Efeito da adição de colesterol e ecdisona na produção in vitro do baculovírus spodoptera frugiperda MNPV

Among the pests that attack corn crop in Brazil, there is Spodoptera frugiperda (JE Smith, 1797) (Lepidoptera: Noctuidae), known as fall armyworm, which is the major corn pest. Due to genetic instability during serial passage of baculoviruses in insect cell culture, the viral bioinseticides in vitro production development is the greatest challenge for mass production of this bioproduct. Successive passages of virus using extracellular viruses (BVs), necessary during viral bioinseticides production scaling up, leads to the appearance of aberrant forms of virus, a process so called as "passage effect ". The main consequence of passage effect is the production of occlusion bodies (OB) decrease, preventing its production using in vitro process. In this study, it was carried out a serial passage of baculovirus Spodoptera frugiperda multiple nucleopolyhedrovirus, isolate 18, using Sf21 cells. A decrease in the production of occlusion bodies from 170 to 92 in the third to fourth passage was observed. A factorial experimental design (22) was employed to verify the influence of two input variables, concentration of the hormone 20 - hydroxyecdysone (CH) and cholesterol (CC) on the values of response variables (volumetric and the specific OB production) of the process, seeking to define the optimum operating ranges trying to reverse or minimize the passage effect. The result indicated a negative influence of the cholesterol addition and positive effect in the hormone supplementation which the optimum range found for the concentrations studied were 8 to 10μg/mL and 5 to 6.5 mg / mL, for cholesterol and hormone concentrations respectively. New experiments were performed with addition of hormone and cholesterol in order to check the influence of these additives on the OB production independently. While the best result obtained from the factorial experiment was 9.4 x 107 OB/mL and 128.4 specific OB/cell, with the addition of only 6μg/mL 20-hydroxyecdysone these concentrations increased to 1.9 x 108 OB/mL and 182.9 OB/cell for volumetric and specific OB production, respectively. This result confirms that the addition of the hormone 20-hydroxyecdysone enhances the SfMNPV in vitro production process performance using Sf21 cells

Parasitism capacity of Telenomus remus Nixon (Hymenoptera: Scelionidae) on Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) eggs

Este trabalho estudou a capacidade de parasitismo de Telenomus remus Nixon (Hymenoptera: Scelionidae) em ovos de Spodoptera frugiperda (Smith) (Hymenoptera: Scelionidae) nas temperaturas de 15, 20, 25, 28, 31 e 35ºC objetivando usar esse inimigo natural em programas de controle biológico em culturas onde S. frugiperda é considerada praga. O parasitismo ocorrido nas primeiras 24 h foi de 60,90; 81,65; 121,05; 117,55 e 108,55 ovos parasitados por fêmea em massas ovos com aproximadamente 150 ovos, nas temperaturas de 15, 20, 25, 28 e 31ºC. Fêmeas de T. remus causaram mais de 80% do parasitismo dos ovos nas temperaturas de 15, 20, 25, 28 e 31ºC aos 5, 27, 8, 2 e 2 dias, respectivamente. Na temperatura de 35ºC não houve parasitismo. As maiores taxas de parasitismo ocorreram nas temperaturas de 20, 25, 28 e 31ºC. A longevidade média de fêmeas de T. remus nas temperaturas compreendidas entre 15 e 31ºC variou de 15,5 a 7,7 dias. A temperatura máxima testada (35ºC) foi inadequada ao desenvolvimento de T. remus, sendo que nessa temperatura as fêmeas apresentaram longevidade bastante reduzida (1,7±0,02 dia) e não houve emergência de adultos. Todas as curvas de sobrevivência para T. remus foram do tipo I o que mostram que para todas as temperaturas há um aumento da taxa de mortalidade com o tempo.

Ação de Polistes (Aphanilopterus) simillimus Zikán (Hymenoptera, Vespidae) no controle de Spodoptera frugiperda (Smith) (Lepidoptera, Noctuidae)

The corn is a plantation attacked by a lot of pests, mainly by Caterpillar Spodoptera frugiperda (Smith), producing serious damages in the plants, occasioning unproductiveness. Thus, the goal of this research was to verify the predation of Polistes simillimus (Zikán, 1951) wasps on this pest of a corn plantation using the wasps colonies as a efficient form of this pest management. The present research was developed in a area in the Piracicaba county, São Paulo (22º43'S, 47º38'W), during the period of november/1995-march/1996, introducing 20 P. simillimus colonies in artificial wood shelters around of 5 plots of com, to accompany the foraging activity of the wasps and the development of the wasps colonies. Spodoptera frugiperda (23,07%) was the main prey captured by the wasps and the average rate of capture was 1,54 preys/h. These data gave an estimation of reduction in the occurrence of S. frugiperda (77,16%), due mainly to the wasps action.

Parasitismo em lagarta-do-cartucho, Spodoptera frugiperda (Smith), na região do Triângulo Mineiro, MG

Com o objetivo de avaliar a freqüência e distribuição de parasitóides associados a larvas da lagarta do cartucho, Spodoptera frugiperda (Smith), foram realizadas amostragens em campos comerciais da cultura do milho (Zea mays), nos anos agrícolas 1991/92 (duas regiões) e 1992/93 (cinco regiões). em cada local amostrado foram coletadas aproximadamente 100 larvas, em plantas com 20 a 40 dias após a emergência. As larvas foram criadas em laboratório a 25 ± 2ºC, UR 50 - 60%, fotoperíodo de 14 horas e observadas diariamente. Os parasitóides mais freqüentes foram: Chelonus texanus (Cresson) (Hymenoptera: Braconidae), Diadegma sp. (Hymenoptera: Ichneumonidae) e Archytas incertus (Macquart) (Diptera: Tachinidae). Foi observado que o parasitismo total foi de 10,3% em 1991/92 e 13,8% em 1992/93. Os parasitóides Diptera apresentaram preferência pela fase de pupa da lagarta do cartucho (76,5%), nos dois anos agrícolas. Os parasitóides Hymenoptera tiveram preferência por larvas de 3º e 4º ínstares (41,9 e 45,2%), no ano agrícola 1991/92 e de 2º e 3º ínstares (39,1 e 43,5%), no ano agrícola 1992/93.

Oil-soluble dyes for marking Spodoptera frugiperda (Lepidoptera : Noctuidae)

Although various biological aspects of Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) have been examined, adult movement and dispersal of this insect pest is not well understood. Release-recapture techniques by using marked insects is a useful approach for dispersal studies; however, the marking technique should not significantly affect insect biology or behavior. Therefore, the effect of different concentrations of oil-soluble dyes (Solvent Blue 35 [C.I. 61554], Sudan Red 7B [C.I. 26050], Sudan Black B [26150], Sudan Orange G [C.I. 11920], and Sudan I 103624 [C.I. 12055]) on development, mortality, and fecundity of S. frugiperda was evaluated. Dyes were added to artificial diet used to feed larvae. Larval and pupal development and mortality, adult longevity, and female fecundity were evaluated. High concentrations (400 and 600 ppm) of all dyes led to longer larval and pupal stages. Adult life span and number of eggs were not affected by the dyes. Sudan Red 7B marked both adults and eggs very well. Solvent Blue 35 marked both adults and eggs, but the blue-marked eggs could not be distinguished from some bluish eggs laid by nonlabeled females. Adults and eggs were not adequately marked by the Sudan Black B, Sudan Orange G, and Sudan I 103624 (a yellow dye).

Amostragem seqüential (presença-ausência) para Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) na cultura do milho

The sequential sampling of insect pests (presence-absence) has become important in the last years, specially when the insects are difficult to be quantified. To solve this problem in relation to Spodoptera frugiperda (J. E. Smith), a sequential sampling plan was developed. The sample unit was evaluated considering the presence or absence of the insect, independently of its total number. The experiment was conducted in Jaboticabal, São Paulo State, Brazil, in three fields of 0.5 ha divided in 100 plots of 50 m2 (5 × 10 m). Each plot was identified with a number from 1 to 100. A threshold level of 20% was assumed to set the sampling plan. The analyzed data allowed two lines to be generated: the superior one, representing the condition in chemical control is recommended (S1=1.7095+0.1452N); and the inferior one, when chemical control is not recommended (S0=-1.7095+0.1452N). The sequential sampling was efficient to indicate if control of S. frugiperda on corn crop was necessary or not.

Interaction of Bacillus thuringiensis Cry1 and Vip3A proteins with Spodoptera frugiperda midgut binding sites

Vip3Aa, Vip3Af, Cry1Ab, and Cry1Fa were tested for their toxicities and binding interactions. Vip3A proteins were more toxic than Cry1 proteins. Binding assays showed independent specific binding sites for Cry1 and Vip3A proteins. Cry1Ab and Cry1Fa competed for the same binding sites, whereas Vip3Aa competed for those of Vip3Af. Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Corn yield with reduction of insecticidal sprayings against fall armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae)

The ideal time is more important than amount of insecticidal spraying to adequate the control of Spodoptera frugiperda J.E. Smith (Lepidoptera: Noctuidae) in corn. This study aimed to evaluate lufenuron sequential sprayings effect and its rotation with other active ingredients on the population, damage caused by S. frugiperda and the impact on corn yield. The experiment was carried out in the field with six treatments: (1) one lufenuron spraying, (2) two lufenuron sprayings, (3) three lufenuron sprayings (4) four lufenuron sprayings, (5) sprayings with spinosad, lufenuron, thiamethoxam+lambdacyhalothrin and deltamethrin (in sequence, at ten days intervals) (6) control treatment. Sprayings started twenty days after the seedling had emerged and then every ten days for a maximum of four sprays. Both caterpillar population (20.9-21.7 larvae/plot) and index of damage (1.2-1.7) observed in corn plants were significantly lower in treated plots compared to control (untreated) (31.7 larvae/plot and index of damage 2.7), regardless of spraying amount. The results showed that multiple insecticide applications to control S. frugiperda do not guarantee higher yields in corn, ranging from 6375.2 to 7650.1 kg ha -1. Only one spraying of lufenuron was enough to prevent significant reduction in corn yield (6749.9 kg ha -1). © 2012 Asian Network for Scientific Information.

Air-assistance in spray booms which have different spray volumes and nozzle types for chemically controlling spodoptera frugiperda on corn

The study aimed to evaluate the performance of air assistance in spray booms using different types of nozzles and spray volumes. We took into account spray deposits, fall armyworm control and crop corn performance in a narrow row cropping system. The experiment was carried out at the experimental area of Sao Paulo State University, Botucatu/SP, Brazil, during the 2008/2009 agricultural season, in randomized blocks with a factorial scheme (2×2+1) and four replications. Two spray nozzles (flat fan nozzle and hollow cone nozzle) were tested, combined with two air assistance levels in the spray boom (with and without air assistance) and a treatment control. In the experimental spraying, Spinosad insecticide was sprayed in amounts of 48 g active substance (a.s.)/ha. The air assistance in the spray boom increased the spray deposits in the V 4 growth stage of the corn plants. Moreover, the application of this technology showed higher efficiency on fall armyworm control, reaching a 100% level 15 days after spraying, in the V 10 growth stage of the plants. The hollow cone nozzle increased the spray deposit level on the corn plants compared with the flat fan nozzle, at growth stage V 4. However, the flat fan nozzle, combined with air assistance technology, was more effective for controlling fall armyworm in the same growth stage (V 4), although the hollow cone nozzle increased the deposit levels on the plants. All the technologies tested in the study promoted a reduction of plant damage from fall armyworm attack. Corn productivity is directly related to the control efficiency of fall armyworm.

Effects of spray nozzles and spray volume on spodoptera frugiperda management and narrow row corn performance

The high demand of pesticides in the production systems makes the application technology one of the main alternatives to optimize the products efficiency. In this context, the study aimed to evaluate the effects of spray nozzles and spray volumes on spraying deposits, armyworm control and crop corn performance in narrow row sowing system. The experiment was carried out at experimental area of Sao Paulo State University, Campus of Botucatu/SP, Brazil, during the 2009/2010 agricultural season, in randomized blocks with factorial scheme (2x2+1) and four replications. It was tested two flat fan spray nozzles (with and without air induction) combined with two spray volumes (100 and 200 L ha-1) plus a control treatment. There was no influence of spray nozzles (without air induction) in the spray deposits levels on plants. However, the flat fan nozzle with air induction was more effective on fall armyworm, with 100% of control against 47.84% from other at 15 days after spraying. The increase in the spray volume promoted high spray deposits (415.4 and 388.6 μL g-1 dry mass for flat fan nozzle with and without air induction, respectively at V10 growth stage) and consequently, the highest spray volume (200 L-1) was more efficient in the fall armyworm suppression, with 100% of control. All the technologies tested showed lower plant injury from fall armyworm. The insecticide sprayed with different technologies did not affect the parameters of plant height and leaf area index. The corn productivity was directly related with control efficiency of fall armyworm. © 2012 Academic Journals Inc.

Efeitos da interação e toxicidade das proteínas Cry1 e Vip3Aa de Bacillus thuringiensis, Berliner em Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae)

Pós-graduação em Microbiologia Agropecuária - FCAV

Dinâmica dos fatores de mortalidade de Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) em milho com e sem liberação de Telenomus remus Nixon (Hymenoptera: Platygastridae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Bioecologia comparada de duas linhagens de Telenomus remus Nixon (Hymenoptera: Platygastridae) parasitando ovos de Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae)

Pós-graduação em Agronomia (Entomologia Agrícola) - FCAV

Resistência de cultivares de amendoim de hábitos de crescimento ereto e rasteiro a Spodoptera frugiperda, em laboratório

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Fatores naturais e Telenomus remus Nixon (Hymenoptera: Scelionidae) na mortalidade de Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) em milho

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)