Ézio Marques da Silva

Impact of integrated pest management on the population of leafminers, fruit borers, and natural enemies in tomato

The objective of this work was to evaluate the impact of integrated pest management (IPM) in the productivity of the tomato and in the populations of leafminers, fruit borers, and natural enemies in tomato crops. The treatments were calendar (spraying twice weekly with insecticides and fungicides), IPM (spraying when action thresholds were achieved), and control (no pesticide was applied). IPM was the most efficient system of pest control due to presenting similar productivity and 65.6% less pesticide applications than in the calendar. The attack of Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) and Liriomyza spp. (Diptera: Agromyzidae) to the leaves only achieved the action threshold in the final phase of the cultivation. The main fruit borer was Neoleucinoides elegantalis (Guen.) (Lepidoptera: Crambidae), followed by T. absoluta and Spodoptera eridania (Cr.) (Lepidoptera: Noctuidae). The natural enemy populations were severely reduced by excessive pesticide applications. Predators were more abundant than parasitoids. The most abundant predators were Araneidae, Anthicus sp. (Coleoptera: Anthicidae), Cycloneda sanguinea larva (L.) (Coleoptera: Coccinellidae), Staphylinidae adults (Coleoptera), Orius sp. and Xylocoris sp. (Hemiptera: Anthocoridae), Formicidae (Hymenoptera), and Phlaeothripidae (Thysanoptera). The most abundant parasitoids were Hymenoptera of the families Eulophidae, Braconidae (Bracon sp. and Chelonus sp.), Trichogrammatidae [Trichogramma pretiosum (Riley)] and Bethylidae (Goniozus nigrifemur Ashmead), besides Tachinidae (Diptera).

Natural Biological Control and Key Mortality Factors of Diaphania hyalinata (Lepidoptera: Pyralidae) in Cucumber

Key mortality factors due to natural biological control of the melonworm, Diaphania hyalinata, were investigated. Mortality factors were quantified in cucumber plots and used to develop a life table. The highest mortality of the melonworm took place during the egg stage (90.08% mortality) when the most important mortality factor was the predator Paratrechina sp. (Hymenoptera: Formicidae). However, the critical mortality stage of this insect pest was the fifth larval instar and its key mortality factor was parasitism by tachinid flies (aff. Amazohoughia, Eucelatoria sp. and aff. Lixophaga).

Natural mortality factors of Leucoptera coffeella (Lepidoptera: Lyonetiidae) on Coffea arabica

Abstract The natural mortality of the coffee leafminer, Leucoptera coffeella (Guérin-Méneville) was investigated in three strata of coffee plant canopy for three seasons through construction and analysis of ecological life tables. Mortality of the leafminer was similar on all thirds of the canopy. Total mortality of immature stages was 95%, with 38.5, 43.8 and 12.7% occurring during egg, larval, and pupal stages. Rainfall killed 39.3% of eggs and larvae, and together with egg inviability (16.3%) and Vespidae (11.3%), were the highest mortality factors. Six wasp parasitoids caused 8% of larval mortality. Egg and larva were the critical stages. Variation in mortality was primarily associated with egg inviability, rainfall, and parasitism by Horismenus sp. (Hymenoptera: Eulophidae). Physiological disturbances during molting and metamorphosis also contributed for fluctuations in mortality of the leafminer. Tactics of integrated pest management to enhance natural mortality of the leafminer while conserving or augmenting the action of natural enemies are discussed.

Seletividade fisiológica de inseticidas aos inimigos naturais de Plutella xylostella (L.) (Lepidoptera: Plutellidae) em brássicas

The conservation of natural enemies is a fundamental component in the integrated pest management. In this work, one studied the selectivity of seven insecticides, used in the management of Plutella xylostella (L.) (Lepidoptera: Plutellidae), to the parasitoid Oomyzus sokolowskii (Kurdjumov) (Hymenoptera: Eulophidae), and to the predators Discodon sp. (Coleoptera: Cantharidae) and Lasiochilus sp. (Hemiptera: Anthocoridae). The organophosphates methamidophos and methyl parathion, and the carbamate carbaryl showed high toxicity to the three natural enemies studied. Dimethoate showed selectivity in favor of Discodon sp. in the dose and sub-dose. The insecticide acephate showed a high impact on Discodon sp. at the time of the application, and its effect was reduced with half of the concentration of the active ingredient. Deltamethrin showed selectivity to O. sokolowskii in both dosages. Permethrin was selective to Lasiochilus sp. only in the sub-dose. Discodon sp. was more tolerant to the dose and sub-dose of dimethoate and to the sub-dose of acephate than O. sokolowskii and Lasiochilus sp. The predator Lasiochilus sp. was more tolerant to the dose and sub-dose of permethrin than O. sokolowskii and Discodon sp. The parasitoid O. sokolowskii was more tolerant to the dose and sub-dose of deltamethrin than Lasiochilus sp. and Discodon sp. The results of this research were obtained in conditions of extreme exposition. Thus, the results indicate that it is probable that the selective insecticides will not be harmful to the natural enemies in the field.

Identificação e quantificação dos componentes de perdas de produção do tomateiro

Identification and quantification of tomato yield loss components The components of loss in tomato production were identified and quantified, in the summer-autumn period. The critial component and the key factor in the cultivation loss become evident using the methodology of the crop life table. The experiment was conducted at the Universidade Federal de Vicosa, Minas Gerais State, Brazil, from January to June 2001 and consisted of two treatments (cultivars Santa Clara and F1 Debora Plus) in a randomized complete block design with 5 replications. During the tomato cycle, the number of dead plants, the causes of this and the number of flowers and fruits/ plant were evaluated. At harvest, the healthy fruits were counted, weighted and classified; the causes of fruit damage were identified and the loss quantified. Total loss was more influenced by the fluctuation of the component plants (r=0,89) (P<0,01) than by other production components; consequently, plants were considered the critical production components of tomato. TSWV virus was the only factor affecting plant death, being considered the key-factor in the loss of this tomato production.

Toxicity of Leaf Extracts of Ageratum conyzoides to Lepidoptera Pests of Horticultural Crops

ABSTRACT The insecticidal activity of the hexane and alcohol extracts of the plants Ocimum selloi B., Ruta graveolens L., Leonotis nepetaefolia L., Datura stramonium L., Cordia verbenaceae L., Mentha piperita L., Mormodica charantia L. and Ageratum conyzoides L. were tested against larvae of Diaphania hyalinata (L.) (Lepidoptera: Pyralidae). Among these, the extract of only A. conyzoides showed biological activity. The hexane extract of this plant species was therefore successively fractionated by silica gel column chromatography for isolation and purification of the active chemical constituents. The insecticidal activity of the fractions and compounds were monitored through bioassays with larvae of D. hyalinata (L.), Dione juno juno (Cr.) (Lepidoptera: Nymphalidae) and Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae). The compounds 5,6,7,8,3′,4′,5′-heptamethoxyflavone; 5,6,7,8,3′-pentamethoxy-4′,5′-methylenedioxyflavone and coumarin were identified as the active compounds in the fractions. The increasing order of susceptibility to coumarin was D. hyalinata < D. juno juno < T. absoluta. The increasing order of toxicity to D. juno juno was 5,6,7,8,3′-pentamethoxy- 4′,5′-methylenedioxyflavone < coumarin < 5,6,7,8,3′,4′,5′-heptamethoxyflavone.

Seleção de atrativos alimentares e toxicidade de inseticidas para o manejo da broca-pequena-do-tomateiro

O objetivo deste trabalho foi avaliar a preferencia alimentar, o limiar de ingestao e efeito toxico inseticidas associados atrativos, em adultos Neoleucinodes elegantalis. Foram testados os atrativos: melado e mel a 10%, extrato hexânico de frutos verdes de tomate a 0,4%, sacarose a 5%, suco de laranja e suco de uva a 30%, vinagre de vinho tinto a 10% e proteina hidrolisada a 5%. Com base no teste de preferencia alimentar, foram selecionados os atrativos sacarose, melado, mel e suco de laranja, para determinar o limiar de concentracao capaz de estimular a alimentacao de adultos de N. elegantalis. Foi testado o efeito toxico de inseticidas associados ao mel a 10%. A sacarose e o mel apresentaram o melhor resultado em relacao ao numero de pousos e ao tempo de pouso e de alimentacao de adultos de N. elegantalis. Os inseticidas nao afetaram negativamente a atracao pelo alimento dos adultos de N. elegantalis. Carbaril, cartape, deltametrina, fenpropatrina, indoxacarbe, lambda-cialotrina e lufenurom provocaram 100% de mortalidade em adultos (machos + femeas), apos 24 horas de exposicao, e mostraram-se promissores para o uso em iscas toxicas.

Natural mortality factors of tomato leafminer Tuta absoluta in open-field tomato crops in South America: Natural mortality of tomato leafminer

BACKGROUND Little importance has been given to the role of natural mortality factors (biotic and abiotic) in the regulation of tomato leafminer Tuta absoluta (Lepidoptera: Gelechiidae) populations. The present study determined the action of mortality factors on T. absoluta populations infesting cultivated tomato crops. Eighty ecological life tables for T. absoluta in field cultivated tomato plants were constructed and analyzed. RESULTS Total T. absoluta mortality was 99.08%, with 38.76% mortality during the egg phase, 57.20% in the larva phase and 3.12% in the pupal phase. The main mortality factors during the egg stage were predation, parasitism and egg inviability. In the larval stage, the main mortality factors were predation, parasitism, entomopathogenic agents and physiological disorders. In the pupal stage, the main mortality factor was predation. The larvae of the third and fourth instar were more susceptible to the action of mortality factors and the predatory wasp, Protonectarina sylveirae, was the main insect predator of these larvae. CONCLUSIONS The T. absoluta population is regulated under field conditions by the action of natural enemies of the larvae. The predatory wasp P. sylveirae is very important in the regulation of T. absoluta populations in open-field tomato crops in Brazil.