Rhagoletis pomonella (Diptera: Tephritidae) flies were exposed for 3 days in laboratory cages to yellowish, green or white surrogate leaves with or without food (sucrose) on the leaf surface. When tested in an arena minutes after fly removal from an exposure cage, yellowish surrogate leaves were more attractive to tested flies than green surrogate leaves irrespective of the nature of surrogate leaves to which flies had been exposed. However, flies exposed to green surrogate leaves having food exhibited greater propensity to alight on green surrogate leaves than flies exposed to yellowish or white surrogate leaves having food. This propensity disappeared when flies were tested 24 h after termination of exposure to green surrogate leaves having food. There was no evidence of enhanced propensity of flies exposed to yellowish surrogate leaves having food to alight on yellowish surrogate leaves when tested minutes after removal from an exposure cage. We discuss the potential ecological significance of the evidence presented here that R. pomonella flies are capable of learning to associate the presence of food with green color of leaf surface on which food could be found.
Nociceptors belong to Ad and C afferents that are equipped in the periphery with receptors for detecting potentially damaging physical and chemical stimuli. This review summarizes experimental evidence that these receptors represented by ionic channels are also functionally expressed on the cell bodies of sensory neurones in short-term cultures. The nociceptors belong predominantly to the small and medium size DRG neurones in which algogens such as weak acids, capsaicin, bradykinin and serotonin produce inward currents that can generate impulse activity. It seems likely that the neurones which are not sensitive to algogens but to GABA, ATP or glutamate, agents not producing pain in humans, belong to other categories of DRG neurones equipped for detecting other modalities of sensation. New techniques for physical stimulation of DRG neurones in culture may be of great help in the search for complementing the criteria for distinguishing nociceptors among other neurones in culture. It is suggested that such an in vitro model will be useful for studying cellular mechanisms of nociception.
The skin histology from the Danubian spined loach Cobitis elongatoides disputes the notion that the spawning marks (lighter spots on the body sides of the females) are the result of physical damage to the epidermis by a male during spawning. Physiological changes that induce a specific local decrease in lateral pigmentation in some individuals appear to be a more likely source.
The eye nematode Thelazia callipaeda Railliet et Henry, 1910 (Spirurida: Thelaziidae) is a vector-borne zoonotic nematode infecting a range of wild and domestic carnivores as well as humans. It is considered to be a causative agent of emerging and neglected disease and currently invades central part of Europe. Nematodes were collected from the eye of a dog living in Prague, which never travelled outside the Czech Republic. The nematodes were identified based on their morphology and partial sequence of the cox1 gene as T. callipaeda haplotype 1. This finding represents the northernmost record of autochthonous canine thelaziosis in Europe. The insufficient control of imported animals as well as free movement of dogs and wild carnivores within Europe probably facilitates spreading of T. callipaeda throughout the continent. To better understand the spreading of T. callipaeda and to prevent its zoonotic transmissions, information about the risk of this infection in newly invaded countries should be disseminated not only among veterinarians and physicians, but also within the community of pet owners and hunters., Milan Jirků, Roman Kuchta, Elena Gricaj, David Modrý and Kateřina Jirků Pomajbíková., and Obsahuje bibliografii
Cannibalism, the act of eating an individual of the same species has been little studied in omnivorous insect predators. Dicyphus errans (Wolff) (Hemiptera: Miridae) is a generalist omnivorous predator that commonly occurs in tomato greenhouses and field crops in the Mediterranean basin. In this work cannibalism among same-aged neonate nymphs of D. errans was studied when 1, 2, 4, 8 or 16 individuals were placed in a Petri dish along with or without heterospecific prey. Although nymphs were unable to complete their development in the absence of prey they survived longer when there were initially 2 individuals per dish than in any other treatment including a single individual. This may indicate that cannibalism in this predator has positive effect on nymphal survival, which however was not the case at higher densities. The presence of heterospecific prey increased nymphal survival and individuals were as equally successful in completing their development as when kept singly. Developmental time in all the treatments was very similar. Adult weight of both females and males was significantly greater when a nymph was reared alone and similar in all the other treatments. The results indicate that cannibalism occurs among neonates of D. errans if heterospecific prey is scarce and has a negative effect on adult weight when heterospecific prey is abundant. This should be considered in studies on enhancing the biocontrol efficiency or mass rearing of this predator.