A rapid knockdown effect of Penicillium citrinum for control of the mosquito Culex quinquefasciatus in Thailand.

Twenty local isolates of entomopathogenic fungi were determined for control of the larvae and adults of Culex quinquefasciatus. In a laboratory experiment, a Penicillium sp. CM-010 caused 100% mortality of third-instar larvae within 2 h using a conidial suspension of 1 × 106 conidia ml⁻¹. Its LC50 was 3 × 105 conidia ml⁻¹, and the lethal time (LT50) was 1.06 h. Cloning and sequencing of its internal transcribed spacer region indicated that this Penicillium species is Penicillium citrinum (100% identity in 434 bp). Mortality of the adult was highest with Aspergillus flavus CM-011 followed with Metarhizium anisopliae CKM-048 from 1 × 109 conidia ml⁻¹. P. citrinum CM-010 at 1 × 106 conidia ml⁻¹ killed 100% larvae within 2 h while Bacillus thuringiensis var. israelensis at 5 ITU ml⁻¹ required 24 h. This P. citrinum CM-010 also greatly reduced survival of C. quinquefasciatus larvae in an unreplicated field test. Light and transmission electron micrographs showed that the fungal conidia were ingested by the larvae and deposited in the gut. The metabolite patulin was produced by P. citrinum CM-010 instead of citrinin.

Greenhouse evaluation of Bacillus subtilis AP-01 and Trichoderma harzianum AP-001 in controlling tobacco diseases / Avaliação em estufa de dois agentes biológicos de controle de doenças do tabaco

Two biological control agents, Bacillus subtilis AP-01 (LarminarTM) and Trichoderma harzianum AP-001 (TrisanTM) alone or/in combination were investigated in controlling three tobacco diseases, including bacterial wilt (Ralstonia solanacearum), damping-off (Pythium aphanidermatum), and frogeye leaf spot (Cercospora nicotiana). Tests were performed in greenhouse by soil sterilization prior to inoculation of the pathogens. Bacterial-wilt and damping off pathogens were drenched first and followed with the biological control agents and for comparison purposes, two chemical fungicides. But for frogeye leaf spot, which is an airborne fungus, a spraying procedure for every treatment including a chemical fungicide was applied instead of drenching. Results showed that neither B. subtilis AP-01 nor T. harzianum AP-001 alone could control the bacterial wilt, but when combined, their controlling capabilities were as effective as a chemical treatment. These results were also similar for damping-off disease when used in combination. In addition, the combined B. subtilis AP-01 and T. harzianum AP-001 resulted in a good frogeye leaf spot control, which was not significantly different from the chemical treatment.

Dois agentes de controle biológico, Bacillus subtilis AP-01 (Larminar®) e Trichoderma harzianum AP-001 (Trisan®) foram avaliados separadamente ou em combinação quanto à capacidade de controlar três doenças do tabaco: murcha bacteriana (bacterial wilt, Ralstonia solanacearum), tombamento de mudas (damping-off, Pythium aphanidermatum), e mancha olho-de-rã (frogeye leaf spot, Cercospora nicotiana). Os testes foram realizados em estufa, esterilizando-se o solo antes da inoculação dos patógenos. Os patógenos causadores da murcha bacteriana e tombamento de mudas foram inicialmente encharcados e acompanhados com os agentes de controle biológico e, para comparação, com um fungicida químico. Para a mancha olho-de-rã, causada por um fungo anemófilo, utilizou-se um processo de spray ao invés do encharcamento. Os resultados indicaram que nenhum dos dois agentes de controle biológico, aplicado isoladamente, foi capaz de controlar a murcha bacteriana, mas quando em combinação a capacidade de controle foi similar ao do tratamento químico. Resultados semelhantes foram obtidos para o tombamento de mudas. Além disso, a combinação de Bacillus subtilis AP-01 e Trichoderma harzianum AP-001 resultou em um controle muito eficiente da mancha olho-de-rã, que não diferiu significativamente daquele obtido com o tratamento químico.

Evaluation of Metarhizium anisopliae (Deuteromycota: Hyphomycetes) for control of broad mite Polyphagotarsonemus latus (Acari: Tarsonemidae) in mulberry.

A study on 12 entomopathogenic fungi for controlling broad mite (Polyphagotarsonemus latus (Banks)) in mulberry found that Metarhizium anisopliae CKM-048 was the most virulent strain in controlling both larvae and adult broad mites at the concentration of 2 x 10(8) conidia/ml. There was no ovicidal effect when tested with broad mite eggs. Median lethal concentrations (LC(50)) of M. anisopliae in killing larvae and adults were 8.7 x 10(6) and 1.3 x 10(7 )conidia/ml, respectively. Median lethal times (LT(50)) of larvae and adults were 2.4 and 3.8 days, respectively, at the concentration of 2 x 10(8) conidia/ml. The fungus was found to produce protease and chitinase. Scanning electron microscope (SEM) studies were done to monitor the infection steps of the fungus on broad mites. A greenhouse test on mulberry trees revealed that M. anisopliae could reduce the broad mite population within 4 days after treatment. However, after 7 days, its efficacy was decreased significantly.

Greenhouse evaluation of Bacillus subtilis AP-01 and Trichoderma harzianum AP-001 in controlling tobacco diseases.

Two biological control agents, Bacillus subtilis AP-01 (Larminar(™)) and Trichoderma harzianum AP-001 (Trisan(™)) alone or/in combination were investigated in controlling three tobacco diseases, including bacterial wilt (Ralstonia solanacearum), damping-off (Pythium aphanidermatum), and frogeye leaf spot (Cercospora nicotiana). Tests were performed in greenhouse by soil sterilization prior to inoculation of the pathogens. Bacterial-wilt and damping off pathogens were drenched first and followed with the biological control agents and for comparison purposes, two chemical fungicides. But for frogeye leaf spot, which is an airborne fungus, a spraying procedure for every treatment including a chemical fungicide was applied instead of drenching. Results showed that neither B. subtilis AP-01 nor T harzianum AP-001 alone could control the bacterial wilt, but when combined, their controlling capabilities were as effective as a chemical treatment. These results were also similar for damping-off disease when used in combination. In addition, the combined B. subtilis AP-01 and T. harzianum AP-001 resulted in a good frogeye leaf spot control, which was not significantly different from the chemical treatment.