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In the present study, the influence of three sex ratios (1:1, 1:2, and 1:3; female:male) of the miridEngytatus varians(Distant) (Hemiptera) on different biological parameters and on its offspring was evaluated. The prey preference of different developmental stages of this predator for different nymphal instars (N) ofBactericera cockerelli(Sulcer) (Hemiptera: Triozidae) was also evaluated. The fertility was significantly higher (24 nymphs/female) in the 1:3 sex ratio than in the 1:1 and 1:2 sex ratios (14 and 16 nymphs/female, respectively). The females in the 1:1 and 1:2 sex ratios lived 1.14 and 1.43 days more (27 and 28 days, respectively) than those in the 1:3 sex ratio (26 days). The nymphs derived from the females of the three sex ratios (first filial generation, F1) had five instars and a duration of 17 or 18 days. The ratio of the F1generation females was not affected by the sex ratio of their parents. In choice tests, independent of whether the preys were placed on a single or multiple tomato (Solanum lycopersicumL.) leaflets, the consumption of females and males and N3, N4, and N5nymphs ofE. variansonB. cockerelli, generally showed the order of N2>N3>N4>N5. In conclusion, the findings revealed in this study can help to improve the rearing methodology for increasing populations ofE. varians. In addition, they can serve as a guideline for releasing this predator in times when there is an abundance of early instar nymphs ofB. cockerelli.

Este estudio estimó la diversidad de avispas del género Blacus Nees (Braconidae, Blacinae) en dos ecosistemas forestales del noreste de Michoacán, en el Eje Neovolcánico Transversal: Parque Nacional Cerro de Garnica (PN C-Garnica) y Zona Protectora Forestal Los Azufres (ZPF Los Azufres). Se elaboró un mapa de cobertura vegetal con imágenes satelitales de estos ecosistemas forestales. La captura de especímenes se realizó mensualmente desde marzo 2008 hasta febrero 2010 con la ayuda de platos-trampa de color amarillo. Se capturó un total de 172 especímenes de 17 especies del género Blacus, de los cuales 84.3% provinieron del PN C-Garnica (13 especies) y 15.7% de la ZPF Los Azufres (10 especies). El porcentaje de similitud indicó una composición de especies diferente entre las dos áreas estudiadas (índice de Jaccard = 0.35). En el PN C-Garnica se capturaron significativamente más especímenes por mes que en la ZPF Los Azufres (12.1 ± 4.0 vs 2.3 ± 1.20). De acuerdo con el índice de Shannon-Wiener, la diversidad fue similar en ambas áreas estudiadas (2.1 vs 1.9). Los estimadores de riqueza Chao 2 y Jackknife 2 indicaron que en ambas áreas se capturó ~60% de las especies esperadas. Se concluye que el PN C-Garnica y la ZPF Los Azufres mantienen una alta diversidad de especies de Blacus. Las mayores abundancias, así como la mayor riqueza de especies se encontraron en el PN C-Garnica, la cual es una zona con mayor grado de perturbación.

BACKGROUND The multiple nucleopolyhedrovirus of Spodoptera frugiperda (SfMNPV) plays an important role in regulating its natural host and has high potential for use as a bioinsecticide. However, information about how agricultural practices such as fertilization and plant biotic interactions affect the biocontrol efficacy of SfMNPV is limited. In this study, we examined how multitrophic maize-mycorrhiza-insect herbivore interactions affect the biocontrol efficacy of SfMNPV against S. frugiperda under full and reduced mineral nitrogen fertilization. Two fully factorial greenhouse pot experiments with three factors were performed: (i) arbuscular mycorrhizal fungi (AMF) (with and without AMF), (ii) nitrogen fertilization (50% and 100% N), and (iii) insect (with and without of S. frugiperda). The biocontrol efficacy of SfMNPV against S. frugiperda was examined using detached leaves under controlled environmental conditions. RESULTS Associating maize with AMF resulted in multitrophic cascade effects. Plants with AMF showed suppression of plant growth and increased leaf N and P content, which coincided with increased foliar herbivory and larval biomass that finally reduced the susceptibility of S. frugiperda to SfMNPV. Reduced levels of N fertilization mitigated these observed cascade effects on the biocontrol efficacy of SfMNPV with maize mycorrhizas. CONCLUSION Our results show that AMF can modulate S. frugiperda-SfMNPV interactions via plant-mediated phenotypic responses to the mycorrhizal association and are most likely linked with increased leaf food quality for S. frugiperda. These results call for further studies to address the mode of interaction and possible implications for pest management in maize agroecosystems. © 2021 Society of Chemical Industry.

The ectoparasitoid Tamarixia triozae is a promising biological control agent of the tomato psyllid, Bactericera cockerelli, based on its high parasitism rates on different crops. The parasitism, host feeding, and transgenerational effects (in terms of sex ratio) of T. triozae females exposed to three insecticides (soybean oil, imidacloprid, and abamectin) as eggs, larvae, and pupae were evaluated when a mixture of second, third, fourth, and fifth instars of the host B. cockerelli was offered. The concentrations bioassayed of each insecticide corresponded to the minimum field-registered concentration [MiFRC] and one-half the MiFRC. No parasitism of B. cockerelli second instars was recorded when parasitoid's females were exposed in any of the three immature stages to any of the insecticides. In contrast, in some cases, parasitism of T. triozae females treated as eggs, larvae, or pupae with soybean oil and imidacloprid was reduced in third, fourth, or fifth instar. In most cases, the host feeding was reduced in second and third instar of the host B. cockerelli when T. triozae females were treated as eggs, larvae, or pupae. Any insecticide modified the sex ratio in the F2 generation. In conclusion, both parasitism and host feeding were affected by the insecticides depending on the concentration and on the nymphal instar of the host B. cockerelli offered.

A greenhouse study was conducted to investigate the degradation kinetics of spinosad, flufenoxuron, dimethoate and imidacloprid in tomato (Solanum lycopersicum L.) foliage and their residual toxicity on Engytatus varians (Distant) (Hemiptera: Miridae), a predator of the tomato psyllid Bactericera cockerelli (Sulcer) (Hemiptera: Triozidae). Insecticides were sprayed at 100% and 50% of their maximum field-registered concentrations (MFRC). Starting 6 h after spraying, leaf samples were taken every 10 d for 40 d and analyzed while E. varians adults were exposed to treated leaves to evaluate residual toxicity. Immediately after application at 100% MFRC, the residue concentrations were 73.34 μg g−1 spinosyn A and 59.2 μg g−1 spinosyn D, 9.21 μg g−1 flufenoxuron, 71.49 μg g−1 dimethoate and 31.74 μg g−1 imidacloprid. At 50% MFRC, initial residue concentrations were between 75% and 90% those at 100% MFRC. The estimated half-life (DT50) of spinosyns A and D, flufenoxuron, and dimethoate was between 34 and 40 d, while that of imidacloprid was 112 d. Flufenoxuron caused no mortality, while mortality due to spinosad was less than 10%, and only during the first 10 d. Mortality caused by either imidacloprid or dimethoate was around 100% up to 10 d after application, then decreased to around 30% after 40 d. Dimethoate toxicity was approximately proportional to residue concentration, while for imidacloprid there was an apparent threshold around 15 μg g−1. These results can be used to establish periods harmless for release of E. varians in the control of B. cockerelli on tomato crops under greenhouse conditions.

Acalitus orthomera (Keifer) es registrado por primera vez en el Municipio de Ziracuaretiro, Michoacán, México, asociado a brotes vegetativos en cultivos de zarzamora; se proporciona información sobre su daño y su importancia en este cultivo es discutida.

Predation byEngytatus varians(Distant) adults on different development stages of the prey speciesBactericera cockerelli(Sulcer) (egg, second, and third nymphal instars),Spodoptera exigua(Hübner) andSpodoptera frugiperda(J. E. Smith) (egg, first, and second larval instars) was evaluated using tomato (Solanum lycopersicumL.) leaflets or plants. These insects are the primary pest of several agriculturally important crops. The influence ofE. variansage on the predation capacity was also analysed.Engytatus variansfemales consumed significantly moreB. cockerellieggs and nymphs than males. Additionally, female predators consumed significantly more second than third instar prey at two predator ages, while males consumed significantly more the second instar than third instar prey at all predator ages. In most of the cases, females also consumed significantly moreS. exiguaandS. frugiperdaeggs than males; however, in terms of larvae consumption, this difference was observed only in some predator ages. Females consumed more the first than second instarS. exiguathan males, whereas this behaviour was only observed in males when the predators were 15 and 17 days old. No significant differences were observed in the consumption of first and second instar ofS. frugiperdafor both sexes of the predators. Predator age did not cause any systematic effects on the predation rates of any prey species. Based on these results, we confirmed thatE. varianshas potential as a biological control agent forB. cockerelliand also for theSpodopteraspecies bioassayed.

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.

BACKGROUND Control of the Asian citrus psyllid Diaphorina citri Kuwayama, the most important pest of citrus worldwide, is based on the use of insecticides, though unsatisfactory results have recently been reported. In this study, insecticide resistance of D. citri to three insecticides (bifenthrin, malathion, and chlorpyrifos) was examined. RESULTS Three populations (designated Dci-CParacuaro, Dci-El Junco, and Dci-Antunez) of both adults and fourth-instar D. citri individuals were collected in 2014 at two different times and on one occasion, respectively, from three locations (Crucero de Paracuaro, El Junco, and Antunez). These locations represent the major commercial Mexican lemon production areas in the Apatzingan Valley in the state of Michoacan, Mexico. The three populations of D. citri adults and fourth-instar nymphs at the different collection times showed low levels of resistance (≤7-fold) to bifenthrin, but were very resistant to malathion (≤345- and ≤432-fold for adults and fourth instars, respectively) and chlorpyrifos (≤2435- and ≤1424-fold for adults and fourth instars, respectively). CONCLUSION Resistance levels to the tested insecticides were highly variable but homogeneous among seasons and localities. Resistance management programmes that include crop sanitation, use of biological and cultural control practices, and rotation of insecticide classes should be established, particularly in areas where D. citri has developed resistance to malathion and chlorpyrifos. © 2017 Society of Chemical Industry

Lethal and sublethal effects of refined soybean oil, imidacloprid, and abamectin on Tamarixia triozae (Burks; Hymenoptera: Eulophidae) were assessed after exposure of the eggs, larvae, and pupae of this parasitoid to three concentrations of these active substances: the LC50 for fourth-instar Bactericera cockerelli (Sulc.; Hemiptera: Triozidae)and 50% and 100% of the minimum field-registered concentration (MiFRC). Soybean oil caused 26-61% mortality in T. triozae eggs and 6-19% in larvae; mortality in both eggs and larvae was ≤19% for imidacloprid and 4-100% for abamectin. All three compounds caused T. triozae pupae, with the exception of the abamectin 50% (47%) and 100% (72%) MiFRC. The mortality of larvae and pupae derived from treated eggs was ≤39% for all three insecticides, and that of pupae derived from treated larvae was ≤10%. In general, emergence of adults developed from treated eggs, larvae, and pupae was affected more by abamectin than by the other treatments. The proportion of females derived from all three development stages was not affected by treatment with the compounds, except when the parasitoid was treated as larvae with the soybean oil 100 and 50% MiFRC (66 and 68%, respectively) or when treated as pupae with the imidacloprid LC50 and 100% MiFRC (~60%). Female longevity was generally higher than that of males. The use of imidacloprid, soybean oil, and abamectin in combination with T. triozae for pest control may be effective when the parasitoid is in the pupal stage because this stage is less susceptible than other immature stages., Centro de Estudios Parasitológicos y de Vectores

Tamarixia radiata (Waterson) (Hymenoptera: Eulophidae) is an idiobiont ectoparasitoid of the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae). This study evaluated natural parasitism of the different nymphal instars of D. citri by T. radiata on three different dates in 2015 at four sites with Mexican lemon (Citrus aurantifolia Swingle) groves and at one site with orange jasmine (Murraya paniculata [L.] Jacq.) plants in the Apatzingan Valley, Michoacan state. Different patterns of parasitism by T. radiata were observed among the different nymphal instars of D. citri, sites, and collection dates. No parasitism of first and second instars was observed, and it only reached up to 5.0% in third instars. In fourth and fifth instars, parasitism was highly variable (2-69 and 1-38%, respectively). In terms of the accumulated parasitism across host instars, the highest percentages were observed in the collections conducted in May in Crucero de Paracuaro (86%) and Antunez (91%), and they were approximately 45% in the collections conducted on 23 March in Antunez and on 10 April in Nueva Italia-2. In the remaining collections, parasitism was between 2 and 15%. Our results suggest that T. radiata is an important mortality factor for populations of D. citri; this could have potentially important implications for the biological control of D. citri and for the management of huanglongbing, a disease transmitted by D. citri, in citrus groves.

Engytatus varians (Distant) (Hemiptera: Miridae) es una especie zoofitófaga debido a que se alimenta de las plantas hospederas y de los insectos que viven en ellas como áfidos, moscas blancas, pseudocóccidos y lepidópteros. Actualmente, esta especie presenta una amplia pero imprecisa distribución. En este trabajo se reporta por primera vez la presencia de E. varians en México depredando ninfas del psílido del tomate, Bactericera cockerelli (Šulc) (Hemiptera: Triozidae) bajo condiciones de invernadero. En promedio, una ninfa de cuarto estadio de E. varians se alimentó de 46% de las ninfas de tercer estadio de B. cockerelli en un periodo de 24 h. Este resultado muestra que este depredador podría representar un candidato potencial para el manejo del psílido del tomate. También se incluye información de su distribución, plantas hospederas y presas.

The leafroller, Amorbia cuneana (Walsingham) (Lepidoptera: Tortricidae), is recorded for the first time in blackberry (Rubus sp. cultivar Tupi) in Rancho Huatarillo, Municipality of Peribán, in the state of Michoacán, Mexico. It is important to assess the damage that this insect may cause to the plants, in order to avoid the possibility that it reach the pest status in the later crop.

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.

BACKGROUND: The immediate lethality caused by spinosad has been widely studied onSpodopteraexigua(H¨ ubner). However, long-term effects can also provide valuable information on insecticide toxic action. Here, the persistence of spinosad on Capsicum annuum L. foliage and the lethal and sublethal effects of greenhouse-aged foliar residues of this insecticide on third instars of S.exigua are reported. RESULTS: Foliage was collected at 0, 3, 5, 10, 20, 30, 40 and 50 days after application, and spinosad residues were measured. Residues decreased over time according to first-order kinetics. The average rate constant and half-life of disappearance were 4.44×10 −3 and156 daysand5.80×10 −3 and120 daysfor60and120 mg L −1 respectively.Larvalmortalitygraduallydecreased, corresponding to the residues, but was still appreciable (35 and 65% for 60 and 120 mg L −1 respectively) when the larvae were fed with foliage collected 50 days after treatment. Subsequently, pupal development was reduced and varied between 20 and 60% and between 21 and 41% for 60 and 120 mg L −1 , respectively, in all ages of leaf residues that were bioassayed. At all time points, the consumption rate by the larvae was reduced between 62 and 84% for both concentrations that were bioassayed. CONCLUSION:Itisconcludedthat,underthepresentgreenhouseconditions,thedegradationofspinosadwasslowerthanthat reported by other authors in the field, and, because of that, its residues could cause lethal and sublethal effects to S. exigua larvae. c � 2012 Society of Chemical Industry

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.

BACKGROUND: Resistance to spinosad and methoxyfenozide has been studied in several insect pests, but there is a lack of information on Spodoptera exigua (Hubner) in Mexico. Therefore, evidence for the development of resistance in this pest to both compounds was examined. The effects of methoxyfenozide on reproductive parameters of S. exigua adults were also determined. RESULTS: Third instars from a field population were exposed for 24 h to the LC50 of spinosad or methoxyfenozide for over six generations (G2–G7). No significant reduction in susceptibility to either compound was detected for up to five generations. In G7, LC50 values for insects exposed to spinosad and methoxyfenozide were respectively 2.75-fold and 1.25-fold greater than for G1 larvae. Oral treatment with methoxyfenozide reduced the fecundity and fertility of G7 adults, confirming sublethal effects on reproduction. Finally, five populations (Se-La Floriza, Se-Lazareto, Se-Bachigualato, Se-Los Agustinos and Se-Villa de Arista) of S. exigua were collected from fields in three states of Mexico for resistance monitoring to spinosad and methoxyfenozide. With the exception of Se-Villa de Arista, the other populations showed significant resistance to spinosad, with resistance ratios between 16- and 37-fold, compared with a susceptible laboratory colony. In contrast, only one population (Se-Lazareto) showed significant resistance to methoxyfenozide (13-fold). CONCLUSION: Resistance management programmes should be established, particularly in areas where S. exigua has developed resistance to spinosad. Copyright © 2008 Society of Chemical Industry

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...

RESUMEN. Los enrolladores de hojas Argyrotaenia montezumae Walsingham y Amorbia sp. son espe-cies de tortricidos asociados a plantas de zarzamora, en Michoacan, Mexico. En este estudio se analiza y compara la abundancia y diversidad de parasitoides asociados a estas especies de enrolladores en dos plantaciones comerciales en Los Reyes, Michoacan. Se recolectaron 1682 hojas tiernas infestadas con larvas de enrolladores, de donde se obtuvieron 994 ejemplares de cuatro especies de parasitoides. Los parasitoides obtenidos fueron Chelonus sp. (41.6%), Apanteles n. sp. (34.2%), Colpoclypeus michoaca-nensis Sanchez y Figueroa (23.1%) y Bracon sp. (1%). Apanteles n. sp. registro el porcentaje de parasi-tismo mas alto (26.9%) y el que con mayor periodicidad se presento. Palabras clave: Zarzamora, tortricidos, parasitismo natural, periodicidad, control biologico Martinez, A. M., Barreto-Barriga, O., Pineda, S., Rebollar-Alviter, A., Chavarrieta, J. M. & Figueroa, J. I. 2014. Parasitoids associated with the blackberry leafrollers

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

Susceptibility to methoxyfenozide of Spodoptera 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 significantly lower than those of 6-d-old residues. Furthermore, larval weight of fourth instars fed for 48 h with pepper, Capsicum annum L., leaves containing methoxyfenozide was significantly suppressed. Spinosad and methoxyfenozide reduced in a dose-dependent manner the fecundity and fertility of S. littoralis adults when treated oral and residually. Likewise, when methoxyfenozide was administered orally in three different adult crosses, the fecundity was strongly affected, independently of the treated sex. We conclude that the combination of lethal and sublethal effects of methoxy-fenozide and spinosad might exhibit significant effects on the population dynamics of S. littolaris.

Apanteles nr. aristoteliae (Viereck) (Hymenoptera: Braconidae) es un endoparasitoide de larvas del enrollador de las hojas Amorbia sp. (Lepidoptera: Tortricidae). En este estudio se determinó, bajo condiciones de laboratorio (22 ± 2 ºC, 60 ± 5% de humedad relativa y un fotoperiodo de 16:8 h [luz: oscuridad]) el ciclo de vida, parasitismo, proporción sexual y longevidad de adultos de este parasitoide. La duración del ciclo de vida fue de 42.45 ± 0.76 días. El tiempo de desarrollo de los estados de huevolarva, pupa y adulto fue de 14.04 ± 0.05, 9.22 ± 0.07 y 19.36 ± 0.74 días, respectivamente. A lo largo de toda su vida, cada hembra de A. nr. aristoteliae parasitó 73.33 ± 7.55 larvas del enrollador de las hojas Amorbia sp. La proporción sexual de la generación F1 fue de 95.1% machos (n = 912). La longevidad de los adultos fue significativamente distinta (U = 564, P = 0.01) entre los machos apareados (27 ± 2.55 días) y vírgenes (19.75 ± 0.70 días), pero no (U = 182, P = 0.3) entre las hembras apareadas y que fueron sometidas a parasitación durante toda su vida (26.4 ± 2.88 días) y vírgenes (23.13 ± 1.4 días). Con el fin de obtener un mejor conocimiento de los parámetros de vida del parasitoide A. nr. aristoteliae, es necesario realizar futuros estudios que incluyan diferentes condiciones de cría (ej., temperatura y espacio).

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.

The impact of commonly used organophosphate (chlorpyrifos, methamidophos), carbamate (carbaryl), and pyrethroid (cypermethrin) insecticides on insect natural enemies was compared with that of a nucleopolyhedrovirus (Baculoviridae) of Spodoptera frugiperda (J. E. Smith) (Lepidoptera Noctuidae) in maize grown in southern Mexico. Analyses of the SELECTV and Koppert Side Effects (IOBC) databases on the impact of synthetic insecticides on arthropod natural enemies were used to predict approximately 75-90% natural enemy mortality after application, whereas the bioinsecticide was predicted to have no effect. Three field trails were performed in mid- and late-whorl stage maize planted during the growing season in Chiapas State, Mexico. Synthetic insecticides were applied at product label recommended rates using a manual knapsack sprayer fitted with a cone nozzle. The biological pesticide was applied at a rate of 3 x 10(12) occlusion bodies (OBs)/ha using identical equipment. Pesticide impacts on arthropods on maize plants were quantified at intervals between 1 and 22 d postapplication. The biological insecticide based on S. frugiperda nucleopolyhedrovirus had no adverse effect on insect natural enemies or other nontarget insect populations. Applications of the carbamate, pyrethroid, and organophosphate insecticides all resulted in reduced abundance of insect natural enemies, but for a relatively short period (8-15 d). Pesticide applications made to late-whorl stage maize resulted in lesser reductions in natural enemy populations than applications made at the mid-whorl stage, probably because of a greater abundance of physical refuges and reduced spray penetration of late-whorl maize.