Objective Agricultural Entomology and Nematology Flashcards

Fundamental vocabulary terms and definitions covering major insect pests, entomological physiology, nematode characteristics, and integrated pest management concepts mentioned in the text.

Systemic insecticides

Insecticides that are translocated through the vascular system of a plant or the circulatory system of an animal.

Apodeme

An internal ridge of the exoskeleton in insects.

Rhyniella praecursor

A collembolan fossil from the Devonian period of Scotland (1926) recognized as the earliest known fossil insect.

Occasional pest

A pest whose General Equilibrium Position (GEP) is usually below the Economic Injury Level (EIL), rarely crossing it.

Sporadic pests

Pests whose GEP is generally below EIL, but sometimes cross it and cause severe loss in specific places or periods, such as Sugarcane pyrilla.

Potential pests

Organisms that are not pests at present because their GEP is always less than EIL, but may cause economic loss if the environment changes.

Dead heart

The drying of the central shoot in young rice plants caused by the rice stem borer, $Scirpophaga\,incertulas$, or sorghum shoot fly, $Atherigona\,soccata$.

White ear

The drying of the panicle in older rice plants caused by the rice stem borer, $Scirpophaga\,incertulas$.

Platygaster oryzae

A larval parasitoid used to control the rice gall midge.

Brown plant hopper (Nilaparvata lugens)

A vector of rice virus diseases including rice grassy stunt and ragged stunt.

Hopper burn

Damage symptoms in cotton crops caused by the cotton leaf hopper, $Amrasca\,biguttula\,biguttula$.

Osmeteria

Orange-colored glands that the caterpillar of the Lemon butterfly everts out when disturbed, emitting a characteristic smell.

Primary pests

Insects that attack healthy stored grains and cause initial damage.

Secondary pests

Insect pests that cause further damage to grains or stored products already damaged by other insects.

Nasute soldiers

Termite soldiers possessing a special rostrum for ejecting offensive secretions for chemical warfare.

Half life

The length of time it takes for a pesticide to lose half of its toxicity in a given environment.

LD 50 (Median lethal dose)

The amount of insecticide per unit weight required to kill $50\,\%$ of a specific organism, usually expressed as $mg/kg$ body weight.

Semiochemicals

Chemical substances that mediate communication between organisms, classified into pheromones and allelochemics.

Allomone

An interspecific semiochemical that provides a benefit to the emitter.

Kairomone

An interspecific semiochemical that provides a benefit to the receiver.

Juvenile hormone (JH)

Also called neotinin; a terpene-natured hormone secreted by corpora allata that keeps larvae in a juvenile condition.

Ecdysone

The moulting hormone (MH); a steroid-natured hormone secreted by the prothoracic glands (PTG).

Hypognathous

An orthopteroid-type head where the long axis is vertical and mouthparts are ventrally placed, projecting downwards.

Prognathous

A coleopteroid-type head where the long axis is horizontal and mouthparts are directed forward.

Opisthognathous

A hemipteroid-type head where the head is deflexed and mouthparts are directed backwards and held between the forelegs.

Johnston's organ

A mass of sense cells present in the pedicel (second antennal segment) used as a chordatonal organ in insects like mosquitoes.

Corbicula

The pollen basket; a shallow cavity on the outer surface of the hind tibia used by bees to carry pollen.

Halteres

Modified knobbed hind wings in true flies that act as balancing organs during flight.

Physogastry

The obesity of the abdomen in the queen termite due to excessive egg production.

Furcula

A 'Y' shaped springing organ present on the venter of the fourth abdominal segment in Collembola.

Spermatheca

A storage organ in the female reproductive system where sperm received during copulation is kept.

Polyembryony

A form of asexual reproduction involving the production of two or more embryos from one egg by subdivision, often seen in parasitic insects like $Platygaster$.

Paedogenesis

Reproduction by immature insects (parthenogenesis) where stages like pupae and adults are lost.

Stomatostylet

A protrusible hollow stylet in the order Tylenchida formed by the fusion of stomal walls.

Odontostylet

A replaceable stylet in the order Dorylaimida formed from the oesophagial wall.

Phasmids

Paired lateral sense organs usually located on each side of a nematode's tail.

Siderophores

Chelating agents produced by microorganisms to bind iron.

Bordeaux mixture

A mixture of $CuSO_{4}$ and lime used as a fungicide, originally discovered by P.M.A. Millardet in 1885.

Stifling

The process of killing silkworm pupae to prevent them from emerging as moths and damaging the silk yarn.

Pebrine

A silkworm disease caused by the parasitic protozoan $Nosema\,bombycis$.