First Report of Colletotrichum siamense causing Anthracnose on White Frangipani (Plumeria alba L.) in Malaysia

Plumeria alba L. is a flowering plant in the family Apocynaceae and widely cultivated in Malaysia as a cosmopolitan ornamental plant. In January 2020, anthracnose lesions were observed on leaves of Plumeria alba planted in Agricultural Farm, Universiti Putra Malaysia, in Selangor state, Malaysia. The disease mainly affected the leaves with symptoms occurring with approximately a 60% disease incidence. Ten symptomatic leaves were sampled from 3 different trees in the farm. Symptoms initiated as small circular necrotic spots that rapidly enlarged into black lesions with pale brown borders. Diseased tissues (5×5 mm) were surface-sterilized with 70% ethanol for 1 min, rinsed three times with sterile distilled water, dried on sterile filter papers, plated on PDA and, incubated at 25 °C with a 12-h photoperiod. A total of seven single-spore isolates with similar colony morphologies were obtained from tissue samples. After 7 days, the colonies raised the entire margin and showed white-to-gray aerial mycelium, orange conidial masses in the center and appeared dark brown at the center of the reverse view. The conidia were 1-celled, hyaline, smooth-walled, cylindrical with narrowing at the center, averaged (13-15 μm × 3 - 4 μm) (n=40) in size. Morphological characteristics of the isolates were similar to those detailed in taxonomic description of Colletotrichum sp. (Prihastuti et al. 2009). For molecular identification, genomic DNA of two representative isolates, PL3 and PL4 was extracted from fresh mycelium using DNeasy Plant Mini Kit (Qiagen, USA). The internal transcribed spacer (ITS) region, actin (ACT) and calmodulin (CAL) genes were amplified using ITS5/ITS4 (White et al. 1990), ACT-512F/783R (Carbone and Kohn 1999) and CL1C/CL2C primer sets (Weir et al. 2012). A BLAST nucleotide search of GenBank using ITS sequences showed 100% identity to Colletotrichum siamense ex-type culture ICMP 18578 (GenBank accession no. JX010171). ACT and CAL sequences showed 100% identity with C. siamense ex-type isolate BPD-I2 (GenBank accession no. FJ907423 and FJ917505). The sequences were deposited in GenBank (ITS: accession nos. MW335128, MT912574), ACT: accession nos. MW341257, MW341256, CAL: accession nos. MW341255 and MT919260). Based on these morphological and molecular characteristics, the fungus was identified as C. siamense. Pathogenicity of PL3 and PL4 isolates was verified using four healthy detached leaves of Plumeria alba. The leaves were surface-sterilized using 70% ethanol and rinsed twice with sterile water before inoculation. The leaves (three inoculation sites/leaf) were wounded by puncturing with a sterile needle through the leaf cuticle and inoculated in the wound site with 10-μl of conidial suspension (1×106 conidia/ml) from 7-days-old culture on PDA. Four leaves were used as a control and were inoculated only with 10-μl of sterile distilled water. Inoculated leaves were kept in humid chambers for 2 weeks at 25 °C with 98% relative humidity on a 12-h fluorescent light/dark period. The experiment was repeated three times. Anthracnose symptoms were observed on all inoculated leaves after 3 days, whereas controls showed no symptoms. Fungal isolates from the diseased leaves showed the same morphological characteristics as isolates PL3 and PL4, confirming Koch's postulates. C. siamense has been reported causing anthracnose on rose (Rosa chinensis) in China (Feng et al. 2019), Coffea arabica in Thailand (Prihastuti et al. 2009) and mango leaf anthracnose in Vietnam (Li et al. 2020). To our knowledge, this is the first report of Colletrotrichum siamense causing leaf anthracnose on Plumeria alba in Malaysia. Accurate identification of this pathogen provides a foundation in controlling anthracnose disease on Plumeria alba

Insect pests of vegetables in Malaysia and their management using entomopathogenic fungi

The domestic economy in Malaysia is dominated by agriculture, which accounts for about 10% of the Gross Domestic Product (GDP), and contributed more than 23% of the total export earnings. Vegetable comprises about 15% of the daily food intake of the Malaysian population. Vegetables in Malaysia are mostly produced by smallholder farmers and this industry provides millions of employments for the peoples, especially the rural dwellers. Insect pest is one of the major constraints of vegetable production in Malaysia. During growth, different species of insect pests such as armyworms, caterpillars, beetles, aphids, whiteflies, mites, and thrips cause serious damage to different vegetable crops, which reduce yield and make it unsuitable for human consumption. Integrated Pest Management (IPM) has been internationally recognized approach to pest control. IPM programme for insect pest of vegetable include, cultural control, physical control, mechanical control, biological control (parasitoids, predators, and entomopathogens), Plant Resistance to insects (PRI), and chemical control. Comparably, entomopathogenic fungi has demonstrated advantageous performance in infecting hosts directly through the integument. This paper aims to review some of the available literature on the IPM of insect pests of vegetables in Malaysia with more emphasis on insect pathogenic fungi as a contribution to components of IPM

Impacts of 2 species of predatory Reduviidae on bagworms in oil palm plantations

Integrated pest management (IPM) is widely practiced in commercial oil palm agriculture. This management system is intended to minimize the number of attacks by pest insects such as bagworms on crops, as well as curb economic loss with less dependency on chemical pesticides. One practice in IPM is the use of biological control agents such as predatory insects. In this study, we assessed the response of predatory natural enemies to pest outbreak and water stress, and document the habitat associations of potential pest predators. The abundances of 2 predatory insect species, namely Sycanus dichotomus and Cosmolestes picticeps (Hemiptera: Reduviidae), were compared bagworm outbreak sites and nonoutbreak sites within oil palm plantations. We also examined habitat characteristics that influence the abundances of both predatory species. We found that the abundance of C. picticeps was significantly higher in bagworm outbreak sites than in nonoutbreak sites. There were no significant differences in the abundance of S. dichotomus among outbreak and non-outbreak sites. Both species responded negatively to water stress in oil palm plantations. Concerning the relationship between predatory insect abundance and in situ habitat quality characteristics, our models explained 46.36% of variation for C. picticeps and 23.17% of variation for S. dichotomus. Both species of predatory insects thrived from the planting of multiple beneficial plants in oil palm plantations. The results suggest that C. picticeps can be used as a biological agent to control bagworm populations in oil palm plantations, but S. dichotomus has no or little potential for such ecosystem service

Evaluation of artificial diet on growth development of Elaeidobius kamerunicus faust (Coleoptera : Curculionidae)

The rearing of Elaeidobius kamerunicus is difficult as it required the anthesis male inflorescence of oil palm as the breeding and feeding ground for the weevils. To date, utilisation artificial diets for rearing of E. kamerunicus has not been extensively studied. Thus, the objectives of this study were to compare growth development of the larvae using adopted artificial diet formulations and the natural rearing of E. kamerunicus besides determining the nutritional component of the natural food (male inflorescence of oil palm at anthesis). Three artificial diet types adopted from the diet of Anthonomus tenebrosus (Coleoptera: Curculionidae) and Anthonomus grandis (Coleoptera: Curculionidae) were compared with the natural food source towards the growth development of E. kamerunicus. The proximate composition of the natural food source obtained from the field was determined. The findings showed that overall mortality was significantly different for diet types evaluated (P < 0.01). The natural feed caused shorter life cycle of the larvae (10.85±0.34 days). Sex ratio of 0.54 with higher number of female adult was also recorded on natural feed while the artificial diet caused total mortality on the larvae. Nutritional study of the male spikelet at anthesis shown it has 75% moisture content, 20% carbohydrate, 4% protein and less than 1% fat. The formulated artificial diets were found to have lesser essential nutrients to support the growth of larvae. This study provided new knowledge in the formulation of artificial diets and the importance of macronutrient composition on the growth of E. kamerunicus

Effect of temperature on germination, radial growth, and sporulation of the new isolates of Metarhizium anisopliae and their virulence to Whitefly, Bemisia tabaci (Hemiptera: Aleyrodidae)

Metarhizium anisopliae is a potential entomopathogenic fungi (EPF) to control insect pests in Malaysia, yet little is known about the temperature influence on its growth and efficacy. The average daily temperature in Malaysia is between 21 °C and 32 °C, with some parts of Cameron Highland in Peninsular Malaysia experiencing temperatures as low as 14 °C. Therefore, for effective field application, the most effective EPF isolates should be tolerant to the temperature of the country. Here we conducted a laboratory experiment to determine the effects of average daily temperatures in Malaysia (15, 20, 25, and 30 °C) on conidial germination, radial growth, and conidial density of seven new isolates of M. anisopliae. However, at 25 and 30°C, the three isolates (Ma-2, Ma-9, and Ma-15) produced the highest number of conidia and were therefore selected for virulence test against the second instar of whitefly, Bemisia tabaci. The percentage mortality of the three isolates ranged between 36.1% and 97.7% across different temperatures for 7 days post-treatment. The isolates Ma-15 caused the highest percentage mortality of 97.7% and the shortest LT50 and LT90 values (1.68 and 3.98 days, respectively), at 30 °C incubation temperature. This study confirms that the growth and virulence of Malaysian isolates of M. anisopliae are strongly influenced by temperature and could be used as promising candidates for biocontrol of B. tabaci on vegetables planted in a tropical climate such as that of low land and highland in Malaysia, although extensive field and semi-field bioassays, as well as the development of ideal formulation, are still required

Cytotoxicity and anticancer activity of Donkioporiella mellea on MRC5 (normal human lung) and A549 (human lung carcinoma) cells lines

Polypores are mushrooms which are rich in bioactivities and for generations, they have been widely used as herbal remedies. Despite their significant importance in treatments of various health issues, only a few local species have been reported for their pharmacological potentials. The present study was carried out to establish cytotoxicity potentials of Donkioporiella mellea, a local polypore species collected from forested areas in Malaysia at cellular levels on normal human lung (MRC5) and human lung carcinoma (A549) cell lines. Survival and inhibition rates were analyzed by 3-(4, 5)-dimethylthiahiazo (-z-y-l)-2,5-diphenyltetrazoliumbromide (MTT) while monitoring changes on cellular shapes by inverted phase contrast microscopy. Survival rates of MRC5 cells were observed to be significantly higher than A549 after treatments with various concentrations of polypore extracts. MRC5 cells showed excellence in survival performance when treated with hot and cold aqueous extracts. Cold aqueous extract showed higher cytotoxicity activities compared to hot aqueous extract () with inhibitory concentration (IC50) values of 414.29 μg/ml and >1000 μg/ml, respectively. Treatments with tamoxifen as a control exhibited necrotic features in both cell lines. The results suggest that D. mellea possesses pharmacological potentials that can be utilized for human consumption as a new bioresource alternative, thus encouraging research advancement in mycological and nutraceutical studies

Influence of parental dura and pisifera genetic origins on oil palm fruit set ratio and yield components in their D × P progenies

This research was conducted to study the performance of biparental dura × pisifera (D × P) progenies and their parental genetic origins on fruit set and yield components. Twenty-four D × P progenies developed from 10 genetic origins were used for this study. Analysis of variance showed that there was genetic variability based on the evaluation of individual progenies. Deli Ulu Remis × Nigeria of progeny ECPHP500 recorded the highest bunch number (22.91), and fresh fruit bunch (184.62 kg palm−1 year−1) and Deli Banting dura × AVROS pisifera (ECPHP550) had the highest average bunch weight (10.36 kg bunch−1 year−1). Progenies PK4674 (61.12%) and PK4465 (60.93%) had the highest fruit set, and the highest oil yield of 52.66 kg bunch−1 was noticed by progeny PK4674. Estimation of variance components, coefficients of variation, heritability, and genetic gain were calculated to establish the genetic variability. To validate the genetic disparity among the progenies, an unweighted pair-group procedure with arithmetic mean (UPGMA) and principal component was employed based on their quantitative traits. Through the UPGMA and principal component, the 24 progenies were clustered into 7 clusters, whereas cluster V had the highest fruit set (60.62%) and cluster IV had the highest oil yield (43.71 kg palm−1 year−1). For oil palm tissue culture and breeding programs, progeny PK4674 will be more useful for developing planting materials of high oil yielding with stable performance. However, we recommend that future studies incorporate molecular studies with conventional breeding

Effects of in situ habitat quality and landscape characteristics in the oil palm agricultural matrix on tropical understory birds, fruit bats and butterflies

The expansion of commercial oil palm crop has modified much of the natural landscape, subsequently leading to biodiversity loss in Southeast Asia. Aside from large-scale oil palm monoculture plantations, self-managed oil palm smallholdings are also becoming common in palm oil producing countries, but less is known about how management of the smallholdings affects faunal biodiversity. We argue that it is critically important to understand the role of habitat complexity at the local and landscape scales for maintaining faunal biodiversity in oil palm smallholdings. We used passive sampling methods to survey understory birds, fruit bats, and butterflies in oil palm smallholdings on the west coast of Peninsular Malaysia. We quantified the diversity in each taxon and measured in situ habitat quality and landscape metrics. We found that oil palm smallholdings located near rice fields supported fewer bird species. Proximity to roads can give rise to bird and fruit bat richness. Bird and fruit bat richness declined at sites with high crop density. Fruit bat richness declined, but butterfly richness increased, with the height of oil palm stands. Butterfly richness declined with distance from riparian habitats. Decreased coverage and height of ground vegetation also negatively affected butterfly species richness. We also found that the number of farm houses is positively related to bird, fruit bat, and butterfly species richness. Of the three taxa, only butterfly richness was positively influenced by crop diversity. We found that habitat complexity enables smallholdings to support a diverse community of birds and butterflies, but not fruit bats. These findings imply that oil palm smallholdings can be managed in a conservation agricultural matrix, as the smallholdings were able to maintain farmland biodiversity

Role of beneficial plants in improving performance of predators of oil palm bagworm

The use of beneficial plants in the oil palm plantation is nature and food plant for insect predators widening year by year. This technique has been widely used in Malaysia. The effectiveness and advantages of this beneficial plant depends on several factors such as the presence of insects naturally, the existence of pests and abiotic factors. Research on the role of useful plants is critical to ensure and increase the effectiveness of natural enemies. The use of natural enemies as biological control agents against bagworms in palm plantation will be expanded. According to the Malaysian Palm Oil Board (MPOB), pest especially bagworms are becoming more common in Malaysia, still the effectiveness of the beneficial plants for protecting and food source for natural enemies in this country been carried out. In this study, the abundance and performance of predators against bagworm in palm plantations was done every month in three different oil palm fields. Sampling was performed using sweep nets of 30 cm diameter in three different localities; fields with cultivation of three beneficial plants namely Antigonon leptopus, Cassia cobanensis and Turnera subulata, single planting beneficial plants namely Turnera sp. and estate without beneficial plant. A total of 1,035 individuals of two species were found, namely Cosmolestes picticeps (n = 924) and Sycanus dichotomus (n = 111) both of Hemiptera order and Reduviidae family. They dominated the study areas that are practicing cultivation of three beneficial plants a significantly higher (F = 21.75; p <0.001) and (F = 32.21, p <0.001), compared to estate planting a single beneficial plant and without beneficial plant respectively. Fluctuations in insect predators correlated with rainfall and the presence of bagworm. Data showed that the sampling population, the adult insect predators found in the study area, with peaks identified particularly in May, June, July, September and October 2015 on estates that planting these three types of beneficial plants. Antigonon leptopus, Cassia cobanensis and Turnera subulata were the plants with potential to increase the number of predators in oil palm plantations. This was proved when bagworm outbreak incidences dropped on the planting of three species of beneficial plants than the other two regions. The population of predators, C. picticeps and S. dichotomus were not significantly correlated with rainfall parameters and bagworm. Studies showed that predation, tripled the number of bagworms where Metisa plana eaten by adults S. dichotomus compared to C. picticeps. Furthermore, the reaction function M. plana on different densities of 2, 4, 6, 8 and 10 S. dichotomus showed the reaction function of type II, with 1.9, 3.4, 5, 6.4 and 8.1 individually rate than 0.9, 1.4, 2.1,1.9 and 2.3 of predation by C. picticeps rates. Therefore, based on the results obtained in this study, predators S. dichotomus can be used to control bagworm. The results showed a large number of adult S. dichotomus attracted to useful plants namely, C. cobanensis and T. subulata compared than most other plants, A. leptopus, Asystasia intrusa, Euphorbia heterophylla and Ageratum conyzoides. The study of the nutrient content in the flower nectars and six plants was carried out using the GS-MS method. Results showed that all plants contained volatile composition to attract insect predators. For the review on the role of useful plants, T. subulata was tested on different combination treatments where the comparison with the existence of S. dichotomus, oil palm trees, bagworms and T. subulata were implemented. The insect predators need shelter and food sources such as nectar and honey for a longer life span. This was evident when the cage has only insect predators, palm trees and T. subulata. There was no significant difference between the cage with S. dichotomus, oil palm trees, T. subulata and M. plana, life span of S. dichotomus male and female (30.40 and 30.84 days) as compared to male and female (31.08 and 31.72 days) respectively. The cultivation of the suggested beneficial plant in oil palm to maintain the abundance of natural enemies to control pests of oil palm leaves is of major concern