Biological Control

• Yellow Vein Mosaic Virus (YVMV) of Okra (Abelmoschus esculentus):
• is true: Transmitted in nature in a persistent, circulative manner by the whitefly (Bemisia tabaci).
• is true: The characteristic diagnostic initial symptom is intense vein clearing followed by brilliant yellow network of veins contrasting with green interveinal areas.
• is false: YVMV is a bipartite or monopartite begomovirus with satellite DNA that is not mechanically (sap) transmissible under normal field conditions.
• is false: While late-infected plants produce small yellowish fruits, infected plants are not necessarily 'severely stunted' unless infected at the earliest seedling stage.
• Conclusion: Statements (A) and (B) only are true (Option 3).

Correct option: (3) (A) and (B)

• Citrus Nematode (Tylenchulus semipenetrans) Biology:
• Egg Sac Gelatinous Matrix: Sedentary mature females of Tylenchulus semipenetrans remain semi-endoparasitic in citrus feeder roots. They secrete a protective gelatinous matrix into which eggs are deposited.
• Secretion Site: In Tylenchulus semipenetrans, the gelatinous matrix is uniquely secreted through the excretory pore, located anteriorly near the vulva.
• Contrast with Root-Knot Nematodes: In Meloidogyne (root-knot nematodes), the gelatinous matrix is secreted by six rectal glands. Tylenchulus lacks caudal glands; Statement I is correct and Statement II is incorrect (Option 3).

• Status of Indian Wildlife and Fauna:
• Statement (I) is true: The House Sparrow (Passer domesticus) is an omnivorous bird feeding on seeds, grains, and insects whose populations have declined rapidly due to urbanization, pesticide use, and lack of nesting sites, prompting nationwide conservation efforts (e.g., State Bird of Delhi, World Sparrow Day).
• Statement (II) is evaluated: Nilgai or Blue bull (Boselaphus tragocamelus) is the largest Asian antelope. In the examination key, Statement II was marked incorrect because it is an antelope rather than a member of the domestic cattle/cow genus (Bos).
• Conclusion: Statement (I) is correct but Statement (II) is incorrect (Option 3).

• Spodoptera frugiperda (Fall Armyworm) $\rightarrow$ (II) 2018: First reported invading maize fields in Shivamogga, Karnataka, in May 2018, rapidly spreading across the Indian subcontinent.
• Phenacoccus solenopsis (Cotton Mealybug) $\rightarrow$ (IV) 2006: Emerged as a severe invasive epidemic on Bt cotton across Gujarat, Maharashtra, and Punjab around 2006.
• Tuta absoluta (Tomato Leafminer / Pinworm) $\rightarrow$ (III) 2014: First detected infesting tomato crops in Pune, Maharashtra, in late 2014.
• Aleurodicus rugioperculatus (Rugose Spiralling Whitefly) $\rightarrow$ (I) 2016: First documented on coconut palms in Pollachi, Tamil Nadu, and Palakkad, Kerala, in 2016.
• Correct Option: Option 2 ((A) - (II), (B) - (IV), (C) - (III), (D) - (I)).