UPSC CSE Prelims 2012

Correct Option (d):

All three categories of organisms listed-bacteria, fungi, and flowering plants-include species that are utilized as biopesticides. Biopesticides are naturally occurring substances or organisms that control pests through non-toxic and environmentally friendly mechanisms.

• Bacteria: Bacillus thuringiensis (Bt) is a widely used bacterial biopesticide. It produces specific protein toxins (Bt toxins) that are harmful to the larvae of certain insect pests upon ingestion, disrupting their digestive system.
• Fungi: Several fungal species act as biopesticides. For instance, entomopathogenic fungi like Beauveria bassiana and Metarhizium anisopliae infect and kill insect pests. Additionally, Trichoderma species are employed as biofungicides to suppress various plant pathogens in the soil and on plant surfaces.
• Flowering plants: Botanical pesticides are derived from certain flowering plants. Azadirachta indica (Neem) is a prominent example, whose extracts, particularly azadirachtin, possess insecticidal, antifeedant, and repellent properties against a broad spectrum of agricultural pests.

Incorrect Options:

• Option (a) is incorrect because, in addition to bacteria, species of fungi and flowering plants are also effectively employed as biopesticides, offering a diverse range of pest control mechanisms.
• Option (b) is incorrect as it excludes bacteria. Bacteria, especially Bacillus thuringiensis, are a cornerstone of modern biopesticide applications due to their specific action against key insect pests.
• Option (c) is incorrect because fungi are significant sources of biopesticides. Fungal species like Beauveria bassiana and Trichoderma provide effective control against insect pests and plant diseases, respectively, and should not be omitted.