Avaliação da infestação da plantação de Khaya anthotheca WELW, C.DC, pela Hypsipyala spp. Lepidoptera: Pyarlidae na reserva florestal de Moribane, em Sussundenga

Abstract

Khaya anthotheca (WELW.) C. DC, is one of the important tropical trees of the Meliaceae family with wood of high commercial value, and is susceptible to attack by Hypsipyla spp, (Lepidoptera; Pyralidae) pest that has limited the production of trees in this family . The study was carried out in order to assess the incidence of this pest in the Kanthotheca plantation at the age of 7 in the Moribane Forest Reserve in the District of Sussundenga in the province of Manica. The evaluated plantation has 35 plots, with 4 plants each, 4x4 spacing, in a total of 121 plants. In each plot, infested and non-infested plants were counted, height was measured, stem branching and bifurcation were evaluated, and larvae were harvested. The collected larvae were deposited in the flasks and fed pieces of the terminal parts of branches, until their passage to other stages, death or the emergence of parasitoids. Flasks and food were changed whenever necessary and hatched parasites were identified. The data were submitted to the calculation of larvae density, percentage of infestation, percentage of parasitism and relative abundance of the natural enemy. The evaluation of the spatial distribution of the pest and analysis of correlation and regression between percentage of infestation and number of larvae per plant, and between height class and percentage of infestation were also carried out. Nineteen larvae were collected, one in the leaf axilla, none in the stems, the rest inside the shoots and none of the pupae. The observations made show that there is a preference of the pest to succulent sprouts. The degree of infestation was 30.6% with a higher incidence for classes from 2 to 4 m with 57.4% of plants infested in these classes. The density of larvae in the plantation was 0.16 larvae per plant, with the highest incidence for class 3-4 m, with 3 being the maximum number of larvae found per plant. Pearson's correlation coefficient was significant for the relationship between the percentage of infestation and the average number of larvae, and not significant for the relationship between height classes and percentage of infestation. The parasite ide of the nematode class was the natural enemy of the pest recorded in this work, affecting the larval stage of the pest. The degree of parasitism was 47%. The evaluation of the pest's spatial distribution showed that the pest has an aggregated arrangement. In the entire plantation, 51% of the plants had a regular stem and 30% with a bifurcated or branched stem in the last quarter of the trunk.