Diversity of <i>Bacillus thuringiensis</i> strains isolated from coffee plantations infested with the coffee berry borer <i>Hypothenemus hampei</i>

Abstract

Abstract:The coffee berry borer Hypothenemus hampei Ferrari (Coleoptera: Scolytidae) was first reported infecting Costa Rican coffee plantations in the year 2000. Due to the impact that this plague has in the economy of the country, we were interested in seeking new alternatives for the biological control of H. hampei, based on the entomopathogenic bacteria Bacillus thuringiensis. A total of 202 B. thuringiensis isolates obtained from Costa Rican coffee plantations infested with H. hampei were analyzed through crystal morphology of the crystal inclusions and SDS-PAGE of δ-endotoxins, while 105 strains were further evaluated by PCR for the presence cry, cyt and vip genes. Most of the Bt strains showed diverse crystal morphologies: pleomorphic (35%), oval (37%), bipyramidal (3%), bipyramidal and oval (12%), bipyramidal, oval and pleomorphic (10%) and bipyramidal, oval and cubic (3%). The SDS-PAGE analyses of the crystal preparations showed five strains with δ-endotoxin from 20 to 40 kDa, six from 40 to 50 kDa, seven from 50 to 60 kDa, 19 from 60 to 70 kDa, 29 from 70 to 100 kDa and 39 from 100-145 kDa. PCR analyses demonstrated that the collection showed diverse cry genes profiles having several genes per strain: 78 strains contained the vip3 gene, 82 the cry2 gene, 45 the cry1 and 29 strains harbored cry3-cry7 genes. A total of 13 strains did not amplified with any of the cry primers used: cry1, cry2, cry3-7, cry5, cry11, cry12 and cry14. Forty-three different genetic profiles were found, mainly due to the combination of cry1A genes with other cry and vip genes. The genetic characterization of the collection provides opportunities for the selection of strains to be tested in bioassays against H. hampei and other insect pests of agricultural importance. Rev. Biol. Trop. 52(3): 757-764. Epub 2004 Dic 15.

Bacillus thuringiensis in caterpillars and associated materials collected from protected tropical forests in northwestern Costa Rica

“…These results are in accordance with reports where foliar surfaces and insectfavoring habitats have been indicated as frequent sources of Bt isolation (Ben-Dov et al 1997, Bravo et al 1998, Arrieta et al 2004. However, this is the first report of Bt isolation from fecal pellets of caterpillars collected in tropical protected environments.…”

Characterization of a Bacillus thuringiensis strain collection isolated from diverse Costa Rican natural ecosystems

“…In contrast, the vip1 gene was not detected in this collection and only one strain presented the vip2 gene. Different results were obtained in a Costa Rican collection isolated from coffee plantations where the frequency of the vip2 gene was higher (Arrieta et al 2004).…”

“…Estruch et al (1996) found this gene in only 15% of the strains of their collection. Arrieta et al (2004) also reported a widespread distribution of this gene in strains isolated from Costa Rican agricultural ecosystems. In contrast, the vip1 gene was not detected in this collection and only one strain presented the vip2 gene.…”

Screening and identification of a Bacillus thuringiensis strain S1/4 with large and efficient insecticidal activities

“…Such result was certainly specific for our strains collection. For example, Arrieta et al found the vip3 gene in 74% and the vip2 or vip1 in <12% of a set of B. thuringiensis strains isolated from Costa Rican coffee agro‐ecosystems. The observed frequency of the vip3 genes was 48.9% and the vip1 and vip2 genes was around 10% of the strains isolated mainly from Spain and Bolivia .…”