The inhibitory effect of a combination of imidacloprid and permethrin on blood feeding by mosquitoes in dogs raised under outdoor conditions

Combinations of imidacloprid and permethrin were frequently used to control harmful arthropod of companion animals. The inhibitory effects on blood-feeding activity of mosquitoes in dogs raised under outdoor conditions were evaluated by using combination of 10% (w/v) of imidacloprid and 50% (w/v) of permethrin as spot-on form. Dogs in the treated group received the combination imidacloprid/permethrin spot-on. After treatment, dogs in the control and treated groups were kept separately from the evening (17:00) to the morning of the following day (09:00) in two different kennels installed outdoors to mimic realistic dog-raising conditions. Mosquitoes in the kennels were collected by light traps placed in the kennels and a sweep net to determine evidence of blood feeding, and for species identification. Mosquitoes were collected at Days 5, 3 and 1 before agent treatment, and the Day of treatment, and Days 3, 7, 14, 21, 28, 35 and 42 after treatment. The percentages of blood-fed mosquitoes measured at Days 0, 3, 21, 28 and 42 after treatment were statistically significantly lower (p<0.01) in the treated group than in the control group. The most commonly collected mosquito, Culex tritaeniorhynchus, revealed statistically significant lower percentages (p<0.01) of blood-fed mosquitoes in the treated group than in the control group at the Day of treatment, and Days 3, 7, 21, 28 and 42 after treatment. It appeared that the test agent was effective in inhibiting blood feeding by adult female mosquitoes, and the efficacy lasts for 42 days after treatment under outdoor conditions.     

Effect of low salinity on the expression profile of Na+/K+‐ATPase and the growth of juvenile chub mackerel (Scomber japonicus Houttuyn)

Chub mackerel (Scomber japonicus Houttuyn) is one of the most commercially important scombroid fish used as a food resource. Recently, there has been a demand for efficient rearing methods of this fish for a full‐life cycle aquaculture. In the present study, we evaluated the physiological responses in the juvenile S. japonicus to different ambient salinities. A significantly higher gain of the body mass was observed in the juveniles reared in 24 g/L and 13 g/L seawater than in those reared in natural seawater (34 g/L) within 40 days of the experimental period without affecting mortality. A principal enzyme for osmoregulation, Na⁺/K⁺‐ATPase, was expressed in the ionocytes located in the gill filaments of the juveniles. The number and the cell size of ionocytes and the enzymatic activity of Na⁺/K⁺‐ATPase in the gills decreased within 10 days after the low‐salinity challenge, which implies the reduction of the energy‐consuming active ion secretion under the low‐salinity environment. The physiological capacity for adaptation to low‐salinity seawater in chub mackerel could be basic knowledge to carry out culturing of these fish in coastal sea pens where ambient salinity fluctuates. The improvement of the growth performance by rearing in low‐salinity seawater will contribute to the efficient production of the seed juveniles for aquaculture.     

Molecular characterization of kisspeptin 2 dodecapeptide in sixteen species of Scombridae

Fisheries Science - Kisspeptin is an endogenous ligand that modulates gonadotropin-releasing hormone (GnRH) secretion and plays an essential role in the reproduction of mammals. In fish, two...     

Age and growth of the lizardfish <Emphasis Type="Italic">Saurida elongata</Emphasis> from the Tsushima/Korea Strait

We studied the age and growth of the lizardfish Saurida elongata using ground thin sections of otoliths (sagittae) from specimens collected in the Tsushima/Korea Strait between May 1999 and June 2001. A total of 695 individuals with fork lengths (FL) ranging from 189 to 478 mm were examined. The frequency of translucent zone occurrence at the outer margin of the otoliths indicated that translucent zones formed once a year between November and February. Most of the males examined were estimated to be 2–7 years old and the females, 3–9 years old. The maximum estimated age of a male specimen was 10 years and that of a female, 11 years. The estimated von Bertalanffy growth curves were FL _t  = 451{1 − exp[−0.172(t + 2.50)]} and FL _t  = 515{1 − exp[−0.151(t + 2.47)]} for males and females, respectively. At all ages, the FL at a specific age for females was greater than that for males, suggesting that females of this species grow faster than males.     

Jack mackerel <Emphasis Type="Italic">Trachurus japonicus</Emphasis> juveniles use jellyfish for predator avoidance and as a prey collector

ABSTRACT:   Juveniles of carangid fishes including jack mackerel Trachurus japonicus are known to associate with jellyfishes. The function of this association behavior was studied through rearing experiments and underwater visual observations. Association behavior of jack mackerel with moon jellyfish in experimental tanks was more frequent in the presence compared to the absence of predators (chub mackerel Scomber japonicus ). In the experimental tanks, the presence of jellyfish, however, did not mitigate predation by these predators. Although jack mackerel did not feed on the jellyfish itself, they frequently fed on the captured prey ( Artemia nauplii) whilst in the gut cavity of the jellyfish. Underwater observations of giant jellyfish Nemopilema nomurai off Kyoto and Fukui prefectures revealed that approximately 30% of these jellyfish were accompanied by jack mackerel juveniles with body sizes ranging 10–45 mm standard length (SL). Considering that jack mackerel juveniles found in subtidal rocky reefs ranged 40–120 mm SL, we considered that jack mackerel from 10 to 45 mm SL associate with jellyfish as a hiding place as well as a food collector, until they find a suitable reef habitat when they attain approximately 40 mm SL.     

Establishment of a tracing technique for transplanted bluefin tuna germ cells in recipient’s gonads using monoclonal antibodies specifically recognizing bluefin tuna spermatogenic cells

Fisheries Science - Our ultimate aim is to establish a small-bodied surrogate broodstock (e.g., mackerel) that produces functional gametes of the Pacific bluefin tuna Thunnus orientalis using...     

Detection of the schizont stage in experimentally infected cattle with Japanese Theileria sergenti

Calves infected with a sporozoite suspension of the Ikeda strain of Theileria sergenti were examined in attempts to detect the schizont stage. A suspension equivalent to the contents of 70-200 ticks was inoculated subcutaneously into 10 splenectomized calves. Schizonts and micromerozoites were found in the prescapular lymph nodes of 5 calves about 8 days after the sporozoite inoculation. Schizonts detected at the time of nuclear division had large and diffuse nuclei, and many of the schizonts were very large and extracellular in lymph node smears. The schizonts were also detected by the direct fluorescent antibody staining.     

Brain abscess in a Japanese black calf: utility of computed tomography (CT)

Computed tomography (CT) was used for diagnosis of brain abscess in a 6-month-old, Japanese black calf presented with neurological dysfunction, compulsive circling and vision disturbance. CT images showed asymmetric lateral ventricles, and presence of intra-cranial multiple low absorption lesions surrounded by capsule suggestive of abscess in the right cerebral hemisphere. Postmortem examination revealed marked swelling of right cerebral hemisphere and olfactory bulb. Multilocular large abscess containing creamy pus was found to occupy most area of periventricular and lateral ventricle. Fusobacterium necrophrum was isolated from the abscess contents as the causative agent. These results demonstrate that CT is useful tool for tentative diagnosis of bovine brain abscess.     

Gene silencing of a cubilin-related serine proteinase from the hard tick Haemaphysalis longicornis by RNA interference

RNA interference (RNAi) has been recently exploited to determine gene function by degrading specific mRNAs in several eukaryotic organisms. We constructed a double stranded RNA (dsRNA) from a previously cloned Haemaphysalis longicornis serine proteinase (HlSP) gene to test the importance of the function of the HlSP gene product during blood-feeding. Growth of unfed ticks treated with HlSP dsRNA was significantly inhibited compared to that of PBS-treated ticks. This inhibition was supported by the level of HlSP mRNA. HlSP may play a crucial role for blood-feeding in these ticks. This is the first report on gene silencing of a functional serine proteinase in hard ticks.