Preferência alimentar de Thaumastocoris peregrinus e análises bioquímicas de diferentes materiais genéticos de Eucalyptus

Abstract

Species of the genus Eucalyptus and their clones and hybrids are source of material and commercial products. Production occurs especially in monocultures making it susceptible to insect-pest attack. Thaumastocoris peregrinus is an exotic insect that causes damage to eucalyptus forests. As it is a long rotation crop, the control of this pest can be carried out with alternative strategies, such as the selection of resistant genetic material. In this sense, the present work had as objective to evaluate the feeding preference and survival of T. peregrinus. The biochemical composition was associated with the results. The six genetic materials of Eucalyptus were collected in an experimental area denominated Test of Multiple Use of Eucalyptus from the UTFPR, Campus Dois Vizinhos. Three bioassays were performed: 1) Feeding preference of T. peregrinus adults in a multiple choice test among six eucalyptus genetic materials. The experiment was conducted in a controlled environment of 26 ± 2 ° C, RH 70 ± 10% and photophase of 14 hours. Eppendorf type plastic tubes with 2mL of water were placed in the petiole of whole leaves and arranged in plastic containers. For each treatment was inserted ten adult insects of T. peregrinus evaluating the presence of insects in the leaves at eight-hour intervals, for a period of five days, as well as counting feces and eggs present on the leaves at the end of the 5th day; 2) Adult confinement bioassay of T. peregrinus was carried out in a controlled environment of 26 ± 2 ° C, RH 70 ± 10% and photophase of 14 hours where eppendorf type plastic tubes were coupled with 2mL of water in leaf petiole ten adult insects of T. peregrinus were inserted for each treatment and their survival was evaluated at eight-hour intervals for a period of five days, as well as counting feces and eggs present in leaves at end of the 5th day; 3) Biochemical analysis of leaves collected from eucalyptus genetic material. It was determined proteins, total and reducing sugars and phenylalanine ammonia-lyase in three different treatments (0 hours, 24 hours without the presence of the insect and 24 hours with presence of T. peregrinus). For the first bioassay, Clone H-13 was the most preferred genetic material for feeding T. peregrinus (36.57%), with a higher mean number of eggs (3.80) and faeces (68, 75). However, Clone GFMO-27 was the least preferred for feeding, (3.97%) and egg laying (0). In confinement, the highest percentage of live insects was Eucalyptus propinqua (89.34%) and the lowest percentage for Eucalyptus pellita x Eucalyptus tereticornis (4%), also the lowest mean number of feces was verified (71,40). Clone H-13 is preferred by T. peregrinus adults for feeding, egg laying and stool numbers. The biochemical analyzes revealed variations in the analyzed substances and FAL activity in the genetic materials evaluated, as well as when exposed to T. peregrinus.