The coconut and the oil palm are cultivated throughout the tropics where it is interwoven into the lives of the people and provide a variety of products. The pest problem is one of the major constraints for achieving higher production and productivity in these palms especially the recent invasion of exotic invasive whiteflies.
Since 2016, as many as six exotic whiteflies viz., rugose spiraling whitefly, Aleurodicus rugioperculatus during 2016, Bondar’s nesting whitefly, Paraleyrodes bondari and nesting whitefly, Paraleyrodes minei during 2018, and palm infesting whitefly, Aleurotrachelus atratus invaded in these palm plants in India. Extensive spread along the coastal regions and gardens near the backwater of India is predicted owing to the favorable weather factors and availability of host plants.
All these invasive species are highly polyphagous and have a host preference towards many economically important palm plants. Species of exotic whiteflies with similar habits co-exist in the same niche and have a similar pattern of growth and development. The most insidious spread of these species in India is likely mediated by humans through the movement of infested seedlings and plant materials. Nymphs and adults of these invasive whiteflies not only feed aggressively on leaf sap resulting in depletion of nutrients and water which leads to premature leaf drop and drying but also produce wax and excretes sticky honeydew that deposits on infested plants and inter-crops. It further leads to the extreme growth of black sooty mold development which results in the reduction of photosynthetic efficiency in palms and the marketability of intercropped crops. Currently, it has become a regular pest of coconut and oil palm in India, warranting control measures to avoid crop losses.
Soon after the report of these invasive species in India, ICAR-NBAIR took a proactive measure to contain the damage through regular monitoring, exploration of biocontrol agents, development of mass production protocol, demonstrations, sensitizing the growers through an awareness program and development of bio-intensive management strategies. Natural enemies of insect pests play a key role in reducing the levels of pest populations below those causing economic injury to crop plants. Both natural and applied biological control tactics are important in successful management of pest populations. Unlike annual crops, plantation crops provide the more congenial conditions for parasitoids, predators, and entomopathogens for their growth and perpetuation.
Notably, ICAR-NBAIR identified and validated a potential entomopathogenic fungus, Cordyceps (=Isaria) fumosorosea (ICAR-NBAIR Pfu-5) - “Shatpada Rugose Whitefly Kill” for the management of these invasive whiteflies, which have been commercialized.
This fungus is formerly Isaria fumosorosea or Paecilomyces fumosoroseus and is widely distributed in temperate and tropical regions as an important biocontrol agent, especially whiteflies and psyllids. ICAR-NBAIR also has standardization for mass production and formulation technology (talc, grain, and oil-based) for potential strains with higher bio-efficacy, field persistence, and longer shelf life. Shelf-life for about 90, 180, 210 days, talc, oil, and rice grain-based formulations, respectively.
Under field conditions, 72.20-78.28 reduction in the overall population of these whiteflies was observed in C. fumosorosea treated palm with two sprays at 15-day intervals. This fungus potentially kills all life stages of these invasive whiteflies including eggs. Dosage, application method, and spray volume were standardized for the effective management of these invasive whiteflies in coconut and oil palms.
Further, it was found that C. fumosorosea is safer than natural enemies associated with the coconut ecosystem i.e parasitoid, Encarsia guadeloupae, Goniozus nephantidis, predator, Apertochrysa astur and mulberry silkworm, Bombyx mori. Under favorable conditions, C. fumosorosea was known to regulate these invasive whitefly populations through epizootics. Further, it was found that infected adult individuals of rugose spiraling whiteflies which are capable of transferring, C. fumosorosea conidia to another healthy individual cause the spread of infections and the onset of epizootics under field conditions.
ICAR-NBAIR conducts field demonstrations and large-scale mass production strategies of C. fumosorosea regularly for different stakeholders, progressive farmers (on-farm production techniques), line department officials, subject matter specialists of ICAR-KVKs and officials of Central Integrated Pest management centers.
Therefore, these biocontrol agents can be integrated simultaneously for the management of invasive whiteflies in coconut. Recently, we attempted to spray this oil-based formulation of C. fumosorosea through an agriculture drone. Economic analysis of the impact of these advisories resulted in a Rs 9500/ha reduction in crop protection and 900 ml of pesticides/ha. Besides the bio-suppression of invasive whiteflies, this also conserves the natural enemies in the coconut ecosystem and saves the environment.
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