To investigate the genetic basis of cross-resistance to insecticides, we conducted genetic analyses of resistance to three organophosphate insecticides, malathion, prothiophos, and fenitrothion. After isofemale lines resistant and susceptible to all of the three organophosphates had been screened from natural populations of Drosophila melanogaster (Meigen), chromosomal analyses were performed by using chromosome-substituted lines between the resistant and the susceptible lines. The chromosomal analyses revealed that both the second and the third chromosomes contributed to resistance to the organophosphates, suggesting that this resistant line possessed at least two factors for organophosphate resistance. However, the relative contribution of each chromosome was different in resistance to different organophosphates. We further carried out genetic mapping of a resistance factor for each organophosphate on each of the two chromosomes. Each resistance factor was mapped to the position of each chromosome, about II-62 and III-50. Results of the chromosomal analyses and the genetic mapping revealed that at least two resistance factors exhibiting different patterns of cross-resistance to the organophosphates existed within a natural population of D. melanogaster. Based on this research, genetic variation in insecticide resistance within natural populations and complex as well as simple aspects of the mechanism of cross-resistance are discussed.

A 3-yr, multi-state survey of farmers who had planted transgenic Bacillus thuringiensis (Bt) corn was conducted to evaluate perceptions of Bt corn performance and its utility as a management option for European corn borer, Ostrinia nubilalis (Hübner). A questionnaire was sent to farmers in Illinois, Iowa, Kansas, Minnesota, Nebraska, and Pennsylvania who had grown Bt corn during the growing seasons of 1996, 1997, or 1998. There were 7,427 usable questionnaires returned with the following response percentages: 1996 (42.1%), 1997 (35.0%), and 1998 (22.6%). Adoption rates, based on percentage of acreage planted to Bt corn, increased dramatically from 1996 (10.5%) to 1998 (40.7%). The states growing the highest percentage of Bt corn were Minnesota, Iowa, and then Nebraska. However, Illinois, was adopting Bt corn at the fastest rate. Historical use of insecticides did not influence the adoption of Bt corn. In addition, of those farmers who used insecticides to control European corn borer, the percentage that decreased their use of insecticides nearly doubled from 13.2% (1996) to 26.0% (1998) over this 3-yr period. The primary reason farmers planted Bt corn was to eliminate the yield loss caused by European corn borer. Scouting for European corn borers decreased from 91% (scouting 2.2 times a year) in 1996 to 75% (scouting 1.8 times a year) in 1998. The percentage of farmers not scouting for European corn borers increased from 9.6% (1996) to 25% (1998). Most farmers believed yields of Bt hybrids were either similar to or greater than the yields of non-Bt hybrids. Minnesota farmers perceived the greatest yield advantages. Farmers are becoming more aware of insect resistance management guidelines; however, they also clearly show preferences for having the flexibility to use different spatial plantings of Bt and non-Bt corn. Finally, after having planted Bt corn and obtained excellent control of European corn borer, most farmers believed that this insect had been causing more yield loss than they previously had suspected in their non-Bt corn. The data represented here provide an historical foundation for how transgenic Bt corn was used by farmers during the first 3 yr of commercial availability, their initial perceptions on the performance of this technology, and their attitudes regarding management of the European corn borer.

Tephritid fruit flies comprise the most important group of quarantined pests of fresh produce. Most quarantine treatments of fresh agricultural commodities are directed against these pests, and considerable effort in detection, trapping, and population control is expended worldwide to prevent these pests from invading new territories. Ionizing radiation has been studied for 70 yr for its possible use as a quarantine treatment against fruit flies, but has only been applied commercially on a limited basis since 1995. The treatment has great potential and will probably be used extensively in the future as it is tolerated by more species of fruits than any other major treatment. The U.S. Department Agriculture, Animal and Plant Health Inspection Service only recently proposed allowing irradiation for fresh agricultural imports from other countries, and other countries are studying proposals to do likewise. In 1991, the International Consultative Group on Food Irradiation recommended a generic dose against all tephritid fruit flies of 150 Gy. This article examines the literature dealing with irradiation quarantine treatments against fruit flies and recommends minimum absorbed doses of 70 Gy for Anastrepha spp., 101 Gy for Bactrocera jarvisi and B. tryoni, and 150 Gy for all Tephritidae except when fruits have been stored in hypoxic atmospheres.

The longevity and reproductive success of newly emerged, unfed adult Aethina tumida Murray assigned different diets (control = unfed; honey-pollen; honey; pollen; empty brood comb; bee brood; fresh Kei apples; and rotten Kei apples) were determined. Longevity in honey-fed small hive beetle adults (average maximum: 167 d) was significantly higher than on other diets. Small hive beetles fed empty brood comb lived significantly longer (average maximum: 49.8 d) than unfed beetles (average maximum: 9.6 d). Small hive beetle offspring were produced on honey-pollen, pollen, bee brood, fresh Kei apples, and rotten Kei apples but not on honey alone, empty brood comb, or in control treatments. The highest reproductive success occurred in pollen fed adults (1773.8 ± 294.4 larvae per three mating pairs of adults). The data also show that A. tumida can reproduce on fruits alone, indicating that they are facultative parasites. The pupation success and sex ratio of small hive beetle offspring were also analyzed. Larvae fed pollen, honey-pollen, or brood had significantly higher pupation success rates of 0.64, 0.73, and 0.65 respectively than on the other diets. Sex ratios of emerging adults fed diets of pollen or brood as larvae were significantly skewed toward females. Because small hive beetle longevity and overall reproductive success was highest on foodstuffs located in honey bee colonies, A. tumida are efficient at causing large-scale damage to colonies of honey bees resulting in economic injury for the beekeeper. Practical considerations for the control of A. tumida are briefly discussed.

Three laboratory experiments were performed to assess parasitization of freeze-killed house fly puparia, buried 0 to 6 cm in media, by Muscidifurax raptor Girault & Saunders, Muscidifurax raptorellus Kogan & Legner, Muscidifurax zaraptor Kogan & Legner, Trichomalopsis sarcophagae (Gahan) and Urolepis rufipes (Ashmead) (Hymenoptera: Pteromalidae). Virtually no parasitization occurred at depths greater than 1 cm in large arenas (988 cm²) with densities of 0.3 puparia and 0.008 female parasitoids per cm². Parasitization was observed at depths as great as 4 cm for three of five species in small arenas (3 cm²) with densities of 6.4 puparia and 1.0 female per cm². Combined across experiments, M. raptor achieved the highest level of parasitization, followed by M. zaraptor, M. raptorellus, U. rufipes, and T. sarcophagae. The greatest number of F₁ females was produced by the gregarious species T. sarcophagae (834♀♀) and M. raptorellus (708♀♀), and then by the solitary species M. raptor (530♀♀), M. zaraptor (365♀♀) and U. rufipes (163♀♀). High parasitization by M. raptor and high production of offspring by T. sarcophagae identify these species as being particularly attractive as biological control agents.

Laboratory fecundity assessments are routinely used to determine the quality of commercially reared Trichogramma egg parasitoids before release for pest control, but there is little information on the relevance of this trait to the field success of Trichogramma. Herein, we characterize the parasitism success of strains of Trichogramma carverae Oatman & Pinto in the laboratory on a factitious (Sitotroga cerealella Olivier) and a natural (Epiphyas postvittana Walker) host. Differences in fecundity of the strains in the laboratory were consistent with a heritability of ≈10%, allowing ranking of the strains from highest to lowest fecundity. The strains with particularly high and low fecundities were tested for successful parasitism in the field. Results of the field releases show that strain differences in laboratory fecundity did not influence field performance. The implications of this result for fecundity as a quality indicator for commercial stocks are discussed.

The oriental beetle Exomala (Anomala) orientalis (Waterhouse) is an important pest of turfgrass in Korean golf courses, and although a few chemical insecticides are registered for insect pest control, they are not very effective against scarab larvae. There is also a growing concern in Korea about the run-off of insecticides into sensitive habitats and the potential for groundwater contamination. A safe and environmentally sound alternative is needed to conventional insecticides. We therefore evaluated six Korean entomopathogenic nematode isolates: S. carpocapsae Pocheon, S. glaseri Dongrae, S. glaseri Mungyeong, S. longicaudum Gongju, S. longicaudum Nonsan, and Heterorhabditis sp. Gyeongsan for their potential as bioinsecticides for control of E. orientalis. In addition, we evaluated a reduced chemical insecticide approach that combined chlorpyrifos-methyl with nematodes. In laboratory tests Heterorhabditis sp. Gyeongsan was the most efficacious, causing100% mortality of the second and 38% of the third instars. All other nematode isolates caused 50–80% mortality of the second and 15–30% of the third instars. E. orientalis pupae were highly susceptible to all the Korean entomopathogenic nematode isolates except S. carpocapsae. In artificially infested field plots, all Korean nematode isolates cause 50–70% mortality of the third instar. A combination of a one-half rate of Heterorhabditis sp. and a one-half rate chlorpyrifos-methyl was synergistic, causing 91% mortality compared with 69% for the full rate of Heterorhabditis sp. or 22% for the full rate of chlorpyrifos-methyl. In a second field trial, a natural infestation of preoverwintering third instar was treated. In this trial a one-half rate of S. longicaudum Nonsan plus a one-half rate of chlorpyrifos-methyl caused 96.8% mortality, much more than a full rate of S. longicaudum Nonsan (45.9% mortality) or a full rate of chlorpyrifos-methyl (28.7% mortality). The interactions of Heterorhabditis sp. and S. longicaudum Nonsan with chlorpyrifos-methyl in our field trials appear to be synergistic.

A yolk protein enzyme-linked immunosorbent assay (YP-ELISA) was developed for the predator Orius insidiosus (Say). The YP-ELISA is intended to assess reproductive response to dietary and other rearing conditions, and to assist in quality control and diet development for mass rearing. Hybridomas and monoclonal antibodies were produced against homogenates of eggs dissected from females. Hybridomas were selected for secretion of IgG that reacted with extracts of both females and their eggs, and that did not react with male extracts. Each cloned hybridoma produced a monoclonal antibody that specifically reacted on western blots against one of the two major yolk polypeptides, apoVn-I (180,000 molecular weight) or apoVn-II (40,000). Yolk protein ELISAs were developed with these antibodies to assess yolk protein content of female O. insidiosus as a measure of reproductive fitness and as a potential predictor of fecundity. Protocols for an indirect antigen ELISA and double antibody sandwich ELISA were developed to assess yolk protein contents of eggs and total contents in whole body homogenates. ELISA standards consisted of homogenates of eggs collected 0–24 h following oviposition. As determined with the sandwich ELISA, yolk protein contents of eggs declined with age before hatch, with a half-life of 32–34 h. Results were similar whether the detecting antibody-enzyme conjugate was anti-apoVn-I or anti-apoVn-II. Optimal conditions and sampling parameters were developed for the sandwich ELISA, which demonstrated minimal nonspecific interference in whole-insect extracts. In an initial application of the YP-ELISA, oviposition rates over a 10-d period were compared with yolk protein contents at the end of that period, dependent on diets of differing nutritional composition and quality. High and low yolk protein contents correlated with oviposition rates on respective diets, though oviposition showed more graded response to diets than did yolk protein. Improvements in sampling methods are discussed.

At Mediterranean fruit fly rearing centers, genetic sexing strains such as the male-only temperature sensitive lethal (tsl) strains, are replacing many of the older bisexual strains, such as Maui-93. Three tests were performed to compare the performance of the Vienna-4 (which carries tsl) and Maui-93 strains. Using standard laboratory quality control tests, the Maui-93 strain had higher percent fliers and a lower percentage deformed and partially eclosed flies. Analyses of data from field mark-recapture tests with Jackson traps failed to find significant differences in recapture numbers between the two strains. In field cage survivorship tests, the Vienna-4 strain showed significantly lower mortality in comparison to the Maui-93 strain. These results suggest that although the quality of Vienna-4 flies is lower than Maui-93 at the time of adult emergence, it is comparable with or better than Maui-93 several days later, because weaker flies have been eliminated from the cohort. The benefits of releasing only sterile males, instead of both males and females, was not factored into the quality assessment in this study, but would be an additional benefit in using a strain that carries a tsl mutation.

Previous research indicates a correlation between leaf area index (LAI) and yield of full-season soybean [Glycine max (L.) Merrill], which is a single crop planted early in the season. Leaf area index values of at least 3.5–4.0 in the reproductive stages are required for maximum potential yield. It is unknown how yields of double-crop soybean, which is planted late into harvested small grain fields, respond to changes in leaf area index. We hypothesized that double-crop soybean would be more sensitive to defoliation than full-season soybean. This study used linear and linear plateau models to describe the yield response of full-season and double-crop soybean to reductions in leaf area index through manual defoliation, and evaluated the yield response of double-crop soybean to reductions in leaf area index through natural insect defoliation. From 15 manual defoliation experiments over 3 yr, significant linear decreases in yield occurred in both full-season and double-crop soybean when leaf area index values were below 3.5–4.0 by developmental stages R4 to R5, whereas yields usually reached a plateau at higher leaf area index levels. Average yield loss was 769 ± 319 kg ha⁻¹ for each unit decrease in leaf area index below the plateau; average maximum yield was 3,484 ± 735 kg ha⁻¹. From eight field experiments over 2 yr, insect defoliators had no effect on double-crop soybean yield; leaf area index levels were above 4.0 by the developmental stage when leaf area index estimates were taken (R3 to R6). Therefore, double-crop soybean that maintains leaf area index values above the 3.5–4.0 critical level by mid-reproductive developmental stages can tolerate defoliating pests.

To quantify the damage caused by twospotted spider mite, Tetranychus urticae Koch, feeding on cucumber, Cucumis sativus L., leaf-cell and -tissue damage was assessed. On the abaxial leaf surface, adult T. urticae could feed through the spongy parenchyma and part of the palisade parenchyma of the leaf, while immature T. urticae could feed only through the sponge parenchyma. T. urticae punctured individual epidermal cells and consumed the contents of the mesophyll cells. Injured leaves had more empty space in the spongy parenchyma and fewer chloroplasts per cell. Damage also occurred even in the adjacent uninjured parenchyma cells without additional T. urticae feeding injury. Net photosynthetic rate, total chlorophyll content, and greenness of the leaf were significantly affected by feeding as quantified by mite-days. The percent loss of these parameters increased linearly or nonlinearly as mite-days increased, regardless of mite developmental stages. At 1,000 mite-days per 6 cm², net photosynthetic rate was reduced by ≈50 and 95%, total chlorophyll content was reduced by ≈55 and 80%, and greenness was reduced by ≈50 and 80% by feeding by immature and adult T. urticae, respectively.

Economic control of Rhagoletis mendax was achieved by applying insecticidal sprays to commercial lowbush blueberry vegetative fields, in a biennial production system, rather than to the fruiting fields, when the threshold was exceeded. The viability of this integrated pest management of R. mendax for lowbush blueberries was demonstrated over a 9-yr interval in New Brunswick where three sites were monitored for 2 yr, eight sites for 4 yr, and one site for 9 yr. Control of R. mendax in lowbush blueberry fields was achieved in 2 yr when the fields were isolated, and in 3 yr when there were adjacent lowbush blueberry fields.

Seasonal population trends and damage to citrus trees by the leafminer Phyllocnistis citrella Stainton were studied in the Valencia area of eastern Spain from 1996 to 1999. The area-wide seasonal flushing pattern of citrus trees and leafminer population trends were determined in 10 mature citrus orchards. In the 10 orchards, the annual percentage of new shoots that developed in the spring ranged from 51 to 96% for individual orchards (mean of 80%). Phyllocnistis citrella populations damaged new leaves from July to November. During this period, ≈45% of the new leaf area was lost due to leafminer mining. In addition, at three mature citrus orchards, two ‘Navelina’ sweet oranges from 1996 to 1999 and one ‘Clementine’ mandarin (variety ‘Clemenules’) in 1998 and 1999, the leaf area damage, spring flushing pattern, and crop yield were determined in trees sprayed one to three times a year with abamectin (Epimeck, 0.02%) to control P. citrella and compared with nonsprayed control trees. In these three orchards, damaged leaf area in summer–fall flushes was on average 52% in nonsprayed and 8% in sprayed trees. No significant differences were found between sprayed and nonsprayed trees in the spring flushing and flowering pattern, number of fruits or fruit diameter. In Mediterranean areas, P. citrella damaged only 5–15% of the annual new leaf area of mature trees and yield was usually not affected by the pest.

A dimensionally stable sensor composed of a closed-cell polyethylene sheet on which a silver particle circuit was painted and sandwiched between two spruce stakes was tested for use in a monitoring program to detect subterranean termites. Sensors were connected to a datalogger for continuous monitoring of sensor circuit breakages over 12 mo, and were manually inspected monthly to assess sensor performance. The mean monthly sensor accuracy for three field test sites was 98.7%, with most false responses caused by early timing of the monthly inspection when termites entered the station before damaging the sensor circuits. Mean sensor longevity (the time for a sensor circuit to break in the absence of termites) of the dimensionally stable sensors was 11.7 mo; a substantial improvement over the 4.4-mo longevity recorded previously for wooden sensors.

A portable, low-frequency acoustic system was used to detect termite infestations in urban trees. The likelihood of infestation was rated independently by a computer program and an experienced listener that distinguished insect sounds from background noises. Because soil is a good insulator, termite sounds could be detected easily underneath infested trees, despite the presence of high urban background noise. Termite sounds could be detected also in trunks, but background noise often made it difficult to identify termite signals unambiguously. High likelihoods of termite infestation were predicted at four live oak (Quercus virginiana Mill, Fagacae), two loblolly pine (Pinus taeda L., Pinacae), and two baldcypress (Taxodium distichum Rich. Pinacae) trees that wood-baited traps had identified as infested with Coptotermes formosanus Shiraki. Infestations also were predicted at two pine trees with confirmed recoveries of Reticulitermes flavipes (Kollar). Low likelihoods of infestation were predicted in four oak trees where no termites were found. Additional tests were conducted in anechoic environments to determine the range of acoustic detectability and the feasibility of acoustically estimating termite population levels. There was a significant regression between the activity rate and the number of termites present in a wood trap block, with a minimum detectable number of ≈50 workers per liter of wood. The success of these field tests suggests that currently available acoustic systems have considerable potential to detect and monitor hidden infestations of termites in urban trees and around building perimeters in addition to their present uses to detect and monitor termite infestations in buildings.

Seven selected insecticides were applied to three substrates and bioassayed for barrier efficacy and toxicity against the Formosan subterranean termite, Coptotermes formosanus Shiraki, originating from colonies that differed in their tolerance to the insecticides. A profound substrate effect was seen with all insecticides tested. Sand was the most difficult substrate to penetrate and caused faster and greater mortality of C. formosanus. Increased tolerance in C. formosanus was accompanied by a decrease in penetration of treated substrata with chlordane, methoxychlor, chlorpyrifos, and deltamethrin. The opposite was true in the case of permethrin and bendiocarb. More tolerance C. formosanus displayed decreased mortality in the presence of chlorpyrifos, deltamethrin, bendiocarb, and fipronil. The opposite was true for permethrin.

A strain of Mexican Boophilus microplus (Cz) collected near Coatzacoalcos, Veracruz, Mexico, exhibits a moderate, but significant, level of permethrin resistance. Unlike other highly permethrin resistant strains, the Cz strain does not have a mutation within the sodium channel gene that results in target-site insensitivity. However, the Cz strain possesses a substantial increase in general and permethrin esterase activity relative to highly permethrin resistant and control strains suggesting the involvement of a metabolic esterase(s) in the expression of permethrin resistance. We report the isolation of a 62.8 kDa protein from Cz strain larvae that we think is the esterase previously reported as Cz EST9. In addition, internal amino acid sequence data obtained from the 62.8 kDa protein suggest that it is the gene product of a previously reported B. microplus carboxylesterase cDNA. We propose that the 62.8 kDa protein (Cz EST9) has permethrin hydrolytic activity and as a result plays an important role in Cz strain resistance to permethrin.

Genetic models have been used to examine the evolution of insecticide resistance in pest species subject to data and assumptions regarding genetic, biological, and operational parameters. We used time-series data on pyrethroid tolerance and simple genetic models to estimate underlying genetic and biological parameters associated with resistance evolution in tobacco budworm, Heliothis virescens (F.), and bollworm, Helicoverpa zea (Boddie), Louisiana field populations. Assuming pyrethroid resistance is conferred by one gene at one locus in both species, inheritance of pyrethroid resistance was partially dominant in the tobacco budworm and partially recessive in the bollworm. Relative fitness estimates indicated that fitness costs associated with resistance selected against resistance alleles in the absence of selection pressure in the tobacco budworm, but not in the bollworm. In addition, relative fitness estimates obtained using the indirect method outlined in this study were similar in magnitude to estimates obtained using traditional direct approaches.

Laboratory selection with Cry1Ac, the Bacillus thuringiensis (Bt) toxin in transgenic cotton, initially produced 300-fold resistance in a field-derived strain of pink bollworm, Pectinophora gossypiella (Saunders), a major cotton pest. After additional selection increased resistance to 3,100-fold, we tested the offspring of various crosses to determine the mode of inheritance of resistance to Cry1Ac. The progeny of reciprocal F₁ crosses (resistant male × susceptible female and vice versa) responded alike in bioassays, indicating autosomal inheritance. Consistent with earlier findings, resistance was recessive at a high concentration of Cry1Ac. However, the dominance of resistance increased as the concentration of Cry1Ac decreased. Analysis of survival and growth of progeny from backcrosses (F₁ × resistant strain) suggest that resistance was controlled primarily by one or a few major loci. The progression of resistance from 300- to 3,100-fold rules out the simplest model with one locus and two alleles. Overall the patterns observed can be explained by either a single resistance gene with three or more alleles or by more than one resistance gene. The pink bollworm resistance to Cry1Ac described here fits “mode 1” resistance, the most common type of resistance to Cry1A toxins in Lepidoptera.

We collected grape berry moth, Endopiza viteana (Clemens) (from cultivated and wild Vitis along Lake Erie in Pennsylvania and New York), and measured carbaryl susceptibility in first instars. A model of susceptibility was based on the concentration-mortality curve of laboratory-maintained colonies originating from wild Vitis with no prior history of carbaryl exposure, and a noncommercial vineyard with modest previous exposure to carbaryl. We estimated LC₅₀ and LC₉₀ for susceptible grape berry moth larvae at 45.4 and 2319 μg/ml, respectively. Bioassays on field-collected larvae from commercial vineyards in both states, where grape growers were abiding by current pest management guidelines for carbaryl use, revealed carbaryl resistance ratios from 7 to 71 at the LC₅₀ level. With the loss or restriction of alternative chemical control tactics in the Food Quality Protection Act era, resistance management programs for grape berry moth should be immediately developed and implemented to regain the efficacy of this once effective insecticide and other related chemical compounds.

We simulated the population dynamics and population genetics of two bivoltine species of corn borers, the European corn borer, Ostrinia nubilalis (Hübner), and the southwestern corn borer, Diatraea grandiosella Dyar, in a hypothetical region of irrigated transgenic and nontransgenic corn where insecticide was applied only to the nontransgenic refuge crop. Over the 100-yr time horizon, resistance developed quickly in both species and to both transgenic corn and the insecticide when the allele for resistance to the respective toxin was dominant. When the allele for transgenic resistance was not dominant and the refuge location was constant over the time horizon, spraying the refuge to control southwestern corn borer had no effect on how quickly resistance to the transgenic corn developed. In contrast, the European corn borer developed resistance to transgenic corn much sooner when the refuge was sprayed once per year, and the time to 3% resistance allele frequency decreased as efficacy of the insecticide increased. Only when the refuge was treated less than once every 5 yr (10 generations) did the frequency of application decline enough to permit resistance management for the European corn borer to approximate the effectiveness of an unsprayed refuge. A consistently sprayed refuge <40% of the corn acreage was an inadequate resistance management strategy for the European corn borer even when a low efficacy insecticide (70% mortality) was used. When assumptions about European corn borer adult behavior were changed and the adults behaved similarly to adult southwestern corn borer, the development of resistance to the transgenic crop was slowed significantly.

Thirteen inbred lines of maize (Zea mays L.) with different levels of stem resistance to the stem borer Sesamia nonagrioides Lefevbre were evaluated in the field and the laboratory to determine the antibiotic resistance to this pest. Inbreds CM151, CO125, and EP39 had antibiotic pith as well as stem resistance, so the pith could play a role in stem resistance. Inbreds A509, F473, and PB130 did not have antibiotic pith but had stem resistance; therefore, other mechanisms could confer stem resistance. Finally, the inbred MS1334 had antibiotic pith and did not show stem resistance; thus, other factors could compensate the effect of the pith. Therefore, although pith antibiotic compound seems to play a role in the defense against S. nonagrioides attack, it is not the only possible mechanism of defense.

Aflatoxin, a potent carcinogen, is produced by the fungus Aspergillus flavus Link: Fr. Drought, high temperatures, and insect damage contribute to increased levels of aflatoxin contamination in corn, Zea mays L. Plant resistance is widely considered a desirable method of reducing aflatoxin contamination. Germplasm lines with aflatoxin resistance have been developed. This investigation was undertaken to determine whether crosses among these lines exhibited resistance to southwestern corn borer, Diatraea grandiosella Dyar, and to assess the effects of southwestern corn borer feeding on aflatoxin accumulation. Differences in ear damage among southwestern corn borer infested hybrids were significant. Estimates of general combining ability effects indicated that the lines Mp80:04, Mp420, and Mp488 contributed to reduced ear damage, and SC213 and T165 contributed to greater damage when used in hybrids. Mean aflatoxin levels were 254 ng/g for hybrids infested with southwestern corn borer larvae and 164 ng/g for noninfested hybrids in 2000 when environmental conditions were conducive to aflatoxin production. In contrast, the overall mean aflatoxin level for southwestern corn borer infested hybrids was only 5 ng/g in 1999 when environmental conditions did not favor aflatoxin accumulation. Crosses that included lines selected for aflatoxin resistance as parents (Mp80:04 and Mp313E) exhibited lower levels of aflatoxin contamination both with and without southwestern corn borer infestation in 2000. Only the experimental line Mp80:04 contributed significantly to both reduced southwestern corn borer damage and reduced aflatoxin contamination.

Blissus occiduus Barber has emerged as an important insect pest of buffalograss, Buchloë dactyloides (Nuttall) Engelmann, in Nebraska. This research evaluated selected buffalograss germplasm for resistance to B. occiduus. Eleven buffalograss selections were screened for chinch bug resistance in three greenhouse studies and two field evaluations. Based on chinch bug damage, NE91–118, ‘Tatanka’, ‘Bonnie Brae’, and ‘Cody’ were rated highly to moderately resistant. These four buffalograsses exhibited minimal damage, even though all were heavily infested with chinch bugs. NE84-45-3 and ‘378’ were highly susceptible to B. occiduus. Field evaluations confirmed chinch bug resistance ratings under field conditions. NE91–118 displayed high levels of resistance in the field screening evaluations, whereas Cody and Tatanka showed moderate levels of resistance, and 378 was highly susceptible.

Host plant resistance to the Diaprepes root weevil, Diaprepes abbreviatus (L.) was assessed for seedlings of 54 Poncirus trifoliata (L.) Raf. selections and two families of progeny from crosses between Citrus and P. trifoliata. Weight gain was consistently lower when larvae were reared in pots containing the progeny of Citrus reticulata Blanco ‘Sunki’ x P. trifoliata ‘Flying Dragon’ compared with larvae reared on progeny of ‘Pearl’ (C. reticulata x C. paradisi Macf.) x ‘Flying Dragon’. This is the first evidence of genetic control of resistance to the Diaprepes root weevil within sexually compatible citrus rootstock germplasm. There was a significant positive correlation between percentage root loss and larval weight gain within the resistant progeny, indicating a possible antixenotic effect. Two varieties of P. trifoliata were identified as more resistant than ‘Flying Dragon’ based on larval weight gain.

Resistance in beans, Phaseolus vulgaris L., to the melon thrips Thrips palmi Karny was studied under field conditions at two sites in Colombia. Genotypes were rated for resistance on the basis of visual damage scores, bean production ratings (a visual estimate of pod and seed set), and grain yields. Of 1,138 genotypes tested, only 60 (5.3%) were rated as resistant. Repeated testing allowed us to identify potential sources of resistance in five germplasm accessions (G 02402, G 02852, G 03177, G 03569, and G 04055), one commercial variety (‘Brunca’), six elite breeding lines (A 216, DOR 714, EMP 486, FEB 115, FEB 161, and FEB 162), 41 recombinant inbred lines derived from the BAT 881 × G 21212 cross, and seven recombinant inbred lines derived from a cross between DOR 364 and BAT 477. Resistance was not associated with maturity, growth habit, pubescence, and seed color or seed size. In general, correlations between visual damage scores and bean production ratings and between damage scores and yield were high and significant meaning that selection on damage rating is useful to identify genotypes that may have tolerance as a mechanism of resistance. The continuous distribution of damage scores of 139 recombinant inbred lines suggested that the inheritance of resistance to the melon thrips might be quantitative. Overall, resistance levels in beans can be considered as moderate, because none of the genotypes tested received damage scores of <3 on a 1–9 scale and none was ever rated as highly resistant in terms of bean production ratings.

High carbon dioxide atmospheres combined with high temperature were effective for controlling Indian meal moth, Plodia interpunctella (Hübner) pupae. Pupae were exposed to atmospheres of 60, 80, or 98% carbon dioxide (CO₂) in nitrogen (N₂), or 60 or 80% CO₂ in air at temperatures of 26.7°C or 32.2°C and 60% RH. Controlled atmosphere treatments at 32.2°C controlled pupae faster than the same treatments at the lower temperature. At both temperatures high CO₂ concentration treatments combined with nitrogen killed pupae faster than high CO₂ concentration treatments combined with air. Exposure to 80% carbon dioxide mixed with nitrogen was the most effective treatment causing 100% mortality in 12 h at 32.2°C and 93.3% mortality in 18 h at 26.6°C. High-temperature controlled atmosphere treatments had no adverse effects on quality of two preserved floral products, Limonium sinuatum (L.) and Gypsophila elegans (Bieb.), tested for 12, 18, and 24 h according to industry standards.

Farmers in the Republic of Benin have few resources to invest in protection of stored maize, and prophylactic pesticide application is often recommended by extension and development agencies. Neither the efficacy nor profitability of such an application in traditional maize storage facilities has been addressed quantitatively. In this study, existing management options for stored maize were evaluated monthly over 6 mo in central and southern Benin with respect to their effects on grain injury and on densities of Prostephanus truncatus (Horn) and Sitophilus zeamais Motschulsky. P. truncatus infested 54% of the experimental stores in the study even though Teretrius nigrescens (Lewis), a natural enemy introduced against P. truncatus, was well established in the region. S. zeamais was the most common pest, found in 85% of the experimental storage facilities. Prophylactically treated maize was, on average, worth more than untreated maize for month 1 through 5 in southern Benin, after taking into account market price, pesticide costs, percentage grain damage and weight loss, but maize storage was not profitable overall. No difference was observed between treatments in central Benin. After 6 mo treated storage facilities were not significantly different from untreated storage facilities in terms of either percentage damage or profit in either region. A rapid scouting plan intended to provide farmers with a means for identifying storage facilities at greatest risk of severe P. truncatus infestation was field validated. Given that unsafe pesticide use is prevalent in Benin, research and extension services should clearly state the limitations to prophylactic treatment and increase the effort to educate farmers on appropriate pesticide use, store monitoring and marketing.

Distribution and movement patterns of several species of stored-product pests in a food processing plant were investigated. The objectives of this study were to determine the temporal and spatial variation in abundance of stored-product pests using pheromone traps; assess the effectiveness of trap type, location, and number on monitoring insect populations; and to evaluate the nature of pheromone trap capture hot spots by measuring patterns of insect movement. We determined that the distributions of Trogoderma variabile Ballion, Lasioderma serricorne (F.), Tribolium castaneum (Herbst), and Plodia interpunctella (Hübner) within the facility were typically clumped and that foci of high trap captures, based on visual observation of contour maps, varied among species and over time. Trap type and location influenced the number of T. variabile captured: traps on the floor and along walls captured more individuals than hanging traps and traps next to support pillars. T. variabile was the predominant insect pest at this facility and from mark-recapture studies, we found that individual beetles moved across multiple floors in the facility and from 7 to 216 m though the warehouse.

Degradation and insecticidal effectiveness of spinosad residues were evaluated in Kansas during November 2000 to November 2001 in farm bins holding wheat (34-metric ton capacity). About 50 kg of hard red winter wheat from each of three bins were brought to the laboratory and treated separately with 1-ml aqueous suspensions of spinosad to provide rates of 0.1, 0.5, 1, 3, 6 mg (AI)/kg of wheat. Wheat treated with distilled water served as the control treatment. Untreated and spinosad-treated wheat samples (250 g each) were placed in three plastic pouches of two different mesh sizes, and buried 2.5 cm below the grain surface. Pouches with large mesh openings were used to monitor insect infestations and kernel damage in untreated and spinosad-treated samples. Pouches with small mesh were used for extracting spinosad residues and for conducting laboratory bioassays with adults of the lesser grain borer, Rhyzopertha dominica (F.) and red flour beetle, Tribolium castaneum (Herbst) at 28°C and 65% RH. Wheat temperature and relative humidity near the pouches during the 1 yr of storage ranged from −10 to 32°C and 50 to 70%, respectively. Moisture of wheat samples varied from 12.4 to 13%. Observed spinosad residues on wheat samples were 25% less than the calculated rates of 0.1 to 6 mg/kg. However, these residues were stable during the 1 yr of storage, and killed all R. dominica adults exposed for 14 d in the laboratory. Mortality of T. castaneum adults increased with an increase in spinosad rate. The linear regression slope of LD₅₀s (0.3–2.7 mg/kg) against storage time was not significantly different from zero, indicating no loss in spinosad toxicity to T. castaneum adults. Insect species, insect numbers, and kernel damage over time in wheat samples inside pouches with large mesh openings were highly inconsistent, and failed to accurately characterize spinosad performance. Laboratory bioassays with R. dominica and T. castaneum adults using grain from pouches with small mesh openings accurately gauged spinosad persistence and insecticidal activity under the field conditions.

Freeze-dried, granular sugar baits containing boric acid as the toxicant were evaluated against house flies, Musca domestica L., in two bioassays with toxicant dose ranges of 3, 5, 7, 8, and 12%, and 3, 5, 9, 17, and 33% boric acid, respectively, calculated and expressed on a dry weight basis. Flies in bioassay 1 were mixed sex and unstarved and flies in bioassay 2 were females only and starved 4 h before testing began. LC₅₀s were 8.97 and 14.33%, and LT₅₀s were 59.75 and 53.34 h in bioassays 1 and 2, respectively. Baits were tested at concentrations as high as 33%, however there was no indication of repellency as seen previously with liquid baits. Reasons for lack of repellency and potential uses for baits are discussed. Development of efficacious granular baits would allow the presentation of higher levels of boric acid in volumes much smaller than required for liquid baits.

An electric walk-through fly trap was evaluated for the management of the horn fly, Hematobia irritans (L.), on dairy cattle in North Carolina over 2 yr. The trap relies on black lights and electrocution grids to attract and kill flies that are brushed from the cattle passing through. During the first season, horn fly densities were reduced from >1,400 to <200 flies per animal. Horn fly density averaged 269.2 ± 25.8 on cattle using the walk-through fly trap twice daily, and 400.2 ± 43.5 on the control group during the first year. The second year, seasonal mean horn fly density was 177.3 ± 10.8 on cattle using the walk-through fly trap compared with 321.1 ± 15.8 on the control group. No insecticides were used to control horn flies during this 2-yr study.