INFESTATION OF CITRUS BLACK FLY, ALEUROCANTHUS WOGLUMI ASHBY, 1915 (HEMIPTERA: ALEYRODIDAE) IN AN AGROECOLOGICAL ORCHARD IN PARAIBA STATE

Aleurocanthus woglumi is present in Paraiba state since 2009, causing a lot of damage to the citrus production in the State. There is a lack of knowledge about the bioecology of this Aleyrodidae member under the climatic conditions of Paraíba State. Thus, in order to know the population density of the pest and study the interference of climatic factors upon these insects, yellow sticky traps were installed evenly distributed in the orchard in the agroecological citrus property in Areia city, in Paraiba state. There were two distinct population peaks of the pest, one in September 2011 and another in April 2012. The lowest densities of the pest were recorded between October and December 2011, a period in which there was no new budding. The population monitoring of A. woglumi in Paraiba state has allowed knowing the time in which the insect occurs in the orchard and the variations in the number of individuals throughout time

Potassium silicate-induced resistance against blackfly in seedlings of

Introduction. Citrus trees in Brazil are often attacked by the blackfly, Aleurocanthus woglumi Ashby. The induction of resistance to control this pest is required to maintain the sanitary and nutritional quality of the crop. The aim of this study was to evaluate the potential of silicon in the form of potassium silicate (K2SiO3) to modify the activity of enzymes involved in the defence of Citrus reticulata and to find any correlation between the activity of these enzymes and the development of A. woglumi. Materials and methods. The study was conducted in a greenhouse using seedlings of C. reticulate cv. ‘Dancy’ in the following one-application treatments: T1: Infestation with A. woglumi and no K2SiO3 (control, “C”); T2: No A. woglumi and no K2SiO3 (absolute control “AC”); T3: 17 g L-1K2SiO +A. woglumi, T4: 35 g L-1K2SiO +A. woglumi; T5: 52 g L-1 K2SiO +A. woglumi; and T6: 70 g L-1K2SiO +A. woglumi. To perform the enzymatic analyses, one leaf was removed separately from each mandarin seedling after 10, 30, 50, 70, and 90 days of continuous feeding of A. woglumi. The activity of peroxidase, polyphenol oxidase and phenylalanine ammonia-lyase was assessed. Results and discussion. The correlation between peroxidase activity and A. woglumi development was positive. The peroxidase and polyphenol activities indicated strong induction of plant defences against A. woglumi. The increase in peroxidase and polyphenoloxidase activity revealed the induction of synthesis of compounds for plant defence against A. woglumi, but this effect depended on the time of A. woglumi feeding and on the concentration of silicon. Conclusion. Silicon was shown to be an elicitor that potentiates the defence mechanisms of C. reticulata to A. woglumi