Image Of The Sensilium In Flies

pronotal ctenldium metanotum antesensilial seta pronotal ctenldium metanotum antesensilial seta

Flea Image Morphology
FIGURE 7.1 Morphology of generalized adult flea, female. T, abdominal tergites; St, abdominal sternites. (From Lewis, 1993b.)
Human Morphology Female

FIGURE 7.2 Morphology of the head and prothorax of representative adult fleas of medical and veterinary importance. (A) Cat flea (Ctenocephalidesfills)-, (B) Dog flea (C. cants); (C) Human flea (Pulex irritans); (D) Northern rat flea (Nosopsyllusfasciatus); (E) Oropsylla montana, a North American rodent flea; (F) Oriental rat flea (Xenopsylla chcopis); (G) Hoplopsyllus anomalus, a North American rodent flea; (H) European mouse flea (Leptopsylla segnis); (I) Myodopsylla insignis, a North American bat flea; (J) Rabbit flea (Cediopsylla simplex). (From Matheson, 1950.)

FIGURE 7.2 Morphology of the head and prothorax of representative adult fleas of medical and veterinary importance. (A) Cat flea (Ctenocephalidesfills)-, (B) Dog flea (C. cants); (C) Human flea (Pulex irritans); (D) Northern rat flea (Nosopsyllusfasciatus); (E) Oropsylla montana, a North American rodent flea; (F) Oriental rat flea (Xenopsylla chcopis); (G) Hoplopsyllus anomalus, a North American rodent flea; (H) European mouse flea (Leptopsylla segnis); (I) Myodopsylla insignis, a North American bat flea; (J) Rabbit flea (Cediopsylla simplex). (From Matheson, 1950.)

Phrygane EggsHoplopsyllus
FIGURE 7.6 Genitalia of a male flea, the western chicken flea (Ceratophyllus niger). (Modified from Smit, 1957.)

FIGURE 7.7 Immature stages of the cat flea (Cunocephalides fdis): egg. (Courtesy of Nancy C, Hinlde and National Pest Control Association.)

larvae then ingest. Some flea larvae supplement their diet by feeding on other small arthropods in the host nest, and cannibalism among flea larvae appears to be common.

Duration of the pupal stage usually lasts 1—2 weeks but is influenced by ambient temperature and host availability, Eclosed adult fleas of several species can remain within the cocoon as pre-emergent adults until suitable host or environmental cues stimulate their emergence. Pre-emergent adult cat fleas can remain quiescent inside cocoons for 4—5 months to avoid desiccation or other environmental extremes that would kill free-living fleas.

Many fleas, including most of those of medical or veterinary importance, undergo continuous generations under favorable conditions. The cat flea is a good example. Indoors, thc generation time for this flea is usually about 1 month but can be as short as 20 days. Other fleas, such as alakurts associated with migrating ungulates in Asia, and species parasitic on migrating birds are more likely to pass through just one generation per year in synchrony with host availability. Some fleas, especially in temperate regions, may undergo four or five generations each summer but fewer or none during the winter. Host availability clearly affects the number of generations in many fleas. Longevity of fleas in the absence of available hosts is greater at low temperatures and high humidity, such as during winter in temperate regions. Under optimal conditions, adult fleas of certain species may survive away from the host for more than a year.

Adult Fle Away
FIGURE 7.8 Immature stages of the cat flea (Ctenocefhalidss felts)-. larva. (Courtesy of Nancy C. Hinkle and National Pest Control Association.)

Specialized or unusual life cycles have evolved in many fleas, including some species of medical or veterinary significance. Females of the genera Tungaand Neotunga, for example, burrow into host dermal tissue, where they undergo a dramatic size increase (up to 1000-fold) accompanied by extensive morphological degeneration. This type of growth, called neosomy, involves major integu-mental chitin synthesis during the adult stage. The genital opening of the female protrudes through the pore in the host skin to facilitate mating with the free-living males; fertilized eggs are likewise extruded through this opening. Because of the great size increase of neosomic females, they are able to produce many relatively large eggs. In some cases this has led to a reduction in the number of larval instars from three to two; further modifications are exhibited by Tunga monositus, a parasite of New World rodents, in which neither larval instar feeds. The chigoe (Tunga penetrans) is an important human parasite that belongs to this group of fleas.

Adult females of some fleas oviposit randomly into the environment, where the resulting larvae must search for organic matter suitable to eat. Examples are vermipsyl-lid fleas in the genera Vermipsylla and Dorcadia, called

Immature Fleas
PIGURE 7.9 Immature stages of the cat flea {Ctenocephalides felis): pupa. (Courtesy of William H. Kern, Jr. and National Pest Control Association.)
Immature Fleas
HGURJB 7.10 Immature stages of the cat flea (Ctenocephalidesfelis): cocoon covered with debris from substrate. (Courtesy of Nancy C. Hinkle and National Pest Control Association.)

alakurts, that feed on large ungulates, remaining attached for several days. At the other end of the spectrum, females of Uropsylla tasmanica cement their eggs to the fur of their Australian hosts (dasyurid marsupials) and the larvae burrow into host skin, where they subsist as subdermal parasites. Mature U. tasmanica larvae drop to the ground, where they spin a cocoon and pupate in a manner typical of most other fleas. Larvae of the hare-infesting Euhoploplsyllus glacialis are ectoparasitic, and those of some other fleas feed on host carcasses or even on the superficial tissues of moribund hosts.

Fleas have evolved a plethora of specialized behaviors and ecologies to locate and exploit their hosts. Host-finding behavior is extremely important for adult ectoparasites, such as fleas, in which the immature stages typically occur off the host. Important stimuli used by fleas for host location include host body warmth, air movements, substrate vibrations, sudden changes in light intensity, and odors of potential hosts or their products (e.g., carbon dioxide, urine). The sensilium, antennae, and eyes are important organs used by fleas to detect potential hosts. In cases in which adult fleas emerge from their cocoons in close association with their host, locating a food source is not difficult. However, fleas of other groups of hosts, such as ungulates or migrating birds, typically must employ more elaborate strategies for this purpose. These include jumping towards dark or moving objects and moving towards warmth and COj sources.

Some fleas are stimulated to emerge from their pupal case and cocoon by mechanical compression and vibrational stimuli, which often indicate the presence of a potential host. This response is especially noticeable in flea-infested human premises that have been temporarily vacated for weeks or months. When humans or pets return to the premises, these stimuli are largely responsible for synchronized emergences of adult fleas from their cocoons.

Allergy Relief

Allergy Relief

Have you ever wondered how to fight allergies? Here are some useful information on allergies and how to relief its effects. This is the most comprehensive report on allergy relief you will ever read.

Get My Free Ebook


Responses

  • elisabetta
    What is tergites and sternites?
    1 year ago

Post a comment