The fall armyworm, Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae), is a major pest of maize and frequently demands control measures. The timing of insecticide application is a key factor in determining its efficiency, so an experiment was designed to investigate this. Application of insecticide was based on three criteria: (i) the number of trap-caught moths in a Delta-type trap with a commercial sex pheromone lure placed in the center of the target area, soon after plant emergence; (ii) the percentage of plants exhibiting pinhole-type damage (10% or 20%), and (iii) the percentage of plants exhibiting shot hole-type damage (10% or 20%) compared to a check plot without any control measures. We found that the number of trap-caught moths was, compared to the other methods, the2 best means of deciding on insecticide application in maize to control the fall armyworm. Using pheromone traps, we obtained the best performance of the insecticide Spinosad, causing >90% larval mortality. Without insecticide application, maize yield reduction due to fall armyworm larva damage was 39%.

NoteRESUMO: Diatraea saccharalis (Fabr.) (Lepidoptera: Pyralidae) passa a maior parte de seu ciclo biológico no interior do colmo da planta hospedeira, onde fica protegida contra a ação dos métodos convencionais de controle. O controle biológico tem sido considerado uma alternativa viável para o controle desta praga em cana-de-açúcar (Saccharum officinarum L.) e milho (Zea mays L.), dois hospedeiros preferenciais. Este trabalho relata a ocorrência no Brasil de Tetrastichus howardi (Olliff) (Hymenoptera, Chalcidoidea: Eulophidae) parasitando pupas de D. saccharalis em colmos de plantas de milho. Ele também inclui dados preliminares sobre alguns aspectos biológicos do parasitóide. Uma fêmea de T. howardi foi capaz de produzir até 66 descendentes em uma única pupa do hospedeiro e, aparentemente, não faz distinção entre diferentes idades da pupa. O ciclo de vida do parasitóide foi ao redor de 25,5 dias. A presença do parasitóide no Brasil abre uma nova perspectiva sobre a supressão da broca da cana, considerando os resultados promissores já obtidos em países asiáticos. O inseto é bem adaptado à condição de laboratório, podendo ser produzido em grande número, tornando assim, uma opção adicional para o manejo integrado nas culturas onde D. saccharalis é praga chave, tais como a canade-açúcar, milho e sorgo (Sorghum

No abstract

The fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) is a key pest of maize (Zea mays L.) crop, and invariably demand control measures. However, the time of insecticide application has not been properly defined, leading to an inefficiency in the control and, therefore, without getting the maximum from the treatment procedure. Many times the pest has been reaching population density that would demand control measure very early in the season. To detect such populations and, therefore, to decide about the time of the insecticide application, the experiment was conducted installing soon after the plant emergency, a delta type Pherocon 1C trap with a commercial synthetic sexual pheromone (Bio spodoptera ® Chem Tica International, S.A.). Insecticide first application was made ten days after the capture of three adults per trap/ha. A second application was accomplished when was again captured a minimum of three moths, but initiating the counting four-days after the previous insecticide application. This same procedure was adopted for a third application. The evaluated insecticides provided a significant reduction in the infestation level, for variable periods, depending on the chemical suggesting that the pheromone trap can be a useful tool in integrated pest management program in maize crop in Brazil.

Spodoptera frugiperda is a major pest causing maize yield loss in Brazil. There is therefore a need for control methods, notably for organic farming because classical pesticides are not allowed. A potential solution for organic maize is to apply the biological control agent Trichogramma pretiosum to reduce S. frugiperda populations. Here, we tested the application of one, two, or three releases of T. pretiosum. We measured plant damage ratings, egg masses parasitized, and grain yield. Results show that 79.2 % of egg masses were parasited. Maize yields for parasited plots increased of 701 kg/ha versus control plots. This result equals a 19.4 % gain of productivity and US$96.5 gain per hectare. Therefore, biological control with egg parasitoids is a promising alternative to control S. frugiperda in organic maize.

No abstract

Doru luteipes (SCUDDER, 1876) is considered one of the best natural enemies of the fall armyworm Spodoptera frugiperda (J. E. Smith, 1797) (Lepidoptera: Noctuidae), feeding on their eggs and small caterpillars. For its conservation it is necessary to use selective insecticides to S. frugiperda and harmless to the predator. Therefore, objective of the present work was to evaluate the toxicity of insecticides registered to control of S. frugiperda. It was conducted bioassays with D. luteipes adults treated with insecticides directly by exposure to residues of compounds applied on glass plates and the consumption of eggs of S. frugiperda contaminated and offered each one, 24 and 48 hours after treatment. The insecticides were classified according to indices proposed by IOBC/WPRS. For adults D. luteipes treated directly with insecticides, triflumuron was harmless (class 1); chlorfenapyr and etofenprox as slightly harmful (class 2) teflubenzuron/-cypermethrin and spinosad moderately harmful (class 3) and thiamethoxan/-cyhalothrin harmful (class 4). In bioassay exposure of D. luteipes residues of insecticides applied to glass plates, all products were harmful to the predator, except triflumuron which was considered slightly harmful. The survival of adults after consumption of contaminated eggs was 46.7% for the insecticide tiametoxam/-cialotrina considered slightly harmful to the predator. The other insecticides were innocuous. Due to the low toxicity presented by the triflumuron to the D. luteipes adults, this compound can be recommended in programs aimed at integrated pest management the preservation of this natural enemy. All other products must be evaluated in greenhouse and field to prove its toxicity.

No abstract