184 A. Patel et al.
Wang et al. ( 2008 ) studied the cry-type gene
of wild Bt strain UV17, identified and a novel
cry1Ba gene was cloned. The cry3Aa7 gene,
which was highly toxic to coleopteran pests, was
introduced into UV17, and a recombinant strain
designated as UV173A was obtained. Bioassay
results showed that UV173A was not only high-
ly toxic against Plutella xylostella (50 % lethal
concentration [LC 50 ] = 18.03 μg ml−1), but also
against coleopteran Leptinotarsa decernlineata
(LC 50 = 0.19 μg ml–1). The recombinant strain
was then tested in field trials to monitor its spatial
variation of population and to investigate the im-
pact on non-target invertebrates. A recombinant
Bt strain, UV173A with broad insecticidal spec-
trum was obtained, and it did not cause adverse
effects on the population of non-target organisms
(Table 5 , Fig. 3 ).Table 4 Bioassays of wildtype strain and integrative recombinants. (Yue et al. 2005a)
Test pests Strains Regression equation of toxicity Correlation coefficient LC 50 value (μL/mL)
P.xylostella YBT1520 Y = − 1.348 + 2.073X 0.94 1.066
BMB1520–B Y = 3.382 + 0.538X 0.99 1.203
BMB1520–E Y = − 1.165 + 2.312X 0.98 1.186
BMB1520–F Y = 2.797 + 1.122X 0.97 1.019
S.exigua YBT1520 Y = 2.684 + 0.681X 0.97 1.597
BMB1520–B Y = 2.793 + 0.925X 0.98 1.308
BMB1520–E Y = − 1.331 + 2.074X 0.93 1.048
BMB1520–F Y = 1.668 + 1.125X 0.98 0.856
Fig. 3 Re-isolation of the released strain UV173A inside
and outside the release plot. Included in graphs are con-
centrations of total bacteria within the plot (log CFU g−1
soil dry weight), the released strain UV173A within the
plot (log CFU g−1 soil dry weight), as well as at 20 m from
the plot. All samples were analyzed in duplicate (Wang
et al. 2008 )
Strains Insecticidal activity (LC 50 ; 95 % confidence interval)
Plutella xylostella
(μg ml−1)Leptinotarsa decernlineata
(mg ml−1)
UV17 18.21 (16.0–20.0) > 500.0
UV173A 18.03 (13.0–22.0) 0.19 (0.09–0.33)
Bt22 NA 0.44 (0.25–0.80)
NA no activity (Wang et al. 2008)Table 5 Insecticidal activ-
ity assay of lyophilized
spore crystal mixtures of
the strains
Strains Insecticidal activity (LC 50 ; 95 % confidence interval)
P. xylostella
(μg ml−1)H. amigera
(μg ml−1)S. exigua
(μg ml−1)P. aenescens
(mg ml−1)
G03 0.71(0.49–1.07)a 1.48(1.2–1.77)a 2.98(1.85–3.98)a NA
G033A 0.86(0.56–1.26)a 1.76(1.29–2.22)a 4.26(2.74–6.51)a 0.35(0.24–0.57)b
Bt22 NA NA NA 0.22(0.12–0.36)b
NA no activity
a Only for the 130 kDa components contained in the dry powder of tested stain (Wang
et al. 2006 )
b Only for the 67 kDa components contained in the dry powder of tested stainTable 3 Insecticidal assay
results of lyophilized
spore-crystal mixtures of
the strains