Search results for "Instar"
showing 10 items of 56 documents
Population dynamics of Antarctophthirus microchir (Anoplura: Echinophthiriidae) in pups from South American sea lion, Otaria flavescens, in Northern …
2009
We analysed population dynamics of the louse Antarctophthirus microchir in pups of the South American sea lion, Otaria flavescens, at the Punta León rookery (Argentina) over a period of 2 years. A total of 136 pups were aged and marked at the beginning of the lactation period ashore, then sampled for lice at different times within 30 days. Sampling was restricted to the chest and belly, two sites where lice were especially abundant. This concentration on ventral areas might protect lice from thermal stress in the austral summer. Infestation patterns in pups ≤3 days old suggested that the potential for transmission increased from first nymphs to adults. Population trends of each instar with …
DNA Content and Synthesis in Several Tissues and Variation of Moulting Hormone-Level in Gryllus bimaculatus DEG (Ensifera, Insecta)
1983
The mode of growth of several tissues in Gryllus bimaculatus was investigated during postembryonic development by cytophotometric methods. In contrast to the situation in holo- metabolous insects, the tissues growing by endomitosis reach only moderate levels of polyploidy. In this case the growth of tissues is achieved by mitotic divisions of small cells with subsequent polyploidization. The time courses of DNA synthesis were measured within the 3rd and, for comparison, the 8th larval instar by incorporation of labelled thymidine followed by autoradiography. Hemocytes, cells of the regeneration crypts of the midgut, gonads and nervous tissue showed a continuous incorporation rate; by contra…
Morphogenesis of the wing Anlagen in the mealworm beetle tenebrio molitor during the last larval instar.
1990
The wing Anlagen of Tenebrio develop from epidermal cells located on the lateral margins of meso- and metathoraces. Three to four days after larval ecdysis, these cells start to proliferate slowly, continuing to do so until day 13 which corresponds to the period of the pupal commitment of the remaining epidermis. The wing Anlagen cells then proliferate rapidly until day 18.5. Three days before pupal ecdysis, the mitotic index falls suddenly while 40% of the Anlagen cells disappear owing to cell degeneration. The sudden changes observed in the mitotic index are correlated with two hemolymphatic peaks in ecdysteroid levels. Anlagen of the forewings and hindwings show similar development excep…
Microbiota Variation Across Life Stages of European Field-Caught Anopheles atroparvus and During Laboratory Colonization: New Insights for Malaria Re…
2021
The potential use of bacteria for developing novel vector control approaches has awakened new interests in the study of the microbiota associated with vector species. To set a baseline for future malaria research, a high-throughput sequencing of the bacterial 16S ribosomal gene V3-V4 region was used to profile the microbiota associated with late-instar larvae, newly emerged females, and wild-caught females of a sylvan Anopheles atroparvus population from a former malaria transmission area of Spain. Field-acquired microbiota was then assessed in non-blood-fed laboratory-reared females from the second, sixth, and 10th generations. Diversity analyses revealed that bacterial communities varied …
Degeneration of moulting glands in male crickets
1998
The degeneration of the prothoracic glands of the male cricket, Gryllus bimaculatus, was analyzed by using an in vitro assay for ecdysteroid release from the moulting glands in last instar nymphs as well as in adult animals, and correlated with light and transmission electron microscopy. Apoptosis was examined by the TUNEL-reaction. The ability to synthesize ecdysteroids reached a peak at the 8th day of the last larval instar, identified as the moulting peak. After adult ecdysis it decreased to barely measurable values. Prothoracic gland degeneration was initiated at the time of the moulting peak, characterized by TUNEL positive reactions, nuclear and cytoplasmatic condensation, a striking …
CHEMICAL AND PHYSICAL SIGNALS MEDIATING CONSPECIFIC AND HETEROSPECIFIC AGGREGATION BEHAVIOR OF FIRST INSTAR STINK BUGS
2004
We investigated cues that mediate the aggregation behavior of immature pentatomid bugs by using nymphs of six different pentatomid bug species (Nezara viridula, Acrosternum hilare, Chlorochroa ligata, Chlorochroa sayi, Thyanta pallidovirens, and Euschistus conspersus). When first instars of any two species were put together in a Petri dish, they readily formed heterospecific aggregations similar to their natural conspecific aggregations. The chemical profiles of first and second instar nymphs of each species were determined by solvent extraction with pentane, followed by GC-MS analysis. Immature bugs of the different species had some compounds in common, and some that were more species spec…
Crystal cell pattern modification in a melanotic tumor strain of Drosophila melanogaster.
1988
3rd instar larvae of the melanotic tumor tu-pb strain of Drosophila melanogaster hold a lower number of free-circulating crystal cells in their hemolymph than the wild type ones. This pattern could result from an abnormal retention of mature crystal cells in the hematopoietic organs, as the strong hemocyte melanization inside the lymph glands of heat-treated tu-pb larvae seems to demonstrate. Melanotic tumor formation and modification of the crystal cell pattern may be related.
Breaking the temperature-size rule: Thermal effects on growth, development and fecundity of a crustacean from temporary waters
2013
The temperature-size rule (TSR) is a well-established phenomenon to describe the growth response of ectotherms to temperature by which individuals maintained at low temperatures grow more slowly, but attain a larger size upon maturity. Although there are adaptive and non-adaptive theories about the plasticity of body size in response to temperature, these cannot be applied to all ectotherms, and little is known about the changes in growth and development rates through ontogeny. The ostracod species Heterocypris bosniaca, an inhabitant of freshwater temporary ponds, was used to examine the growth and development rates of its nine growth stages and female fecundity at four different temperatu…
Preliminary study on the biology, natural enemies and chemical control of the invasive Macrohomotoma gladiata (Kuwayama) on urban Ficus microcarpa L.…
2015
[EN] The phenology and natural enemies of Macrohomotoma gladiata (Kuwayama) (Hemiptera. Homotomidae) on Ficus microcarpa L. in Valencia (Spain) were studied in 2013. During the study, all immature instars of the pest were found on infested shoots indicating overlapping generations. However, two consistent increases in the proportion of the first two nymphal instars were detected in early March and June, possibly suggesting the beginning of spring and summer generations. Eggs of Macrohomotoma gladiata were usually found below the stipules of new healthy shoots, arranged in groups of 15-30 units. First two nymphal instars usually preferred the innermost part of the shoot, whereas the older de…
Dacnusa cicerina (Hymenoptera: Braconidae: Alysiinae), A New Species of Endoparasitoid of Liriomyza cicerina (Diptera: Agromyzidae)
2008
Abstract The larvae, pupa, adults, and venom apparatus of Dacnusa cicerina sp. n., an endoparasitoid of Liriomyza cicerina (Rondani), found on Cicer arietinum Linnaeus in Spain, are described, illustrated, and compared with those of allied species. The mature larva of Eurytoma sp., possibly a hyperparasitoid of D. cicerina, also is described, illustrated, and compared with those of allied species. Keys to discriminate adults are provided and morphological structures of phylogenetic value are discussed. The adults of D. cicerina are similar to those of Dacnusa rodriguezi Docavo & Tormos (1997). The immature larvae are similar to those of Dacnusa areolaris (Nees) and Dacnusa dryas (Nixon), an…