Molecular identification of Trichogramma species from regions in Brazil using the sequencing of the ITS2 region of ribosomal DNA.

Nr Santos,Rp Almeida,Dam Araújo,Iqm Padilha,Aj Creão-Duarte

doi:10.1590/1519-6984.14813

Abstract

The objective of this work was the identification and differentiation of Trichogramma exiguum Pinto and Platner species, T. pretiosum Riley, and T. galloi Zucchi using sequences of the ITS2 region of ribosomal DNA. After extracting DNA from the studied species, a PCR reaction was performed, where the amplified samples were subjected to sequencing. The sequences obtained were submitted to a similarity search in GenBank (NCBI - National Center for Biotechnology Information) using the BLAST program, aiming to determine the similarity of these sequences with the species already deposited in the referenced database, and then multiple sequences were aligned using version 2.0 of the ClustalX program. According to the results of the multiple alignments of all sequences obtained, it was possible to observe the differences between the T. pretiosum, T. galloi and T. exiguum species. It was concluded that using the sequences of the ITS2 region of the ribosomal DNA was efficient in the differentiation of the studied Trichogramma species, which suggests a strong inter-specific variation among species.

Highlights

The use of Trichogramma species for biological control began with Flanders (1930), with work on mass multiplication of Trichogramma spp. in Sitotroga cerealella eggs Olivier, 1789 (Lepidoptera: Gelechiidae), a technique that rapidly dispersed in several countries (Navarro, 1998).In South America, the use of Trichogramma species is still limited, mainly due to the high commercial production cost of parasitoids and the intensive use of pesticides, though the estimated area using these parasitoids is 1.2 million hectares (Van Lenteren and Bueno, 2003).Braz
With the results of the search for similarities by BLAST tool in the GenBank database (NCBI – National Center for Biotechnology Information), it was found that they all correspond to the desired regions, consistent with the sequences of Trichogramma species, obtaining 95% similarity to T. pretiosum, a value of 91% for T. galloi and 92% for T. exiguum (Table 1)
Using the genetic distance matrix (Table 2), it can be seen that species T. galloi and T. exiguum were more genetically distant with 0.238 and T. exiguum and T. pretiosum were closer having a genetic distance of 0.189

Summary

Introduction

The use of Trichogramma species for biological control began with Flanders (1930), with work on mass multiplication of Trichogramma spp. in Sitotroga cerealella eggs Olivier, 1789 (Lepidoptera: Gelechiidae), a technique that rapidly dispersed in several countries (Navarro, 1998).In South America, the use of Trichogramma species is still limited, mainly due to the high commercial production cost of parasitoids and the intensive use of pesticides, though the estimated area using these parasitoids is 1.2 million hectares (Van Lenteren and Bueno, 2003).Braz. The use of Trichogramma species for biological control began with Flanders (1930), with work on mass multiplication of Trichogramma spp. in Sitotroga cerealella eggs Olivier, 1789 (Lepidoptera: Gelechiidae), a technique that rapidly dispersed in several countries (Navarro, 1998). In South America, the use of Trichogramma species is still limited, mainly due to the high commercial production cost of parasitoids and the intensive use of pesticides, though the estimated area using these parasitoids is 1.2 million hectares (Van Lenteren and Bueno, 2003). Due to the importance of its use, to succeed in a biological control program with the Trichogramma species, correct identification is essential, so one can check if they respond to the climatic conditions of the region and culture that they will be applied to (Borba et al, 2005)

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Conclusion