Author(s):
Duarte, Gonçalo Nuno Abraços Henriques Gomes
Date: 2013
Persistent ID: http://hdl.handle.net/10400.5/6702
Origin: Repositório da UTL
Subject(s): Nesidiocoris tenuis; tomato; phytophagy; vertical population distribution; pyrethrins; susceptibility
Description
Mestrado em Engenharia Agronómica - Instituto Superior de Agronomia
Nesidiocoris tenuis Reuter spontaneously colonizes tomato crops along the Mediterranean basin. This insect is both beneficial and harmful since it feeds on pest species but also on the tomato plant itself. The phytophagous feeding originates plant damage, mostly necrotic rings in stems and flower abortion. To understand the behavior of N. tenuis on tomato, population vertical distribution on the plant and the relation between N. tenuis and the abundance of prey, in particular whiteflies,and the damage caused to the plant, were observed. Both nymphs and adults of N. tenuis preferred the uppermost part of the plant and their density decreased towards the soil. The coefficient of the correlation between N. tenuis nymphs and plant damage is similar to that of the correlation between nymphs plus adults of N. tenuis and plant damage, suggesting that nymphs are the most important stage for plant damage production. An assay to evaluate susceptibility to pyrethrins was carried out: two distinct populations with different exposure histories were compared. Consistent differences between to two populations were not found. Field data did not support the existence of less susceptibility on the previously exposed population.