Effect of Different Honey Concentrations on Survival, Longevity and Reproduction of Trichospilus pupivorus (Hymenoptera: Eulophidae), a Parasitoid of Coconut Black-Headed Caterpillar, Opisina arenosella (Lepidoptera: Oecophoridae)

Many coconut producing countries in Asia are facing a serious infestation of Opisina arenosella (Lepidoptera: Oecophoridae) or commonly called the coconut black-headed caterpillar. Recently, the pest has been detected in the coconut (Cocos nucifera) planting area in Pahang, Malaysia. Thus, an initiative to manage the pest by using parasitoids has been started with a study on the effects of diet on survival, longevity and reproduction of naturally occurred parasitoid known as Trichospilus pupivorus (Hymenoptera: Eulophidae). The aim of this study was to identify suitable concentrations of honey that can be used in developing its rearing technique. Two independent experiments were conducted, i.e., a) survival and longevity study; and b) reproduction study. In each study, different honey concentrations were tested on ten (eight replications) and one (five replications) female parasitoids respectively. 30% honey concentrations resulted in high survival rate of the adult during early life with relatively prolonged longevity up to 6.0±0.19 days and significantly produced the highest number of progenies (105.4±0.81). The lowest survival rate was given by 60% honey and significant longevity up to 6.5±0.33 days with no progenies. Further studies on other plausible factors affecting the reproduction and fitness of progenies should also be investigated to ensure efficient rearing techniques.

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

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.