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Bt Research 2013, Vol.4 No.2 8-13
ISSN 1925-1939
http://bt.sophiapublisher.com
8
Research Report Open Access
Comparative Toxicity of
Bacillus thuringiensis
Berliner Strains to Larvae of
Simuliidae (Insecta: Diptera)
Eleny Pereira
1, 3
, Beatriz Teles
2
, Erica Martins
1
, Lilian Praça
1
,
Aldaleia Santos
1
,
Felipe Ramos
1
, Colin
Berry
4
, Rose Monnerat
1
1 EMBRAPA Recursos Genéticos e Biotecnologia, Caixa Postal 02372, CEP 70849-970 Brasília, DF
2 Instituto Nacional de Pesquisas da Amazônia, INPA, Coordenação de Pesquisas em Entomologia, Manaus, AM
3 Universidade de Brasília, Departamento de Biologia Animal, Caixa Postal 4508, CEP 70910-900 Brasília, DF
4 Cardiff University, Cardiff, Wales, UK
Corresponding authors email:
rose.monnerat@embrapa.br;
Authors
Bt Research, 2013, Vol.4, No.2 doi: 10.5376/bt.2013.04.0002
Received: 24 Apr., 2013
Accepted: 03 May, 2013
Published: 19 Jul., 2013
This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and
reproduction in any medium, provided the original work is properly cited.
Preferred citation for this article:
Monnerat et al., 2013, Comparative Toxicity of
Bacillus thuringiensis
Berliner Strains to Larvae of Simuliidae (Insecta: Diptera), Bt Research, Vol.4, No.2 8
-
13
(doi: 10.5376/bt.2013.04.0002)
Abstract
Blackflies (
Simulium
spp.) are widely distributed and can cause serious economic losses causing annoyance to humans
and other animals and damage to health, agriculture and the tourist industry. In addition, they are vectors of diseases eg.
onchocerciasis. One alternative to control this insect is the use of biopesticides based on
Bacillus thuringiensis
(
Bt
) serotype
israelensis but other dipteran-active serotypes have not been tested against these insects. This study assessed the toxicity of standard
Bt
strains belonging to serotypes
israelensis
,
medellin
and
jegathesan
, known to kill dipteran insects, along a collection of
Bt
strains
from Amazonia (a blackfly-endemic area) to find the most effective strains for
Simulium
control. Ninety-six strains were isolated
from soil collected in the Amazon and two of these showed high toxicity against larvae of
Simulium
spp. The biochemical and
molecular characterization of the two strains showed that both produce proteins with molecular weights of 130 kDa, 72 kDa and
30 kDa that are comparable with proteins Cry4A and Cry4B (130 kDa), Cry10 and Cry11 (72 kDa) and Cyt1 and Cyt2 (30 kDa) and
corresponding genes
cry4A
,
cry4B
,
cry10
,
cry11
,
cyt1
and
cyt2
, similar to
Bt
israelensis
, used as standard. These strains also showed
similar toxicity to
Bt israelensis
and higher toxicity than
Bt medellin
and
jegathesan
against blackflies.
Keywords
Biological control; Bioinsecticide; Blackflies;
Bacillus thuringiensis
Background
Blackflies,
Simulium
spp. (Diptera: Simuliidae) have a
broad geographical distribution and their immature
stages inhabit almost all types of lentic and lotic
aquatic environments (Adler, 1994). They have great
importance in medical-veterinary health, as they are
vectors of filariae such as
Mansonella ozzardi
(Manson) and
Onchocerca volvulus
Leuckart
(Marcondes, 2001). When in high density, some
species cause serious economic losses since blood
feeding females annoy humans and other animals
causing damage to health, agricultural productivity
and tourism (Araújo-Coutinho et al., 1988; Adler and
Mason, 1997) and producing serious economic
impacts, eg in Brazil (Mardini et al., 2000; Regis et al.,
2000). The control of blackfly larvae has been
accomplished by the use of synthetic pesticides or
biolarvicides (Mardini et al., 2000) but many
populations have developed resistance to the chemical
insecticides used (Mardini et al., 2000; Campos and
Andrade, 2002). However, the use of biolarvicides
based on
Bacillus thuringiensis israelensis
, is able to
reduce the population of blackflies in these regions
(Mardini et al., 2000).
B. thuringiensis
(
Bt
) has a wide distribution, and is
found in terrestrial and aquatic environments
worldwide (Martin and Travers, 1989). Serotype H-14
(
B. thuringiensis israelensis
) was isolated from
samples collected in breeding sites in Israel and
produces a protein crystal that is toxic to some species
of Diptera (de Barjac, 1978).
B. thuringiensis
serotype
H-14 has been used in control programs in West
Africa and South America with excellent results
(Regis et al., 2000).