Manduca sexta (Lepidoptera: Sphingidae) cadherin fragments function as synergists for Cry1A and Cry1C Bacillus thuringiensis toxins against noctuid moths Helicoverpa zea, Agrotis ipsilon and Spodoptera exigua.
BACKGROUND
Specific Bacillus thuringiensis Berliner (Bt) toxins are effective against a narrow spectrum of species. While specificity is an advantage for limiting adverse effects on non-target organisms, it is also the primary drawback of Bt's application for controlling multiple pest species in agriculture, forestry and other areas. Recently, it was reported that a small toxin-binding fragment of Manduca sexta (Joh.) cadherin acts as a synergist of Bt toxins to M. sexta, Heliothis virescens F. and Helicoverpa zea (Boddie). These insects are quite susceptible to the Cry1A toxins. The first aim of the present study was to determine if longer-sized fragments of M. sexta cadherin differed in the level of toxin enhancement. The second aim was to examine enhancement of Bt toxins against relatively Bt-tolerant insects Agrotis ipsilon (Hufn.) and Spodoptera exigua (Hübner).


RESULTS
Cadherin fragments longer than previously reported had improved synergistic properties. Significant enhancement of Bt Cry1A toxins against A. ipsilon and S. exigua was found. A cadherin fragment also increased Cry1C toxicity to S. exigua.


CONCLUSIONS
The commercial development of this synergist has the potential to widen the spectrum of Bt toxicity to other important agricultural lepidopteran insect pests and thus increase its usefulness in agriculture.
Abdullah
Mohd Amir F
MA
InsectiGen, Inc., 425 River Road, Athens, GA 30602-2771, USA.
Moussa
Saad
S
Taylor
Milton D
MD
Adang
Michael J
MJ
D000595:Amino Acid Sequence; D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000494:pharmacology*; D015820:Cadherins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D004357:Drug Synergism; D004731:Endotoxins / Q000494:pharmacology*; D015870:Gene Expression; D006460:Hemolysin Proteins / Q000494:pharmacology*; D019476:Insect Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D018402:Manduca / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D009036:Moths / Q000187:drug effects*; D010574:Pesticide Synergists / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*
D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D015820:Cadherins; D004731:Endotoxins; D006460:Hemolysin Proteins; D019476:Insect Proteins; D010574:Pesticide Synergists; C030956:insecticidal crystal protein, Bacillus Thuringiensis