Tropical life sciences research最新文献

Controlling pest birds is a complex problem, especially for large areas, compared to individual homes. This study presents a new perspective on pest birds plaguing a large semiconductor factory. We evaluated the efficacy of nine bird deterrent methods: alarm and distress calls broadcasted from portable speaker, sound frequencies ranged from (i) 24.5 kHz-45.5 kHz; and (ii) 13.5 kHz-45.5 kHz together with flashing lights emitted from sonic device, methyl anthranilate (MA), moving and static bird predator models, reflective compact discs, high and low visibility reflective tapes in deterring Barn Swallow (Hirundo rustica), Pacific Swallow (Hirundo tahitica) and Asian Glossy Starling (Aplonis panayensis) from perching on targeted spots. Monthly counts of pest birds roosting at study site were also conducted. Our results showed that alarm and distress calls broadcasted from portable speaker, sound frequencies ranged from 13.5 kHz-45.5 kHz together with flashing lights emitted from sonic device, moving and static bird predator model, reflective compact discs, high and low visibility reflective tapes were significantly effective in deterring pest birds from targeted spots. The pest bird population reached its peak (35,063) in January 2021, while the least (3,685) was recorded in May 2021. The effectiveness of pest bird deterrents might be influenced by the quantity and method of deployment.

Chilli anthracnose is a significant constraint in chilli production and quality in cultivated areas worldwide. Alternative methods are being explored to avoid the use of chemical fungicides, including plant elicitors produced by beneficial microorganisms to enhance plant defense responses. However, studies on the use of biotic elicitors to control chilli anthracnose are limited. In this study, we investigated the efficacy of cell-free supernatant derived from Pseudomonas aeruginosa SWUC02 (CF-SWUC02) and its extracts on the antimicrobial activity and systemic resistance in yellow chilli seedlings. The anthracnose pathogen, Colletotrichum truncatum CFPL01, was isolated and assessed for its pathogenicity in yellow chilli and other varieties, exhibiting varying levels of susceptibility to anthracnose. CF-SWUC02 exhibited potential antimicrobial activity against several phytopathogens. Furthermore, it affected the mycelial growth and conidial germination of virulent C. truncatum CFPL01. The dichloromethane extract exhibited the highest efficacy in suppressing the growth of C. truncatum CFPL01, while the ethyl acetate extract demonstrated a significant reduction in anthracnose severity on both leaves and seedlings. The ethyl acetate extract also increased phenylalanine ammonia-lyase activity in treated seedlings, demonstrating the induction of plant immunity. In summary, the elicitor compounds present in CF-SWUC02 have the potential to reduce anthracnose severity either directly through pathogen inhibition or indirectly via stimulation of the plant defense responses. These findings provide valuable insights for the development of sustainable and effective strategies for the control of chilli anthracnose.

Emerging investigations have indicated that many plant polysaccharides may be beneficial for treating metabolic diseases. To date, the therapeutic efficacy and potential toxicity of polysaccharides extracted from Clinacanthus nutans (C. nutans) remain unexplored. This study investigated the in vivo acute and subacute oral toxicological profiles of the highest doses of C. nutans bioactive polysaccharides (CNBP) extracted from the leaves using conventional toxicity methods. The total of 39 healthy 8-10 weeks male Sprague-Dawley rats (n = 3) were randomly assigned to control (C), acute (A) and subacute (SA) groups receiving 125, 250, 500, 1,000, 2,000 or 3,000 mg/kg/day of CNBP extract, respectively. The acute group received a single dose of CNBP extract, whereas the subacute group received daily single doses of CNBP extract for 14 days. Oral administration of up to 3,000 mg/kg CNBP extract caused no abnormal signs of toxicity during 14 days. However, daily administration of 500 mg/kg or higher doses of CNBP extract for 14 days induced a mild degree of toxicity in the liver, characterised by elevated alkaline phosphatase levels with C (163 ± 9 U/L) vs. SA500 (222 ± 49 U/L), SA1000 (223 ± 29 U/L), SA2000 (238 ± 33 U/L) and SA3000 (252 ± 18 U/L). CNBP extracts exhibit therapeutic potential, exemplified by diuretic, natriuretic, anti-hypertensive, anti-tachycardia, reno-protective and cholesterol-lowering properties. Precautions should be taken when administering the extracts at higher doses and for longer durations.

The oriental scuttle fly, Spiniphora genitalis Schmitz, 1940 (Diptera: Phoridae), was first discovered from Peninsular Malaysia as a specialised decomposer of mollusc carrion but its occurrences on vertebrate carrion suggest that this species could also be utilised as a forensic indicator. However, the larval morphology and development of S. genitalis remain unexplored. In this study, the colony of S. genitalis was reared in the laboratory at ambient temperature range (20.0°C-25.5°C) and relative humidity (71.0%-94.5%) using decomposing beef liver as larval food source. Larval body length was measured at every 6 h and 18 h interval until pupariation and subsequently described. The third instar larva of S. genitalis can be characterised by its fleshy, but ventrally flattened body with posterior tubular extension. The abdominal segments are covered with tubercles and spinulose formations and interestingly, three distinct larval variations were also detected. The transitions from metapneustic first instar to amphipneustic second and third instar larvae were also described according to the characteristics of cephalopharyngeal skeleton, anterior spiracle and posterior spiracle. The lifecycle of S. genitalis reported in this study based on it developmental stages were 23 h-27 h (egg), 162 h-358 h (larva) and 240 h-341 h (pupa). This study established the diagnostic features of S. genitalis which can be useful in forensic analysis and as precursors to the ground plan of Spiniphora larvae taxonomy. The complete growth of S. genitalis larvae on beef liver indicated that the role of this species has been expanded from a specialised mollusc carrion decomposer to a potential forensic indicator.

Human-elephant conflict is a common issue in the agricultural sector, often resulting in crop damage. This study aimed to evaluate the effectiveness of threatening vocalisation playbacks as a mitigation method to deter elephant encroachment into agricultural areas. The study was conducted at the National Elephant Conservation Centre (NECC) in Kuala Gandah, Pahang, Malaysia, involving two male and five female elephants. Five soundtracks were played to observe the elephants' responses: the sound of a buzzing bee, a tiger roar, an elephant rumble, rain (control) and nocturnal jungle sounds (control). The elephants' behaviours were recorded during and after exposure to each soundtrack. The results showed that the elephants responded most strongly to the tiger roar (33%), followed by the buzzing bee sound (23%), while the elephant rumble elicited the fewest responses (8%). The tiger roar and buzzing bee sounds also resulted in the longest halt times, with the elephants stopping and standing still, particularly the older group (p < 0.05). Male and female elephants exhibited similar responses to the sound playbacks (p > 0.05). This study suggests that playback of threatening vocalisations could serve as an additional mitigation strategy to deter elephants from encroaching on agricultural sites, such as oil palm plantations.

This study investigated the effects of Acacia mangium Willd. leaf litter on soil chemical properties of a tropical heath forest in Borneo using a controlled soil incubation experiment. The litter of exotic A. mangium and selected native heath forest species (Buchanania arborescens Blume., Calophyllum inophyllum L., Dillenia suffruticosa Griff. and Ploiarium alternifolium Vahl.) were incubated with heath forest soils collected under natural conditions and nine different treatments of heath forest soils (soils without leaf litter, soils treated with single species leaf litter, and soils treated with native leaf litter with and without A. mangium leaf litter). We quantified mass litter loss (%), and soil concentrations of exchangeable nitrogen ( ${\text{NO}}_3^{-}$ and ${\text{NH}}_4^{+}$ ) and cations (K ⁺ , Ca²⁺ and Mg²⁺), available phosphorus (P), total organic carbon (TOC) and organic matter (OM), and total acidity with exchangeable concentrations of Al³⁺ and H⁺ in each treatment after a 9-month incubation period. Mass litter loss (%) varied significantly between species, with A. mangium leaf litter only showing higher mass loss than D. suffruticosa litter, but lower than C. inophyllum litter. The effects of incubation with single-species native leaf litter were variable and species-specific, but incubation with A. mangium litter increased soil pH and exchangeable ${\text{NO}}_3^{-}$ and K⁺ concentrations and decreased exchangeable Al³⁺ concentrations. Soils incubated with a combination of C. inophyllum and A. mangium leaf litters, as opposed to those incubated with C. inophyllum alone, exhibited decreased pH, lower total organic carbon (TOC), and reduced exchangeable concentrations of potassium (K⁺) and magnesium (Mg²⁺). Additionally, there was an increase in organic matter (OM) content, total acidity, and exchangeable concentrations of ammonium ( ${\text{NH}}_4^{+}$ ) and hydrogen (H⁺). Our results provide preliminary evidence that C. inophyllum may be a promising native plant species for use in enrichment planting of degraded or disturbed tropical heath forests with co-occurring invasive A. mangium.

The microbiomes of Indonesian pineapple plants cover drought-resistant microorganisms that have not yet been studied. Therefore, this research aims to analyse the pineapple's endophytic and rhizobacteria capability to survive and support the plant in drought. The screening used polyethylene glycol (PEG) 6000 with specific osmotic pressures as a form of stress simulation. The isolates were further tested for their production of exopolysaccharides (EPS) and growth hormones (IAA), survival at high temperatures and salinity and other vital, drought-tolerant factors. Based on PEG 6000 analysis with certain osmotic pressure, about 13 isolates could survive at -0.73 MPa. Some isolates can produce EPS up to 89.23 mg/mL at -0.73 MPa, survive at 10% salinity, at a temperature of 50°C, pH 4 and produce IAA up to 7.5 ppm on medium. Most isolates can improve corn seedlings' growth quality and produce ACC deaminase and catalase enzymes. Isolate BDO 8 and BAO 5 showed more constant results compared with others. Based on the 16S rRNA gene, these isolates were identified as Bacillus cereus strain ATCC 14579T.112 and Bacillus cereus strain WHX1 with 99.91% and 100% sequence similarities, respectively. These findings suggest that these isolates could be developed as bioinoculant candidates for use in dry agricultural areas.

The ex-situ propagation of the Malayan tapir in Malaysia is an important conservation strategy to increase the population of this endangered species. However, the scarcity of reproductive physiology studies impedes potential conservation efforts. This study aimed to investigate the expression of estrus signs through observation of estrus behaviour and vulva score in captive Malayan tapirs. This study was conducted from January to April at the Sungai Dusun Wildlife Conservation Centre, Selangor, Malaysia. A total of five female Malayan tapirs aged between 3 to 18 years old were involved in this study. Two of the tapirs were kept with a male partner, while three others were kept individually. Closed-circuit television (CCTV) cameras with night vision and audio recording function connected to a digital video recorder were used to record the female activity from 1930 to 0730 hours. The recorded videos were evaluated for estrus behaviour such as vocalisation, flehmen response, urine spraying and excretion smelling. The vulva score (scale of 0 to 4) was determined based on the vulva size and the presence of discharge. The most common estrus behaviour observed in the female Malayan tapirs was vocalisation (81%), followed by flehmen response (10%), urine spraying (5%) and excretion smelling (4%). The paired females were observed to exhibit more estrus behaviours than the non-paired females. Vulva changes were observed in both groups with evidence of cyclic pattern with an average median length of 31.0 days (range of 28 days to 33 days). Mann-Whitney U test revealed significant difference between paired group and non-paired group for vocalisation and urine spraying. Meanwhile, Spearman's rho test showed a strong positive correlation between vulva score and flehmen response and very strong positive correlation between vulva score and excretion smelling. This study provides important information for the establishment of future captive propagation programmes.

Lempoyang, scientifically known as Zingiber zerumbet, is a plant rich in potential medicinal properties due to its numerous active ingredients. The aim of this study was to investigate the phytochemical composition and antibacterial potential of crude extracts of lempoyang obtained by subcritical water extraction (SWE). Fresh rhizomes of lempoyang were extracted using the one-factor-at-a-time (OFAT) approach with different extraction times (5 min, 10 min, 15 min, 20 min and 25 min), while other extraction parameters were kept constant. The resulting crude extracts, characterised by gas chromatography-mass spectrometry (GCMS), contained 13 different constituents. Among these, 2,6,10-cycloundecatrien-1-one,2,6,9,9-tetramethyl-,(E,E,E)- or zerumbone consistently had the highest percentage area under the peak across all extraction times, ranging from 17.15% to 28.72% at retention times of 19.215 min to 19.270 min. Qualitative screening of these crude extracts revealed the presence of phenolics, alkaloids, flavonoids, terpenoids, saponins and tannins, indicating the rich phytochemical diversity of lempoyang. However, steroids and anthocyanins have not been detected. In terms of antibacterial activity, disc diffusion using the Kirby-Bauer method showed positive results for the 25-minute crude extract against Escherichia coli, yielding a zone of inhibition of 8.63 ± 0.36 mm at a concentration of 100 mg/mL/disc. None of the extracts were found to have detectable antibacterial activity against Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella choleraesuis and Serratia marcescens. These results emphasise the potential of SWE for extracting valuable compounds from fresh lempoyang rhizomes. At the same time, they highlight that different extraction times influence the phytochemical profile and antibacterial activity of the crude extracts at higher extract concentrations.

Proboscis monkeys are largely confined along the eastern coastal zone of Sabah, Malaysia. Sulaman Lake Forest Reserve (SLFR) is the only Class V Mangrove Forest Reserve in the forestry district of Kota Kinabalu, Sabah. This study is in accordance with the conservation strategies outlined in the Sabah Proboscis Monkey Action Plan (2019-2028), which is to focus on areas that have not been surveyed. Prior to this study, the status of proboscis monkeys in this reserve had not been scientifically documented. In addition, the habitat of this colobine species along the coastal zone of Sulaman Bay will be impacted by the construction of Pan Borneo Highway (Work Package 9). Hence, we intend to shed light on the status of proboscis monkeys in the SLFR including local threats to their population. This study discovered a small and isolated relict population of proboscis monkeys through a boat survey approach, which was also derived from interview sessions with local communities. We found that the degradation of mangrove forest integrity is a major threat to this population in the SLFR. It is hoped that this study will trigger more research, especially population size estimation, because such baseline information is crucial in the formulation of effective conservation programmes.