Phytophagous insect fauna of Onopordum spp. thistles in the south of Syria

Thistles from the genus Onopordum (Asteraceae) are of Mediterranean and Eurasian origin. They are very common in the south of Syria, in particular in Damascus and Al Suwayda, and are found in fallow fields, pastures, roadsides and neglected areas. In 2015–2017, several sites with large populations of Onopordum spp. were identified. Weekly surveys of some of the sites, mainly in the regions of Damascus and Al Suwayda, revealed a significant diversity of phytophagous insect species, some of which had a very high population density. A total of 29 insect species were detected, belonging to four orders and 21 families. The most abundant species were from the order Coleoptera. These were observed to be feeding on different plant parts of Onopordum spp. Purely endophagous species comprised 38% of the species observed on Onopordum spp., ectophagous species comprised 45% with 17% of species mixed ectophagous and endophagous. Species that only fed on Onopordum spp. represented 34% of all the species observed.     

Site‐specific management is crucial to managing Mikania micrantha

Increasingly, weeds have been taking on global distributions. With the proliferation of invasive weeds has come the challenge of managing these species over broad geographical regions, with diverse habitats and political jurisdictions. Here, we review the management of Mikania micrantha Kunth (Asteraceae; mile‐a‐minute) throughout its invaded range, extending through most of the Pacific islands and southern and south‐east Asia. Context matters when determining the best course of action for managing M. micrantha, as it has invaded a large variety of agricultural and natural systems. In Queensland, Australia and Florida, USA, M. micrantha has been targeted in relatively successful eradication campaigns, highlighting the importance of early detection and rapid response methods, while elsewhere in its invaded range, populations are either still increasing or showing limited signs of decline. An inter‐regional approach to research and management should incorporate successful management strategies employed throughout the invaded range including, but not limited to, chemical and cultural control practices, manual and mechanical control, classical biological control using the rust fungus Puccinia spegazzinii, plant–plant competition and integrated approaches utilising two or more control methods concurrently. Additional knowledge of M. micrantha genetics is required to determine if management approaches could be fine‐tuned for particular populations. Countries bordering the Mekong River formed a network in 2011 to co‐ordinate the management of invasive species such as M. micrantha. Expanding such a collaborative approach to other regions could further reduce populations of M. micrantha and limit its spread.     

Circadian heart rate changes and light-dependence in the Mediterranean seabream Sparus aurata

Despite the abundant literature on circadian heart rate rhythms in fish, few studies have attempted to elucidate if such pattern is endogenous or if it is modulated by environmental cues. In this study, heart rates were continuously recorded in Sparus aurata acclimated to different light regimes (normal or shifted LD 12:12 cycle and a pulsed 0.75:0.75 LD cycle) to investigate the endogenous nature and the role of light on the circadian pattern of heart rate. Under LD 12:12, the daily pattern of heart rate showed higher values at night and lower rates during the day (average amplitude of the heart rate change of 10.6 ± 5.7 beats min^–1). The circadian pattern was maintained in animals under constant light but the amplitude was decreased (2.4 ± 1.1 beats min^–1). Light masks the expression of the rhythm because under a pulsed LD cycle, heart rate tracks the pulsed LD phases, increasing during the dark phase and decreasing during the light phase. Besides the ultradian pattern imposed, an underlying circadian rhythm was detected, which indicates that the rhythm is endogenous. However, the strong link between heart rate and light obtained under pulsed LD cycles suggest the timing mechanism to be mostly based on external light reception.     

First isolation of Tenacibaculum maritimum from wedge sole, Dicologoglossa cuneata (Moreau)

The first isolation of Tenacibaculum maritimum from wedge sole, Dicologoglossa cuneata, is reported. The pathogen was recovered from ulcers of cultured fish, from three different outbreaks. The six isolates obtained were biochemically and serologically characterized and diagnosis was confirmed by polymerase chain reaction using specific primers and partial 16S rRNA gene sequencing. The isolates constituted a homogeneous phenotypic group; however, they belong to two of the different serotypes described within this species. A virulence evaluation of the isolates using Wedge sole fry was also performed.     

Histopathological effects of cadmium on the gills of the freshwater fish, Macropsobrycon uruguayanae Eigenmann (Pisces, Atherinidae)

Evaluations of histopathological lesions in gill tissue were carried out in the freshwater fish Macropsobrycon uruguayanae following 30 and 60 days of exposure to 1.5 mg 1^-1 of cadmium. The study was conducted on both fed and starved animals in order to determine the influence of feeding condition on cadmium toxicity. The main lesions observed and quantified were: (1) hyperplasia of primary lamellar epithelium; (2) hyperplasia of secondary lamellar epithelium; (3) separation of respiratory epithelium; (4) shortening of secondary lamellae; (5) epithelial necrosis; (6) fusion of adjacent secondary lamellae; (7) hypertrophy of respiratory epithelium; (8) lamellar telangiectasis; (9) hyperplasia of chloride cells; (10) mucinous metaplasia; and (11) inflammatory infiltration. Lesions 6, 8, 9 and 11 were only induced by exposure to cadmium, while lesion 4 could be produced only by starvation. Starved fish also showed a reduction in total body weight and length. Lesion 2 was shown to be non-specific, and produced by either cadmium, starvation or even exposure time. The possible mode of action of the experimental factors are discussed in relation to the observed pathologies.     

Toxicity of aqueous aluminium to the ectoparasitic monogenean Gyrodactylus salaris

Both laboratory and field experiments have demonstrated that aqueous aluminium can act as a paraciticide to the monogenean Gyrodactylus salaris Malmberg, 1957 infecting freshwater salmonids. However, the reproductive conditions of gyrodactylids surviving to cessation of an aluminium exposure is unknown. Therefore, Atlantic salmon (Salmo salar L.) parr infected with G. salaris was experimentally exposed to elevated concentrations of aqueous aluminium for more than 1 month. During this period, the infection increased the first week before it peaked and started to steadily decline approaching elimination. When almost all parasite specimens were eliminated, the water quality was adjusted to normal aluminium-poor freshwater. During the next 3 weeks, the surviving G. salaris were shown to clearly resume their reproduction. The experiment demonstrates the potential of the gyrodactylids to reproduce after cessation of an aluminium exposure. Thus, the as-yet unknown mechanism behind the toxic effects of aluminium on G. salaris survival and reproduction might to some extent be reversible. The present study gives further support for this metal as a parasiticide to G. salaris but demonstrates at the same time that in order to eliminate the parasites totally, the aluminium treatment must eradicate all G. salaris from the skin of the infected hosts. Furthermore, the potential development of resistance to aluminium should also be studied.     

Expression of genes involved in the early immune response at the distal segment of the gut in Atlantic cod, Gadus morhua L. after vaccination with a bacterial antigen

The gastro-intestinal tract serves as the route of infection of most bacterial pathogens in fish, and the immune response genes in the gut produce substances that provide an initial defense during pathogen invasion. The expression of some genes involved in antibacterial defense, cell-mediated immunity and inflammation in the distal intestine of Atlantic cod, Gadus morhua L., was investigated following intraperitoneal vaccination with heat-killed Vibrio anguillarum. Tissue samples of the distal intestine were collected at 0, 1, 3, 7 and 10 days post-vaccination (dpv) and processed for semi-quantitative RT-PCR analyses. Expression of the bactericidal/permeability-increasing protein/lipopolysaccharide-binding protein (BPI/LBP), g-type lysozyme, non-specific cytotoxic cell receptor protein-1 (NCCRP-1) and interleukin-8 (IL-8) significantly increased during the early stages post-vaccination, that is, 1–3 dpv, followed by a decrease in their expression returning to their initial levels. Transferrin and apolipoprotein A-I, although weakly expressed in the distal intestine, also increased in the vaccinated fish. Interleukin-1β (IL-1β) was significantly decreased in its expression level relative to the PBS-injected fish at 3 and 7 dpv. The expression of these immune-related genes in the distal intestine as a result of vaccination provides valuable information on the mechanisms of gut immunity in the fish against pathogenic bacteria, particularly during the early stages of infection.     

Comparative feeding, growth and movements of Atlantic salmon (Salmo salar) parr from riverine and estuarine environments

Abstract– The diet composition, movcments and growth of Atlantic salmon parr rearing in the estuary of Western Arm Brook, Newfoundland were compared with those of parr from riverine habitats over 2 years. Estuarine parr consumed a variety of prey, including many freshwater taxa (mainly insects), which indicated a dependence on freshwater drift from the river. Prey of estuarine origin (amphipods and sticklebacks) were increasingly consumed between spring and autumn. Prey volume per fish and number of prey per fish increased significantly for estuarine parr between spring and autumn, suggesting an improvement in food availability. Riverine parr, however, realized a general decrease in both parameters between spring and autumn. The recapture of 16% ( n = 131) of the 829 parr marked in the estuary in 1987 and 1988 indicated a directed movement toward the head of the estuary and river mouth, as also suggested by the diet analysis. Parr from outer estuary sites were very mobile compared with parr from the estuary site closest to the river mouth, which behaved more like parr in the river proper in displaying strong site fidelity. Movement patterns of parr were primarily along the shoreline. Individual growth rates were highly variable in both environments but especially in the estuary. The mean growth of estuarine parr was 0.23 mm. d⁻¹ between May and October with some evidence of fastest growth having occurred in late spring and early summer (approx. 0.4 mm. d⁻¹); mean growth rate of riverine parr was slower, at 0.12 mm. d⁻¹. The results are discussed in the context that estuarine rearing by salmon parr represents an alternative life-history tactic for the species in river systems in eastern Canada.