Survey on nutritional indices of Green Oak Leaf Roller (Tortrix viridana L.) in grouping and individual nutrition methods

Document Type : Scientific article

Authors

Natural Resources Faculty, Urmia University

Abstract

The forests in Zagros vegetative area are important due to their geographical situation, ecosystem performance, and biodiversity. Green oak leaf roller (Tortrix viridana L.) is one of the most important pests which feeds on oak leaves and sprouts and damage them greatly in Zagros forests. Considering the fact that the larva of this insect has different reactions to feeding upon the leaves of Quercus infectoria and Q. libani in their individually and social lives, measuring its social and individual feeding behavior was investigated in the current study. Collected leaves of these oak species were transferred to laboratory and were stored under 25°C and suitable photoperiod conditions (with two individual and group feeding methods) and were given to the fifth instar larvae of the pest. In the group treatment, 20 replications (each replication with 10 larvae) and in the individual method, 40 replications (each repetition with 1 larva) were considered for each host. The indices of relative consumption rate (RCR), relative growth rate (RGR), efficiency of conversion of ingested food (ECI) and efficiency of conversion of digested food (ECD) were measured. The results of the conducted t-test indicated that the degree of larval biomass, RGR, ECI, and ECD are significantly higher in group feeding method compared to individual feeding (α=0.05). In fact, although larvae eat more when they are individually being fed (due to lack of competition stress), they produced more larval biomass in group feeding method despite they ate less (smaller RCR).

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