Category Archives: Volume 43 No. 2 (2021)

Biology of Tortoiseshell Beetle (Aspidomorpha miliaris Fabr.) on Sweetpotato (Ipomoea batatas Lam) and Its Relatives as Affected by Hosts’ Nutritional Profile

Authors: Erlinda A.Vasquez, Luz G. Asio, Dilberto O. Ferraren and Resa M. Dacera


Several insect pests attack the foliage of sweetpotato at different stages of crop growth which contribute to yield reduction. Weeds belonging to the same genera as the main host can act as alternate hosts of insect pests. The study evaluated the biology of tortoiseshell beetle in the laboratory at an ambient temperature of 27-30oC and 85-90% RH on sweetpotato (Ipomoea batatas) as main host and four other Ipomoea species: three-lobe morning glory (I. triloba), beach morning glory (Ipes-caprae), swamp morning glory (I. aquatica), and five-finger morning glory (I. pentaphylla Syn. I. cairica) as alternate hosts. The beetle underwent four developmental stages – egg, larva, pupa, and adult. It completed its development within 4-6 weeks from egg-laying to adult emergence of 26-40 days, an average of 27.55 to 39.01 days. The total development period of male and female A. miliaris on I. batatas, I. triloba, I. pes-caprae, I. aquatica, and I. pentaphylla were 27.55 and 30.72, 27.52 and 30.49, 29.94 and 35.06, 33.25 and 38.11, and 33.70 and 39.01 days, respectively. Adult longevity of males and females was longer on I. batatas and I. triloba, followed by I. aquatica), I. pentaphylla, and lastly, I. pes-caprae. The highest number of eggs laid was recorded in I. batatas (202.7), followed by I. triloba (173.2), I. pes-caprae (76.0), I. aquatica (71.7), and I. pentaphylla (59.7). The highest egg viability of more than 90% was recorded in I. batatas and I. triloba. Mortality occurred towards the later part of larval development, with the lowest mortality of 8.33% in I. batatas.
The host plants ‘ high protein, N, P, and K contents influenced the shorter life cycle, higher reproductive rate, high percentage egg hatchability, lower mortality, and longer life span. Increased mortality and abnormal wet frass in I. pes-caprae could be accounted for by exceptionally high sugar content in the leaves and secondary metabolites present, especially in other host plants that may have insecticidal activity. Since A. miliaris was also able to complete its life cycle and reproduce on the four weed species, the insect continues to survive without sweetpotato. Any management strategy for this insect by destroying the Ipomoea weed hosts eliminates other sources of infestation in the field.

Keywords: Tortoiseshell beetle, Aspidimorpha miliaris, host suitability, Ipomoea species, host nutrient contents

Annals of Tropical Research 43(2):102-119(2021)
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Influence of plant growth regulators and UV light exposure on the formation and phenolic content of stevia rebaudiana bertoni callus: a preliminary study

Authors: Florina O. Pacaldo and Catherine C. Arradaza


This study was conducted to evaluate the effect of different combinations and levels of plant growth regulators, 2,4-dichlorophenoxy acetic acid (2,4-D) and 6-benzylaminopurine (BAP), on callus induction of Stevia rebaudiana Bertoni leaf and internode explants, and the total phenolic content of Stevia callus as influenced by the length of exposure to ultraviolet (UV) light radiation. Early callus initiation was recorded in leaf explants inoculated in Murashige and Skoog (MS) medium supplemented with 2,4-D and BAP. After a week of incubation, leaf explants showed callus formation while in internode explants, callus formation was observed 2 weeks after inoculation. The culture medium supplemented with 1.5mg L-1 2,4-D + 2.0mg L-1 BAP (T4) was the best treatment for leaf explants with 95% callus formation and the addition of 1.0mg L-1 2,4-D + 4.0mg L-1 BAP (T3) was the best treatment for internode explant with 90% callus formation. After 4 weeks of incubation, the leaf and internode calli were observed as compact, non-embryogenic, and yellowish green in all treatments except those inoculated in MS medium alone (control). Stevia leaf callus was subjected to UV radiation after 4 weeks at varying time of exposure. The exposed calli turned brown signifying a possible increasing production of secondary metabolites. Furthermore, combination of 1.5mg L-1 2,4-D + 2.0mg L-1 BAP (T4) and 3h of UV light exposure yielded the highest phenolic content of 87.71mg GAE per g callus. The results further revealed that both medium composition and time of exposure affect the production of phenolic content of Stevia leaf callus.

Keywords: Stevia rebaudiana Bertoni, Phenolic Content, UV light exposure, Callus, Plant Growth Regulators

Annals of Tropical Research 43(2):88-101(2021)
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In vitro efficacy of different antibiotics against contaminants of tissue-cultured ‘Lakatan’

Authors: Alminda Magbalot-Fernandez, Carlito M. Hindoy Jr. and Leslie T. Ubaub


This study aimed to characterize the bacterial and fungal contaminants of tissue-cultured ‘Lakatan’ banana (Musa acuminata) and find out effective antibiotics against these contaminants. This was conducted at the University of Southeastern Philippines, Tagum-Mabini Campus from October 2015 to February 2016.
This experiment was laid out in a Completely Randomized Design (CRD) with five treatments replicated three times. The treatments were: T1-Control; T2-Streptomycin (200mg L-1); T3-Nystatin (1mL L-1); T4-Streptomycin (200mg L-1) + Nystatin (1mL L-1); and T5- Benomyl (100mg L-1). Data were analyzed using ANOVA and compared through HSD.
Results showed that the different contaminants occurring during the initiation stage of tissue-cultured ‘Lakatan’ banana meriplants were composed of Rhizopus sp., an unidentified fungus, and Gram negative bacterium. Generally, 35% contamination was observed on this stage.
The result revealed that colony diameter of unidentified fungus and Rhizopus sp. were inhibited by Nystatin (1mL L-1). While the bacterial clear zone inhibition was increased by Streptomycin. This study elucidated the effectivity of antibiotics, nystatin and streptomycin against bacterial and fungal contaminants of tissue-cultured ‘Lakatan’ banana.

Keywords: Bacteria, Fungi, Contaminants, Tissue-culture, ‘Lakatan’ banana, Meriplants

Annals of Tropical Research 43(1):35-50(2021)
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Gender differences in the coping mechanisms to disruptions brought by COVID-19 pandemic among working adults in the Rural Philippines: The Case of Visayas State University

Authors: Moises Neil V. Seriño, Therese C. Ratilla, Maria Aurora Teresita W. Tabada, Ma. Salome B. Bulayog, Nilda T. Amestoso, Venice B. Ibañez, Angelita Paradero, Michael P. Mazo, Vergie Ann E. Galenzoga, Chariss C. Verdida, Reyvin N. Sabanal and Michael R. Calungsod


The various social restrictions imposed to contain the spread of COVID-19 virus have brought unprecedented disruptions in people’s lifestyle. The academic institutions were caught unprepared and had to adjust abruptly. With this, we assessed how working adults in a state university in rural Philippines are coping with the disruptions brought by the pandemic. We conducted a cross-sectional online survey on May 18 to 23, 2020 where 133 working adults from the Visayas State University, Leyte, Philippines responded to the survey. Results show that the top most rank coping mechanism for both men and women is doing household chores. Results further suggest that men are more inclined to surfing the net and use social media while women focus more on praying and gardening. Pets are considered as an important companion to cope better with the pandemic. Our results highlight differences in coping mechanisms between working men and women in dealing with the pandemic. Empirical findings suggest that working adults with diversified activities and engaged more in physical activities such as household chores and gardening tend to cope better during lockdowns. In addition, income and access to internet are significant determinants of coping mechanisms. Policy makers and administrators in state university in Philippines may benefit from understanding gender differences in coping with the pandemic and can tailor approaches that may contribute to wellbeing issues among working adults.

Keywords: multiple coping strategies, gender disaggregation, well-being, pandemic, rural Philippines, state university employees

Annals of Tropical Research 43(2):120-133(2021)
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Reformulation of vermicast as organic fertilizer for corn

Authors: Mark Anthony M. Barbadillo1, Renante G. Macapanas2 and Romel B. Armecin2,3*


The increasing demand for healthy and sustainable food production practices has encouraged farmers to switch to the use of organic fertilizers. Information on the nutrient composition of the available organic products is minimal. Hence, this study was conducted to survey and collect samples of vermicast fertilizer materials in Western Visayas and do reformulation work to improve the nutrient composition and perform efficacy trials for corn seedling at the early stage of growth. Among the collected samples, soil pH values ranged from 4.7-7.0, OM from 25.40-45.40%, and total N, P, K, Na, Ca and Mg contents ranged from 0.70-1.40%, 0.04-0.90%, 0.30-1.00%, 0.03-0.17%, 1.30-2.60%, and 0.50-0.80%, respectively. Reformulated vermicasts contained high total N content (1.23-1.37%) but had lower total P, K, Na, Ca and Mg contents than most vermicasts from Western Visayas. The plant height, leaf area and dry matter yield of the corn seedlings using the reformulated vermicast was significantly higher than those seedlings treated with inorganic fertilizer.

Keywords: organic fertilizer, corn, dry matter yield, reformulation, vermicast

Annals of Tropical Research 43(2):76-87(2021)
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Isolation, characterization and antibacterial activity of actinomycetes from soils of the Langun-Gobingob Cave Complex in Calbiga, Samar

Authors: Jeffrae Isaac Albert R. Damayo and Rolly G. Fuentes*


The discovery of rare Actinomycetes from unexplored areas has proven to be a promising source of new antimicrobials. The Langun-Gobingob cave complex in Calbiga, Samar, Philippines is the second largest cave complex in Asia, yet this is the first reported search for actinomycetes conducted in the area. The main objective of this study was to assess the antibacterial activities of culturable actinomycetes from soil samples from the Langun-Gobingob cave complex. Five actinomycete colonies were isolated in pure culture from soil samples using Starch-Casein Agar medium. The isolates were identified by their morphological characteristics and they were characterized by 16S rRNA sequencing. The sequences were matched to sequences uploaded to the NCBI Basic Local Alignment Search Tool (BLAST). Four of the isolates belonged to the Genus Streptomyces and one belonged to the Genus Nocardia. The antibacterial potential of the isolates was tested against gram-positive and gram-negative test bacteria. One Streptomyces isolate exhibited antibacterial activity against the two gram-positive test bacteria. The limited cave area sampled in this study leaves the cave complex mostly unexplored in the search for antibacterial secondary metabolites.

Keywords: Actinomycetes, 16s rRNA, starch-casein agar, BLAST

Annals of Tropical Research 43(2):67-75(2021)
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Phosphorus forms and distributions in soils under selected land use practices at the Federal University of Agriculture, Abeokuta, Ogun State, Nigeria

Authors: Oladoye AO, Busari MA, Abiodun FO, Ojekunle OO, Oyebamiji NA and Olaife BA


The forms and distributions of phosphorus were determined for four different land use practices in Federal University of Agriculture, Abeokuta, with the aim of evaluating the effects of land use and soil depth on soil physical and chemical properties, forms and distributions of phosphorus. The study was a 4×2 factorial experiment laid out in a Randomized Complete Block Design. Factor 1 was four different land use practices (Gmelina arborea, Tectona grandis, Leucaena leucocephala plantations and secondary forest), and Factor 2 was soil samples collected from two soil depths (0-30cm and 30-60cm). The soil pH, electrical conductivity, exchangeable bases (Na, K, Mg and Ca), particle size, organic carbon, total nitrogen, total phosphorus, inorganic phosphorus fractions (Al-P, Fe-P and Al-P) and available phosphorus analyses were carried out using standard procedures. Data collected from the laboratory analysis were subjected to two-way Analysis of Variance while the means among the treatments were separated using Duncan Multiple Range Test. The results showed that the soils had low total and available P contents. The soil under Leucaena leucocephala plantation had the highest total phosphorus (111.05mg kg-1), followed by Tectona grandis (97.63mgn kg-1), Gmelina arborea (96.41mg kg-1) and secondary forest (83.63mg kg-1). Total P decreased with depths (0-30cm and 30-60cm). Inorganic P-fractions were greatly influenced by soil properties such as soil pH, soil electrical conductivity, organic carbon, and soil particle size. The inorganic phosphorus fractions of the soils in all study area occurred generally in the following sequential order; Fe-P>Ca-P>Al-P. The highest inorganic phosphorus recorded in all in the study area was Fe-P, followed by Ca-P and Al-P. Al-P had the lowest content between the depths examined. Lower nutrient concentrations in soils under secondary forest within the depths were due to lower organic matter content, higher nutrient demand, nutrient immobilization by tree species and other flora present. P fractionation investigations are therefore recommended in soils under indigenous species plantation in order to provide adequate understanding of P status in the soils and fertilizer recommendation so as to improve productivity.

Keywords: Land Use, Soil, Phosphorus, Inorganic fractions and Distribution

Annals of Tropical Research 43(2):51-66(2021)
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Degree of damage and infestation of coconut leaf beetle Brontispa longissima (Gestro) on seedlings of selected coconut varieties

Authors: Gladys R. Cabelin and Maria Juliet C. Ceniza


The Coconut Leaf Beetle, scientifically known as Brontispa longissima (Gestro), is an introduced species that is becoming an alarming pest of coconuts in the Philippines. The infestation caused by this pest is damaging to all stages of coconut growth. This study was conducted to assess the degree of damage and infestation caused by Brontispa longissima on the seedlings of 10 selected tall and dwarf coconut varieties in the National Coconut Research Center at Visayas State University, Leyte, Philippines. Among the selected varieties, seedlings of Baybay Tall (green and brown) and Albuera Dwarf varieties succumbed to more damage by B. longissima beetles compared with the other varieties observed with 41-80% of the first openned leaf area damaged. Seedlings of Malayan Yellow Dwarf and Malayan Red Dwarf varieties had the least damage with 0-20% of the first openned leaf area damaged. The high damage ratings of Baybay Tall and Albuera Dwarf were expected because these varieties had high infestation rates and harbored the most numbers of B. longissima adults, eggs, and larval stages, which indicated the preference of B. longissima for these varieties. The developmental period of B. longissima in Baybay Tall and Albuera Dwarf of 44 days and 45 days on the average, respectively, was shorter than in other varieties, indicating that these are suitable and preferred hosts. Baybay Tall seemed to be the most preferred variety. The beetles had least preference for Malayan Yellow Dwarf and Malayan Red Dwarf varieties.

Keywords: B. longissima, coconut varieties, BAYT variety, preference

Annals of Tropical Research 43(2):25-34(2021)
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Mycofumigation with the endophytic fungi Fusarium proliferatum (Matsushima) Nirenberg and Diaporthe sp. for the control of banana and mango anthracnose

Authors: Rochelle B. Cagadas*, Flor A. Ceballo1, Christian Joseph R. Cumagun1 and Ireneo B. Pangga1


Banana and mango are the top commodities in the Philippines that are traded worldwide however, fungal diseases such as anthracnose affect their yield and quality. Environmentally sound control strategies have been explored and one of these is mycofumigation using fungal endophytes. This alternative approach is understudied in the Philippines, hence, the study aimed to evaluate the mycofumigation potential of fungal endophytes collected from Mt. Makiling, Luzon, Philippines and their pathogenicity to banana and mango fruits. In vitro and in vivo mycofumigation assays were conducted with a completely randomized design layout with triplicates per treatment under laboratory conditions.

The fungal endophytes used as mycofumigants, Diaporthe sp. and Fusarium proliferatum, were comparatively effective in controlling the anthracnose of banana and mango. The mycelial growth for in vitro assay of Colletotrichum musae and Colletotrichum gloeosporioides were significantly reduced compared to the control when exposed to volatile organic compounds produced by the fungal endophytes. In addition, the results of the in vivo mycofumigation assay against C. musae showed Diaporthe sp. had a significantly higher inhibition rate (93%) than F. proliferatum (67%) when grown on potato dextrose agar plates.
The bioefficacy of the Diaporthe sp. and F. proliferatum was improved when grown on peanut and corn seed substrates with a reduction of banana and mango anthracnose severity ranging from 82 to 100%. Cultures grown on corn substrate performed better than those grown on peanut. Pathogenicity tests also revealed that these endophytic fungi did not cause disease in the banana or mango fruits indicating their potential as good biocontrol agents against C. musae and C. gloeosporioides.

Keywords: Mycofumigation, endophytic fungi, Diaporthe sp., Fusarium proliferatum, Colletotrichum musae, Colletotrichum gloeosporioides

Annals of Tropical Research 43(2):13-24(2021)
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The effects of calcium fertilizer on anthracnose and Rhizopus tuber rot of yam

Authors: Osijo Adedeji Taiwo1*, Otusanya Marian Olugbemileke1, Afolabi Clement Gboyega1 and Olowokere Florence Alaba1


Yam (Dioscorea spp) production is beset in the field and in storage by major fungal pathogens, namely Colletotrichum gloeosporioides that causes anthracnose in the field, and Rhizopus stolonifer that causes tuber rot in storage. Alternative control measures are imperative as conventional control of these pathogens is either ineffective or detrimental. This study investigated the effects of calcium fertilizer on the incidence and severity of anthracnose and Rhizopus rot of yam. Calcium nitrate fertilizer was applied to soils naturally infected with C. gloeosporioides, at the rates of 0, 3, and 4kg ha-1. D. rotundata variety Efuru was planted. The treatments were arranged in a randomized complete block design with three replicates. Anthracnose disease rating relied on natural endemic infection in the field, while inoculation of harvested yam tubers was carried out using R. stolonifer. There was no significant effect of calcium amendment of the soil on anthracnose severity in D. rotundata or on the agronomic parameters. D. rotundata tubers treated with 3 and 4kg ha-1 calcium soil amendments had reduced infection by R. stolonifer in storage compared to the control treatments. The study concluded that calcium applied to the soil had reduced storage losses by R. stolonifer in D. rotundata but had no influence on anthracnose severity in the field. Therefore, 3kg ha-1 of calcium nitrate applied to the soil can be used to improve D. rotundata tuber resistance to R. stolonifer, and is recommended for high-quality tuber storage.

Keywords: calcium nitrate, soil amendment, anthracnose, Rhizopus stolonifer, Dioscorea rotundata

Annals of Tropical Research 43(2):1-12(2021)
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