Moisés Daniel de Oliveira

Parasitoides do gênero Trichogramma são utilizados em todo o mundo para o manejo de pragas. A capacidade de dispersão desses insetos em cultivos determina o número de pontos necessários de liberação para que haja resultados satisfatórios quanto ao parasitismo e consequentemente, o manejo da praga. Para determinação da capacidade de dispersão de T. pretiosum em cultivos de couve e repolho, foram demarcadas áreas de 26 x 26 m, em que foram colocadas cartelas contendo ovos de A. kuehniella distribuídas de forma concêntricas e equidistantes. No centro de cada área foram liberados 100 mil parasitoides e o parasitismo foi permitido por 24 horas. O delineamento experimental utilizado foi em blocos casualizados, com cinco tratamentos (distância) e quatro repetições. A distância média dispersada foi de 6,27 metros em couve e 6,07 em repolho, enquanto que área de dispersão foi de 81,23 na cultura da couve e 79,03 metros no cultivo de repolho, sendo possível determinar que por hectare são necessários 123 pontos de liberação para couve e 126 para repolho.

Biological control using Trichogramma pretiosum is applied in more than 15 million hectares worldwide; however, the economic aspects of this method need to be clarified. Thus, the present study aimed to determine the cost and profitability of using T. pretiosum in the commercial cultivation of cabbage, purple cabbage, and kale for the management of Plutella xylostella and other lepidopteran pests. The experiment was conducted in an area of commercial cultivation of Brassica sp., located in the municipality of Pardinho, São Paulo, Brazil, for one year from March 2020 to March 2021. The proportions of T. pretiosum used for cabbage and kale were 200,000 females/ha and 300,000 females/ha, respectively. The flooding releases of T. pretiosum provided a 100% reduction in the spraying of chemical insecticides, and represented 36.2% of the manual operations performed in the cultivation of kale. In cabbage cultivation, costs of monitoring and release of T. pretiosum accounted for 19.2% of the manual operations. The acquisition cost of the parasitoids represented 34.1% and 14.0% of material costs in the cultivation of green cabbage and purple cabbage, respectively. In kale crops, it represents 20.9% of consumable material costs. Releases of T. pretiosum cost up to 50% less compared to spraying with chemical insecticides. In addition to providing operation profit during all plantings performed over a year, use of T. pretiosum allows profitability rates above 70% and 50% in the cultivation of green and purple cabbage s, respectively. The acquisition cost of T. pretiosum is low when compared to chemical insecticides, allowing greater profitability of production systems.

Infestation by Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) causes damage to tomatoes with production losses of up to 100%, affecting the physiological and biochemical aspects of host plants. The objective of this study was to analyze the influence of infestation of cryptic species of B. tabaci MED and MEAM1 on the physiological and biochemical aspects of tomato. Tomato plants ‘Santa Adélia Super’ infested with B. tabaci (MED and MEAM1), and non-infested plants were evaluated for differences in gas exchange, chlorophyll - a fluorescence of photosystem II (PSII), and biochemical factors (total phenols, total flavonoids, superoxide dismutase—SOD, peroxidase—POD, and polyphenol oxidase—PPO). Plants infested with B. tabaci MED showed low rates of CO₂ assimilation and stomatal conductance of 55% and 52%, respectively. The instantaneous carboxylation efficiency was reduced by 40% in MED and by 60% in MEAM1 compared to the control. Regarding biochemical aspects, plants infested by MED cryptic species showed high activity of POD and PPO enzymes and total phenol content during the second and third instars when compared to control plants. Our results indicate that B. tabaci MED infestation in tomato plants had a greater influence than B. tabaci MEAM1 infestation on physiological parameters (CO₂ assimilation rate (A), stomatal conductance (gs), and apparent carboxylation efficiency (A/Ci)) and caused increased activity of POD and PPO enzymes, indicating plant resistance to attack. In contrast, B. tabaci MEAM1 caused a reduction in POD enzyme activity, favoring offspring performance.