Leandro Bacci

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).

Seasonal mortality factors of the coffee leafminer, Leucoptera coffeella

Seasonal population fluctuation of the coffee leafminer, Leucoptera coffeella (Guérin-Méneville & Perrottet) (Lepidoptera: Lyonetiidae), led to an investigation of its natural mortality factors during the rainy season when the population level is low and during the dry season when population peaks occur. Life-table data were collected from insecticide-free plots within a 3 ha coffee plantation on the upper, medium and lower canopy. Leafminer mortality was similar among the canopy parts but varied in the two seasons studied. During the rainy season, the generational mortality averaged 94.3%, with 50.2, 33.7 and 10.4% occurring during egg, larval and pupal stages, respectively. During the dry season, total mortality was 89%, with 13.2, 61.0 and 14.8% occurring during egg, larval and pupal stages, respectively. Marginal mortality rates during the rainy season were highest for physiological disturbances, rainfall and egg inviability; but, in the dry season, they were highest for predaceous wasps, physiological disturbances and parasitoids. Egg and larval stages accounted for most of the mortality variation in the rainy season, while the combination of larval and pupal mortality better described the generational mortality in the dry season. Variation in mortality during the rainy season was primarily associated with egg inviability, rainfall and parasitoids. In contrast, predatory wasps and physiological disturbances were the main factors associated with mortality variation during the dry season. These results suggest that weather conditions, natural enemies and plant quality attributes are the main determinants of the population dynamics of L. coffeella.

Effect of integrated pest management practices on tomato production and conservation of natural enemies

1 The present study used a crop life table to determine the critical components of production and the key factors of loss in tomato, and three treatments to identify the integrated pest management (IPM) benefits on the reduction of yield losses and the conservation of natural enemies.

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.

Sampling plan for Thrips (Thysanoptera: Thripidae) on cucumber

This work determines the best technique, sampling unit and the number of samples to compose a sampling plan for Frankliniella schultzei (Trybom) and Thrips palmi (Karny) (Thysanoptera: Thripidae) on cucumber. The efficacy of three sampling techniques: leaf beating on a plastic tray, direct counting of insects on the lower leaf surface, and whole leaf collection in bags were compared in nine commercial cucumber crops using three sampling units (a leaf from a branch located in the apical, median or basal third of the canopy). The number of samples was determined based on the relative variance and the economic precision for the best technique and sampling unit. The direct counting of insects on the apical third of the plant canopy was the best sampling technique for F. schultzei based on one leaf surveyed per plant using 38 plants per field. The best sampling technique for T. palmi was the leaf beating on a tray using one leaf of the apical third per plant and 35 plants per field. When joining both species, the best sampling system was the direct counting on the apical third, and it requires sampling one leaf per plant using at least 35 plants per field. These results facilitate the decision-making for the management of thrips on cucumber and aggregate the benefits of the correct decision for the adoption of strategies for population reduction.

Seletividade de inseticidas, utilizados no controle de Grapholita molesta (Busch) (Lepidoptera: Olethreutidae) em pêssego, a Vespidae predadores

The selectivity of the insecticides carbaryl, deltamethrin, fenitrothion, fenthion, malathion, naled, methyl parathion and trichlorfon to the predators Protonectarina sylveirae (Saussure), Polistes versicolor versicolor (Olivier) and Protopolybia exigua (Saussure) was studied in laboratory using 50 and 100% of the recommended dose for the control of Grapholita molesta (Busch) (Lepidoptera: Olethreutidae) in peach orchards. The insecticides fenitrothion, fenthion, methyl parathion, naled, and trichlorfon showed no selectivity in favour of the wasps at the full recommended dose, all of them causing 100% mortality among the predators except for trichlorfon which caused 96.9% mortality to P. sylveirae. Carbaryl and malathion were selective in favour of P. versicolor versicolor (18.6 and 6.7% mortality, respectively), and deltamethrin was selective in favour of P. versicolor versicolor (3.6% mortality) and P. exigua (11.8% mortality). P. sylveirae was more susceptible to deltamethrin than P. exigua and P. versicolor versicolor. P. versicolor versicolor was more tolerant to malathion and carbaryl than P. sylveirae and P. exigua. Deltamethrin, malathion and naled were less lethal to P. sylveirae when applied at the lower dose; while the same happened to carbaryl and malathion for P. exigua.

Production and quality of tomato fruits under organic management

Information about the production and quality of tomato cultivars under organic management and the conditions of climate and soil from the north region of Minas Gerais State, Brasil, are scarce. Thus, this research was carried out to evaluate the production and quality of tomato cultivars under organic management, in this region. The treatments consisted of four open pollination tomato cultivars (Chadwick Cherry, Pitanga vermelha, Santa Clara and Santa Cruz Kada) and five hybrid cultivars (Marguerita, Nicolas, Ellen, Magestade and Dominador). The experimental design was of randomized blocks with three replications. The experiment was carried out using organic fertilization in the initial preparation of the area, compost and rock phosphate and sprays with Bordeaux mixture, neem oil and fertilizer. The marketable yield varied from 12.3 t ha -1 to 23.9 t ha -1 . The hybrid Marguerita presented higher marketable production (23.9 t ha -1 ). The cultivars Chadwick Cherry and Pitanga Vermelha reached similar production as most cultivars and larger proportions of marketable and giant fruits, and therefore, better market quality. All the cultivars presented low potassium and manganese levels in foliar tissue suggesting an evaluation after various organic manuring cycles and better nutrition conditions are necessary to permit the comparison of the performance of cultivars in this system.

Seletividade de Inseticidas a Brevicoryne brassicae (L.) (Hemiptera: Aphididae) e ao Predador Doru luteipes (Scudder) (Dermaptera: Forficulidae)

The objective of this work was to study the selectivity of the insecticides acephate, deltamethrin, dimethoate, methamidophos, methyl parathion, and pirimicarb to first, second, and third instar nymphs and adults of the predator Doru luteipes (Scudder) (Dermaptera: Forficulidae) in comparison with last instar nymphs of the prey Brevicoryne brassicae (L.) (Hemiptera: Aphididae). Pirimicarb and deltamethrin were highly selective to all developmental stages of D. luteipes; the same was observed with acephate except for first instar nymphs to whom it showed median selectivity. Dimethoate showed median selectivity, but methamidophos and methyl parathion were low selective to the predator. Second and third instar nymphs and adults of D. luteipes were more tolerant to acephate, methyl parathion and pirimicarb than first instar nymphs. First and second instar nymphs showed similar tolerance to deltamethrin, dimethoate and methamidophos. Concentration-response curves for dimethoate (to adults and first and second instar nymphs) and methamidophos (to third instar nymphs) showed steeper slopes indicating an homogeneous response of these developmental stages to these insecticides.

Life tables for the guava psyllid Triozoida limbata in southeastern Brazil

The aim of this study was to identify, quantify, and determine the importance of biological control agents of the psyllid Triozoida limbata (Enderlein) (Hemiptera: Sternorrhyncha: Triozidae). Ecological life tables were developed during four periods to determine the critical stage and key mortality factors of this pest. Predation and parasitism were found to be the two major factors driving the population dynamics of this pest. The major predators of eggs and nymphs of first and second instars were coccinellids, predatory thrips, lacewings, ants, and spiders, while the major predators of third, fourth, and fifth instars were several species of predatory wasps and syrphids. The endoparasitoid Psyllaephagus sp. (Hymenoptera: Encyrtidae) parasitized fifth instar psyllids. The fifth instar was found to be the critical mortality stage of T. limbata, and key mortality factors include the parasitoid Psyllaephagus sp. and predatory wasps.

Inseticidas seletivos à tesourinha Doru luteipes (Scudder) utilizados no controle do pulgão verde em brássicas

The selectivity of the insecticides acephate, deltamethrin, dimethoate, methamidophos, methyl parathion, and pirimicarb were studied on the last nymphal phase of the green peach aphid Myzus persicae (Sulzer) (Homoptera: Aphididae) and on first, second, and third instar nymphs and adults of the Doru luteipes (Scudder) (Dermaptera: Forficulidae). Pirimicarb was highly selective in favor of all developmental stages of D. luteipes. Deltamethrin, methyl parathion and dimethoate were of median selectivity in favor of third instar nymphs of D. luteipes, as was also observed for the first two of these insecticides regarding to nymphs of first and second instars, respectively. Acephate was little selective in favor of second and third instars nymphs, and the same was observed for methyl parathion, deltamethrin and methamidophos to first, second and third instar nymphs, respectively. Dimethoate and methamidophos were more toxic to nymphs of first and second instars of the predator than to the last instar nymphs of the green peach aphid. D. luteipes adults and second and third instar nymphs were more tolerant to acephate, methyl parathion, and pirimicarb than first instar nymphs. D. luteipes first and second instar nymphs showed similar tolerance to deltamethrin, dimethoate, and methamidophos. Concentration-response curves for deltamethrin, methamidophos, and pirimicarb (to all development stages of D. luteipes), for dimethoate (to adults and first and second instar nymphs of the predator), for methyl parathion (to first and third instar nymphs of the predator), and for acephate (to adults of the predator) showed steeper slopes than the concentration-response curves of these insecticides established to M. persicae.