccessful control of spider mites by N. fallacis occurred mostly on tall, vertical plants with sparse canopies. Acceptable spider mite control occurred in four large-scale releases of N. fallacis into production plantings of Abies procera, Thuja occidentalis ‘Emerald’, Malus rootstock, and Viburnum plicatum ‘Newport’. These data suggest that N. fallacis can be an effective biological control agent of multiple spider mite species in a range of low-growing and selected higher growing ornamental plants.

The seasonal abundance of spider mites and their predator Neoseiulus fallacis (Garman) (Acari: Phytoseiidae) was determined during three consecutive years in Washington State red raspberry fields. Tetranychus urticae Koch (Acari: Tetranychidae), Eotetranychus carpini borealis (Ewing) (Acari: Tetranychidae), and N. fallacis were commonly found in Skagit and Whatcom Counties. E. carpini borealis colonized the fruiting canes earlier in the season than T. urticae. The two phytophages overlapped in midseason, but T. urticae entered diapause earlier than E. carpini borealis and N. fallacis. Densities of N. fallacis increased with increase in spider mite densities. However, the numerical response of the predator was more evident for T. urticae than for E. carpini borealis. Nevertheless, the predator was spatially associated with the two prey species. The spatial and seasonal distribution of N. fallacis in relationship to host plant phenology and prey distribution may influence the effectiveness of this predator as a biological control agent against spider mites in red raspberry. Densities of the predator increased too late to prevent spider mite damage. The predatory role of N. fallacis could be enhanced by introducing or conserving predators that are more tolerant to climatic factors that prevail in and around the cane canopy in the beginning of the season.

This study extends our comparative knowledge of Pseudacteon interactions with Solenopsis fire ant workers. Reported in this work are development times for seven Argentinean parasitoid species reared on two hosts, Solenopsis richteri Forel and Solenopsis invicta Buren, under laboratory temperature regimes comparable with those of the climatic zones occupied by these host species. Developmental times spanned 31–66 d across phorid species, and in general did not differ between genders or host species, but were longer at lower temperatures. The size distribution of flies reared was bimodal, with a group of large (Pseudacteon borgmeieri, Pseudacteon nocens, Pseudacteon obtusus, and Pseudacteon tricuspis) and small (Pseudacteon cultellatus, Pseudacteon curvatus, and Pseudacteon nudicornis) species. P. borgmeieri was exceptional with respect to length of developmental time. Also reported are results of initial oviposition and developmental studies of some of these phorid species on other Argentinean Solenopsis ant species; P. curvatus was the only species able to complete its development on nonhost fire ants. These results support the concept of incorporating several complementary species of Pseudacteon in the biological control of pest fire ants.

The impact of a zoophytophagous, insect-free artificial diet upon the developmental rate, life table parameters, and fertility table parameters was examined over 11 consecutive generations for domesticated and wild colonies of Podisus maculiventris (Say) (Heteroptera: Pentatomidae). This study showed that the developmental time, preoviposition period, fecundity, and nymphal survival improved in the domestic colony when fed an insect-free artificial diet for 11 consecutive generations, but remained relatively constant for the wild colony, as did reproductive rate and intrinsic rate of increase. Although, after 11 generations of adaptation to an artificial diet feeding regime, all reproductive and fertility table parameters were still significantly lower than when fed on T. ni larvae as the natural prey, the realized cost of rearing either colony on the artificial diet approached 1.2 times the cost of rearing these insects on a natural prey. This is a significant achievement in the effort to develop cost-effective artificial diets for the mass-rearing of beneficial pentatomids, and has positive implications for the use of one artificial diet to efficiently rear several beneficial insects.

Eggs, crawlers, early nymphs, late nymphs, and adults of the pink hibiscus mealybug, Maconellicoccus hirsutus (Green), were tested for their susceptibility to methyl bromide in 2-h laboratory fumigations at ambient conditions (25°C, 95% RH). Dose–response tests indicated that the egg was the most susceptible life stage with an LC₉₉ of 20.2 mg/liter. Based on probit analysis of dose–response data, no significant differences were observed among susceptibilities of the crawler, early stage or late stage nymphs, or adults at either the LC₅₀ or LC₉₉ level, but late stage nymphs were more tolerant than early stage nymphs in a separate paired comparison test. Confirmatory tests showed that a dose of 48 mg/liter methyl bromide, the USDA-Animal Plant Health Inspection Service treatment dose schedule for mealybugs at 21–26°C, produced 100% mortality of all life stages. On the basis of these results, we conclude that the methyl bromide treatment schedule for mealybugs will provide quarantine security for M. hirsutus infesting commodities for export or import.

In previous migration studies, the presence of citrus pollen on adult Helicoverpa zea (Boddie), in conjunction with synoptic weather systems and 72-h backtrack trajectories, were used to identify source zones of migrants. However, data are lacking regarding the retention of citrus pollen for 72-h by H. zea adults. We exposed laboratory-reared and feral H. zea adults to citrus blooms for a 12-h period in laboratory and field studies and examined insects for the external presence of citrus pollen (i.e., marking) at 12-h intervals through 72 h. Citrus pollen marking was higher for females than males at the time of removal from citrus blooms. Fifteen to 100% of H. zea adults were marked with citrus pollen at 72 h after removal from citrus blooms. Pollen loads ranged from rare (≤10 pollen grains) to moderate (101 to 500 grains) during 1995; only rare and light (11 to 100 grains) pollen loads were detected during 1996. Citrus pollen marking of H. zea adults through 72 h after removal from citrus blooms has not been previously confirmed. These data provide evidence of H. zea using available blooming citrus groves in the absence of a host crop and will impact current perspectives regarding H. zea and host plant interactions and timing of pest management tactics.

The greenhouse whitefly, Trialeurodes vaporariorum (Westwood), has recently become a major insect pest of strawberries in Southern California. The population dynamics of this pest were monitored over 2 yr in six commercial strawberry fields near the coastal communities of Oxnard and Ventura under two crop-production regimes, summer- and fall-planted strawberries. Adult whitefly numbers generally peaked during the February through May period for fall-planted strawberries and during the October through November period for summer-planted strawberries. Population densities varied greatly among fields within each regime and the differences were likely caused by surrounding alternate host crops.

The toxicity of a number of emamectin benzoate homologues and photodegradates to five species of Lepidoptera was investigated using diet and foliar bioassays. The emamectin benzoate homologues B1a and B1b were equally toxic in the diet and foliar assays to Spodoptera exigua (Hübner), Heliothis virescens (F.), Tricoplusia ni (Hübner), and Spodoptera frugiperda (J. E. Smith), within each of these species. Plutella xylostella (L.) was the most sensitive species to emamectin benzoate. The AB1a photodegradate of emamectin benzoate was as toxic as the parent compound in the diet assay. However, in the foliage assay AB1a was 4.4-fold less toxic to S. exigua than the parent compound. The MFB1a photodegradate of emamectin benzoate was as toxic as the parent compound to P. xylostella, and 3.1 to 6.2 times as toxic as the parent compound to the other species in the diet assay. The order of toxicity of the photodegradates were AB1a > MFB1a > FAB1a > 8,9-Z-MAB1a > PAB1a.

We report a protocol using a common desk-top scanner and public domain software for measuring existing leaf area and leaf area removed as a result of herbivory. We compared the accuracy and precision of this method to that of a standard leaf area meter. Both methods were used to measure metal disks of a known area, the area of soybean (Glycine max L.) leaves, and the area removed by simulating leaf feeding with a hole-punch. We varied the amount of injury across a low, medium, and high degree of simulated feeding. The mean area of 10 cm² and 50 cm² metal disks was more accurately estimated with the leaf area meter than the desk-top scanner. Leaf area estimates from both methods were highly correlated. The desk-top scanner accurately estimated the leaf area removed from the low, medium, or high degree of simulated leaf feeding. However, the leaf area meter overestimated low levels of simulated feeding injury. Though measuring a leaf’s surface area with a desk-top scanner requires two steps (creating a digital image file and calculating the area represented by that image), the overall time required to measure leaf injury is shorter than with a leaf area meter. This relatively simple and inexpensive method of estimating leaf area and feeding damage has advantages in certain experimental situations where a prefeeding measurement of the leaf is impossible or undesirable, or when small amounts of feeding occur.

The exotic pine shoot beetle, Tomicus piniperda (L.) (Coleoptera: Scolytidae), established in the north central and northeastern United States (U.S.) and adjacent regions in Canada, is regulated by a federal quarantine that restricts movement of pine material during specific times of the year based on the beetle’s life history. Although climatic variation occurs across T. piniperda’s range, a single set of dates is used for timing the movement of pine logs. We monitored T. piniperda spring flight, fall shoot departure, and air and internal tree temperatures at three sites along a 300-km north-south gradient in Michigan and Indiana. We also estimated dates for initial spring flight (12°C threshold) and fall shoot departure (0°C threshold) across an 850-km gradient using historical temperature records (1901 to 1999). Average daily temperatures in fall 1997 (8 October to 12 December) and spring 1998 (20 February to 21 April) were 1.8 to 2.4°C colder, respectively, at the northern field site than at the southern field site. Fall shoot departure began at approximately the same time (day 289 to 290) at all three field sites, but complete shoot departure was extended by 3 wk at the southern site (day 336) compared with the northern site (day 317). T. piniperda adults were first captured in funnel traps on calendar day 86 at the northern site and on day 59 at the central and southern field sites. Peak flight occurred at approximately the same time (day 86) at all three sites. Within-shoot temperatures were very similar to air temperatures in the fall and aboveground inside-bark temperatures were similar to air temperatures in the spring. Average predicted dates based on historical temperature records varied by 31 d for initial shoot departure and 84 d for initial spring flight between northern Michigan and southern Indiana. Because considerable variation can occur in T. piniperda behavior across a broad geographic range, dates specified in the U.S. Federal quarantine should be adjusted according to local temperatures.

Pheromone traps can be used for evaluating the success of treatments that are applied to either eradicate or delay the growth of isolated low-density populations of the gypsy moth, Lymantria dispar (L.). We developed an index of treatment success, T, that measures the reduction in moth counts in the block treated adjusted by the change in moth counts in the reference area around it. This index was used to analyze the effectiveness of treatments that were conducted as part of the USDA Forest Service Slow-the-Spread of the gypsy moth project from 1993 to 2001. Out of 556 treatments that were applied during this period, 266 (188,064 ha) were selected for the analysis based on several criteria. They included 173 blocks treated with Bacillus thuringiensis (Berliner) variety kurstaki and 93 blocks treated with racemic disparlure. Analysis using general linear models indicated that disparlure treatments were significantly more effective than B. thuringiensis treatments in reducing moth captures. The frequency of repeated treatments in the same area was higher after B. thuringiensis than after disparlure applications. Treatments were more successful if the pretreatment moth counts outside of the block treated were low compared with moth counts inside the block.

We investigated the effects of ultraviolet (UV)-reflective mulch and two rates of nitrogen fertilization on populations of Frankliniella spp. thrips and on the incidence of tomato spotted wilt in field-grown tomato in northern Florida. The higher of the two soil nitrogen fertilizer treatments significantly increased populations of Frankliniella occidentalis (Pergande), whereas mulch reflectance significantly decreased populations of F. occidentalis. Populations of Frankliniella tritici (Fitch) were decreased only by UV-reflective mulch. Decreased thrips populations in UV-reflective mulch plots were probably due to disruptions in host-finding behavior. Increased thrips populations in tomatoes treated with the higher nitrogen fertilization rate were probably due in part to increased nutrients available in flowers. Incidence of tomato spotted wilt was significantly decreased in tomatoes grown on UV-reflective mulch, whereas disease incidence was significantly greater in increased nitrogen-fertilized plots. This research reveals that cultural practices resulted in up to 45% reduction in the numbers of vector and nonvector species of flower thrips and up to 50% reduction in tomato spotted wilt.

Appropriate particle size may be a critical characteristic for effective granular ant baits. We examined the particle size preference of six species of pest ants to an anchovy-based bait. We also examined head capsule widths of Argentine ants, Linepithema humile (Mayr) (mean = 0.54 mm), California harvester ants, Pogonomyrmex californicus (Buckley) (mean = 1.63 mm), red imported fire ants, Solenopsis invicta Buren (mean = 0.9 mm), and southern fire ants, Solenopsis xyloni McCook (mean = 0.76 mm) and compared them with the first and second most preferred particle size. There were differences between particle size of which the most mass was removed and of which there were more particles removed by ants. California Argentine ants, southern fire ants, and Alabama Argentine ants removed more 840 to 1,000-μm particle mass of the anchovy diet but had more visits to dishes containing 420 to 590 μm particles. California harvester ants and Allegheny mound ants, Formica spp., removed more >2,000 μm particle mass but visited dishes containing 1,000 to 2,000 μm particles more often. Red imported fire ants also removed more >2,000μm particle mass but visited dishes with 590 to 840-μm particles most often. Pharaoh ants, Monomorium pharaonis (L.), removed and visited 420 to 590-μm particles more than any other size. A linear regression model determined that particle size preferred by each ant species relates to forager head width. The majority of particles of commercial ant bait, including Amdro, Ascend, Award, Bushwhacker, Max Force with fipronil, and old and new formulations of Max Force with hydramethylnon, were 1,000 to 2,000 μm, but the majority of Niban particles were <420 μm. Altering the size of particles of toxic ant baits to fit the particle size preference of each pest ant species may increase the efficacy of ant baits.

To investigate the relationship between resistance to organophosphate insecticides and fitness components, we first measured resistance to three organophosphates, malathion, prothiophos, and fenitrothion, and productivity, a measure of fitness components, for each of the isofemale lines from the same natural population of Drosophila melanogaster (Meigen). Pearson correlation coefficients indicated that positive correlations among resistance to the organophosphates and negative correlations between resistance to each of the organophosphates and the productivity existed within the natural population. We further investigated the genetic basis of the correlations among resistance to the organophosphates and the productivity, by using chromosome-substituted lines between a resistant and a susceptible inbred line established from the same natural population. Chromosomal analyses indicated that the third chromosome from the resistant line exhibited not only significant, positive effects on resistance to all of the organophosphates tested but also a significant negative effect on the productivity, suggesting positive genetic correlations between resistance to each organophosphate and negative genetic correlations between resistance to each organophosphate and the productivity. In addition, a significant negative effect on the productivity was also detected from the second chromosome, which did not exhibit significant major effects on resistance to the organophosphates. This suggests that fitness components of resistant lines could be also affected by factors independent of insecticide resistance. The dynamics of genetic variation in resistance to the organophosphates within the natural population of D. melanogaster are discussed from the standpoint of negative genetic correlations between resistance to the organophosphates and the productivity.

In this study, acetylcholinesterases (AChEs) were extracted from two Mexican Boophilus microplus strains that demonstrated resistance to the organophosphate (OP) acaricide, coumaphos, in bioassay. The rate of inhibition of the extracted AChEs by the diethyl-OP paraoxon was determined for two resistant strains and two susceptible strains of B. microplus. The time to inhibition of 50% AChE activity was approximately two-fold greater for the resistant strains. Kinetic analysis of the interaction of the resistant AChEs with paraoxon revealed reduced bimolecular reaction constants (k_i). Apparent conformational changes in the AChE of the resistant strains were reflected in reduced K_m and V_max values. The bimolecular reaction constants (k_i) of the resistant strains were most affected by a slower rate of enzyme phosphorylation (k₂).

A strategy for house fly (Musca domestica L.) control in intensive animal units in the United Kingdom was proposed by the Pesticide Safety Directorate (PSD) of the Ministry of Agriculture, Fisheries and Food in 1993. An advice leaflet was circulated to farmers, and label recommendations for insecticides used to control house flies were altered to prevent their long-term and frequent use. A study was carried out between 1996 and 1998 to gather data on insecticide use and resistance in house fly populations and compared with results from a study carried out in 1990–1992 to assess the impact of the 1993 label recommendations. As in the 1990–1992 study, resistance to methomyl, azamethiphos and pyrethrins piperonyl butoxide was assessed. Larvicide tests with cyromazine, which had recently been released in the United Kingdom, were also included in this study. Most of the farmers claimed to have received and read the PSD insecticide advice leaflet, and half claimed to have altered insecticide treatments as a result. Comparing results for insecticides used before and after 1993, the proportion of farmers claiming to have used each of the insecticides had decreased. However, there had been no amelioration in resistance to synergised pyrethrins, and the number of house fly populations with reduced response to the insecticide baits had increased between 1990–1992 and 1996–1998. All the house fly populations tested were fully susceptible to cyromazine. There is an urgent need, therefore, to devise new strategies and particularly to minimize the risk of selecting for resistance to cyromazine.

The genetic basis of cyromazine resistance was investigated in the house fly, Musca domestica L. The ED-R strain, which was collected in Mississippi and selected further in the laboratory, was 116.5-fold resistant compared with the laboratory susceptible strain, OR-S. The SEL strain, which was created by crossing ED-R with OR-S followed by three cycles of reselection and backcrossing to OR-S, was 84.7-fold resistant relative to the susceptible strain. Mortality data from reciprocal crosses of resistant and susceptible flies indicated that resistance was autosomal and not influenced by maternal effects. The relative position of probit lines from the parental strains and reciprocal crosses showed that resistance was expressed as an incompletely dominant trait with D = 0.30 and 0.32 for ED-R and SEL, respectively. To determine the number of genes involved, models of one, two, three, four, and five loci were used to compare observed and expected mortality of F_1ED-R × susceptible backcross. Resistance was best described by a polygenic model of three loci when equal and additive effects of loci were assumed. Another approach, which was based on phenotypic variances, showed that n_E, or the minimum number of freely segregating genetic factors for ED-R, equaled 3.07. ED-R showed greater reductions in fitness compared with SEL independent of the presence or absence of sublethal concentrations of cyromazine. These data suggested that reduced fitness was not due to deleterious pleiotropic effects of the resistance genes themselves but arose from other loci in the ED-R genotype.

Resistance to methyl-parathion among Nebraska western corn rootworm, Diabrotica virgifera virgifera LeConte, populations is associated with increased hydrolytic metabolism of an organophosphate insecticide substrate. An electrophoretic method to identify resistant individuals based on the staining intensity of esterase isozymes on nondenaturing polyacrylamide gels was developed. Three groups of esterases (I, II, and III) were visible on the gels, but only group II esterase isozymes were intensified in resistant populations. A total of 26 and 31 field populations of western corn rootworms from Nebraska (in 1998 and 1999, respectively) were assessed with nondenaturing polyacrylamide gel electrophoresis (PAGE) assays and diagnostic concentration bioassays. Significant correlations were observed between the two diagnostic assays. Group II esterase isozymes provide a reliable biochemical marker for detection of methyl-parathion resistance in individual western corn rootworms and a tool for monitoring the frequency of resistant individuals in field populations.

We studied the genetic basis of resistance to two new acaricides, chlorfenapyr and etoxazole, which have different chemical structures and modes of action in the two-spotted spider mite, Tetranychus urticae Koch. The resistance ratios calculated from the LC₅₀s of resistant and susceptible strains were 483 for chlorfenapyr and >100,000 for etoxazole. Mortality caused by the two acaricides in F₁ progeny from reciprocal crosses between the resistant and susceptible strains indicated that the modes of inheritance of resistance to chlorfenapyr and etoxazole were completely dominant and completely recessive, respectively. Mortality in F₂ progeny indicated that for both acaricides, the resistance was under monogenic control. Repeated backcross experiments indicated a linkage relationship among the two acaricide resistances and malate dehydrogenase, although phosphoglucoisomerase was not linked with them. The recombination ratio between the resistances was 14.8%. From this result, we suggest that heavy spraying of the two acaricides will lead to apparent cross-resistance as a consequence of crossing over; the two resistance genes are so close to each other that it would be difficult to segregate them once they came together on the same chromosome.

Host plant suitability to green cloverworm, Hypena scabra (F.), was evaluated on two conventional soybean varieties (Stine 2499–0 and 2972–2) and two RoundUp Ready Soybeans (Stine 2506–4 and 2892–4) with and without exposure to glyphosate. No differences among treatments were detected on developmental time and survivorship. Developmental time from first instar to adult ranged from 24.7 to 25.5 d, and survivorship ranged from 86 to 96%. No sex bias was observed among treatments (proportion of females ranged from 0.41 to 0.50). Morphological differences were observed between sexes; males had a longer and wider thorax, longer wings, and longer body. Females had longer and wider abdomens. Although treatments did not affect size (calculated with principal component analyses), significant differences were observed between males and females. These results suggest that soybean genetic differences (between conventional varieties and analogous transgenic varieties) or plant stress (induced by glyphosate metabolization) do not affect the plant suitability to H. scabra.

RESUMEN El effecto como hospedero, de dos variedades convencionales de soya (Stine 2499–0 and 2972–2), y dos variedades de soya RoundUp Ready (Stine 2506–4 and 2892–4) expuestas y no expuestas a glyphosato, fueron evaluadas para Hypena scabra (F.). Ninguna diferencia estadística entre los tratamientos fue detectada en la duracción de desarrollo del insecto o su sobrevivencia. La duración de desarrollo de primer instar para adulto ociló entre 24.7–25.5 días, y la sobrevivencia fluctuó entre 86–96%. La proporción sexual (hembra:macho) fue similar entre los tratamientos, la cual ociló entre 0.41–0.5 (proporción de hembras sobre el total de adultos). Diferencias morfológicas fueron observadas entre uno y otro sexo, machos tuvieron un thorax mas largo y ancho, alas mas largas, y fueron mas largos que las hembras. Las hembras tuvieron abdómenes mas largos y anchos. Aunque entre los tratamientos no se encontraron diferencias en tamaño (calculado usando análisis de componente principal), se observaron diferencias significativas entre machos y hembras. Estos resultados indican que las diferencias genéticas en la soya (entre variedades convencionales y variedades transgénicas análogas) o el estrés en plantas (inducido por la metabolización de glyphosato) no afecta la calidad de la planta como hospedero de H. scabra.

Laboratory and screenhouse experiments were conducted to identify antibiosis and tolerance in four wild accessions of cowpea, Vigna unguiculata subsp. dekindtiana, to Clavigralla tomentosicollis Stål, the most damaging pod-sucking bug on cultivated Vigna genotypes in West Africa. The wild accession TVnu 151 showed antibiosis resistance, causing >50% mortality of the nymphs within 3 d of placing them on pods. Nymphs died more quickly on TVnu 151 than on TVnu 72, the wild and resistant control of the V. vexillata species which affected the weights of surviving insects to a much greater degree than TVnu 151. The three other accessions of the subspecies dekindtiana (TVnu 369, TVnu 517, and TVnu 707) did not cause significant mortality to the bugs, but rather extended their developmental time, with surviving adults showing lower weights and slower oviposition rates than those on the susceptible control IT84S-2246. Wild accessions affected male and female bugs differently, resulting in differential survival. This was reflected by the sex ratio which was male biased on the wild accessions (1:0.3–1:0.9), and female biased on IT84S-2246 (1:1.5). No evidence of tolerance was found in the four accessions of V. unguiculata subsp. dekindtiana. Overall, seed traits seemed to be the major resistance component in these wild accessions.

The role of chemical stimuli in host selection and oviposition of Sesamia nonagrioides (Lef) was studied in the laboratory using eight corn hybrids. Female oviposition preference was evaluated on plants of the eight hybrids, their extracts in pentane and methanol, and volatiles collected by steam distillation in ether. Results from two-choice bioassays indicate various degrees of female preference to the hybrids. Four hybrids received more eggs than control plants, whereas the remainder received fewer eggs. Relatively similar results were obtained when filter paper sticks baited with pentane and steam distillation extracts were evaluated. Methanol extracts from all eight hybrids received fewer eggs than the methanol controls. Results showed that pentane and steam distillation extracts contain chemicals that elicit female oviposition response, while methanol extracts may contain chemicals that deter or repel females to oviposition.

Levels of pyridine alkaloids were measured in 18 tobacco, Nicotiana tabacum L., entries from three parental isolines (‘NC 95’, ‘SC 58’, and ‘Coker 139’), grown at Tifton, GA, Florence, SC, and Oxford, NC, in 1991. Levels of alkaloids in bud leaves (first fully unfolded leaf below the apical leaf bud) were negatively correlated to natural infestation ratings of tobacco budworm larvae, Heliothis virescens (F.), 7 wk after transplanting. For artificially infested bud leaves at Oxford, there was a significant negative correlation between levels of total alkaloids and larval weights after 1 wk of feeding. In 1992, four entries from the ‘NC 95’ isoline were grown at Oxford, and samples for alkaloid analyses were taken every 2 wk at several leaf positions on each plant. During weeks 4, 8, 12, and 16, second instar tobacco budworms were caged on individual, intact leaves inside perforated plastic bags in the field. The survival and development of tobacco budworm larvae after 1 wk were negatively correlated with levels of alkaloids at the various leaf positions. Larvae survived better and grew faster on the bud leaves of each entry where alkaloid levels were lower than they did on leaves further down the stalk where alkaloid levels were higher. More larvae survived on the lower leaves of the low alkaloid lines than on the lower leaves of the high alkaloid lines. Even moderate increases in pyridine alkaloids had negative effects on tobacco budworm survival and development. Nicotine constituted >97% of the pyridine alkaloids in the ‘NC95’ isoline each year.

Two maize (Zea mays L.) breeding populations with very high concentrations of maysin, a silk-expressed flavone glycoside, were tested for their ability to resist ear damage by the corn earworm, Helicoverpa zea Boddie, under field conditions. Tests were conducted in 2000 and 2001 at multiple locations in Georgia. The high maysin populations, EPM6 and SIM6, as well as resistant and susceptible checks, were scored for silk-maysin content, H. zea damage, and husk characters. In 2000, there was a negative correlation between husk tightness and earworm damage at three of five locations, while there was no significant correlation between damage and maysin content at any location. In 2001, EPM6 and SIM6 had approximately ten times the maysin content of the low-maysin control genotypes; nevertheless, earworm damage to EPM6 and SIM6 was either greater than or not significantly different from the low-maysin genotypes at all locations. The resistant control genotype, Zapalote Chico, had significantly less earworm damage than EPM6 and SIM6 for both years at all locations. The results of this study highlight the importance of identifying and quantifying husk and ear traits that are essential to H. zea resistance in maize.

The objective of this study was to determine the number of instars of the cranberry fruitworm Acrobasis vaccinii Riley in southeastern New Brunswick based on the distribution of head capsule widths from field and laboratory observations. In 2000, head capsules from field samples were measured across their widest point, and the results were plotted against observed frequencies. The data from field samples suggested that A. vaccinii exhibited five instars in 2000. In 2001, larvae were reared in the laboratory until the final molt, and head capsules were counted and measured. The results were also plotted against observed frequencies. None of the laboratory specimens exhibited more than five instars, supporting the results of the previous year. Various factors are invoked to explain the difference between these results and those of a previous study conducted 50 yr earlier and 200 km away, in which six instars and larger head capsules were reported.

The insecticidal pyrazole ethiprole, applied at rates of 7.5 and 10.0 ppm either alone or in combination treatments with deltamethrin, piperonyl butoxide, and chlorpyrifos-methyl, was evaluated as a protectant of stored wheat and stored corn. The commodities were treated with six treatment combinations, including an untreated control, and held for 6 mo at 22, 27, or 32°C and 57% RH. Bioassays were conducted monthly by exposing the rice weevil, Sitophilus oryzae (L.), and the red flour beetle, Tribolium castaneum (Herbst), on treated wheat and the maize weevil, Sitophilus zeamais (Motschulsky), and the red flour beetle on treated corn. The storage temperature of wheat did not significantly affect mortality of exposed insects (P ≥ 0.05). All rice weevils were dead after 1 wk in all treatments, and no F₁ adults were produced. Mortality of red flour beetles was not dependent on either chemical treatment or bioassay month, and no F₁ adults were produced. The storage temperature of corn did not significantly affect mortality of exposed insects (P ≥ 0.05). Mortality of maize weevils varied from 77.9 to 100% in all chemical treatments, and no F₁ adults were produced. Mortality of red flour beetles was also variable among treatments and bioassay month and no F₁ adults were produced. This is the first published report of a study in which pyrazoles have been evaluated against stored-grain insects.

A common method of aging adult flies, fluorescence spectrometry, was used to monitor the increase of overall pterine titer in head extracts of Anastrepha ludens (Loew). Accumulation of fluorescent compounds was measured as a function of chronological age of flies maintained at 17 and 27°C. Although relative fluorescence increased with age, field studies revealed that this phenomenon could not be used for accurate age estimation, as relative fluorescence did not increase predictably with age over the entire life span. Accumulation of individual pterins, deoxysepiapterin and sepiapterin, were studied in a similar manner. These two specific compounds were separated by high-pressure liquid chromatography and their accumulation was followed at 15 and 30°C in the laboratory and under caged field conditions. While titer of deoxysepiapterin increased steadily in a curvilinear fashion, sepiapterin quickly reached a maximum and then maintained a constant level for the rest of the life of the flies. Based on the physiological response of deoxysepiapterin to chronological time and ambient thermal conditions, this compound was determined to be an age specific biological parameter for the Mexican fruit fly and should allow age estimation in field-collected flies.

The relationship between number of holes in a grain probe trap body and capture of stored-grain pests was determined in laboratory tests using adults of the rice weevil, Sitophilus oryzae (L.), the sawtoothed grain beetle, Oryzaephilus surinamensis (L.), and the red flour beetle, Tribolium castaneum (Herbst). Polyvinylchloride (PVC) probe bodies were attached to electronic sensor heads, and insect captures were recorded electronically using an Electronic Grain Probe Insect Counter (EGPIC) system. In comparisons among PVC probe trap bodies with 60–492 holes, tested at 71 insects per kg in 2.8 kg of soft wheat in cylindrical mini-silos, sawtoothed grain beetle and rice weevil captures were directly related to number of holes in the probe trap body, but there was no relationship for red flour beetle capture. Subsequent tests were conducted comparing sawtoothed grain beetle and rice weevil captures in a PVC probe body with 210 holes over a 40-cm long trapping surface with two commercially available probe traps, a polycarbonate (Lexan) probe trap with 180 holes over a 14-cm long trapping surface and a polyethylene (WBII) probe trap with 750 holes over a 34-cm long trapping surface. The highest percentage capture of both species was in the WBII probe trap, but the 210-hole PVC probe body was as effective as the Lexan probe body for rice weevils and sawtoothed grain beetles at 71 and 17 insects per kg of wheat, respectively.

The sawtoothed grain beetle, Oryzaephilus surinamensis (L.), is an extremely destructive pest of packaged consumer food products. The beetle is not believed to chew directly through packaging materials, but to use openings or flaws in damaged or improperly sealed packages to gain entry. We investigated the behavioral mechanisms by which the sawtoothed grain beetle infests packages with flaws. Significantly more sawtoothed grain beetles infested consumer food packages that had been punctured with 0.4 mm diameter holes, to simulate packaging flaws that preclude adults, than when packages had no flaws. In a test arena, females laid more eggs into or near the hole in a plastic packaging film, when they were able to contact the food through the hole than when they could not contact the food. First instar larvae placed either 1 mm or 1 cm away entered holes when food was present, indicating that packages could become infested if eggs were laid near holes. In the absence of food, neither adults nor larvae responded to holes. This study has shown the importance of sound packaging in preventing insect infestation.

Absorbent recycled paper products were tested and compared with a sodium polyacrylate gelling agent, Aquatain, for solidifying larval diets of the screwworm, Cochliomyia hominivorax (Coquerel). A recycled newsprint product, Terra-Mulch, when mixed with water and dietary ingredients produced a diet medium of homogeneous texture that supported larval growth and development comparable to the standard diet prepared with the gelling agent. Biological yields as calculated from number of pupae per tray from both the diets were similar. Three other types of recycled paper products were tested. Although less homogeneous in texture, these diets were as good as the diet with Terra-Mulch. There were no significant differences in the mean larval and pupal weights, no. of pupae/tray, percent emergence, oviposition, percent hatch, and percent longevity. When tests were conducted through eight consecutive generations, no adverse effect was noticed in any of the life history parameters. Terra-Mulch is inexpensive and biodegradable compared with the gelling agent Aquatain that is expensive and not biodegradable. Replacing Aquatain with Terra-Mulch in the screwworm larval diet for mass rearing may result in an annual savings of more than half a million U.S. dollars in costs of material and labor.