Identification and field evaluation of female sex pheromone of leaf-eating caterpillar, Opisina arenosella (Lepidoptera: Oecophoridae)

Abstract

The leaf-eating caterpillar,Opisina arenosellaWalker, is the most destructive pest of coconut palm in India and Southeast Asia. The management practices employed againstO. arenosellaso far have been unsuccessful in many instances in India, due to the pest behaviour and coconut palm phenology. The life cycle, incidence and behaviour ofO. arenosellaare rather interesting and useful for the intervention of pheromone trapping technique for its management. We conducted the present study with the intention of identifying the female sex pheromone ofO. arenosellaand testing its efficacy under field conditions. Gas chromatography coupled electroantennographic detection (GC–EAD) and gas chromatography–mass spectrometry (GC–MS) analysis of female pheromone glands extract of one-day-oldO. arenosellafemales confirmed the presence of (Z,Z,Z)-3,6,9-tricosatriene (Z3Z6Z9-23Hy) as the dominant sex pheromone component. The male antennal response to female pheromone gland extract and syntheticZ3Z6Z9-23Hy was recorded using GC–EAD, and the results revealed that antennal response was positive to both the treatments at 0.13 mV and 0.14 mV respectively, compared to control (air), which was 0.016 mV. It was also evident from wind-tunnel experiments that the male moth response was high (80%) with the female gland extract, compared to 60% with synthetic pheromone and 0% for control (air). Male moths caught in the traps with and without lure were assessed in two field sites and recorded 69.26% and 54.25% more moth catches in the traps with the lure. We also observed a similar result in the cage experiment in which male moths caught in the traps with and without lure were 64.50% and 12.40%, respectively. The study also confirmed that 93.20% moths caught in the pheromone-baited traps were male. From the study, it is evident that the presence of (Z,Z,Z)-3,6,9-tricosatriene, which is the sex pheromone compound from the female gland extract ofO. arenosella, is an effective attractant in pheromone traps for the male moth under field conditions.

An unusual tricosatriene is crucial for male fungus gnat attraction and exploitation by sexually deceptive Pterostylis orchids

“…For example, (3Z,6Z,9Z)-3,6,9-tricosatriene, which was abundant in Pterostylis concava extracts, is a major sex pheromone component in some geometrid and oecophorid moths. 44,45 The parallels between Pterostylis semiochemicals and moth sex pheromones are particularly interesting as moths have been touted as possible pollinators of sexually deceptive orchids, 46 yet so far none have been reported. Our results raise the possibility that some Pterostylis orchids may be capable of sexually attracting moths.…”

Ecology, invasion history and biodiversity-driven management of the coconut black-headed caterpillar Opisina arenosella in Asia

“…GC-EAD assays showed strong male antennal activity following exposure to female pheromone gland extract and synthetic Z3Z6Z9-23Hy. In cage experiments, higher numbers of O. arenosella adults (93.2% being male) were caught in pheromone-baited traps (Bhanu et al, 2018). Exploratory work by Subaharan et al (2005) reveals how olfactory conditioning possibly can enhance the efficacy of augmentation biological control (Kruidhof et al, 2019).…”

“…Also, field observations unveiled how O. arenosella males are attracted to young female moths ( Chandrasiri and Fernando, 1997 ). Upon dissection of the pheromone glands of virgin O. arenosella females, gas chromatography coupled with electro-antennographic detection (GC–EAD) and mass spectrometry (GC–MS) identified (Z,Z,Z)-3,6,9-tricosatriene (Z3Z6Z9-23Hy) as its main physiologically active compound ( Bhanu et al., 2018 ). GC-EAD assays showed strong male antennal activity following exposure to female pheromone gland extract and synthetic Z3Z6Z9-23Hy.…”

“…Lastly, the laboratory-based identification of BHC kairomones and pheromones has facilitated the development of volatile-based mass-trapping, mating disruption, and monitoring approaches. Following the identification and synthesis of O. arenosella pheromones ( Bhanu et al., 2018 ), pheromone traps have been widely used to monitor BHC population levels and guide management interventions in coconut plantations ( Bhanu et al., 2018 ). The deployment of pheromone traps on its own can reduce BHC population levels by 50-94% ( Chandrashekharaiah, 2013 ).…”

“…In recent years, considerable progress has been made integrating semio-chemicals within O. arenosella IPM packages. This has involved using pheromone traps to assess BHC seasonal dynamics ( Bhanu et al., 2018 ) or for mass-trapping, i.e., as a direct control measure ( Muniyappa et al., 2018 ). While UV light or kairomone trapping still needs to be further refined, the usage of BHC sex pheromones has been tested and refined in India.…”