Abstract. Ayudya DR, Herlinda S, Suwandi S. 2019. Insecticidal activity of culture filtrates from liquid medium of Beauveria bassiana isolates from South Sumatra (Indonesia) wetland soil against larvae of Spodoptera litura. Biodiversitas 20: 2101-2109. The obstacle in utilizing entomopathogenic fungi to control pest insects in wetlands is the inability of their isolates to survive during the saprophytic phase due to the soil being very acidic. Therefore, the exploration of fungi being able to survive in the acidic soil was utilized in the acidic ecosystem. This study aimed to test the toxic activity of Beauveria bassiana culture filtrates from liquid medium at pH 2.5 and 6 against Spodoptera litura larvae. Total of ten isolates collected from South Sumatra, Indonesia was grown in liquid media at pH of 2.5 and 6 for six weeks. The result showed that the culture filtrate from liquid medium at pH 6 was more toxic against the larvae than that at pH 2.5. The mortality of the larvae at pH 6 reached 92%, while that at pH 2.5 it reached 13.33% only. The findings of present study revealed that the culture filtrate isolates of BPdR, BJgTs, BSwTd2, BSwTd3, BSwTd4, BKKPp2 from pH 2.5 media still caused high larvae mortality (6.67-13.33%). These seven isolates are superior due to their toxic nature at pH 2.5. Consequently, present study has increased the chances of success in utilizing these isolates for biological control in acidic ecosystems, such as peatlands, tidal lowlands, and freshwater swamps.
The brown planthopper (BPH), Nilaparvata lugens can cause direct damage and transmit rice diseases. Beauveria bassiana is used to control BPH, however the success of the fungal efficacy on rice fields is affected by external factors, such as temperature. This research aimed to evaluate the conidial viability and density of B. bassiana isolates from Java and Sumatra, exposed to 25 and 34°C and their virulence against BPH nymphs. Twenty six isolates of B. bassiana cultures incubated at 25 and 34°C for 7 days were observed on their conidial density, viability, and virulence against BPH nymphs. The incubation temperature of 34°C was able to decrease conidial density and viability, and virulence of the isolates. However, some isolates of B. bassiana originated from soils or insects in Sumatra, especially from South Sumatra still produced high conidial density and viability as well as high virulent against BPH nymphs, such as TS1D3A, TSID3B, TS1D2A and TS1D2B isolates. The TS1D2B isolate incubated at 34°C still caused the highest percentage of BPH mortality (43.33%) among other isolates. Therefore, the isolates can be used as promosing candidate for biocontrol for N. lugens on rice planted in tropical ecosystem, such as wetland or lowland rice ecosystems in Indonesia.
Abstract. Gustianingtyas M, Herlinda S, Suwandi, Suparman, Hamidson H, Hasbi, Setiawan A, Verawaty M, Elfita, Arsi. 2020. Toxicity of entomopathogenic fungal culture filtrate of lowland and highland soil of South Sumatra against Spodoptera litura larvae. Biodiversitas 21: 1839-1849. The use of secondary fungal metabolites for the active ingredient of mycoinsecticide is more effective and more easily integrated with other pest control techniques. This study aimed to measure the toxicity of the culture filtrate of entomopathogenic fungi originating from South Sumatra against the Spodoptera litura larvae. Beauveria bassiana (25 isolates) and Metarhizium anisopliae (20 isolates) of South Sumatra were cultured in liquid media and filtered to produce culture filtrate. The larvae which were sick due to the filtrate showed the symptoms of decreased appetite and were not actively moving, while the dead larvae were characterized by being wrinkled, dry, black integument, and odorless. Mortality caused by B. bassiana filtrate was the highest 98% (BJgTs isolate) and not significantly different from the BSwTd2 isolate (94.67%). Yet, the LT50 BSwTd2 isolate was shorter (5.92 days) compared to the LT50 BJgTs isolate (6.35 days). The most toxic M. anisopliae filtrate produced the mortality of 96% (MKbTp2 isolate) and 85.33% (MPdB isolate) each of which had LT50 of 7.36 days and 8.09 days, respectively. So, the most toxic culture filtrate was BSwTd2 isolate of B. bassiana and MKbTp2 isolate of M. anisopliae. The entomopathogenic fungi producing filtrate which are toxic have the potential to be active ingredients of mycoinsecticides.
Despite its large acreage, riparian wetland has been underutilized in Indonesia. Intensity of agricultural activities on this wetland was very low mainly due to two unfavorable extremes, i.e. unpredictable occurrence of flooding during rainy season and drought during dry season. Relevant, affordable, and acceptable technologies are required as solution to this problems. The technologies should be developed based on actual needs, preferences, and absorptive capacity of smallholder farmers, to ensure adoption. Objective of this study was to explore needs, preferences, and absorptive capacity of smallholder farmers through direct observation on their farming practices and dialogs on constraints in intensifying food production at riparian wetlands in Indonesia. The study was conducted at five villages in riparian wetland ecosystem in South Sumatera, Indonesia, from January to June 2016. This qualitative research was conducted in two stages: started with no-preconception Grounded Theory procedure; then, followed by questionnaire-guided survey. Results of this study indicated that intensive observation on farmer's practices and dialogs on constraints in intensifying food production could reveal needs, preferences, and absorptive capacity of smallholder farmers. Observed farmers' practices include land preparation and soil quality improvement, seedling preparation, transplanting, cropping management, and harvesting. Dialogs disclosed that unmanageable constraint but urgently needed by smallholder farmers in intensifying food production was technology solution for uncertain and uncontrollable natural flooding and drought occurrence at riparian wetlands. Government intervention is expected for constructing infrastructure for water management at riparian wetlands, i.e. polder system.
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