Ivan Cruz

Damage of Spodoptera frugiperda (Smith) in different maize genotypes cultivated in soil under three levels of aluminium saturation

This study was conducted to assess the damage caused by artificial infestation by the fall armyworm Spodoptera frugiperda (J. E. Smith) larvae in Al-tolerant and Al-susceptible maize cultivars at different levels of Al saturation (low, medium and high) in an acid soil. The experiments were conducted in the field, in Sete Lagoas, MG, Brazil, during four consecutive years in plots corrected with lime, according to the soil analysis to provide three levels of aluminum saturation: toxic (m > 50%), intermediate (m < 20%), and without aluminum (m < 5%). Three maize cultivars were used, BR 201 tolerant (hybrid with yellow endosperm), BR 400 (yellow sweet maize) and BR 451 (High Quality Protein Maize, white endosperm) sensitive to toxic levels of Al saturation, respectively. The treated plots were artificially infested with young larvae. The non-infested plots were maintained free from natural infestation of the fall armyworm using granular insecticide applied directly to the whorl. Yield reductions due to fall a...

Relação entre a lagarta-do-cartucho e seus agentes de controle biológico natural na produção de milho

This work had the objective of quantifying the losses in the maize hybrid BRS 3123 due to the attack of fall armyworm (Spodoptera frugiperda), in the absence or presence of its natural enemies. Fifteen days after the plant emergency, an artificial infestation (one egg mass per square meter) was accomplished. The larvae fed on the plant, without the interference of its natural enemies, by using an appropriated protection cage (initial protection for two days after infestation, until a maximum protection period of 16 days). The damage caused by the pest, determined through a visual scale from 0 (plants without damage) to 5 (dead plants), was on average, 4.01, 1.39, 1.09 and 0.93 for the pest protection period of 16, 6, 4 and 2 days, respectively. In the absence of the biological control agents, the attack of the pest caused losses of 47.27% in the dry matter production and losses of 54.49% in grain yield. The results evidenced the importance of natural enemies in the suppression of fall armyworm in maize crop.

CONTROLE INTEGRADO DE SPODOPTERA FRUGIPERDA (SMITH & ABBOTT) UTILIZANDO-SE O PARASITÓIDE TELENOMUS REMUS NIXON

Este estudo foi conduzido em 1996 e 1997 para avaliar a eficiencia da liberacao de Telenomus remus Nixon (cerca de 200.000 adultos/ha), sozinho ou integrado ao virus de poliedrose nuclear de Spodoptera frugiperda (VPNSf) ou a um inseticida quimico seletivo, para o controle de Spodoptera frugiperda (Smith & Abbott). Os experimentos foram conduzidos em delineamento experimental de blocos ao acaso, com seis tratamentos e quatro repeticoes. Foram avaliados os danos provocados pela praga as folhas (escala de 0 a 5) e o rendimento de espigas. De maneira geral, os danos provocados pela praga foram significativamente superiores nas parcelas testemunhas (nota media de 2,94). Nao houve diferenca significativa entre os demais tratamentos (media 1,04). De maneira semelhante, houve diferenca significativa no rendimento de espiga entre testemunha (7.165 kg/ha) e demais tratamentos (9.084 kg/ha). Nao houve efeito dos tratamentos no comprimento da espiga e no dano as espigas.

Selective effects of natural and synthetic insecticides on mortality of Spodoptera frugiperda (Lepidoptera: Noctuidae) and its predator Eriopis connexa (Coleoptera: Coccinellidae).

Spodoptera frugiperda Smith (Lepidoptera: Noctuidae) is a serious pest of corn in several American countries. It is mainly controlled with synthetic insecticides. The objectives of this study were to evaluate the effects of the natural products, neem oil and pyroligneous extract, and the synthetic insecticide, lufenuron, at 2.50mL water (0.25 %) on the mortality of 2-, 4- and 6-day-old caterpillars of S. frugiperda, and their selectivities against fourth instar larvae of Eriopis connnexa Germar (Coleoptera: Coccinellidae). Four- and 6-day-old S. frugiperda caterpillars showed higher mortality after exposure to neem oil (83.33 ± 0.83 and 89.58 ± 0.90 %, respectively) and lufenuron (95.83 ± 0.96 and 85.41 ± 0.83 %), compared to pyroligneous extract (68.75 ± 0.69 and 31.25 ± 0.31 %). The deleterious effect of pyroligneous extract was higher in 2- (83.33 ± 0.83 % mortality) and 4-day-old (68.75 ± 0.69 %) S. frugiperda caterpillars than in 6-day-old caterpillars (31.25 ± 0.31 %). Larval mortality of the predator E. connexa was lower with neem oil and pyroligneous extract (25.00 ± 0.33 %) than with lufenuron (91.66 ± 1.22 %). Neem oil is thus recommended for control of S. frugiperda because of its high toxicity, combined with its relatively low toxicity to larvae of the natural enemy E. connexa.

Parasitism rate and viability of Trichogramma maxacalii (Hym.: Trichogrammatidae) parasitoid of the Eucalptus defoliator Euselasia apison (Lep.: Riodinidae), on eggs of Anagasta kuehniella (Lep.: Pyralidae)

Parasitism rates and viability of individuals of two populations of Trichogramma maxacalii (Hymenoptera: Trichogrammatidae) were evaluated in two Eucalyptus plantations in the Counts of Ribeirao Preto, State of Sao Paulo and Nova Era, State of Minas Gerais, Brazil. These parasitoids were reared on eggs of the host Anagasta kuehniella (Lepidoptera: Pyralidae) with or without honey and were exposed to eggs of the host after 0, 6, 12, 24, 36, 48 and 60 h after emergence. Each recently emerged parasitoid female was placed in a 4.0 cm 0.7 cm glass tube with a blue 3.5 cm 0.5 cm cartoon with 40 glued non-viable eggs of A. kuehniella and parasitism was permitted during 24 h. Viability of T. maxacalii (above 96.0%) was not affected by the presence of food, by the origin of the parasitoid population, or by the period in which it was kept without eggs of the host. However, parasitism rate was higher than 75.0% and lower than 65.0%, for parasitoids with or without honey, respectively. Individuals of the population from Sao Paulo showed higher parasitism rates when they received eggs of the host at longer periods after its emergence. Parasitism was higher for the population from Minas Gerais when eggs of the host were provided soon after emergence. Parasitism behaviour in these two populations shows that they can be combined to obtain a better efficiency of T. maxacalii in programs of mass release against Euselasia apisaon (Dalman) (Lepidoptera: Riodinidae) in Eucalyptus plantations. # 2000 Elsevier Science B.V. All rights reserved.

Isolation, Identification, Synthesis, and Field Evaluation of the Sex Pheromone of the Brazilian Population of Spodoptera frugiperda

Several studies have shown intraspecific geographical variation in the composition of sex pheromones. Pheromone lures from North America and Europe were not effective against the fall armyworm Spodoptera frugiperda (Smith, 1797) (Lepidoptera: Noctuidae) in Brazil, so we examined the composition of the sex pheromone produced by females from Brazilian populations. Virgin female gland extracts contained (Z)-7-dodecenyl acetate (Z7-12:Ac), (E)-7-dodecenyl acetate (E7-12:Ac), dodecyl acetate, (Z)-9-dodecenyl acetate, (Z)-9-tetradecenyl acetate (Z9-14:Ac), (Z)-10-tetradecenyl acetate, tetradecyl acetate/(Z)-11-tetradecenyl acetate (Z11-16:Ac), and (Z)-11-hexadecenyl acetate. The relative proportions of each acetate were 0.8:1.2:0.6:traces:82.8:0.3:1.5:12.9, respectively. This is the first time that E7-12:Ac has been reported from the pheromone gland of S. frugiperda. Only three compounds, Z9-14:Ac, Z7-12:Ac, and E7-12:Ac, elicited antennal responses, and there were no differences in catch between traps baited with either Z7-12:Ac + Z9-14:Ac or Z7-12:Ac + Z9-14:Ac + Z11-16:Ac blends. However, the Z7-12:Ac + Z9-14:Ac + E7-12:Ac blend was significantly better than Z7-12:Ac + Z9-14:Ac, indicating that E7-12:Ac is an active component in the sex pheromone of the Brazilian populations of S. frugiperda.

Efeito da idade de lagartas de Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) no desempenho do parasitóide Campoletis flavicincta (Ashmead) (Hymenoptera: Ichneumonidae) e consumo foliar por lagartas parasitadas e não-parasitadas

The potential of parasitism of Campoletis flavicincta (Ashmead) (Hymenoptera: Ichneumonidae) on Spodoptera frugiperda (Smith) larvae of different ages and foliar consumption of parasitized and non-parasitized larvae were evaluated. When 3-d old larvae were offered to the parasitoid the number of pararasitized larvae was 232/female, similar to what was obtained with 2-d old larvae (182 larvae/female); with 4-5-d old larvae, parasitism was 80.7 and 71.0/female, respectively. Healthy larvae consumed 209.3 cm2 of leaf, while parasitized larvae consumed 14.5 cm2 (6.9% of consumption by healthy larvae).

Non-target impact of chlorpyrifos on soil arthropods associated with no-tillage cornfields in Brazil

The present study was undertaken to assess the side-effects of chlorpyrifos on springtails, ants and oribatid mites associated with the soil surface of no-tillage cornfields in Brazil. Three 0.3 ha cornfields were divided into plots and, during tasseling, the plants in areas to be treated were sprayed twice with insecticide, with a 3 day interval. Pitfall traps were used to sample soil arthropods 1 week before and 1, 2, 3, 4, 5 and 8 weeks after spraying. Principal components analysis detected no negative effect of insecticide chlorpyrifos on the assemblage of soil arthropods. Nonetheless, the activity of the ant Solenopsis saevissima (Fr. Smith) was lower 2 weeks after spraying but recovered afterwards, while the frequency of Ectatomma brunneum Fr. Smith, was significantly reduced only at the third week after spraying, and did not show any recovery until the end of the study. Chlorpyrifos did not decrease the overall abundance of Collembola. However, it had a significant impact on the members of the order Symphypleona, there being significantly lower captures of Sminthurides spp. soon after chlorpyrifos spraying without any sign of increase afterwards. There was no effect on oribatid mites. Our results, overall, suggest that the impact of chlorpyrifos on soil arthropods from tropical crop fields can be less severe than expected.

Deleterious activity of natural products on postures of Spodoptera frugiperda (Lepidoptera: Noctuidae) and Diatraea saccharalis (Lepidoptera: Pyralidae).

The control of Lepidoptera pests should be carried out before hatching of their caterpillars to avoid damage to the crops. The aim of this work was to assess the activity of neem (trade name: Natuneem®, producer: Base Fértil, Chapadão do Sul, Brazil) and pyroligneous extracts (trade name: Biopirol 7M®, producer: Biocarbo, Itabirito, Brazil) at 10 mL/L (1%) and 20 mL/L (2%) contents on egg masses of different ages of Spodoptera frugiperda Smith (Lepidoptera: Noctuidae) and of Diatraea saccharalis F. (Lepidoptera: Pyralidae) at Embrapa Corn and Sorghum in Sete Lagoas, Minas Gerais State, Brazil. The tests took place in an unbiased casualized design with 12 treatments and four replications. The insecticides were diluted in water, and 0.04 mL of the solution was applied to recently laid and one- and two-day-old eggs of S. frugiperda and D. saccharalis. Caterpillars hatching from recently laid egg masses of S. frugiperda was lower with 2% pyroligneous extract [(0.02 ± 0.00)%]. Recently laid eggs and one- or two-day-old eggs of D. saccharalis presented lower caterpillar hatching with 1% neem extract [(0.00 ± 0.00)%, (0.00 ± 0.00)%, and (1.00 ± 0.01)%] and 2% neem extract [(0.00 ± 0.00)%], compared to 1% pyroligneous extract [(27.30 ± 3.22)%, (28.40 ± 3.32)%, and (37.80 ± 4.14)%] and 2% pyroligneous extract [(42.20 ± 4.49)%, (48.70 ± 4.97)%, and (56.60 ± 5.52)%], respectively. Neem and pyroligneous extracts had impact on hatching of S. frugiperda and D. saccharalis caterpillars.

Growth and Nutrition of Mollicute-Infected Maize

Maize bushy stunt phytoplasma (MBSP) and corn stunt spiroplasma (CSS) diseases are widespread in Brazil. The leafhopper Dalbulus maidis is the insect vector for these pathogenic mollicutes. The effects of these diseases on the development of maize plants and the possible interaction of soil water availability on these effects were evaluated in two experiments carried out on potted plants. Experiment 1 was carried out in a 2 × 4 factorial, where factor 1 corresponded to healthy and mollicute-infected plants and factor 2 to the maintenance of 40, 60, 80, and 100% of the total soil water availability. Leafhoppers collected from a field with high incidence of these diseases were used to inoculate plants with mollicutes. There were three treatments in experiment 2: healthy plants, plants infected with phytoplasma, and plants infected with spiroplasma. MBSP was predominant in experiment 1. The infected plants grew less and lowered nutrient uptake, in distinct proportions, indicating a differential effect of mollicutes on nutrient uptake independent of available soil water. Soil water availability did not significantly affect plant growth and nutrient uptake or mollicute infection. The results indicated that plants infected by mollicutes contained less protein than healthy plants. Experiment 2 showed a reduction in growth of plants infected with mollicutes and less nutrient uptake by spiroplasma-infected plants. The results showed a detrimental effect of the spiroplasma on Mg uptake. Both experiments showed more water retention by infected plants than by healthy ones. These experiments clearly demonstrated that reduced plant growth and nutrient uptake are major effects on plants infected with MBSP and CSS.