In-situ Efficacy of Selected Biorational Insecticides against Infestation of Tomato Leafminer Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae)
Abstract
Tomato is an important vegetable crop of Iraq. However, its production is severely hampered by the infestation of tomato leafminer Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) which has been a challenging pest for tomato growers all over the world including Iraq. As this pest species has attained resistance against most of the conventional synthetic insecticides, alternate insecticidal options that would be more biorational and environment-friendly, such as reduced-risk non-conventional synthetic insecticides, botanical extracts, and entomopathogenic preparations. In this study, some biorational pesticides were evaluated against tomato leafminer infestation under field conditions. Insecticidal treatments included two types of alcoholic plant extracts, i.e. leaf extract of Mirabilis jalapa L. and seed extract of colocynth Citrullus colocynthis., two non-conventional environment-friendly synthetic insecticides, i.e. flubendiamide (Belt® 480 SC) and spirotetramat (Movento® 100 SC), and the wettable powder formulation of an entomopathogenic fungus, i.e. Beauveria bassiana (2 × 1010 spores g-1). Results showed the effectiveness of insecticides spirotetramat and flubendiamide either alone or by their combined foliar application with B. bassiana in controlling tomato leaf miner. Minimum average fruit infestation (4.0 to 8.2%), leaf tunnelling percentage (9.4 to 12.6%) and infestation severity (1.17 – 1.63%). Control treatment was observed to have maximum fruit infestation (50.5%), leaf tunneling (36. 4%), and infestation severity index (2.19%). Overall study results suggest the integration of these synthetic insecticides spirotetramat and flubendiamide and B. bassiana formulations in the future IPM programs against tomato leafminer infestations. Keywords: Beauveria bassiana, botanical insecticides, tomato pinworm infestation, entomopathogenic fungi, nonconventional synthetic insecticides .