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The mirid Engytatus varians (Distant) is a promising biological control agent of the tomato borer, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), one of the most destructive pests of tomato (Solanum lycopersicum L.). The effects of five insecticides commonly used on tomato crops in Brazil were evaluated on E. varians in laboratory and semifield conditions. Glass Petri dish with residues of chlorfenapyr, thiamethoxam, and abamectin caused ˃90% mortality in both stages of the predator 72 h post-treatment, except imidacloprid that caused 78% of nymphs mortality. Teflubenzuron caused 24 and 66% mortality on adults and nymphs, respectively. The offspring of females derived from treated nymphs with teflubenzuron was significantly lower than the control but not when females were treated as adults. Longevity of males derived from nymphs treated with teflubenzuron was significantly reduced, but no effects were observed on females. When males and females were treated as adults with teflubenzuron there were no effects on their longevity. In the greenhouse-aged tomato plants, the 2 h-old residues of thiamethoxam, chlorfenapyr, and abamectin caused more than 70% of mortality of third instar of E. varians at 72 h post-treatment, 12 day-old residues of all three compounds caused a mortality lower than 30%. These data suggest that teflubenzuron can be associated with releases of E. varians adults, while the use of other evaluated pesticides should be avoided in this situation. Although, the low persistence of these products indicate that their spraying and later releases of E. varians adults on tomato crops are a possible strategy to control T. absoluta.

The biological activity of 4 Mexican isolates (SeSIN6, SeSIN8, SeSLP6, and SeSLP8) of the homologous multiple nucleopolyhedrovirus SeMNPV and their effects on the development of the beet armyworm, Spodoptera exigua (Hubner) (Lepidoptera: Noctuidae), were studied. An exotic isolate of SeMNPV from the United States (SeUS2) was used as a reference. Early third-instar larvae were inoculated with 5 × 106 occlusion bodies per mL, resulting in 78% mortality for SeUS2 and approximately 90% mortality for each of the 4 Mexican isolates at 144 h post-inoculation. At 168 h postinoculation, 100% mortality was obtained in all cases. All of the isolates, including SeUS2, significantly reduced the body weights of S. exigua larvae compared with the control larvae; however, at 120 h post-inoculation, the differences among isolates were not significant. All of the isolates reduced the development time of third-instar S. exigua larvae (range: 1.2– to 1.6–fold) compared with the control larvae. An independent experiment was performed to determine production of occlusion bodies and mean time to death. Third-instar S. exigua larvae (15 h after molting) were inoculated with each isolate using the same concentration mentioned above. The occlusion body production rate was similar among all isolates. The isolates SeUS2, SeSLP6, and SeSLP8 yielded the fastest mortality (range: 187–191 h). Thus, the biological activities of the Mexican SeMNPV isolates were similar to the activity of the exotic isolate, indicating that these indigenous viruses are promising for the biological control of S. exigua in Mexico. Resumen Se estudio la actividad biologica y los efectos sobre el desarrollo del gusano soldado Spodoptera exigua (Hubner) (Lepidoptera: Noctuidae) de 4 aislados mexicanos (SeSIN6, SeSIN8, SeSLP6 y SeSLP8) de su nucleopoliedrovirus multiple homologo (SeMNPV). Se uso como referencia un aislado exotico, originario de Estados Unidos (SeUS2). La inoculacion de larvas recien mudadas de tercer estadio con 1 × 106 cuerpos de inclusion per mL resulto en 78% de mortalidad para SeUS2 y aproximadamente 90% para 4 aislados mexicanos a las 144 h post inoculacion. A las 168 h post inoculacion se observo una mortalidad del 100% en todos los casos. Todos los aislamientos, incluyendo el SeUS2, provocaron un efecto significativo en la reduccion del peso corporal promedio de las larvas de S. exigua en comparacion con el control; sin embargo, a 120 h post inoculacion las diferencias entre aislados no fueron significativas. Todos los aislados redujeron el tiempo de desarrollo de las larvas de tercer instar (rango: 1.2–1.6 veces) en comparacion con el control. Se realizo un experimento independiente para determinar la produccion de cuerpos de inclusion y el tiempo medio de muerte. Para ello, las larvas de tercer estadio de S. exigua (15 h despues de la muda) se inocularon con cada aislado utilizado la misma concentracion descrita arriba. La tasa de produccion de cuerpos de inclusion fue similar entre todos los aislados probados. Los aislados SeUS2, SeSLP6, y SeSLP8 causaron una mortalidad mas rapida (rango: 187–191 h). Se concluyo que la actividad biologica de los aislados mexicanos del SeMNPV fue similar a la observada en el aislado exotico, indicando que estos virus son prometedores para el control de S. exigua en Mexico. View this article in BioOne

The effects of 2 concentrations (15 and 30%) of ethanolic Argemone ochroleuca Sweet (Papaveraceae) extracts were determined on the feeding behavior and development of 3rd instar larvae of the fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) through their continuous ingestion of treated maize leaves for 48 h. The extracts were obtained from dried whole plants including stems, leaves, and flowers. Armyworm food consumption was slightly reduced (by 13 to 14%) at both concentrations compared with the controls. Larval growth was significantly affected only at the highest concentration, with a 23% reduction in larval weight after 48 h of feeding on the treated leaves and a 38% reduction after another 48 h of feeding on an untreated artificial diet. By contrast, the duration of the larval and pupal stages was prolonged by 43% (from 13.5 to 19.4 d) and by 8% (from 2.1 to 2.2 d), respectively. Total larval mortality was also higher at the highest concentration (31%) than in controls (10%). During the pupal stage, neither the number of pupae that formed nor their mortality or weight was significantly affected by the treatments. However, both of the bioassay concentrations significantly lengthened the duration of the pupal stage in males, whereas in females, only the higher concentration did. In addition, no effect was observed on the adult emergence, sex ratio, and fecundity. In summary, the primary effect of ethanolic A. ochroleuca extracts appears to be a reduction in feeding, which simultaneously slows larval growth and increases mortality.

The leafroller Argyrotaenia montezumae (Walsingham) (Lepidoptera: Tortricidae) was found feeding on blackberry leaves ( Rubus sp.) in three localities of Michoacan, Mexico, for the first time in 2008. Several biological parameters of this insect were assessed under laboratory conditions (25 ± 2°C, 75 ± 5% relative humidity, and a photoperiod of 16:8 [L:D] h). The egg, larval (five instars), prepupal, pupal, and adult stages lasted 7.28, 21.62, 3.89, 8.37, and 17.64 d, respectively. Larval growth of A. montezumae followed Dyar's rule, and the growth ratios for the widths between the genae and the distance between the frontal setae of the head were 1.43 and 1.54, respectively. Female and male pupae weighed 33 and 21 ± 0.56 mg, respectively. The adult sex ratio (percentage of females) was 48%. When females oviposited on the inner walls of a transparent plastic container, the cumulative number of eggs per female over a lifetime was 391, with preoviposition and oviposition periods of 3.5 and 8.1 d, respectively. Peak oviposition activity was recorded when female age ranged from 4 to 8 d (47.35 and 52.12 eggs per female, respectively). The egg hatching percentage was 92.24%. The influence of the oviposition substrate color on the fecundity of A. montezumae was assessed using high-density polyethylene of different colors. The overall number of eggs per female was higher on green (352.5), blue (327.86), and yellow (250.60) substrates than on transparent (192.22) and pink (197.00) substrates.

This study describes the biological activity of two Spodoptera frugiperda multiple nucleocapsid nucleopolyhedrovirus (SfMNPV) isolates recovered from the soil of maize crops in the states of Yucatan and Chiapas, Mexico (Sf-YUC and Sf-CHI). The biological activity was determined for four Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) field populations: Sf-Motozintla, Sf-Erongaricuaro, Sf-Abasolo, and Sf-Culiacancito. As a reference, a laboratory colony (Sf-Lab) was used. Biological characterization was compared with that for a characterized SfMNPV isolate from Nicaragua (Sf-NIC). The LC50 values for both the Sf-NIC and Sf-CHI isolates did not differ in any of the insect populations tested. In contrast, the Sf-YUC isolate was less active than the Sf-NIC isolate in the Sf-Motozintla population, but this isolate was more active in the Sf-Erongaricuaro and Sf-Abasolo populations. The killing speed and OB productivity were variable among isolates in each insect population. A small-scale field trial was performed to evaluate the degree of pest control achieved by the Sf-YUC isolate, applied at a rate of 3 × 1012 OBs/ha, in maize grown in central Mexico. The larval mortality caused by the virus was 58%, 78%, and 84% at 2, 5, and 7 d post application, respectively. At 7 d post application, the incidence of insect parasitoids in the virus treatment was significantly lower than in the control. In conclusion, the insecticidal characteristics of both Mexican isolates (Sf-CHI and Sf-YUC) varied according to their insect population. In addition, the Sf-YUC isolate may be suitable as the basis for a biopesticide for the control of S. frugiperda in Mexico.

A new species of Apanteles from Mexico is described and illustrated. Apanteles montezumae Sanchez, Figueroa and Whitfield, new species, attacks Argyrotaenia montezumae Walsingham and Amorbia cuneana (Walsingham) (Lepidoptera: Tortricidae) on Rubus sp. in Michoacan state, Mexico.

The blackberry, Rubus sp., crop in the state of Michoacan, Mexico is the second-most important crop after avocado, Persea americana Mill., in relation to value of production and employment. In this study was identified a blackberry leafroller, its parasitoids, and population dynamics in two commercial orchards at Michoacan, Mexico, during the growing seasons of 2007 and 2008. Collected rolled leaves containing larvae and pupae where maintained in a laboratory until leafroller adults and their parasitoids emerged. Population dynamics of moths were determined using wing traps containing the sex pheromone of Argyrotaenia citrana (Fernald) (Lepidoptera: Tortricidae). Numbers of males caught peaked in September and November 2007 at the two locations. After these months, numbers gradually decreased to almost zero during the dry season in 2008. Moths that emerged were identified as Argyrotaenia montezumae (Walsingham) (Lepidoptera: Tortricidae). Of the A. montezumae larvae collected in the field, 38% w...

The combined and alone effects of azadirachtin (AZA) and Spodoptera frugiperda multicapsid nucleopolyhedrovirus (SfMNPV) on the mortality and food consumption of third instar S. frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) were evaluated under laboratory conditions using maize leaf bioassays. The LC50 values for SfMNPV and AZA were determined to be 1.30x106 viral occlusion bodies (OBs)/ml and 6.54 mg l-1 at 192 h and 144 h after treatment, respectively. These LC50 values were estimated for 4 days of continuous exposure. Although the interaction of SfMNPV with AZA increased the percentage of mortality observed in most of the cases, only one mixture (1x106 OBs/ml + 5 mg l-1) resulted in a synergistic effect on mortality of S. frugiperda. Application of SfMNPV (1x106 OBs/ml), AZA (0.5, 0.1 or 0.25 mg l-1) or SfMNPV–AZA mixtures resulted in a significant reduction in the maize-leaf piece consumption of larvae treated in the third instar across the experiment, by onefold, 2–5-fold, and 2–3-fold, respectively, compared with the control. However, the interaction of two SfMNPV–AZA mixtures (1x106 OBs/ml + 5 mg l-1 and 1x106 OBs/ml + 10 mg l-1) did not reduce the food consumption compared with AZA alone. It was concluded that SfMNPV–AZA mixtures require validation to determine whether this mixture may offer a valuable means of improving the efficacy of the SfMNPV.

Summary The combined and individual effects of spinosad and Spodoptera frugiperda multiple nucleopolyhedrovirus (SfMNPV) (Baculoviridae) on the mortality and food consumption of 3rd instars of S. frugiperda were evaluated using maize-leaf bioassays. The mortality data from spinosad (0.001 mg/L)-SfMNPV (106 OBs/mL) mixtures showed a low synergistic effect at 144 h after treatment. The consumption rate was significantly reduced by 2- to 12-fold in the spinosad—SfMNPV mixture treatment compared with the control, but no difference in consumption rate was observed between this treatment and the treatment with spinosad alone. Laboratory observations on the efficiency of spinosad—SfMNPV mixtures require validation in field studies under commercial growing conditions.

Lepidopteran erebid Zale phaeograpta (Hampson) has recently been found feeding on blackberry leaves (Rubus sp., cultivar “Tupi”) in two sites of Michoacan, Mexico. The life cycle and several life parameters of this insect, including parasitism, were examined in the laboratory. The egg, larva (seven instars), prepupa, pupa, and adult stages lasted 4.1, 35.9, 3.1, 14.5, and 29.1 d, respectively. Eggs are turquoise blue. The prolegs of first-instar larvae have an enlarged dark area that runs laterally. From second instar onwards, a whitish longitudinal dorsal band is observed along the entire body. Third-instar larvae wear a pair of dorsal protuberances in abdominal segment VIII. The fourth- and fifth-instar larvae are cream-colored, whereas sixth instars are entirely creamy. Pupa is covered with a waxy bloom. The apical margin of the forewings in males has two silvery bands, whereas in females, a dark band is present. Female and male pupae had the same weight (0.5 g) and measured 2.21 and 2.25 cm, respectively. The adult sex ratio of females to males was 1.1:1. The cumulative number of eggs laid by female during her lifetime was 281, with preoviposition and oviposition periods of 9.9 and 7.3 d, respectively. Maximum oviposition occurred 3.9 d after the start of oviposition (87.7 eggs per female). Larvae of Z. phaeograpta were parasitized by Microplitis sp. (Braconidae) (33%) and a currently unidentified Ichneumonidae species (9%), and pupae were parasitized by Brachymeria comitator (Walker) and another unidentified Brachymeria sp. (Chalcididae).

The combined and alone effects of azadirachtin (AZA) and Spodoptera frugiperda multicapsid nucleopolyhedrovirus (SfMNPV) on the mortality of S. frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) were evaluated in the laboratory. For this, diet surface contamination bioassays were performed on S. frugiperda in the third instar. LC50 values for SfMNPV alone were determined to be 430 and 373 viral occlusion bodies (OBs)/mm2 at 192 and 216 h after treatment, respectively. LC50 values for AZA alone were estimated for two periods of continuous exposure (4 or 5 days). In this case, LC50 values were 45.5 and 16.8 mg L−1 at 216 h after treatment (4 or 5 days of larval exposition to insecticide, respectively). We observed that although the interaction of AZA with SfMNPV increased viral pathogenicity, such improvements were of greater magnitude and more consistent at the lower OB concentration used (177 OBs/mm2). Application of SfMNPV (430 OBs/mm2), AZA (26.4 mg L−1) or SfMNPV–AZA mixtures resulted in a sign...

A greenhouse study was conducted to investigate the persistence of methoxyfenozide in pepper (Capsicum annuum L.) foliage. An aqueous suspension of methoxyfenozide was sprayed on pepper plants at concentrations of 72 and 144 mg of active ingredient (a.i.)/L. Foliage was collected at different intervals of time (0, 3, 5, 10, 20, 30, 40, and 50 days) after the treatment, and the methoxyfenozide residue was measured by high-performance liquid chromatography. The foliage was also used in bioas- says to determine the residual toxicity on and the consumption rate of the third-instar larvae of the beet armyworm, Spodoptera exigua (H¨ ubner) (Lepidoptera: Noctuidae). The methoxyfenozide concentrations observed after 50 days had decreased to 19 and 69 µg/g per sample, corresponding to a loss of 61% and 28% from the application concentra- tions of 72 and 144 mg a.i./L, respectively. When fitting a first-order kinetics degradation model, the half-life (DT50) of this compound was 76 days. Both application concentrations of methoxyfenozide caused a high mortality rate (≥97%) when the larvae were fed the pepper foliage collected at all of the time intervals. Lastly, at all of the time points, the consumption rate by the larvae was reduced to between 57% and 92% for both concentra- tions that were bioassayed. Our results indicate that, under the present greenhouse condi- tions, the degradation of methoxyfenozide was slower than that reported by other authors and that its residues were highly toxic to S. exigua larvae. The implications of these results for the management programs of this pest are discussed.

This study describes four multiple nucleocapsid nucleopolyhedrovirus isolates recovered from infected larvae of beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae), on crops in two different geographical regions of Mexico. Molecular and biological characterization was compared with characterized S. exigua multiple nucleopolyhedrovirus (SeMNPV) isolates from the United States (SeUS1 and SeUS2) and Spain (SeSP2). Restriction endonuclease analysis of viral DNA confirmed that all Mexican isolates were SeMNPV isolates, but molecular differences between the Mexican and the reference isolates were detected using PCR combined with restriction fragment length polymorphism (RFLP). Amplification of the variable region V01 combined with RFLP distinguished the two Mexican isolates, SeSLP6 and SeSIN6. BglII digestions showed that the majority of the isolates contained submolar bands, indicating the presence of genetic heterogeneity. Amplification of the variable regions V04 and V05 distinguished between American and the Spanish isolates. Biological characterization was performed against two laboratory colonies of S. exigua, one from Mexico, and another from Switzerland. Insects from the Mexican colony were less susceptible to infection than insects from Se-Swiss colony. In the Se-Mex colony, SeSP2 was the most pathogenic isolate followed by SeSIN6, although their virulence was similar to most of the isolates tested. In Se-Swiss colony, similar LD50 values were observed for the five isolates, although the virulence was higher for the SeSLP6 isolate, which also had the highest OB (occlusion body) yield. We conclude that the Mexican isolates SeSIN6 and SeSLP6 possess insecticidal traits of value for the development of biopesticides for the control of populations of S. exigua.

The toxicity and sublethal effects of methoxyfenozide were evaluated in third instars of the beet armyworm, Spodoptera exigua (Hubner) (Lepidoptera: Noctuidae), that fed on contaminated semisynthetic diet. The LC50 value was estimated at 0.23 mg of active ingredient (AI)/kg diet (range, 95% CI: 0.17–0.37) at 264 h after treatment. The effects on development, survival, and reproduction were observed in third instars of this pest that survived exposure to an LC25 concentration of methoxyfenozide. The larvae from the insecticide treatment exhibited lower pupal weights, an increase in both larval and pupal developmental times and a higher frequency of malformations of the wings in adults than untreated larvae. Adults from the methoxyfenozide treatment did not show reduced fecundity (mean cumulative number of eggs laid per female), but fertility as measured by the percentage of eggs hatched (fertility) was significantly reduced compared with untreated control insects. No significant effects were observed on pupal sex ratio. We concluded that the lethal and sublethal effects of methoxyfenozide are likely to have a significant impact on S. exigua populations on treated crops.

Susceptibility to methoxyfenozide ofSpodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) larvae was determined through exposure of neonate and fourth instars to dipped and sprayed pepper,Capsicum annum L., leaves. Methoxyfenozide and spinosad were tested against adults of this noctuid by oral, residual, and topical application. In larvae, we evaluated five (range, 0.001–10 mg active ingredient [AI]/liter) and six (range, 1–250 mg [AI]/liter) concentration levels by instars, respectively, by using two application methods at three different age leaf residues (0, 3, and 6 d after application). According to LC50 values, no significant differences were observed between the same age leaf residues of both application methods at 96 and 72 h after ingestion treatment on neonates and fourth instars, respectively. Nevertheless, toxicity of methoxyfenozide decreased significantly after time. For both application methods, the LC50 values of the first leaf residue (0 d after application) were significant...

The toxicity of spinosad and methoxyfenozide against neonates and fourth instars of Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) was tested under laboratory conditions. According to LC50 values, no significant differences were observed between spinosad (0.50 mg [AI]/kg diet) and methoxyfenozide (0.54 mg [AI] /kg diet) after 48 h of ingestion treatment on neonate larvae, based on the overlap of 95% CL. Similarly, on fourth instars, no significant differences were observed between LC50 (2.98 and 5.17 mg [AI]/kg diet for spinosad and methoxyfenozide, respectively, at 96 h after ingestion of artificial diet) and LD50 (4.74 and 2.68 μg [AI]/g larva for spinosad and methoxyfenozide, respectively, at 144 h after topical application). In addition, spinosad and methoxyfenozide significantly suppressed weight gain of neonates and fourth instars continuously fed with artificial diet containing the insecticides. The second part of this project was focused on the effects of methoxyfenozide on the reproduction of S. littoralis by determining the effect on oviposition in three different crosses and the pharmacokinetics pattern of (14C)-methoxyfenozide in the body tissues of female and male adults after topical application in their excrement and in the deposited eggs to test transport through the female and the male adult. Methoxyfenozide negatively affected the reproduction of adults regardless the treated sex, presumably because of its presence in the adult body, accumulation in the laid eggs, and slow excretion of the product. We conclude that spinosad and methoxyfenozide represent an important choice to be used in integrated pest management where S. littoralis is a major pest.

The incorporation of stilbene-derived optical brighteners into baculovirus formulations can substantially enhance virus infectivity and persistence of inoculum in the field. We evaluated the effect of the optical brightener Tinopal UNPA-GX (Sigma Chemical Co.) on the weight, development time, adult emergence and sex ratio of the principal pest of maize in the Americas, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae). Tinopal UNPA-GX was incorporated into semi-synthetic diet at a final concentration of 0.1 or 0.05% (w/v) and larvae of S. frugiperda were individually reared on the Tinopal-treated or an untreated control diet. In both Tinopal treatments, the weights of larvae and pupae were significantly reduced by up to 36 and 13%, respectively. The duration of larval development was increased by up to 30% compared to the controls. Adult emergence was high in all treatments (≈90%) and was not affected by the presence of Tinopal in the diet. Significant differences in the proportion of adult fem...

Certain optical brighteners are effective UV protectants, and can improve the insecticidal activity of baculoviruses. We evaluated the effect of 10 optical brighteners, from four chemically different groups, on the insecticidal activity of a nucleopolyhedrovirus (SfMNPV) in third instar Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae). The most effective optical brighteners were Blankophor BBH and Calcofluor M2R, both of which are stilbenes. The distyryl-biphenyl derivative, Tinopal CBS, had no effect, whereas the stilbenes, Blankophor CLE and Leucophor SAC and the styrylbenzenic derivative, Blankophor ER, resulted in a decrease in virus induced mortality compared to larvae infected with SfMNPV alone. Mixtures of SfMNPV + 0.1% Calcofluor M2R had relative potencies of 2.7, 6.5, and 61.6 in the second, third, and fourth instars, respectively. The mean time to death differed with instar, but was not affected by the addition of 0.1% Calcofluor M2R. Analysis of published studies indicated that the concentration of Calcofluor M2R-related stilbenes was positively correlated with the relative potency observed in mixtures with homologous NPVs. The average magnitude of optical brightener activity did not differ significantly between early instars of 10 species of Lepidoptera. We conclude that virus formulations containing optical brighteners may be valuable for control of late instar lepidopteran pests.

Stilbene-derived optical brighteners greatly enhance the infectivity of a number of baculoviruses. This technology has been patented for use with insect pathogenic viruses in the United States and Canada. A baculovirus is currently being tested for its potential as a biological insecticide of Spodoptera frugiperda (Lepidoptera: Noctuidae), the principal insect pest of maize in Mesoamerica. A multiply embedded nucleopolyhedrovirus isolate originally from Nicaragua was bioassayed alone and in the presence of the optical brightener Tinopal LPW (1%), using second instar S. frugiperda larvae. The LC50 value of the virus alone was calculated at 82.1 polyhedral inclusion bodies (PIBs)/mm 2 of diet compared with 0.71 PIBs/mm 2 in the presence of Tinopal LPW. In contrast to other studies, the mean time to death of larvae exposed to virus and Tinopal LPW was significantly extended compared to larvae inoculated with virus alone. Analysis of the results of eight independent field trials in Mexico and Honduras revealed a significant positive relationship between log virus dose and percentage mortality observed in S. frugiperda larvae. Virus-induced mortality was approximately 50% at the highest application rate tested: 1000 larval equivalents (LE) of virus/ha. When the impact of parasitism was taken into account, larval mortality increased to 45.0‐90.7% in plots treated with virus at 250 LE/ha or more. A cost analysis indicated that approximately 60% pest control can be achieved as a conservative estimate with virus application and the action of parasitoids for the price of a chemical insecticide. Formulating the virus with an optical brightener appears to be an attractive option based on laboratory findings but requires field testing. The use of optical brightener technology will probably be feasible for maize growers in Mesoamerica only if it is highly effective at very low concentrations (F0.1%) or the volume of the virus application can be reduced. r 2000 Academic Press

The long-term effects of methoxyfenozide on the longevity and reproductive processes of beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae), adults were assessed after exposure by ingestion. Methoxyfenozide significantly reduced adult male longevity compared with females by 1.1 and 1.5 d at 75 and 150 mg (AI)/liter, respectively. Fecundity decreased by >60% with both concentrations at 72 and 96 h after treatment, but at 48 h, no significant effect was observed. The carbohydrate, protein, and lipid content in the eggs were determined as representatives of the biochemical effects of methoxyfenozide associated with the disruption of reproductive processes. The content of carbohydrates in the eggs laid 48 h at treatment was similar to that of controls, but it increased by ≈1.5 and 2-fold in eggs laid after 72 and 96 h, respectively, compared with controls (15 μ g per egg). Protein content was reduced ′2.5 and ′3-fold for each treatment concentration, respectively, compared with the controls (25 and 23 μg per egg for 75 and 150 mg [AI]/liter, respectively) in eggs collected 72 and 96 h after treatment. Lipid content significantly decreased by ≈1.6-fold in both treatment concentrations in eggs collected at 48 and 96 h after treatment compared with the controls (24 and 21 μg per egg for 48 and 96, respectively), but it was similar to controls (=19 μg per egg) at 72 h (≈15 μg per egg) for both concentrations. The biochemical effects of methoxyfenozide on S. exigua egg formation detected in this work are consistent with the reduction in fertility observed, as reported previously. Fil: Luna, Juan Carlos. Universidad Michoacana de San Nicolás de Hidalgo; México Fil: Robinson, Virginia Angélica. Universidad Michoacana de San Nicolás de Hidalgo; México Fil: Martinez, Ana Mabel. Universidad Michoacana de San Nicolás de Hidalgo; México Fil: Schneider, Marcela Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; Argentina Fil: Figueroa, Jose Isaac. Universidad Michoacana de San Nicolás de Hidalgo; México Fil: Smagghe, Guy. University of Ghent; Bélgica Fil: Viñuela, Elisa. Universidad Politécnica de Madrid; España Fil: Budia, Flor. Universidad Politécnica de Madrid; España Fil: Pineda, Samuel. Universidad Michoacana de San Nicolás de Hidalgo; México

The lethal and sublethal effects of the ecdysone agonist methoxyfenozide on the fall armyworm, Spodoptera frugiperda (J. E. Smith), were investigated by feeding a methoxyfenozide-treated diet to fifth instars until pupation in doses corresponding to the LC10 and LC25 for the compound. Larval mortality reached 8% and 26% in the low and high concentration groups, respectively, on the seventh day of the experiment. A progressive larval mortality of 12% for the LC10 and 60% for the LC25 was observed before pupation. Treated larvae exhibited lower pupal weights, higher pupal mortality, presence of deformed pupae, and more deformed adults than untreated larvae. The incorporation of methoxyfenozide into the diet had a significant effect on the timing of larval development. The development period for males and females was about seven days longer than the controls for both concentrations tested. In contrast, the compound affected neither pupae nor adult longevity. Finally, S. frugiperda adults that resulted from fifth instars treated with methoxyfenozide were not affected in their mean cumulative number of eggs laid per female (fecundity), nor percentages of eggs hatched (fertility), or the sex ratio. Our results suggest that the combination of lethal and sublethal effects of methoxyfenozide may have important implications for the population dynamics of the fall armyworm., Centro de Estudios Parasitológicos y de Vectores

The incidence of cannibalism of larval Spodoptera frugiperda (Lepidoptera: Noctuidae) on maize under field conditions was investigated using field cages. Cannibalism was found to account for approximately 40% mortality when maize plants were infested with two or four fourth-instar larvae over a 3-day period. Field trials examined the effect of larval density on the prevalence of natural enemies of S. frugiperda. The abundance of predators (earwigs, staphylinids, other predatory beetles, and Chrysoperla spp.) was significantly greater on maize plants with higher levels of larval feeding damage, while the relationship between predator abundance and number of S. frugiperda larvae per plant was less clear. As larval damage is probably a more reliable indicator of previous larval density than numbers collected at an evaluation, this indicates that predation risk will be greater for larvae living in large groups. Parasitism accounted for 7.1% mortality of larvae in sorghum, and involved six species of Hymenoptera and Tachinidae. There was no effect of larval density or within-plant distribution on the probability of larval attack by parasitoids. The selective benefits of cannibalism, in relation to the risk of predation and parasitism, are discussed.

A new species of Colpoclypeus Lucchese (Hymenoptera: Eulophidae) is described and illustrated. Colpoclypeus michoacanensis Sánchez & Figueroa attacks Argyrotaenia montezumae Walsingham (Lepidoptera: Tortricidae) on blackberry plants. A key is included to separate C. michoacanensis from C. florus (Walker), the only other species in this genus.

Stilbene-derived optical brighteners can markedly enhance the insecticidal activity of certain baculoviruses. We evaluated the influence of an optical brightener on the rate at which Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) developed resistance to nucleopolyhedrovirus (SfMNPV). Two laboratory colonies of S. frugiperda were inoculated with an LC50 of SfMNPV, in the absence or presence of the optical brightener Tinopal LPW (0.1%), over a period of two and 11 generations, in the first and second experiment, respectively. Compared with the initial susceptibility of the insect colony, resistance ratios of 11- and 12-fold were observed after two generations of treatment with SfMNPV + Tinopal LPW and SfMNPV alone. Similar, but variable degrees of resistance were observed in the long-term experiment with resistance ratios of 8- to 35-fold after seven to 11 generations. The presence of Tinopal LPW alone, or in mixtures with SfMNPV, did not cause any systematic change in insect resistance in either experiment. At the end of the long-term experiment, debilitating effects on pupal weight, adult fecundity, and longevity were observed in the insects exposed to Tinopal LPW alone or in mixtures with SfMNPV, but the pattern of such effects among treatments differed in each generation. We conclude that optical brighteners are unlikely to affect the rate of development of resistance to nucleopolyhedroviruses applied as biological insecticides.