Susceptibility of twolined spittlebug (Hemiptera: Cercopidae) life stages to entomophagous arthropods in turfgrass

Prosapia bicincta (Say) (Hemiptera: Cercopidae), the twolined spittlebug, is an economic pest of turfgrass in the southeastern United States. No data concerning natural enemies of P. bicincta in turfgrass have been reported previously. We compared predation of spittlebug eggs, nymphs, and adults in the laboratory by potential generalist predators commonly found in turfgrass: bigeyed bugs Geocoris uliginosus Say and Geocoris punctipes Say; red imported fire ant, Solenopsis invicta Buren; wolf spiders (Lycosa sp. Walckenaer); carabid beetles Harpalaus pensylvanicus DeGeer and Calosoma sayi Dejean; and tiger beetles Megacephala carolina carolina L. Eggs were readily consumed by generalist predators. S. invicta consumed 100% of the eggs offered. H. pensylvanicus and C. sayi were also significant predators of P. bicincta eggs. Nymphs live in spittlemasses that protect them from attack by predators, but exposed nymphs were susceptible to attack when mechanically removed from their spittlemasses. S. invicta and M. carolina carolina caused significant mortality of exposed nymphs. P. bicincta adults are aposematic and have the ability to reflex bleed; however, reflex bleeding did not prevent attack by predators. S. invicta and M. carolina carolina killed 100% of the adult spittlebugs offered in laboratory bioassays. Lycosa sp. are less voracious predators of adults. Sound background knowledge about P. bicincta and its potential natural enemy complex is important for the development and implementation of a detailed, site-specific, biologically based pest management program in turfgrass.     

Evaluation of turfgrass species and cultivars for potential resistance to twolined spittlebug (Hemiptera: Cercopidae)

Potential resistance to the twolined spittlebug, Prosapia bicincta (Say), was evaluated among 56 turfgrass genotypes. Greenhouse, laboratory, and field bioassays identified differences in spittlebug survival and development, host preference and damage levels, and turfgrass tolerance to and ability to recover from pest induced injury. All centipede grasses demonstrated high levels of susceptibility, followed by bermudagrasses, seashore paspalums, and zoysiagrasses. Average nymphal survival to the adult stage ranged from 1.5 to 78.1%. Development required 38.1-62.0 d under greenhouse conditions, depending on plant taxa. Among seashore paspalums, nymphal survival to the adult stage was lowest and duration of development was longest on HI-1, 'Sea Isle 2000', 561-79, and 'Mauna Kea'. Reduced spittlebug survival and increased developmental times were also observed on the bermudagrasses BERPC 91-15 and 'Tifway'. Although zoysiagrasses supported spittlebug development and survival to the adult stage, developmental times were extended on the zoysiagrass cultivars 'Emerald' and 'El Toro'. Spittlebug preference varied with generation evaluated. First-generation spittlebugs inflicted the greatest damage on TC201 (centipede grass), 'Primavera' (bermudagrass), and 'Emerald' (zoysiagrass) in choice tests. In the fall, second-generation spittlebugs damaged TC201 (centipedegrass) and 'Sea Isle 1' (paspalum) most severely, whereas 561-79 (paspalum) and 'Emerald'(zoysiagrass) were less severely affected. Among taxa included in field trials, HI-1, 'Mauna Kea', 'Sea Isle 2000',and AP-14 paspalums, 'Tifway' bermudagrass, and 'Emerald' zoysiagrass were most tolerant (demonstrated the best regrowth potential following twolined spittlebug feeding).     

Characterization of fall armyworm mitochondrial DNA (Lepidoptera: Noctuidae)

Mitochondrial DNA from the fall armyworm, Spodoptera frugiperda (J.E. Smith), was cloned and characterized using restriction enzyme mapping. Genome size is approximately 16.3 kilobase (Kb), consistent with that of most animals. Three fragments, 8.1 Kb, 6.2 Kb, and 2.0 Kb, were produced by digestion with restriction enzyme Xbal and cloned into a pUC19 vector. Twenty-nine restriction enzymes were used to generate a detailed physical restriction enzyme map of the three cloned fragments. These data represent the first detailed characterization of a lepidopteran mitochondrial genome. © 1992 Wiley-Liss, Inc.     

Genetic characterization of fall armyworm (Lepidoptera: Noctuidae) host strains in Argentina

Fall armyworm is a major economic pest throughout the Western Hemisphere. Previous studies of populations in the southern United States, Brazil, and the Caribbean demonstrated the existence of two morphologically identical but genetically distinct host strains that can only be distinguished using genetic markers, including polymorphisms in the mitochondrial Cytochrome Oxidase I (COI) gene and in the Z-chromosome linked Triose phosphate isomerase (Tpi) gene. The strains differ in some physiological and behavioral characteristics, most notably their preference for different plant hosts, but are capable of hybridizing in the laboratory and in the field. These traits suggest that the strains are in the process of divergence, which may or may not be hemispheric in scope. The objective of this study was to determine whether the two strains are present in Argentina. It was found that the strain-diagnostic haplotypes of the COI and Tpi genes subdivided the Argentina population into two major groups. Each group displayed biases in their distribution among different host plants that were generally consistent with expected strain behavior. The overall results indicated that Argentina fall armyworm exhibit similar genetics and behavior to populations in the rest of the hemisphere. In addition, the Argentina populations had comparable haplotype frequencies to those from Brazil and Texas, consistent with possible interactions with these fall armyworm groups, but appeared to have had minimal exchanges with those from Puerto Rico or Florida.     

Regulation of vitellogenesis in the fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae)

Studies were undertaken to investigate vitellogenesis and its regulation in female adults of the fall armyworm, Spodoptera frugiperda. A single female-specific protein, likely to be the S. frugiperda vitellogenin (Vg), appeared approximately 5 h after adult eclosion in the hemolymph of virgin females. The concentration of the protein increased with age as sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed. A protein with the same relative molecular mass was also present in egg extracts, but absent from hemolymph samples from male moths. The relative molecular mass of the designated S. frugiperda Vg was determined as 164.5+/-2.5 kDa. Vitellogenic oocytes became visible 36-48 h after emergence and egg deposition began on day 3 of adult life. Vg could not be detected in the hemolymph of females decapitated directly after eclosion. When decapitated virgin females were injected with the JH-mimic methoprene (MP), the level of Vg was comparable to that in non-decapitated moths, indicating that vitellogenesis in S. frugiperda depends on juvenile hormone (JH). However, the number of vitellogenic oocytes was somewhat lower than in non-decapitated virgin females. Injection of 20-hydroxyecdysone (20E) promoted Vg production to a similar extent in decapitated female moths, but in contrast to methoprene injection, treatment with 20E never resulted in the production of vitellogenic oocytes. In vitro cultivated ovaries of adult females dissected directly after eclosion produced lower amounts of ecdysteroids than those isolated on day 1 after emergence. Our results suggest a crucial role for 20E in the induction of vitellogenesis in the noctuid S. frugiperda, while JH seems to be essential for the continued uptake of Vg by developing oocytes and may trigger 20E biosynthesis in the ovary.     

叉角厉蝽对草地贪夜蛾的捕食功能反应

叉角厉蝽Eocanthecona furcellate(Wolff)是一种极具应用潜力的重要捕食性天敌。为了探明叉角厉蝽3龄若虫对草地贪夜蛾Spodoptera frugiperda(J.E.Smith) 3龄幼虫的控害效果,在室内条件下,观察了叉角厉蝽对草地贪夜蛾幼虫的捕食行为,研究了叉角厉蝽对草地贪夜蛾3龄幼虫的捕食功能反应。结果表明,叉角厉蝽以口针从草地贪夜蛾腹部或者体躯末端插入取食,被取食后的草地贪夜蛾呈干瘪状死亡。叉角厉蝽3龄若虫对草地贪夜蛾3龄幼虫的捕食功能反应模型符合Holling II型方程,为:Na=0.6702 N/(1+0.0133 N),叉角厉蝽若虫对草地贪夜蛾3龄幼虫的日最大捕食量、瞬时攻击率和处理时间分别为50.25头、0.6702 d和0.0199 d。叉角厉蝽的捕食量与猎物密度正相关,寻找效应与猎物密度负相关,叉角厉蝽的捕食作用存在较强的种内干扰作用。试验证实叉角厉蝽对草地贪夜蛾具有较好的控害效果,为其田间应用释放技术提供了理论依据。     

Grass species and endophyte effects on survival and development of fall armyworm (Lepidoptera: Noctuidae)

Grass selections including 10 zoysiagrasses, 18 paspalums, 34 Bermuda grasses, tall fescue, creeping red fescue, and perennial ryegrasses with and without endophyte were evaluated for potential resistance to fall armyworm, Spodoptera frugiperda (J. E. Smith), larvae. Laboratory evaluations assessed the degree of antibiosis among >70 grass lines to first-instar fall armvworms. When all parameters measured were considered, the trend in resistance to fall armyworm among endophyte-infected (E+) and endophyte-free (E-) cool season grasses from greatest to least was: 'Dawson' E+ > APR 1234 > 'Dawson' E- > 'Rosalin' E+ > Lp 5425, 'Rosalin' E-, ATF 480 > 'Tulsa' or: E+ slender creeping red fescue > E+ turf- type perennial ryegrass > E- slender creeping red fescue > E+ forage-type perennial ryegrass > E- forage-type perennial ryegrasses, and E+ tall fescue > E- turf-type tall fescue. Among warm season grasses larval weight gain was reduced on all zoysiagrasses. Larval weight gain also was lower on the Bermuda grasses 'Tifsport', 'Tifgreen', 97-4, 97-14, 97-22, 97-28, 97-39, 97-40,97-54, 98-15, 98-30, and 98-45 than when larvae were fed 'Tulsa' tall fescue or the diet control. Only APR1234 and 'Dawson' creeping red fescue reduced larval survival to the same extent that was observed for zoysiagrasses. Survival on Bermuda grasses was least on 97-8. Seashore paspalums were only rarely less susceptible to fall armyworm than tall fescue, although pupal weights were consistently lower on 'Temple 1' and 'Sea Isle 1' paspalums than that on 'Tulsa' tall fescue. Genetic resistance to key grass pests can reduce insecticide use and simplify management of these cultivars.     

Juvenile hormone biosynthesis in the fall armyworm, Spodoptera frugiperda (Lepidoptera, Noctuidae)

The in vitro production of juvenile hormones (JH) was investigated by using corpora allata (CA) of larvae and corpora cardiaca-corpora allata (CC-CA) complexes of adult females of the fall armyworm Spodoptera frugiperda. In female moths, JH release was high compared to that in 5th and 6th instar larvae. Concentrations of 0.11-0.12 mM methionine, 180-200 mM Na(+), 5.8-8.3 mM K(+), 10-50 mM Ca(2+) and a pH range of 5.7-6.3 yielded optimal incorporation of L-[methyl-(3)H] methionine in vitro by CC-CA complexes. The highest hourly incorporation occurred during a 9-h incubation period following a 1.5-h lag-phase. JH release from CC-CA complexes of adult females was shown to be age-dependent with a peak value on day 2 (approx. 4 pmol h(-1) CA(-1)). By a combination of reversed phase (RP)- and normal phase (NP)-high performance liquid chromatography (HPLC), two major labelled products released by the complex were separated. One compound co-migrated with chemically synthesized JH II diol, the second compound with JH III diol. Only traces of JH II and III could be detected in some samples. Gland extracts also contained both the major radiolabelled products. Double labelling experiments using [3H]methionine and [14C]acetate confirmed their de novo synthesis in CC-CA complexes of female moths. The nature of chemically synthesized reference JH III diol was proved by LC-MS (ESI mass spectrometry) and 1H-NMR (nuclear magnetic resonance spectroscopy).     

草地贪夜蛾的性信息素通讯研究进展

草地贪夜蛾Spodoptera frugiperda原产于美洲,具有长距离迁飞特性。该虫于1988年入侵欧洲,2016年入侵非洲,并引起巨大的粮食损失,2018年入侵亚洲,2019年从缅甸传入中国,并在短时间扩散至全国10多个省。草地贪夜蛾依赖性信息素通讯,实现雌雄间识别、交配和繁衍,为了深入研究草地贪夜蛾的性信息素通讯及其机制并开发更高效的预测预报和防治技术,本文综述了草地贪夜蛾性信息素通讯的研究现状。1967年首次报道草地贪夜蛾性信息素为顺9-十四乙酸酯,随后发现有不同的鉴定结果,1986年确认其性信息素由顺9-十四乙酸酯和顺7-十二乙酸酯两个组分组成,其比例为96.6∶3.4时表现出最强的引诱活性。除此而外,对不同地理种群的研究发现,草地贪夜蛾雌蛾的信息素腺体提取物还存在顺9-十二乙酸酯、顺11-十六乙酸酯和反7-十二乙酸酯,田间实验表明这些物质在性信息素通讯中也可发挥作用。根据分子标记和喜食寄主,草地贪夜蛾可分为玉米品系和水稻品系。两个品系在外部形态上无法区分,性信息素组分也相同,但在组分比例上存在一定的差异。两个品系间存在一定程度的生殖隔离,但室内可以正交和反交并产生可育的F1代,F1代的性信息素比例与母本的比较相似。关于草地贪夜蛾雄性对性信息素的感受机制方面研究较少,仅见有感器形态的鉴定和对性信息素组分的触角电位反应研究的报道。根据目前草地贪夜蛾在我国的发生情况及其性信息素通讯机制的研究现状,我们建议尽快开展以下研究：(1)鉴定草地贪夜蛾我国入侵种群的雌性性信息素,尽快用于其种群动态监测及防治;(2)研究草地贪夜蛾雄性对性信息素的嗅觉编码机制;(3)研究草地贪夜蛾两个品系的行为隔离程度及其演化结局。     

Effects of bacillus thuringiensis transgenic corn on corn earworm and fall armyworm (Lepidoptera: Noctuidae) densities

We examined 17 pairs of near-isogenic hybrids of Bacillus thuringiensis (Bt) (176, Mon810, and Bt11) and non-Bt corn, Zea mays L., to examine the effects of Bt on larval densities of Helicoverpa zea (Boddie) and Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) during 2 yr. During ear formation, instar densities of H. zea and S. frugiperda were recorded for each hybrid. We found that H. zea first, second, and fifth instar densities were each affected by Mon810 and Bt11 Bt corn but not by 176 corn. Surprisingly, first and second instars were found in higher numbers on ears of Mon810 and Bt11 corn than on non-Bt corn. Densities of third and fourth instars were equal on Bt and non-Bt hybrids, whereas densities of fifth instars were lower on Bt plants. S. frugiperda larval densities were only affected during 1 yr when second, and fourth to sixth instars were lower on ears of Mon810 and Bt11 hybrids compared with their non-Bt counterparts. Two likely explanations for early instar H. zea densities being higher on Bt corn than non-Bt corn are that (1) Bt toxins delay development, creating a greater abundance of early instars that eventually die, and (2) reduced survival of H. zea to later instars on Bt corn decreased the normal asymmetric cannibalism or H. zea-S. frugiperda intraguild predation of late instars on early instars. Either explanation could explain why differences between Bt and non-Bt plants were greater for H. zea than S. frugiperda, because H. zea is more strongly affected by Bt toxins and more cannibalistic.     

Comparison of haplotype frequencies differentiate fall armyworm (Lepidoptera: Noctuidae) corn-strain populations from Florida and Brazil

Fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is a major economic pest throughout the Western Hemisphere. Populations can be subdivided into two morphologically identical but genetically distinct strains (corn-strain and rice-strain) that differ in their host plant preferences. These strains can be distinguished by using polymorphisms in the mitochondrial cytochrome oxidase 1 gene. Additional sequence analysis of this locus identified two sites that were highly polymorphic in the corn-strain population and that produced four different haplotype subgroups. Comparisons of the frequency distribution of these haplotypes found no seasonal or plant host specificities, but they did demonstrate that the Brazil corn-strain population is different from corn-strain fall armyworm found in Florida. The development of a rapid means of distinguishing fall armyworm populations originating from Brazil versus Florida provides an opportunity for investigating and comparing the genetic complexity and long-range movements of this important agricultural pest.     

氰氟虫腙对草地贪夜蛾的毒力与田间防效

【目的】本研究旨在明确氰氟虫腙对草地贪夜蛾Spodoptera frugiperda幼虫的毒力水平和田间防治效果,为科学使用氰氟虫腙防治草地贪夜蛾提供参考依据。【方法】采用饲料混毒法在室内测定了氰氟虫腙与4种常用杀虫剂甲维盐、氯虫苯甲酰胺、虱螨脲和茚虫威对草地贪夜蛾3和6龄幼虫的致死中浓度(LC₅₀)及LC₉₀值,以及LC₉₀浓度的这些杀虫剂对3龄幼虫的致死中时(medium lethal time, LT₅₀)值。采用人工喷雾方法测定了玉米田中22%氰氟虫腙悬浮剂(6.6 g/667 m²)、22%氰氟虫腙悬浮剂(17.6 g/667 m²)、5.7%甲维盐水分散剂(1 g/667 m²)和150 g/L茚虫威悬浮剂(2 g/667 m²)对草地贪夜蛾幼虫的防效。【结果】室内生测结果显示,供试的5种杀虫剂中氰氟虫腙对草地贪夜蛾3和6龄幼虫均具有较高的毒力,其LC₅₀值分别为2.64和4.3...     

Studies on the life history and biological control of the spittlebug,Clastoptera undulata uhler (Cercopidae: Hemiptera)

Résumé Une invasion deClastoptera undulata fut découverte aux Bermudes en 1959 et il a été tenté de lutter contre cet insecte par l'introduction de l'EncyrtideCarabunia myersi, parasite des larves originaires de la Jama?que. Les recherches accomplies sur le cycle deClastoptera undulata aux Bermudes sont présentées ainsi que les observations faites dans la nature sur une espèce voisine,C. flavidorsa, à la Jama?que. Des informations sur la biologie deCarabunia myersi et un compte rendu sur son introduction et son établissement aux Bermudes sont donnés. Aux Bermudes, la plupart des individus deC. undulata hivernent à l'état d'œuf et les effets possibles sur la population du parasite sont discutés.      

Effects of neem-based insecticides on beet armyworm （Lepidoptera： Noctuidae）

Abstract Three commercial neem [ Azadirachta indica A. Juss (Meliaceae)]-based insecticides, Agroneem, Ecozin, and Neemix, and a non-commercial neem leaf powder, were evaluated for oviposition deterrence, antifeedant effect on larvae, and toxicity to eggs and larvae of the beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae), on cotton leaves in the laboratory. Oviposition deterrence in no-choice, and two- and fivechoice assays, was observed for the neem-based insecticide treatments when compared with a non-treated control. Neem-based insecticides also deterred feeding by beet armyworm larvae. Direct contact with neem-based insecticides decreased the survival of beet armyworm eggs. Survival of beet armyworm larvae fed for 7 days on leaves treated with neembased insecticides was reduced to 27, 33, 60, and 61% for neem leaf powder, Ecozin, Agroneem, and Neemix, respectively. Possibilities for adoption of neem-based insecticides in commercial cotton for beet armyworm control are discussed.     

Reproductive seasonality of the ground and tiger beetle (Coleoptera: Carabidae,Cicindelidae) fauna in North Sulawesi (Indonesia)

Carabidae and Cicindelidae collected from January to December in 1985 by a number of different collecting methods in the Dumoga‐Bone National Park area of N. Sulawesi (Indonesia) were examined to assess their reproductive seasonality. The state of gonad maturity was assessed through dissection of 5099 specimens, representing 203 species of Carabidae and 15 species of Cicindelidae. For the Carabidae, 45.7% of females and 12.0% of males were ‘immature’ (non‐reproductive). For the Cicindelidae the corresponding figures were 38.7% and 18.5%. In carabids the peak month for immatures is July and this corresponds with the highest percentage of females that are post‐reproductive (as evidenced by the presence of the corpora lutea). A similar but less pronounced trend is found in male carabids. The proportion of immatures varies less in cicindelids during the year. Analysis of data for carabids from different habitats and lifestyles (leaf litter, dead wood and under bark, fossorial, riparian, grass/marsh, log‐runners, leaf‐runners, and termitophiles), suggests that different guilds have different patterns of reproductive seasonality. Furthermore, the reproductive seasonality may differ between species within these guilds. The effects on reproductive seasonality of the considerable local variation in climate in the study area and of sampling at different altitudes and with a range of collecting methods are also considered.     

Genetic basis of resistance to fall armyworm (Lepidoptera: Noctuidae) and southwestern corn borer (Lepidoptera: Crambidae) leaf-feeding damage in maize

Leaf-feeding damage by first generation larvae of fall armyworm, Spodopter frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), and southwestern corn borer, Diatraea grandiosella Dyar (Lepidoptera: Crambidae), cause major economic losses each year in maize, Zea mays L. A previous study identified quantitative trait loci (QTL) contributing to reduced leaf-feeding damage by these insects in the maize line Mp704. This study was initiated to identify QTL and their interactions associated with first generation leaf-feeding damage by fall armyworm and southwestern corn borer. QTL associated with fall armyworm and southwestern corn borer resistance in resistant line Mp708 were identified and compared with Mp704. Multiple trait analysis (MTA) of both data sets was then used to identify the most important genetic regions affecting resistance to fall armyworm and southwestern corn borer leaf-feeding damage. Genetic models containing four and seven QTL explained southwestern corn borer and fall armyworm resistance, respectively, in Mp708. Key genomic regions on chromosomes 1, 5, 7, and 9 were identified by MTA in Mp704 and Mp708 that confer resistance to both fall armyworm and southwestern corn borer. QTL regions on chromosomes 1, 5, 7, and 9 contained resistance to both insects and were present in both resistant lines. These regions correspond with previously identified QTL related to resistance to other lepidopteran insects, suggesting that broad-spectrum resistance to leaf feeding is primarily controlled by only a few genetic regions in this germplasm.     

Bioactivity of neem, Azadirachta indica, against spittlebug Mahanarva fimbriolata (Hemiptera: Cercopidae) on sugarcane

The effect of neem, Azadirachta indica A. Juss, on some biological parameters of Mahanarva fimbriolata (Stil) (Hemiptera: Cercopidae) was studied in the laboratory by using NeemAzal-T/S, Nimkol-LS, and an aqueous neem seed extract. Initially, the LC,, was estimated for nymphs. Later, nymphs fed on sugarcane, Saccharum officinarum L., roots were sprayed with the respective LC,, for each product. The adults were maintained in cages on sugarcane plants sprayed at the base with the maximum rate recommended commercially for the crop (3 liter/ha). Moistened cotton discs surrounding the base of the plant were used as oviposition substrates. The LCso values estimated for NeemAzal, Nimkol, and aqueous extract were 0.014, 0.225, and 0.611%, respectively. There was a reduction in spittlebug longevity, regardless of sex, in relation to the control. Males exposed to the neem products, and aqueous extract showed longevity reductions of approximately 50%, whereas for females the reductions were 55-60%. The neem products and extract reduced fecundity by 75-85%. Morphological and physiological changes were observed in 9% of the eggs from individuals submitted to NeemAzal. Neem-based products, especially NeemAzal, have potential for the control of M. fimbriolata.     

Risk predictive model for damage caused by the spittlebug Aeneolamiapostica (Walker) Fennah (Hemiptera: Cercopidae)

This paper evaluated the risk that Aenolamia postica (Walker) Fennah populations reach the economic threshold in sugar cane fields in Veracruz, México. A risk deductive model was constructed to include the sequence of events leading to damaging populations, considered the top event or critical failure in the crop. Model events were identified and quantified, and model was validated on field conditions. The model components and their state values were identified as: temperature e" 28 degrees C, precipitation e" 45% during June and July, soil clay content e" 40%, infested adjoining fields, deficient weed control, wind dominance, crop phenology and variety, deficient chemical and biological control, and irrigation. Sensitivity analysis showed that the most important events triggering high densities of A. postica were high temperatures and precipitation, previous field infestation, nymph and weed presence. Event probability estimates were combined using Boolean algebra to compute the minimum, mean and maximum probabilities for the top event, yielding values of 0.417, 0.563, y 0.734 respectively. Model was tested in field, by selecting sugar cane fields having the model properties and compared to fields without these features. Fields were sampled in both conditions during 2004 year and high-risk fields had significantly (F = 13, 4, gl = 1, 18, P = 0,0018) higher densities (2.4 adults m(-1)) than low-risk plots (0.4 adults m(-1)) thus agreeing with the model forecast.     

Using haplotypes to monitor the migration of fall armyworm (Lepidoptera: Noctuidae) corn-strain populations from Texas and Florida

Fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), infestations in most of North America north of Mexico arise from annual migrations of populations that overwinter in southern Texas and Florida. A comparison of the cytochrome oxidase I haplotype profiles within the fall armyworm corn-strain, the subgroup that preferentially infests corn (Zea mays L.) and sorghum (Sorghum vulgare Pers.), identified significant differences in the proportions of certain haplotypes between the Texas and Florida populations. These proportional differences were preserved as the populations migrated, providing a molecular metric by which the source of a migrant population could be identified. The migratory pattern derived from this method for several southeastern states was shown to be consistent with predictions based on analysis of historical agricultural and fall armyworm infestation data. These results demonstrate the utility of haplotype proportions to monitor fall armyworm migration, and they also introduce a potential method to predict the severity of cotton crop infestations in the short term.     

Plant-incorporated Bacillus thuringiensis resistance for control of fall armyworm and corn earworm (Lepidoptera: Noctuidae) in corn

Fall armyworm, Spodoptera frugiperda (J.E. Smith), and corn earworm, Helicoverpa zea (Boddie), perennially cause leaf and ear damage to corn, Zea mays L., in the southeastern United States. Transgenic Bacillus thuringiensis (Bt) hybrids with the Bt11, MON810, or 176 events expressing the Cry1Ab insecticidal endotoxin from were evaluated for control fall armyworm and corn earworm at seven locations in Georgia during 1999 and 2000. Corn was planted at the recommended time for each location and 1 and 2 mo later in the southern locations. All Bt events consistently reduced whorl infestation and damage, although event 176 did not prevent whorl damage in the later plantings in the southern locations in both years. All events also reduced seedling damage by the lesser cornstalk borer, Elasmopalpus lignosellus (Zeller), in one trial and stalk infestations and tunnel length by southwestern corn borers, Diatraea grandiosella Dyar, in another trial. Hybrids containing Bt11 and MON810 events reduced ear infestations in all trials, although reductions were small in later plantings. Nevertheless, both events reduced grain damage from earworms and armyworms by an average +/- SE of 52.5 +/- 5.1% in all trials. The hybrid containing event 176 did not reduce ear infestations and damage. Total grain aflatoxin concentrations were not significantly affected by Bt resistance in any trial (N = 17). Yield responses were variable with the prevention of yield loss being proportional to the severity of insect damage. Although plantings made after the recommended time did not consistently benefit from Bt resistance, Bt11 and MON810 events were effective in reducing damage to field corn when large infestations occurred. The Bt11 and MON810 events mitigated the risk of severe lepidopteran damage to corn, thereby making later plantings of corn feasible in double-cropping systems.