1.Ovicidal Efficacy of Metarhizium anisopliae (Hypocreales: Clavicipitaceae) towards Rhipicephalus sanguineus (Acari: Ixodidae) Eggs
Nur Izzati, Z.A. ; Syazwan, S.A. ; Lee, S.H. ; Ruhil Hayati, H. ; Peng, T.L.
Tropical Biomedicine 2021;38(No.1):102-105
Rhipicephalus sanguineus, commonly known as brown dog tick is a widespread species with
considerable public health and economic importance. Tremendous efforts were performed
to control the tick populations with the concern of resistance build-up and environmental
issues. Alternative towards microbial control thus emerged as one option to reduce tick
populations. In this study, the ovicidal efficacy of a native isolate entomopathogenic
hyphomycetes fungi, Metarhizium anisopliae strain HSAH5 was evaluated against eggs of
R. sanguineus. Spray applications with three different conidial concentrations of 105, 106 and
107 conidia mL-1; 40 ppm of Flumethrin and a negative control. The M. anisopliae strain was
found highly virulent to R. sanguineus eggs by reducing the hatching percentages to ≈30%
compared with 8.9% in Flumethrin eggs. The result showed a significantly higher mortality in
M. anisopliae group than those of the control groups (F = 42.08, df = 32, P < 0.001) at 30 days
post-infection. However, there are no significant differences within the M. anisopliae group,
in which the mortality between different conidial concentrations is almost the same. The
estimated LC50 of M. anisopliae against eggs of R. sanguineus is 1.36 × 103 conidia ml-1. Thus,
these results suggest M. anisopliae strain HSAH5 could be a potential biocontrol agent of
R. sanguineus in the integrated approach to managing ticks in the residential landscape by
targeting on the eggs.
2.Detection of pathogenic Vibrio species and antibiogram activity in Asian Seabass (Lates calcarifer) in Tumpat, Kelantan
Auzureen, A.M.Z.1 ; Michael, M.S. ; Mohamed, M. ; Peng, T.L. ; Fauzi, F. ; Mohamad, N.F.A. ; Ahmad, N.S. ; C.W. Salma, C.W.Z. ; Hamdan, R.H.
Tropical Biomedicine 2022;39(No.4):569-574
Some of Vibrio species is well known as pathogenic bacteria in aquaculture and the marine industry. Its
infection is able to generate a massive outbreak and affect the fish population, especially for net caged
fish such as seabass. This study was conducted to investigate the prevalence of Vibrio spp. isolated
from seabass (Lates calcarifer) in Sri Tujuh Lagoon, Tumpat, Kelantan. Then, to determine the antibiotic
resistance in Vibrio isolates. Polymerase chain reaction (PCR) was used to detect Vibrio species using
specific primer VR169 and VR744 with estimation base pair size band, 597 bp and further identified
by sequencing. On the other hand, antibiotic susceptibility tests were continued by using 13 types of
antibiotics; kanamycin (K30), chloramphenicol (C30), neomycin (N10), ampicillin (AMP10), nitrofurantoin
(F300), tetracycline (TE30), streptomycin (S10), norfloxacin (NOR10), ciprofloxacin (CIP5), nalidixic acid
(NA30), gentamicin (CN10), doxycycline (DO30) and sulfamethoxazole (SXT100). As a result, 14 Vibrio
isolates were identified, including Vibrio fluvialis (n=6), Vibrio parahaemolyticus (n=3), Vibrio harveyi
(n=2) and each isolate for Vibrio vulnificus, Vibrio alginolyticus and Vibrio spp. The results showed that
all isolates were sensitive to most antibiotics except ampicillin, neomycin and streptomycin. The MAR
index value was ranging from 0 to 0.31. This study demonstrates the prevalence of Vibrio spp. in seabass
and the report on multidrug resistance strains that could be of concern to the fish farmers. In addition,
data from this study can be further used in fish disease management plans.