Aislamiento y caracterización de microorganismos entomopatógenos en dos sistemas de producción agrícola familiar representativos de la comunidad San Francisco.

Abstract

This research aimed to isolate and characterize entomopathogenic microorganisms from two family farming systems (organic and conventional) in San Francisco community. Six soil samples (2kg) were collected using the L-sampling technique at 20 cm depth close to the rhizosphere. The trapping method was used with larvae of Galleria mellonella L4, described by Zimmerman, 1986 to isolate entomopathogenic microorganisms, A bifactorial Completely Randomized Design with three replications was used for statistical analysis obtaining 15 bacteria, 17 fungi and a nematode with entomopathogenic characteristics. To determine the effective isolates, mortality tests were carried out with a concentration of 1.2 per 10 at seven spores/mL and bacteria/mL, identificating four effective fungal isolates that caused 100% mortality at 5 days, belonging to the genera Metarhizium (SFSCC2R2-A3; SFSOC2R3-A3) and Beauveria (SFSCC3R2-A1; SFSOC2R2-A1) from each system, which morphologically and molecularly characterized correspond to Beauveria bassiana and Metarhizium anisopliae species, while for bacteria there was no effective isolate; in the case of the nematode with concentrations of 2, 3 and 4 nematodes/larvae caused 70 percent mortality after 8 days and it was identified as Steinernema carpocapsae;. By Probit analysis the Lethal Dose 50 (LD50) for B. bassiana (SFSCC3R2-A1; SFSOC2R2-A1) showed 6.22 and 6.09 per ten at seven spores/mL and for M. anisopliae (SFSCC2R2-A3; SFSOC2R3-A3) 2.16 and 4.51 per ten at seven spores/mL, with a Time to Lethal 50 (TL50) of 5 days respectively; the LD50 of S. carpocapsae is 3 nematodes per larva, and TL50 of 8 days. It is concluded that the effective entomopathogenic fungi found in the agricultural systems of this community constitute an alternative of local biological control and it is recommended to perform bio scaling of the effective strains.