Chandrika Mohan

Leaf-eating caterpillar ( Opisina arenosella)-induced yield loss in coconut palm

Coconut is one of the major crops of commercial importance among the palms. The leaf-eating caterpillar Opisina arenosella Walker is the most important lepidopteran pest of coconut palm in India and Sri Lanka. Assessment of crop loss is essential for a realistic planning for research and developmental policies. Information on the yield loss in coconut due to O. arenosella attack is very meagre. In the present study, results of investigations carried out on leaf-eating caterpillar-induced yield loss in coconut palms in Kerala, India, for a period of 4 years (2002-2005) are presented. A maximum crop loss of 45.4% in terms of nut yield was recorded from infested palms in the succeeding year of severe pest incidence. The infested palms also showed reduction in bunch and leaf production to the tune of 21.0 and 13.8%, respectively. The pest-attacked palms regained their normal yield potential by the fourth year after heavy pest infestation.

First record of Asian grey weevil (Myllocerus undatus) on coconut from Kerala, India

The occurrence of Asian grey weevil Myllocerus undatus (Curculionidae: Coleoptera) damaging coconut (Cocos nucifera L.) seedlings is reported for the first time from Kerala, India. A mild to moderate level of infestation damaging 5–10% leaf lamina of un-split leaves with a typical notching-like symptom along the leaf margins is noticed on the majority of the coconut seedlings belonging to different coconut varieties, viz., ‘Chowghat Orange Dwarf’, ‘Chowghat Green Dwarf’, ‘Malayan Green Dwarf’, ‘West Coast Tall’ and Dwarf x Tall hybrids. M. undatus has not been reported as a destructive pest on any of the crops from India and is considered to be a pest of quarantine significance. Adult weevils have a characteristic tri-spined hind femur and elytra strongly angled broader than the prothorax.

Direct and indirect influences of intercrops on the coconut defoliator Opisina arenosella

AbstractCoconut palm (Cocos nucifera) infestation by Opisina arenosella (Lepidoptera: Oecophoridae) in the Indian subcontinent may occur in November to May each year in the same or adjoining areas of plantations. Parasitoids of O. arenosella may also be consistently present at these times. During other periods, pests and/or parasitoids could be maintained on intercrops that are commonly grown throughout the year. Field surveys of 54 intercrop species in Kerala, India, found that O. arenosella attacks banana, but not others, while laboratory screening showed that O. arenosella can mature on jack fruit, cashew and oil palm. Larvae of 20 lepidopteran species found on intercrops were screened for use by Goniozus nephantidis (Hymenoptera: Bethylidae), a larval parasitoid of O. arenosella, which oviposited on two species but its offspring failed to mature. Thirteen intercrop herbivore species were screened for use by Brachymeria nosatoi (Hymenoptera: Chalcididae), a pupal parasitoid of O. arenosella, which completed development on the pyralids Herculia nigrivita, Syllepte derogata and Psara basalis. Further, connectance trophic webs were compiled using prior field records of coconut, 33 species of intercrops, 58 species of lepidopteran herbivores and 29 species of primary parasitoids. Both laboratory and literature evidence suggests that populations of O. arenosella are unlikely to be maintained by feeding on intercrops or strongly influenced by direct competition with other lepidopterans but are likely to be affected by sharing parasitoids. Intercrop herbivores have clear potential for maintaining parasitoids of O. arenosella, and we recommend thirteen plant species as intercrops that should aid in conservation biocontrol.

Coconut Water as a Promising Culture Media for Hirsutella thompsonii Fisher, a Pathogen of Coconut Mite

Coconut eriophyid mite Aceria guerreronis Keifer has emerged as a major pest of coconut in the country since 1998. Among the various biocontrol agents, Hirsutella thompsonii is a promising fungal pathogen used in field biosuppression of the pest. Influence of various synthetic and laboratory-derived growth media, viz., Potato Dextrose Agar (PDA), Sabouraud Dextrose Agar (SDA), Glucose Yeast Extract Agar (GYA), and Carrot Agar (CA), was compared with a locally available inexpensive substrate, coconut water on growth, and sporulation of H. thompsonii. Fungal growth characters, viz., radial growth, conidial production, and micromorphometry of the fungal mycelium and spore, were recorded. Results indicated comparable growth in coconut water media (1.91 cm/20 days) to that of PDA (1.94 cm/20 days). In solid media, laboratory-derived coconut water agar showed significantly higher spore count (12.9 × 104spores/cm3) followed by laboratory-derived PDA (11.38 × 104spores/cm3). Regarding conidial production in broth culture, maximum spore production of H. thompsonii was observed in Sabouraud Dextrose broth (51.2 × 104spores/cm3). Coconut water showed comparable spore count (18.2 × 104spores/cm3) to that of Potato Dextrose broth (19.6 × 104spores/cm3) and Glucose Yeast Extract broth (18.6 × 104spores/cm3). There was no significant difference in micromorphometric characters among the media tested. The results suggest the potential of using coconut water for mass production of H. thompsonii in the laboratory.

Biocontrol Potential and its Exploitation in Coconut Pest Management

Many insects cause economic loss to the cultivated crops, forest crops, stored products and domestic animals. These are called as pests. They have enormous capacity to multiply and their population increases significantly. But natural checks such as adverse climate, lack of proper food, want of growing space and natural enemies limit their multiplication. The method of control exerted by the natural enemies viz. parasites, predators and pathogens is termed as biological control or biological pest suppression. Today this cost-effective and ecofirendly method is being successfully tested under different cropping systems to ward off the pest problems. The present chapter documents the exploitation of the potential bioagent in the management of the important coconut pests and thereby sustain the productivity of the coconut palms.