Effectiveness test of Eucalyptus leaf extract (Eucalyptus sp.) and Lemongrass extract (Cymbopogon citratus (DC) Stapf.) on mortality of leaf roller pests (Strepsicrates sp) in vitro

Plant Pest and Disease Laboratory, Agroecotechnology Study Program, Faculty of Agriculture, Mulawarman University, Samarinda 75123, Indonesia

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Abstract

Strepsicrates sp pests in eucalyptus plants are a major constraint that can reduce plant productivity. This study aimed to test the effectiveness of a combination of eucalyptus leaf extract and lemongrass extract on leaf roller pest mortality in vitro and to determine its effective concentration. The study used an experimental method with a completely randomized design consisting of seven treatments with three replications. The application of eucalyptus and lemongrass leaf extracts by wetting the test larvae's food leaves was carried out. To determine their effectiveness, observations were made on larval mortality, the percentage of pupae and imago formation, and other symptoms found in Strepsicrates sp. The results showed that the combination of eucalyptus leaf extract and lemongrass as a botanical pesticide was effective against mortality, pupae and imago formation of Strepsicrates sp. The best treatment was at a concentration of 300 mL L⁻¹, but it was not significant with a concentration of 250 mLL⁻¹ so that the recommended concentration is 250 mL L⁻¹ because it caused 83.33% larval mortality, 16.67% pupae formation and no imago formation. Sublethal effects were in the form of developmental disorders, namely, morphological malformations in the pupae and imago stages.