Study On Whiteflies

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    Recent studies have indicated that approximately 1.35 lakh hectares of coconut and oil palm in India are affected by the rugose spiralling whitefly.

    About

    • Extensive studies were carried out from 2015 to 2020 across the country to understand the patterns of occurrence, the intensity of the infestation of whitefly
    • Researchers extracted genomic DNA from individual adult whiteflies and explained in detail about eight invasive species found in India.
    • Most of these species are native to the Caribbean islands or Central America [or both].

    How did the Whiteflies Enter India?

    • Most probably a nymph or baby insect may have come along with imported plants. 
    • Also nowadays with globalisation, it is also possible that tourists may have brought the insect along with plants.
    • Out of curiosity, people randomly pluck and bring tiny plants which lead to the accidental introduction of invasive species. 

    Reported Whiteflies

    • The first invasive whitefly reported from Kerala in 1995 has now spread across the country, and a study has now detailed the damage caused by the pest.
      •  The first reported invasive spiralling whitefly Aleurodicus dispersus is now distributed throughout India except Jammu & Kashmir.
    • Similarly, the rugose spiralling whitefly which was reported in Pollachi, Tamil Nadu in 2016 has now spread throughout the country including the islands of Andaman Nicobar and Lakshadweep. 
      • Aleurodicus dispersus and Aleurodicus rugioperculatus have been reported on over 320 and 40 plant species, respectively.

    Concerns

    • Damage to Crops
      • Whiteflies are one of the top ten devastating pests in the world that damage more than 2000 plant species and also function as vectors for some 200-plant viruses.
      • Cotton is one of the worst hit crops by these, in 2015 two third of the cotton crop was destroyed by the pest in Punjab.
    • Ineffectiveness of Insecticides
      • Whiteflies have been difficult to control by using available synthetic insecticides.
    • Reasons of increase 
      • The team found that the host range of all of the invasive whiteflies was increasing due to their polyphagous nature (ability to feed on various kinds of food) and prolific breeding.

    Measures Needed

    Biological Control Method

    • The whiteflies are difficult to control by using synthetic insecticides, and hence currently naturally occurring insect predators, parasitoids and entomopathogenic fungi (fungi that can kill insects) can be used.
      •  These are not just environmentally friendly but also economically feasible
    • Entomopathogenic fungi specific to whiteflies are isolated, purified, grown in the lab or mass-produced and applied into the whitefly infested field in combination with the release of lab-reared potential predators and parasitoids.

    Proper Monitoring

    • Continuous monitoring of the occurrence of invasive species, their host plants and geographical expansion is needed, and if required, import of potential natural enemies for bio-control programmes can also be carried out.

    Awareness among citizens

    • We need to create awareness among the citizens, especially travellers.

    Phytosanitary Regulations

    • The state should ensure stricter phytosanitary measures at relevant places to reduce the chances of incoming exotic species.

    Use of Biotechnology

    •  In a move to fight against whiteflies, National Botanical Research Institute (NBRI) Lucknow has developed a pest-resistant variety of cotton and is going to start field trials this year from April to October in Faridkot Center of Punjab Agriculture University, Ludhiana.

    Rugose Spiralling Whitefly                           

    • The rugose spiralling whitefly(Aleurodicus rugioperculatus) has been reported from
    • India from Tamil Nadu, Karnataka, Kerala and Andhra Pradesh.
    • It is an invasive pest that attacks a wide range of host plants including palms, woody ornamentals, and fruits. Coconut and banana are among the most preferred host plants. 

     Image Courtesy: Entomology 

    Damage Symptoms and Diagnosis

    • Nymphs and adults of the whitefly suck the sap on the under surfaces of the leaflets.
    • Extensive feeding of the insect leads to the excretion of honey dew which subsequently gets deposited on the upper surface of the leaves
    • Honey dew excrement, being sweet and watery, attracts ants and encourages growth of the fungus Capnodium sp. which causes disfigurement of hosts affecting the photosynthetic efficiency of the plant.

    Management

    • Spraying starch solution (1%) to dislodge the heavy sooty mould deposition on the leaves of infested plants.
    • Use of yellow sticky traps to trap the adult whiteflies
    • Encourage build up of parasitoids (Encarsia sp.) and re-introduce parasitized pupae to emerging zones of whitefly outbreak.
    • In case of severe infestation, spray neem oil 0.5%
    • No insecticides should be applied to manage the pest.

    Source :TH