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Construction of a hypervirulent and specific mycoinsecticide for locust control.

Fang W, Lu HL, King GF, St Leger RJ - Sci Rep (2014)

Bottom Line: We found that expression of four insect specific neurotoxins improved the efficacy of M. acridum against acridids by reducing lethal dose, time to kill and food consumption.Coinoculating recombinant strains expressing AaIT1(a sodium channel blocker) and hybrid-toxin (a blocker of both potassium and calcium channels), produced synergistic effects, including an 11.5-fold reduction in LC50, 43% reduction in LT50 and a 78% reduction in food consumption.However, specificity was retained as the recombinant strains did not cause disease in non-acridids.

View Article: PubMed Central - PubMed

Affiliation: Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou. 310058, Zhejiang, China.

ABSTRACT
Locusts and grasshoppers (acridids) are among the worst pests of crops and grasslands worldwide. Metarhizium acridum, a fungal pathogen that specifically infects acridids, has been developed as a control agent but its utility is limited by slow kill time and greater expense than chemical insecticides. We found that expression of four insect specific neurotoxins improved the efficacy of M. acridum against acridids by reducing lethal dose, time to kill and food consumption. Coinoculating recombinant strains expressing AaIT1(a sodium channel blocker) and hybrid-toxin (a blocker of both potassium and calcium channels), produced synergistic effects, including an 11.5-fold reduction in LC50, 43% reduction in LT50 and a 78% reduction in food consumption. However, specificity was retained as the recombinant strains did not cause disease in non-acridids. Our results identify a repertoire of toxins with different modes of action that improve the utility of fungi as specific control agents of insects.

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Related in: MedlinePlus

LC50 values for the wild-type strain versus transformants at 6 and 7 days after inoculation.WT: wild-type strain; AaIT1 and Hybrid are transformants expressing AaIT1 and hybrid-toxin, respectively. AaIT1/Hybrid: a 1:1 combination of transformants AaIT1 and hybrid-toxin.
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f3: LC50 values for the wild-type strain versus transformants at 6 and 7 days after inoculation.WT: wild-type strain; AaIT1 and Hybrid are transformants expressing AaIT1 and hybrid-toxin, respectively. AaIT1/Hybrid: a 1:1 combination of transformants AaIT1 and hybrid-toxin.

Mentions: At 5 days post-inoculation, too few insects infected with the wild-type fungus had died to allow meaningful calculation of effective conidial doses. However, LC50 values for the transgenic strains were 12,468 conidia (expressing AaTI1), 3,982 conidia (hybrid-toxin) and 986 conidia (combining 324-AaIT1 and 324-HYBRID). At 6 days after inoculation, LC50 values were reduced 2.2-fold by AaIT1, 8.4-fold by hybrid-toxin, and 11.5-fold by combining AaIT1 and hybrid-toxin, compared to the wild-type LC50 of 4,649 conidia. Seven days after inoculation, LC50 values were reduced 1.4-fold by AaIT1, 7.5-fold by hybrid-toxin, and 10.4-fold by combining AaIT1 and hybrid-toxin, compared to the wild-type LC50 of 1,792 conidia. Thus, at all three time points, expressing hybrid-toxin reduced the LC50 to a significantly greater extent than AaIT1 (P < 0.001), and combining AaIT1and hybrid-toxin further reduced effective conidial dose by a highly significant extent (P < 0.001) (Fig. 3).


Construction of a hypervirulent and specific mycoinsecticide for locust control.

Fang W, Lu HL, King GF, St Leger RJ - Sci Rep (2014)

LC50 values for the wild-type strain versus transformants at 6 and 7 days after inoculation.WT: wild-type strain; AaIT1 and Hybrid are transformants expressing AaIT1 and hybrid-toxin, respectively. AaIT1/Hybrid: a 1:1 combination of transformants AaIT1 and hybrid-toxin.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4256560&req=5

f3: LC50 values for the wild-type strain versus transformants at 6 and 7 days after inoculation.WT: wild-type strain; AaIT1 and Hybrid are transformants expressing AaIT1 and hybrid-toxin, respectively. AaIT1/Hybrid: a 1:1 combination of transformants AaIT1 and hybrid-toxin.
Mentions: At 5 days post-inoculation, too few insects infected with the wild-type fungus had died to allow meaningful calculation of effective conidial doses. However, LC50 values for the transgenic strains were 12,468 conidia (expressing AaTI1), 3,982 conidia (hybrid-toxin) and 986 conidia (combining 324-AaIT1 and 324-HYBRID). At 6 days after inoculation, LC50 values were reduced 2.2-fold by AaIT1, 8.4-fold by hybrid-toxin, and 11.5-fold by combining AaIT1 and hybrid-toxin, compared to the wild-type LC50 of 4,649 conidia. Seven days after inoculation, LC50 values were reduced 1.4-fold by AaIT1, 7.5-fold by hybrid-toxin, and 10.4-fold by combining AaIT1 and hybrid-toxin, compared to the wild-type LC50 of 1,792 conidia. Thus, at all three time points, expressing hybrid-toxin reduced the LC50 to a significantly greater extent than AaIT1 (P < 0.001), and combining AaIT1and hybrid-toxin further reduced effective conidial dose by a highly significant extent (P < 0.001) (Fig. 3).

Bottom Line: We found that expression of four insect specific neurotoxins improved the efficacy of M. acridum against acridids by reducing lethal dose, time to kill and food consumption.Coinoculating recombinant strains expressing AaIT1(a sodium channel blocker) and hybrid-toxin (a blocker of both potassium and calcium channels), produced synergistic effects, including an 11.5-fold reduction in LC50, 43% reduction in LT50 and a 78% reduction in food consumption.However, specificity was retained as the recombinant strains did not cause disease in non-acridids.

View Article: PubMed Central - PubMed

Affiliation: Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou. 310058, Zhejiang, China.

ABSTRACT
Locusts and grasshoppers (acridids) are among the worst pests of crops and grasslands worldwide. Metarhizium acridum, a fungal pathogen that specifically infects acridids, has been developed as a control agent but its utility is limited by slow kill time and greater expense than chemical insecticides. We found that expression of four insect specific neurotoxins improved the efficacy of M. acridum against acridids by reducing lethal dose, time to kill and food consumption. Coinoculating recombinant strains expressing AaIT1(a sodium channel blocker) and hybrid-toxin (a blocker of both potassium and calcium channels), produced synergistic effects, including an 11.5-fold reduction in LC50, 43% reduction in LT50 and a 78% reduction in food consumption. However, specificity was retained as the recombinant strains did not cause disease in non-acridids. Our results identify a repertoire of toxins with different modes of action that improve the utility of fungi as specific control agents of insects.

Show MeSH
Related in: MedlinePlus