Experiments on flea morphology

Summary

This experiment is from the official website of Human Parasitology of Shandong University

Operation method

Experiments on flea morphology

Principle

The flea belongs to the insect order Daphnia. The body is laterally compressed, the head is triangular, and the feet are stout and good at jumping. The life history of the flea is holomorphic, including eggs, larvae, pupae and adults. Adult pregastric has several butyl spines, which are related to disease transmission. Adult fleas are sensitive to temperature and have strong hunger tolerance. Fleas suck both animal and human blood, and can transmit diseases between animals and recognized, plague and endemic typhus are natural epidemic diseases transmitted by them.

Move

I. Self-observation

1. Adult slide specimen: flattened on both sides of the body, wingless, divided into head, thorax and abdomen.

(1) Head: triangular in shape, with a pair of antennae, divided into three sections, located in the antennal fossa on both sides of the head. The antennal fossa divides the head into two parts: the upper part of the head is called the forehead and the lower part is called the cheeks. There is a single pair of eyes in front of the antennal fossa, with a bristle called an ocular seta in front of or below the eyes. The mouthparts are piercing and sucking. The presence or absence of the buccal pecten and the position of the ocular setae are the basis for classification.

(2) Thorax: Three segments, anterior, middle and posterior, each segment consisting of dorsal, ventral and lateral segments. The presence or absence of ctenophores on the dorsal segment of the anterior thorax and the presence or absence of chitinous rods on the lateral segments of the middle thorax are the basis for classification. Wingless, with 3 pairs of strong feet.

(3) Abdomen: composed of ten segments, each of segments 1-8 has a pair of valves, and the eighth segment has a rounded anal plate with sensory function. The female flea has a rounded caudal end, and through the abdominal segments, the chitinous spermathecae are clearly visible. The morphology of the receptacle is the basis for classification. The mating apparatus of male fleas consists of a pair of upper and lower clasping apparatus, which is of taxonomic significance.

Note: The presence or absence of eyes, the position of ocular setae, the presence or absence of buccal and thoracic pecten, the morphology of the spermathecae and the male ectoparasites, etc., are the basis for classification.

II. Demonstration

Life history stages (slide specimen).

1. Egg: oval, uncovered, ca. 0.5 × 0.34 mm.

2. Larva: milky white, elongated body, without legs and eyes, mouthparts are chewing.

3. Pupa: the larva spits out silk to make a cocoon after maturity, and turns into a pupa inside the cocoon.

Third, several common fleas:

1. Itchy flea (Pulex irritans): buccal pecten and prothoracic pecten are absent, the eye setae are located below the eye, the mesothoracic lateral plate without vertical lateral plate rod, the female flea fertilization vesicle is gourd-shaped.

2. Xenopsylla cheopis: buccal and prothoracic pecten are absent, ocular setae are located in front of the eye, the mesothoracic lateral plate has vertical lateral bars, and the fertilization vesicle of the female flea is in the shape of a "C".

3. Citellophilus tesquorum sungaris: no buccal pecten, prothoracic pecten. The female flea has an oval head and a banana-shaped tail.

Cat flea (Ctenocephalides felis): buccal pecten and prothoracic pecten are present, head is long and pointed. The spermatophore of the female flea is in the shape of a "C".

C. canis: buccal pecten and prothoracic pecten are present, the head is shorter, the forehead is rounded, and the female flea's fertilization vesicle is "C"-shaped.

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