UPHESC Assistant Professor Entomology PYQs

Concept: Population movements: immigration = one-way movement INTO an area; emigration = one-way movement OUT of an area; migration = periodic two-way movement.

1. The question says 'one way inward' → immigration (adds to population density).
2. Dispersal is the general term for spreading of individuals in any direction.

Short trick: IMmigration = IN; EMigration = EXit.

Concept: The female mosquito's proboscis has six needle-like stylets enclosed in the grooved labium (sheath).

1. Stylets: labrum-epipharynx (1) + hypopharynx (1) + mandibles (2) + maxillae/laciniae (2) = 6.
2. The labium does not pierce; it bends back as the stylets enter the skin.
3. Bugs (Hemiptera) have only 4 stylets (2 mandibular + 2 maxillary).

Short trick: Mosquito 6, bug 4, thrips 3 (rasping-sucking).

Concept: Brain hormone (PTTH – prothoracicotropic hormone) acts only to activate the prothoracic glands for moulting; in most adult (pterygote) insects the prothoracic glands degenerate after the final moult, so there is no PTTH–ecdysone moulting axis.

1. Juvenile hormone is present in adults – it regulates vitellogenesis, accessory gland activity and reproduction (gonadotropic role).
2. Eclosion hormone is released at adult emergence (eclosion) and triggers the emergence behaviour.
3. Epideictic (spacing/marking) signals are released by adults, e.g. the oviposition-marking pheromone of fruit flies.
4. Hence the one not needed in the adult is the brain hormone (PTTH).

Short trick: Adults do not moult → no brain hormone → no ecdysone.

Concept: Know the family of common insects.

1. Leaf hopper → Cicadellidae (c); Lady bird beetle → Coccinellidae (d).
2. Green lacewing (Chrysoperla) → Chrysopidae (e); House fly (Musca domestica) → Muscidae (a).
3. Tiger moth (e.g. hairy caterpillars) → Arctiidae (b). Code: c-d-e-a-b.

Short trick: Name inside family: Musca–Muscidae, Coccinella–Coccinellidae, Chrysopa–Chrysopidae.

Concept: Lipaphis erysimi is the mustard aphid (Aphididae, Hemiptera), an insect with incomplete metamorphosis.

1. Its young are nymphs; both nymphs and adults suck sap from leaves, inflorescence and pods.
2. 'Grub' is the larva of beetles and 'larva/caterpillar' of moths – not applicable to aphids.

Short trick: Hemiptera → nymph + adult both damage.

Concept: Sawfly larvae (Hymenoptera: Tenthredinidae) look like caterpillars but carry 6–8 pairs of prolegs without crochets; lepidopteran caterpillars have at most 5 pairs, with crochets.

1. Athalia lugens proxima (mustard sawfly) larva has 8 pairs of abdominal prolegs (on segments 2–8 and 10).
2. Achaea janata (castor semilooper) has only 3 pairs (semilooper); Pericallia ricini and Pieris brassicae have the normal 5 pairs.

Short trick: More than 5 pairs of prolegs → sawfly, not moth.

Concept: Fall armyworm, Spodoptera frugiperda (Noctuidae), native to the Americas, was first reported in India in May–July 2018.

1. It was found on maize at Shivamogga (Karnataka) by UAHS/ICAR-NBAIR.
2. It later spread to sorghum, sugarcane, millets etc., but maize is its main and first-recorded host in India.

Short trick: FAW 2018, Karnataka, Maize.

Concept: The phase theory was proposed by B.P. Uvarov (1921): locusts exist in a solitary and a gregarious phase that differ in colour, form and behaviour.

1. Crowding converts solitaria into gregaria (via transiens) – the swarming phase.
2. Example: desert locust Schistocerca gregaria, migratory locust Locusta migratoria.

Short trick: Uvarov → phase theory → locust.

Concept: Yellow stem borer, Scirpophaga incertulas, lays eggs in masses covered with buff hairs near the tips of rice leaves in the nursery.

1. Clipping the leaf tips of seedlings before transplanting removes these egg masses and reduces dead-heart.
2. Gundhi bug lays eggs in rows on leaves/panicle, leaf folder lays single eggs, grasshoppers lay eggs in soil.

Short trick: Leaf-tip egg mass → stem borer → clip before transplanting.

Concept: The green leafhopper, Nephotettix virescens / N. nigropictus (Cicadellidae), inserts its eggs with its ovipositor in rows into the leaf tissue.

1. Eggs (8–16 per row) are embedded in the parenchymatous tissue of the leaf sheath/leaf midrib, under the epidermis.
2. They are not laid in soil or inside the true stem; the nymphs hatch in 6–9 days.

Short trick: Leafhopper = endophytic oviposition in leaf tissue.

Concept: White grub, Holotrichia consanguinea / H. serrata (Scarabaeidae: Melolonthinae), is univoltine.

1. Adults emerge with the first monsoon showers (May–June), lay eggs in soil; grubs feed on roots till September–October.
2. It pupates and passes the winter in soil as adult/pupa – only one generation per year.

Short trick: Monsoon beetle → one generation a year.

Concept: The term/idea 'integrated control' was first used by Hoskins, Borden and Michelbacher (1939) – chemical control should supplement biological control.

1. Stern, Smith, van den Bosch and Hagen (1959) defined integrated control and gave the ET/EIL concept.
2. The term IPM was used by Smith and van den Bosch (1967) and became popular in 1970s.
3. Paul Müller discovered insecticidal property of DDT in 1939 (not 1937) – unrelated.

Short trick: 1939 Hoskins = integrated control idea; 1959 Stern = ETL; 1967 = IPM term.

Concept: Imidacloprid is a neonicotinoid (IRAC Group 4A) – it acts as an agonist of the nicotinic acetylcholine receptor (nAChR) in the insect CNS.

1. It binds the receptor like acetylcholine but is not broken down by AChE → continuous stimulation, paralysis, death.
2. AChE inhibition = organophosphates/carbamates; mitochondrial electron transport inhibitors = fenpyroximate, rotenone; octopamine agonist = amitraz.

Short trick: Neonicotinoid = nicotine-like = nAChR agonist.

Concept: Pedigo's formula: EIL = C / (V × I × D × K).

1. C = cost of control per unit area; V = market value per unit produce.
2. I = injury units per insect (crop injury per pest density); D = damage (yield loss) per unit injury.
3. K = proportionate reduction of injury by control (often taken as 1, giving EIL = C/VID).

Short trick: C-V-I-D-K: Cost, Value, Injury/insect, Damage/injury, Kill-proportion.

Concept: Painter's three mechanisms of host plant resistance: antixenosis (non-preference), antibiosis and tolerance.

1. Antibiosis = adverse effect of the plant on the insect's biology – reduced growth, survival, fecundity, prolonged development.
2. Antixenosis affects the insect's behaviour (host selection); tolerance is the plant's ability to withstand/recover from damage.

Short trick: Anti-BIO-sis → affects BIOlogy.

Concept: Fipronil is a phenylpyrazole (fiprole) insecticide – IRAC Group 2B, a GABA-gated chloride channel blocker.

1. Oxadiazine = indoxacarb (sodium channel blocker).
2. Neonicotinoids (imidacloprid) and thianicotinyls (thiamethoxam) act on nAChR.

Short trick: FIProle = FIPronil = Phenylpyrazole.

Concept: LC50 = concentration of a toxicant that kills 50% of the test population.

1. If a smaller concentration kills half the insects, the chemical is more potent.
2. So toxicity is inversely related to LC50/LD50: low LC50 → more toxic.

Short trick: Low LC50 = little needed to kill = more toxic.

Concept: Allelochemicals act between species and are named by who benefits.

1. Kairomone – benefits the receiver only (e.g. host odour guiding a parasitoid to its host).
2. Allomone – benefits the emitter only (e.g. defensive secretions); Synomone – benefits both (e.g. floral scent and pollinator).
3. Apneumone comes from a non-living source.

Short trick: Kairomone = Kamaayi receiver ki; Allomone = Apna (emitter) faayda; Synomone = Saajha.

Concept: The Insecticides Act, 1968 regulates import, manufacture, sale, transport, distribution and use of insecticides in India.

1. The Act and the Insecticides Rules (1971) were brought into force from 1 August 1971.
2. It set up the Central Insecticides Board (CIB) and the Registration Committee (RC).

Short trick: Act 1968 → Rules + enforcement 1971.

Concept: Pesticides are named after the target: Avi = bird.

1. Avicides are chemicals used against birds – to kill or repel them (e.g. anthraquinone, methiocarb, 4-aminopyridine).
2. Acaricides – mites; molluscicides – snails/slugs; nematicides – nematodes.

Short trick: Avis (Latin) = bird → avicide.