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Tephritid fruit flies are major pests that limit fruit production around the world; they cause important damages, increasing directly and indirectly annual costs, and their management is predominately based on the use of chemical insecticides. This research investigated the insecticidal activity of the crude extract obtained of Metarhizium brunneum Petch EAMb 09/01-Su strain and its capacity to secrete secondary metabolites including destruxins (dtx). Dtx A and A2 had insecticidal activity against Ceratitis capitata (Wiedemann) when administered per os. The crude extract of seven Metarhizium and one Beauveria isolates were evaluated per os against medfly adults. The crude extracts of the isolate EAMb 09/01-Su resulted in mortality ranging between 95 and 100% at 48 h. The high-pressure liquid chromatography profile showed two active peaks (F5B and F6 subfractions) related with dtx A2 and dtx A, which caused 70 and 100% mortality on C. capitata at 48 h postfeeding, respectively. The LC50 was 104.92 ppm of dtx A, contained in the F6 subfraction, and the LT50 was 4.16 h at a concentration of 400 ppm of dtx A contained in the F6 subfraction. Moreover, the average survival time of adults exposed to this subfraction was 12.6 h with only 1 h of exposure. The insecticide metabolites of the F6 subfraction of the EAMb 09/01-Su isolate retained >90% of its insecticidal activity after exposure to 60°C for 2 h and 120°C for 20 min. These results highlight the potential of this strain as a source of new insecticidal compounds of natural origin for fruit fly control.

The susceptibility of preimaginal and adult olive fruit fly, Bactrocera oleae (Gmelin) (Diptera: Tephritidae), to a strain of the mitosporic ascomycete Metarhizium brunneum (Petch) (Hypocreales: Clavicipitaceae) and the insecticidal activity of its crude extract to olive fruit fly adults were investigated. Strain EAMb 09/01-Su caused 60% mortality to B. oleae adults, with average survival time (AST) of 8.8 d. In soil treatments against pupariating third-instar larvae, preimaginal B. oleae mortality reached 82.3%, whereas preimaginal mortality targeting puparia was 33.3%. The crude extract of EAMb 09/01-Su strain caused 80.0% adult mortality when administered per os, with AST of 27.7 h. The crude extract was demonstrated to be quite thermostable and photoresistant. These results indicate that M. brunneum EAMb 09/01-Su strain and its crude extract show potential to be used in an integrated pest management olive fruit fly management strategy targeting both adults and preimaginals.

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The physicochemical and microbiological dynamics during the fermentation phase of the CCN51 cocoa material was evaluated in three maturity stages (stage 2: 130-152 days after anthesis (DAA), stage 3: 153-174 DAA, and stage 4: 175-196 DAA). Through the microfermentation technique, the physicochemical variables (pH, titratable acidity, total soluble solids, and fermentation index) were monitored every 24 hours. The microbiological dynamics were evaluated by counting the colony forming units (CFU) in a plaque, quantifying three types of microorganisms (Bacillus, acetic acid bacteria and yeasts). In the three maturity stages assessed, a decrease in the pH of the beans was observed as the fermentation progressed; between 72 and 96 hours after fermentation, the pH of stage 4 beans was different from stages 2 and 3. Simultaneously, an increase in the pH of the pulp was observed without differences between the stages. Brix degrees did not show statistical differences between stages, however, the values of total soluble solids showed that the microorganisms present in stage 3 were more effective in metabolizing these in comparison with those of stages 2 and 4. Regarding the fermentation index, stage 4 reached the maximum value (1.35 ± 0.16) at 120 hours, meanwhile stages 2 and 3 reached it at the end of the fermentation (1.35 ± 0.01 and 1.55 ± 0.29, respectively) at 168 hours. The microbiological dynamics in the three cocoa fruit maturity stages evidenced the absence of lactic acid bacteria and the presence of mesophilic aerobic bacilli. Yeasts were present throughout the fermentation in the three maturity stages, being more favored by stage 2, meanwhile, acetic acid bacteria were favored by stage 3. Outstanding microorganism species were characterized molecularly as Pichia kudriavzevii,Bacillus subtilisBacillus megaterium, and Bacillus tequilensis. Stage 3 showed the best characteristics to obtain good quality cocoa.

Microbial activity involved in the cocoa beans fermentation process is essential to maintain and improve the organoleptic and nutritional qualities of chocolate; therefore, the aim of this investigation was to search and select microbial isolates with the potential to improve the quality of cocoa beans. Fermentation experimentswere conducted on farms located in Maceo (Antioquia), San Vicente de Chucurí (Santander), and Rivera and Algeciras (Huila), Colombia. Yeast, lactic acid bacteria (LAB), acetic acid bacteria (AAB), and mesophilic aerobic microorganisms were obtained from different fermentation batches. The growth of these microorganismswas tested in six treatments as follows: 50% cocoa pulp agar (CPA), high concentrations of glucose (10%), ethanol (5%), and acetic acid (7%), an acidic pH of 3.0, and a high temperature of 50oC for 24 h. The isolates with the highest growth were identified by 18S and 16S rRNA gene analysis, revealing a high diversity ofspecies associated with cocoa fermentation, including eight species of yeasts (Debaryomyces hansenii, Meyerozyma guillermondii, Wickerhanomyces anomalus, Pichia guillermondii, Pichia kudriavzevii, Trichosporon asahii, Candida parapsilosis, and Pichia manshurica), six species of LAB (Pediococcus acidilactici, Lactobacillus brevis, Lactobacillus plantarum, Lactobacillus farraginis, Lactobacillus rhamnosus, and Leuconostoc mesenteroides), four species of AAB (Gluconobacter japonicus, Acetobacter tropicalis, Acetobacter pasteurianus, and Acetobacter malorum/tropicalis), and three species of Bacillus spp. (Bacillusaryabhattai /megaterium, Bacillus subtilis, and Bacillus coagulans). In general, microbial populations increased in cocoa batches after 12 h of fermentation and decreased after 84-96 h. All the yeast isolates grew in 10% glucose and CPA, 85.7% in 5% ethanol, and 95% at a pH of 3.0. All the yeast isolates were affectedby 7% acetic acid and incubation at 50oC for 24 h. Eighty-five percent of the LAB grew in 10% glucose, 100% in 5% ethanol, 42.8% in CPA, 64% at a pH of 3.0, and 35.7% grew after being exposed to 50oC for 24 h; all were affected by 7% acetic acid. As for the AAB, 100% grew in 10% glucose, 71% in 7% ethanol, 100% grew in CPA, in 7% acetic acid, and at a pH of 3.0, while 100% were affected by incubation at 50oC. Three yeast isolates, W. anomalus, D. hansenii and M. guillermondii, three LAB isolates, P. acidilactici, L. brevis, and L. plantarum, and three AAB isolates, A. tropicalis, A. pasteurianus and G. japonicus, were selected as promising strains to be used in a microbial starter culture for cocoa bean fermentation to improve the organoleptic quality of cocoa.

BACKGROUND: Cacao is important for the economy of many countries in the humid tropics. Its quality is affected when fruits are not collected at the optimal harvest point. The aim of this study was to obtain maturity indices for producers to facilitate the timely harvest and improve the development of fermentation and the sensorial quality of cacao. The growth and respiration processes, and the physicochemical changes during the maturation of three cacao genotypes were determined. Physiological follow-ups measuring fruit length and diameter were performed from 30 days after anthesis to fruit deterioration in the tree. RESULTS: Growth equations were obtained, establishing four maturity stages based on days after anthesis, and fruit length and diameter. Nineteen descriptors were used for the characterization, and through Pearson's correlation and principal component analysis (PCA), five descriptors were identified as representative of the maturity stages of the cacao fruit. PCA results and respiration measurements established that stage 3 presented the highest substrate availability for obtaining good fermentation and quality cacao. This stage showed values between 124 and 197 days after anthesis with lengths between 167.7 and 249.73 mm, and diameters between 64.4 and 95.8 mm, according to the locality. CONCLUSION: Three growth phases of the cacao fruits were established considering days after anthesis. Both the edaphoclimatic conditions and the cacao genotype characteristics influenced this determination. Stage 3 of fruit maturation shows the best physicochemical conditions for good fermentation.