Brinjal shoot and fruit borer infestation in relation to plant age and season

Pest categorisation of Leucinodes orbonalis

The EFSA Panel on Plant Health performed a pest categorisation of the eggplant fruit and shoot borer, Leucinodes orbonalis Guenée, (Lepidoptera: Crambidae), for the territory of the EU. L. orbonalis is a tropical and sub-tropical species native to Asia and Australia with India considered its centre of origin. Following taxonomic revision, literature reporting L. orbonalis from sub-Saharan Africa should be regarded as referring to members of a complex of other species of Leucinodes native to Africa and not as referring to L. orbonalis. L. orbonalis is not present in the EU and is not a regulated EU pest. L. orbonalis is a major pest of Solanum melongena (eggplant) in Asia where larvae feed within leaves, stems, shoots and fruits. Larvae can also feed on a range of other plants, mostly within Solanaceae although L. orbonalis is generally not reported as a pest of crops other than S. melongena. However, in recent years L. orbonalis has emerged as a pest of Solanum tuberosum in south-west India. In tropical areas there can be 10 generations per year if conditions are suitable. L. orbonalis has been intercepted 350 times in the EU from a range of Asian countries on a range of produce, mostly larvae in fruits of S. melongena. Biotic factors (host availability) and abiotic factors (climate suitability) suggest that some small areas of the EU could be suitable for establishment. Adult L. orbonalis can fly and the species could spread within the EU. The introduction of L. orbonalis into the EU would have an economic impact, most likely on S. melongena production, the magnitude of which is uncertain. Measures are available to prevent the entry of L. orbonalis into the EU. L. orbonalis satisfies the criteria that are within the remit of EFSA to assess for this species to be regarded as a potential Union quarantine pest.

Characterization of Eggplant Genotypes for Different Resistance Mechanisms Against Leucinodes orbonalis

Host plant resistance mechanisms play an important role in developing cultivars with resistance to the target pests; information regarding morphological and biochemical factors contributing to the resistance is essential for developing pest-resistant cultivars. As a result, we investigated the contribution of various morphological and biochemical characters in forty-two eggplant genotypes against Leucinodes orbonalis Guenée, in Himachal Pradesh, India. Out of all the phenotypic parameters evaluated, pericarp thickness (r = 0.89) has significantly positive correlation with fruit infestation, whereas trichome density had significantly negative correlation (r = - 0.89). Analysis of the biochemical compounds in the eggplant genotypes revealed that total phenols (r = - 0.71), polyphenol oxidase (r = - 0.63), peroxidases (r = - 0.35), phenylalanine ammonium lyase (r = - 0.71) and solasodine (r = - 0.81) had significantly negative correlation with the per cent fruit infestation by L. orbonalis while the reducing sugars (r = 0.66) and non-reducing sugars (r = 0.62) showed a significantly positive correlation. Molecular characterization by random amplified polymorphic DNA (RAPD) primers also revealed the presence of high genetic diversity among different eggplant genotypes, where 17 polymorphic RAPD primers produced a total of 167 amplicons, among which 144 amplicons were polymorphic and 23 monomorphic bands. PCR-amplified DNA fragment size ranged from 100 to 2500 bp, mean polymorphism was 86.42% and the average PIC value was 0.444. Jaccards coefficient-based dendrogram grouped 40 eggplant genotypes into two major clusters. Results also revealed that the resistant genotypes accumulated higher levels of defensive biochemical enzymes such as phenols, PO, PPO, PAL and solasodine to confer insect resistance. Molecular characterization also revealed that genotypes in the present study were genetically diverse and could be used in future breeding and improvement programmes in this crop. Genotypes, IC411485 and IC090951, in particular, can be used as varied parents in breeding programmes to generate improved lines in terms of resistance to L. orbonalis.