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Aims@#Symbiotic bee fungus associated with the stingless bee larval food has been revealed to play a major role in performing a mutual relationship with the host. The fungus is believed capable to produce crucial nutrients that are required for larval pupation. However, detailed information on the fungus identification isolated from the larval food of our native Indo-Malaya stingless bee, Heterotrigona itama (Hymenoptera: Apidae), is poorly understood. Hence, this study was conducted to determine the effect of fungus isolated from the stingless bee larval food on the survival of H. itama larvae and identify the isolated fungus using both morphological and molecular analyses.@*Methodology and results@#Elisa plates designed with F-bottom type were used as artificial brood cells in a controlled condition. The eggs transferred to Elisa plates were kept in the incubator with 75%-100% humidity and 25 ± 2.5 °C of temperature. This study carried out in three different treatments: (1) microbes-free larval food, (2) fresh larval food and (3) microbes-free larval food with fungus supplement. Results showed that the survival of H. itama larvae depends on the presence of beneficial fungus with the highest survival rate (Treatment 2 = 85.71%). The absence of the beneficial fungus in the fluid food of H. itama showed the lowest survival rate (Treatment 1 = 37.14%). Microscopy analysis showed that the fungus had various forms, including unconjugated asci, round-shaped ascospore and pseudohyphae. The molecular characterisation of the isolated fungi was performed using 23S rRNA gene sequencing using universal primers ITS1 and ITS4. DNA barcoding of three isolated fungi confirmed all isolated fungi matched Panus lecomtei (Basidiomycetes; Poriales; Polyporaceae) with 99.70% of similarity.@*Conclusion, significance and impact of study@#This study provides information on the importance of whitish fungus in appearance that existed in the brood cell, which is proposed to be the crucial component of in-vitro stingless bee queen rearing protocol.
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Aims@#Metarhizium anisopliae is an entomopathogenic fungus (EPF) that exists naturally in the environment and potentially be used as a biological control agent against many insect pests. This study aims to evaluate the effect of nutrient additives on the yield and viability of M. anisopliae spore and to determine the optimum incubation period for maximum spore production.@*Methodology and results@# In this study, M. anisopliae was cultivated by solid-state fermentation using rice as a growth medium. Three different nutrient additives were examined which aimed to maximize the production of M. anisopliae spores. Among the three nutrient additives evaluated, yeast (1.84 ± 0.04 g) supported better growth and spore production than molasses (0.58 ± 0.04 g) and palm oil (0.47 ± 0.09 g). The incubation period between 2-6 weeks produced higher spore yield (0.97 ± 0.02 g spores) at week 4 with a better spore viability (86.30 ± 0.45%) at week 2. @*Conclusion, significance and impact of study@#Hence, it is suggested that the optimum incubation period is between 2 and 6 weeks after inoculation, and M. anisopliae could be mass produced in large quantities on rice substrate with the addition of yeast as the nutrient additives.
Asunto(s)
Agentes de Control Biológico , Viabilidad Microbiana , MetarhiziumRESUMEN
Aims: Subterranean termites, Globitermes sulphureus is one of the significant pests for agricultural crops such as coconut and oil palm, and occasionally attacks building structure in Malaysia. Efforts to control subterranean termite infestations depended heavily on liquid termiticide applications. Natural pathogen of termites such as entomopathogenic fungi (EPF) is a promising alternative to chemical control. The objective of this study was to determine the most virulent EPF such as Metarhizium anisopliae, Beauveria bassiana and Paecilomyces sp. against the subterranean termites, G. sulphureus for the development of bio-insecticide for future use of termite control. Methodology and results: Subterranean termites were collected from mound-building termites found in Universiti Malaysia Terengganu (UMT). Cultivating, harvesting and counting of conidia of EPF were carried out to prepare the desired concentrations for screening test and bioassays, which were 1×103 , 1x105 , 1×107 and control. The pathogenicity testing was observed daily within 1 week under laboratory conditions. Screening showed that M. anisopliae was found to be the most virulent compared to B. bassiana and Paecilomyces sp., achieving 100% mortality within 3-4 days. M. anisopliae was then further tested on termites and it was found that concentration of 1×107 showed the lowest LT50 value, while LC50 of M. anisopliae in 1 day was 2.0151×106 . Conclusion, significance and impact of study: It could be concluded that M. anisopliae is the most virulent EPF against termites and the most effective concentration was ±107 followed by strains of B. bassiana and Paecilomyces sp. However, there is limited field evaluation of EPF against termites in Malaysia. Evaluation on the efficiency of M. anisopliae in the field should be conducted so that its efficacy could be proven and marketed.