ICAR AIEEA PG Entomology 09 July 2023 (Shift 1) Paper

Classification of insect orders and typical examples:

• Mecoptera: Scorpionflies (Panorpa spp.) -> (III).
• Thysanura (Zygentoma): Silverfish (Lepisma saccharina) -> (I).
• Lepidoptera: Lemon butterfly (Papilio demoleus) and moths -> (II).
• Trichoptera: Caddisflies (hairy-winged insects with aquatic case-bearing larvae) -> (IV).

Alternation of convex (+) and concave (-) veins in insect wing venation (fluting):

• Costa (C): Convex (+).
• Subcosta (Sc): Concave (-).
• Radius (R1): Convex (+).
• Radial Sector (Rs): Concave (-).
• Media: Anterior Media (MA) is Convex (+), while Posterior Media (MP) is Concave (-).
  (F) Cubitus: Anterior Cubitus (CuA) is Convex (+), while Posterior Cubitus (CuP) is Concave (-).

Exocrine glands of worker honeybees (Apis mellifera / Apis cerana):

• Worker bees possess four pairs of wax-secreting glands situated on the ventral surface (sternites / sterna) of the 4th, 5th, 6th, and 7th abdominal segments.
• The smooth polished cuticular areas overlying these epidermal hypodermal cells are termed 'wax mirrors' (mirrors of Dreyling). Liquid wax exudes through pores, solidifying upon exposure to air as thin translucent wax scales used for comb construction.

Physiology of insect moulting and integument microstructure:

• Statement (I) is correct: The moulting process initiates when elevated titers of 20-hydroxyecdysone stimulate epidermal cell division and the detachment of the epidermis from the old endocuticle, a biological step termed Apolysis (creating the sub-cuticular space into which moulting fluid is secreted).
• Statement (II) is correct: The epicuticle consists from outside inwards of: Cement layer -> Wax layer -> Polyphenol layer -> Cuticulin layer. The cement layer (secreted by dermal glands) protects the underlying wax layer, but it is notably absent in certain insects including honey bees (Apis) and some scale insects.

Anatomy of insect mouthparts and gustatory chemoreceptors:

• The Labrum (upper lip) has an inner/ventral membranous surface termed the Epipharynx.
• The epipharynx is densely studded with sensory papillae, peg sensilla, and basiconic gustatory sensilla (termed epipharyngeal sensilla) that taste food before ingestion and monitor food quality as it enters the preoral cibarial cavity.