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The fall armyworm, Spodoptera frugiperda (Smith), is an invasive pest of cereal crops that now inhabits southern China year-round. Cultivation of crops unsuitable as host plants has been an effective pest management strategy for some insect pests, but the effects of green manure crops on S. frugiperda have not been investigated. An age-stage two-sex life table and tethered flight performance of S. frugiperda reared on different green manure species were obtained, and a population dynamics model established. Developmental durations of stages, survival rates, and fecundities of S. frugiperda differed significantly depending on host plant. Larvae fed Astragalus sinicus L. did not complete development. Although some larvae fed Vicia villosa Roth and Vicia sativa L. completed development, generation time was significantly prolonged, egg production was halved, and net reproductive rate decreased to 31% and 3% of those reared on corn, respectively. Survival rates of early-instars fed V. villosa and V. sativa were significantly lower than those fed corn. Population dynamics projections over 90 d showed the number of generations of S. frugiperda fed on V. villosa and V. sativa was reduced compared to those reared on corn. Flight performance of S. frugiperda reared on V. villosa decreased significantly compared to corn. Our results show that the three green manure species are unsuitable host plants for S. frugiperda. Therefore, reduction of corn production in southern China through rotation with these green manure crops may be a feasible method of ecological management of this major corn pest in China.

The Mythimna (=Leucania) loreyi (Duponchel) has recently emerged as a major pest of grain crops in China. Little is known about its basic biology and ecology, making it difficult to predict its population dynamics. An age-stage, two-sex life table was constructed for this insect when reared on maize in the laboratory at five constant temperatures (18, 21, 24, 27, and 30 °C). Both the intrinsic rate of increase (r) and finite rate increase (λ) increased as temperature significantly increased and mean generation time (T) decreased significantly with increasing temperature. The highest values for net reproductive rate (R0) and fecundity were observed at 24 °C. However, M. loreyi was able to develop, survive, and lay eggs at all temperatures tested (18-30 °C). Development rates at different temperatures for the egg, larval, pupal, as well as for a total preoviposition period, fit a linear equation. The lower threshold temperatures of egg, larval, pupal, preoviposition, and total preoviposition period were 8.83, 10.95, 11.67, 9.30, and 9.65 °C, respectively. And their effective accumulated temperatures were 87.64, 298.51, 208.33, 66.47, and 729.93 degree-days, respectively. This study provides insight into the temperature-based phenology and population ecology in M. loreyi. The results will benefit population dynamics monitoring, prediction, and management of this insect pest in the field.

To understand the role that temperature and humidity play in the population dynamics of the beet webworm, Loxostege sticticalis L. (Lepidoptera: Crambidae), egg hatch, survival of first-fifth instars, survival of the full larval stage, survival curves, and larval development rates were investigated at combinations of four temperatures (18, 22, 26, and 30°C) and five relative humidities (RH; 20%, 40%, 60%, 80%, and 100%). We found that greatest egg hatch rate, survival rates of the first and second instars, and survival rate of the complete larval stage occurred at 22°C and 60-80% RH; the lowest values for these parameters were observed at 30°C and 20% RH. Survival of first instars was significantly affected by the interaction of temperature and relative humidity. However, survival of third and fourth instars was neither affected by temperature nor relative humidity, and that of fifth instars was significantly affected only by relative humidity level. The survival curve for larvae was well described by a type III Weibull distribution. Duration of larval stage decreased as temperature increased, but was not affected by relative humidity. We therefore conclude that eggs and early instars are the most critical stages for survival to the pupal stage, and 22-26°C and 60-80% RH are the optimum conditions for their survival and development. These findings confirm that temperature and relative humidity are the critical environmental factors affecting the population growth of L. sticticalis, with temperature being more important.

The western bean cutworm, Striacosta albicosta (Smith) (Lepidoptera: Noctuidae), is a destructive insect pest of dry beans and corn within its native range of western Nebraska and eastern Colorado. However, since the initiation of an eastward range expansion ofS. albicosta in the late 1990s, economic damage has been observed in the Midwest, and the species has now reached the Atlantic Coast and Quebec. Economic damage to corn occurs by larval feeding on ears, which is not controlled by commercial transgenic hybrids that express Bacillus thuringiensis (Bt) Cry1Ab, but partial control is observed by corn varieties that express Cry1 F toxins. Inadequate protocols for laboratory rearing ofS.albicosta have hindered controlled efÞcacy experimentation in the laboratory and Þeld. We report anS.albicosta rearing methodology used to maintain a laboratory colony for 12 continuous generations. Rearing procedures were adapted for Bt toxin diet-overlay assays, revealing that S. albicosta larvae exposed to Bt toxin for 14 d were insensitive to Cry1Ab concentrations up to 25,000 ng/cm 2 . In contrast, neonates exposed to Cry1 F toxin at 250 ng/cm 2 , showed reduced developmental rates, with estimated effective concentrations of EC50 1,187.5 ng/cm 2 and EC95 10,000.5 ng/cm 2 . The ability to mass produce this pest insect will enhance fundamental research, including evaluation of control tactics and toxin susceptibility.

Transgenic Bt maize that produces less than a high-dose has been widely adopted and presents considerable insect resistance management (IRM) challenges. Western corn rootworm, Diabrotica virgifera virgifera LeConte, has rapidly evolved resistance to Bt maize in the field, leading to local loss of efficacy for some corn rootworm Bt maize events. Documenting and responding to this resistance has been complicated by a lack of rapid diagnostic bioassays and by regulatory triggers that hinder timely and effective management responses. These failures are of great concern to the scientific and agricultural community. Specific challenges posed by western corn rootworm resistance to Bt maize, and more general concerns around Bt crops that produce less than a high-dose of Bt toxin, have caused uncertainty around current IRM protocols. More than 15 years of experience with IRM has shown that high-dose and refuge-based IRM is not applicable to Bt crops that produce less than a high-dose. Adaptive IRM approaches and pro-active, integrated IRM-pest management strategies are needed and should be in place before release of new technologies that produce less than a high-dose. We suggest changes in IRM strategies to preserve the utility of corn rootworm Bt maize by 1) targeting local resistance management earlier in the sequence of responses to resistance and 2) developing area-wide criteria to address widespread economic losses. We also favor consideration of policies and programs to counteract economic forces that are contributing to rapid resistance evolution.

The western bean cutworm, Striacosta albicosta (Smith) (Lepidoptera: Noctuidae), is a destructive insect pest of dry beans and corn within its native range of western Nebraska and eastern Colorado. However, since the initiation of an eastward range expansion of S. albicosta in the late 1990s, economic damage has been observed in the Midwest, and the species has now reached the Atlantic Coast and Quebec. Economic damage to corn occurs by larval feeding on ears, which is not controlled by commercial transgenic hybrids that express Bacillus thuringiensis (Bt) Cry1Ab, but partial control is observed by corn varieties that express Cry1 F toxins. Inadequate protocols for laboratory rearing of S. albicosta have hindered controlled efficacy experimentation in the laboratory and field. We report an S. albicosta rearing methodology used to maintain a laboratory colony for 12 continuous generations. Rearing procedures were adapted for Bt toxin diet-overlay assays, revealing that S. albicosta larvae exposed to Bt toxin for 14 d were insensitive to Cry1Ab concentrations up to 25,000 ng/cm2. In contrast, neonates exposed to Cry1 F toxin at ≥250 ng/cm2, showed reduced developmental rates, with estimated effective concentrations of EC50 = 1,187.5 ng/cm2 and EC95 = 10,000.5 ng/cm2. The ability to mass produce this pest insect will enhance fundamental research, including evaluation of control tactics and toxin susceptibility.

The boll weevil, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), is a serious pest of cultivated cotton, Gossypium hirsutum L., in the Americas, and reinfestation of zones from which they have been eradicated is of perpetual concern. Extensive arrays of pheromone traps monitor for reintroductions, but occasionally the traps collect nontarget weevils that can be misidentified by scouts. For example, the congeneric pepper weevil, Anthonomus eugenii Cano, and other superficially similar weevils are attracted to components of the boll weevil lure or trap color. Although morphologically distinguishable by trained personnel, the potential for misidentification is compounded when captured weevils are dismembered or partially consumed by ants or ground beetles that sometimes feed on them in the traps. Because misidentification can have expensive consequences, a molecular diagnostic tool would be of great value to eradication managers. We demonstrate that a cocktail of three primer pairs in a single polymerase chain reaction (PCR) amplify species-specific microsatellites that unambiguously distinguish the boll weevil from three other weevil species tested, including pepper weevil; cranberry weevil, Anthonomus eugenii musculus Say; and pecan weevil, Curculio caryae Horn. However, it does not distinguish the boll weevil from the subspecific "thurberia" weevil. A universal internal transcribed spacer primer pair included in the cocktail cross-amplifies DNA from all species, serving as a positive control. Furthermore, the diagnostic primers amplified the target microsatellites from various boll weevil adult body parts, indicating that the PCR technology using the primer cocktail is sensitive enough to positively identify a boll weevil even when the body is partly degraded.

Thirty-seven boll weevils, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), were captured in pheromone traps near Lubbock, TX, in the Southern High Plains/Caprock eradication zone during August–October 2006. No boll weevils had been captured in this zone or neighboring zones to the north earlier in the year, and only very low numbers had been captured in neighboring zones to the south and east. Therefore, the captures near Lubbock were unexpected. Five of the weevils captured the last week of August were preserved and genotyped at 10 microsatellite loci for comparison with a database of genotypes for 22 boll weevil populations sampled from eight U.S. states and four locations in Mexico. The Lubbock population itself is an unlikely source, suggesting that the captured weevils probably did not originate from a low-level endemic population. Populations from eastern states, Mexico, and Big Spring, TX, can be confidently excluded as potential source regions. Although the Weslaco and Kingsville, TX, areas cannot be statistically excluded, they are unlikely sources. The most likely sources are nearby areas in New Mexico, TX, or southwest Oklahoma, or from areas of eastern Texas represented by Waxahachie and El Campo populations. Together, genetic and circumstantial evidence suggest either that the trapped boll weevils are the offspring of a lone mated female that immigrated from eastern Texas earlier in the summer or that weevils originally captured near Waxahachie but now long-dead were planted in the traps by a disgruntled employee of the eradication program.

Eleven spectral vegetation indices that emphasize foliar plant pigments were calculated using airborne hyperspectral imagery and evaluated in 2004 and 2005 for their ability to detect experimental plots of corn manually inoculated with Ostrinia nubilalis (Hübner) neonate larvae. Manual inoculations were timed to simulate infestation of corn, Zea mays L., by first and second flights of adult O. nubilalis. The ability of spectral vegetation indices to detect O. nubilalis-inoculated plots improved as the growing season progressed, with multiple spectral vegetation indices able to identify infested plots in late August and early September. Our findings also indicate that for detecting O. nubilalis-related plant stress in corn, spectral vegetation indices targeting carotenoid and anthocyanin pigments are not as effective as those targeting chlorophyll. Analysis of image data suggests that feeding and stem boring by O. nubilalis larvae may increase the rate of plant senescence causing detectable differences in plant biomass and vigor when compared with control plots. Further, we identified an approximate time frame of 5-6 wk postinoculation, when spectral differences of manually inoculated "second" generation O. nubilalis plots seem to peak.

The European corn borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae), is often controlled with genetically modified corn, Zea mays L., hybrids (Bacillus thuringiensis [Bt] corn) in the United States. If Bt-resistant insects are detected in the field, mitigation-remediation tactics must be implemented to sustain the efficacy of insecticidal, transgenic corn. Mass releasing laboratory-reared, susceptible adults near aggregation sites to mate with locally emerging resistant adults is a possible remediation tactic, but it is imperative that the former remain in or near the release site long enough to mate. Understanding adult dispersal behavior relative to the timing of mating is important, because it directly affects patterns of gene flow and the rate at which Bt resistance moves through a population. Previous work shows that newly eclosed adults do not remain in proximity to their natal field. However, moth age, reproductive development, or mating status may influence the propensity to disperse. The objectives of this study were to determine the effect of adult age (0-3, 4-6, and 7-10 d old) and mating status on dispersal of adults released in small-grain aggregation plots. Less than 1% of the marked adults released in the aggregation plots remained after one night. More males than females were recovered. Age influenced dispersal, with mostly 4-6-d old adults being recovered. Conversely, mating status did not affect the number of adults recovered. Given the paucity of marked adult moths recovered near their release sites, mass releases of adults may not be a viable tactic to combat the spread of resistance to Bt corn.

Pheromone-baited traps are often used in ecological studies of the European corn borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae). However, differences in trap captures may be confounded by trap design, trap location relative to a windbreak, and changes in local weather. The objectives of this experiment were, first, to examine differences in 0. nubilalis adult (moth) captures among the Intercept wing trap, the Intercept bucket/funnel UNI trap, and the Hartstack wire-mesh, 75-cm-diameter cone trap (large metal cone trap) as well as among three cone trap designs. Second, we examined the influence of the location of the large metal cone trap relative to a windbreak on the number of moths captured. Third, we examined the relationship between nightly mean air temperature, relative humidity, wind speed, precipitation, and the number of moths captured in large metal cone traps. The number of moths captured was significantly influenced by trap design, with large metal cone traps capturing the most moths. Wing and bucket traps were ineffective. Differences among trap captures were significant among trap locations relative to a windbreak. Under strong (14 kph) or moderate (714 kph) wind speeds, traps located leeward of the windbreak captured the most moths, but when wind speeds were light (7 kph), traps not associated with windbreaks captured the most moths. The multiple regression model fitted to the relationship between number of moths captured per Julian date and nightly weather patterns was significant. Nightly mean air temperature was the most influential parameter in the model, and its relationship with moth capture was positive.

Genetically modified, insecticidal Bacillus thuringiensis (Bt) corn, Zea mays L., hybrids are used throughout the Corn Belt for European corn borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae), control. To slow development of Bt corn resistance, the Environmental Protection Agency requires growers to plant a refuge. Determining the appropriate distance between a refuge and Bt corn, and development of mitigation-remediation strategies such as mass releases of susceptible moths, requires an understanding of adult dispersal and mating behavior. However, much remains unknown about these behaviors. Because mating often occurs in grass near cornfields where adult O. nubilalis aggregate, we planted small-grain plots as aggregation sites in an attempt to retain mass-released adults. The objectives of this study were to examine influences of pheromone lure, plant density, and plant species on distributions of feral and newly emerged, laboratory-reared O. nubilalis among small-grain aggregation plots. Feral adults were collected in aggregation plots in relative abundance, indicating that small-grain plots were acceptable aggregation sites. In contrast, newly emerged adults that were released weekly as dye-marked pupae were rarely found in aggregation plots, with approximately 150-1,500-fold fewer adults captured than expected if all released adults had occupied the plots foror = 1 d. The majority of newly emerged adults did not colonize the aggregation plots, suggesting that recently eclosed adults leave their natal field and do not colonize the first aggregation sites encountered. Plant species significantly influenced adult distributions among aggregation plots. Mass releases of laboratory-reared pupae in the field may not be a viable remediation tactic because almost all of the newly emerged adults dispersed beyond 300 m of the release point.

The considerable variation in adult size of the boll weevil, Anthonomus grandis grandis Boheman, has been well documented, but the influences of adult size on reproductive rate are not known. We examined the relationship between the size of boll weevils and their feeding and oviposition. Weevils weighed to the nearest milligram were grouped into five categories based on pupal weight:or =5, 6-10, 11-15, 16-20, and20 mg. Numbers of lifetime punctures produced in flower buds (squares) of cotton, Gossypium hirsutum L., by both sexes of adults tended to increase with pupal weight. Boll weevil females with pupal weights10 mg produced progeny with significantly higher survival to adulthood and also produced a higher percentage of female progeny than those with pupal weightsor =10 mg. The population growth indices for females having pupal weights10 mg averaged 1.8-fold higher than those of females weighingor =10 mg. Survivorship of adults of both sexes also tended to increase with pupal weight. The percentage of females laying eggs on any given day averaged 2.1 times higher when their pupal weights were10 mg than when their pupal weights wereor =10 mg. Although small size negatively affected female reproductive potential, even extremely small females produced some viable offspring. However, the penalties of small adult size, in terms of longevity and reproductive potential, suggest that cultural practices that result in the production of small adults may be used to impact weevil populations.

Reintroductions of the boll weevil, Anthonomus grandis grandis Boheman, into areas of the United States where it has been eradicated or suppressed are very expensive to mitigate. There is concern that a cotton gin in an eradication zone may serve as a site of boll weevil reintroductions when processing cotton harvested in a neighboring infested zone. Similarly, there is a question whether weevil-free areas can safely import gin products, such as cottonseed and baled lint, from infested areas without risking an introduction. Many countries require fumigation of imported U.S. cotton bales to protect against boll weevil introductions, costing the U.S. cotton industry millions of dollars annually. In previously reported experiments, we quantified the potential for boll weevils to survive passage through precleaning machinery in the gin. In this study, we quantified survival potential of boll weevils passing through the gin stand and segregating into the cottonseed, mote, or lint fractions. We also examined boll weevil survival when passed with ginned lint through a lint cleaner. We present a flow chart of experimentally determined survival potentials of boll weevils passing through the various subprocesses of the gin, from which one can calculate the risk of a live boll weevil reaching any point in the process. Our data show that there is virtually no chance of a boll weevil being segregated alive into the cottonseed or of one surviving in the lint to approach the bale press. Therefore, quarantine or fumigation of cottonseed and cotton bales to guard against boll weevil introductions is unnecessary.

There is concern that cotton gins may serve as loci for reintroduction of boll weevils, Anthonomus grandis grandis Boheman, to eradicated or suppressed zones when processing weevil-infested cotton from neighboring zones. Previous work has shown that virtually all weevils entering the gin in the seed cotton will be removed before they reach the gin stand. Those not killed by the seed cotton cleaning machinery will be shunted alive into the trash fraction, which passes through a centrifugal trash fan before exiting the gin. The objective of this study was to determine survival potential of boll weevils passed through a trash fan. Marked adult weevils were distributed in gin trash and fed through a 82.6-cm (32.5-in.) diameter centrifugal fan operated across a range of fan-tip speeds. A small number of boll weevils were recovered alive immediately after passage through the fan, but all were severely injured and did not survive 24 h. In another experiment, green bolls infested with both adult- and larval-stage weevils were fed through the fan. Several teneral adults survived 24 h, and there was no evidence that fan-tip speed affected either initial survival of weevils, or the number of unbroken boll locks that could harbor an infesting weevil. Thus, designating a minimum fan-tip speed for ensuring complete kill is not possible for the boll weevil. Experiments suggest that a device installed in a gin that partially crushes or cracks bolls open before entering a trash fan will increase mortality, possibly enough that further precautions would be unnecessary.

There is concern that gins located in boll weevil, Anthonomus grandis grandis Boheman, eradication zones may become points of reintroduction when they process cotton grown in a neighboring infested area. We estimated boll weevil survival through two typical machine sequences used in commercial cotton gins to clean and dry the seed cotton in advance of the gin stand, as well as separately through two incline cylinder cleaners or one or two tower dryers operating at different temperatures. Large numbers of laboratory-reared adult boll weevils were marked with fluorescent powder, fed into the test system, and recovered with the assistance of blacklights. We found no evidence of survival through the seed cotton cleaning systems even when the dryers were not heated, or when passed separately through the two incline cleaners alone. Upper confidence limits (95%) were calculated for the observed zero recoveries based on sample size and the binomial distribution, and these represent the statistical worst-case (i.e., highest) survival potential. Survival through heated tower dryers declined rapidly to zero at higher temperatures, especially when two dryers were running. Although we conclude that the potential for survival of weevils in the seed cotton to the gin stand is zero or close to zero, a small percentage of live weevils was recovered in the green boll/rock trap, which may represent the greatest threat of reintroduction at the gin. Escape of live weevils with the gin trash is also possible, and studies addressing this issue will be presented elsewhere.

There is concern that cotton gins located in boll weevil, Anthonomus grandis grandis Boheman, eradication zones serving customers in adjacent infested zones may serve as a site for boll weevil reintroductions if weevils are transported alive inside cotton modules. We surveyed fields in three distinct areas of Texas and found that weevils can be present in large numbers in cotton fields that have been defoliated and desiccated in preparation for harvest, both as free adults and as immatures inside unopened bolls. Harvested cotton taken from module builders indicated that approximately = 100-3700 adult boll weevils were packed inside modules constructed at the sampled fields. Marked weevils were forced through a laboratory field cleaner (bur extractor) commonly mounted on stripper-harvesters, and 14% were recovered alive in the seed cotton fraction and lived at least to 24 h. Survival of weevils placed inside modules declined over time up to 7 d, but the magnitude of the decline varied with experimental conditions. In one experiment, 91% of the weevils survived to 7 d, whereas under harsher environmental conditions, only 11% survived that long. Together, our results indicate that when cotton is harvested in an infested area, boll weevils likely will be packed alive into cotton modules, and many will still be alive by the time the module is fed into the gin, at least up to 7 d after the module's construction.

Field studies show that, if tillage operations occur 2 days before planting or on planting day and herbicide applications occur 2 days before planting, on planting day, or 2 days after planting, black cutworm, Agrotis ipsilon (Hufnagel), larvae present at the time of tillage or herbicide application can survive and produce significant damage to seedling corn. The number of herbicide- or tillage-killed plants per square meter did not seem to affect the survival of black cutworm unless the plant mortality occurred 8 or 14 days before corn planting (15 or 21 days before corn emergence). Black cutworm that presumably fed only on surface plant debris for 11 days survived and significantly affected the corn crop. On the basis of accumulated centigrade degree-days necessary for black cutworm to shift to subsequent stadia, survivors feeding on plant debris will develop as quickly as survivors feeding on weed seedlings, and both populations can achieve cutting stadia (fourth to sixth) by the time corn emerges.

Two relative methods of sampling Ostrinia nubilalis (Hubner) adults, blacklight trap (BLT) and flush bar (FB), were compared with the more absolute drop-net (DN) method over four flights in central and eastern Iowa (1980–1981). Although light traps showed similar population trends regardless of proximity to cornfields or action sites (aggregations of adults in dense grass), the trends were not the same as those shown by the DN. The FB method, however, showed trends similar to those of the DN, and this sampling procedure can replace the DN during the critical period (first 12 to 17 days) of a moderate to heavy flight. An average of 61 European corn borer adults per 10 m2, indicated by the new FB sampling method, was equivalent to the DN threshold average of 3 European corn borer females per 1 m2 of action site (dense grass) previously established and reported in the literature.