Structure and modifications of insect antennae

STRUCTURE OF INSECT ANTENNAE

Antennae function almost exclusively in sensory perception. Some of the information that can be detected by insect antennae includes: motion and orientation, odour, sound, humidity, and a variety of chemical cues. Antennae vary greatly among insects, but all follow a basic plan: segments 1 and 2 are termed the scape and pedicel, respectively. The remaining antennal segments (flagellomeres) are jointly called the flagellum.

MODIFICATIONS OF INSECT ANTENNAE

1. ARISTATE

Aristate antennae are pouch-like with a lateral bristle. Examples: House and shore flies (order Diptera).

The antennae are important sensory structures used to detect air movement and odors. Among the olfactory receptors are sensilla located in several pits which lie ventrally on the basal one-third of the third segment of the antenna. The antenna is three-segmented with a branched arista projecting dorsally from the third segment. A U-shaped groove around the lateral and dorsal part of the depression housing the pair of antennae is the frontal lunule (the suture through which the ptilinum was everted as the fly emerged from the puparium).

2. CAPITATE

Capitate antennae are abruptly clubbed at the end. Examples: Butterflies (order Lepidoptera)..

3. CLAVATE

Clavate antennae are gradually clubbed at the end. Examples: Carrion beetles (order Coleoptera). Adult carrion beetles feed on decaying animal matter or maggots.

4. FILIFORM

Filiform antennae have a thread-like shape. Examples: Ground and longhorned beetles (order Coleoptera), cockroaches (order Blattaria).

5. GENICULATE

Geniculate antennae are hinged or bent like an elbow. Examples: Bees and ants (order Hymenoptera).

6. LAMELLATE

Lamellate or clubbed antennae end in nested plates. Examples: Scarab beetles (order Coleoptera).

7. MONILIFORM

Moniliform have a beadlike shape. Examples: Termites (order Isoptera).

PECTINATE

Pectinate antennae have a comb-like shape.

Examples: Fire-colored beetles and fireflies

(order  Coleoptera).

9. PLUMOSE

Plumose antennae have a feather-like shape. Examples: Moths (order Lepidoptera) and mosquitoes (order Diptera).

10. SERRATE

Serrate antennae have a saw-toothed shape. Examples: Click beetles (order Coleoptera).

11. SETACEOUS

Setaceous antennae have a bristle-like shape. Examples: Dragonflies and damselflies (order Odonata).