U. Rahardja et Me. Whalon, INHERITANCE OF RESISTANCE TO BACILLUS-THURINGIENSIS SUBSP TENEBRIONISCRYIIIA DELTA-ENDOTOXIN IN COLORADO POTATO BEETLE (COLEOPTERA, CHRYSOMELIDAE), Journal of economic entomology, 88(1), 1995, pp. 21-26
We investigated the genetic inheritance of Colorado potato beetle, Lep
tinotarsa decemlineata (Say), resistance to Bacillus thuringiensis Cry
IIIA delta-endotoxin. Standard reciprocal crosses and backcrosses betw
een susceptible (S) and resistant (R) strains were used to determine t
he characteristics of resistance. Analysis of probit lines from the F-
1 reciprocal crosses indicated that B. thuringiensis delta-endotoxin r
esistance was inherited autosomaly without maternal effects. We estima
ted the degree of dominance to be 0.77 and 0.76 for the (R x S) and (S
x R) F-1 generations, respectively, indicating that B. thuringiensis
CryIIIA delta-endotoxin resistance is conferred by incompletely domina
nt genes. Chi-square analysis of mortality responses of backcrossed of
fspring suggested that resistance might be caused by more than one loc
us. The stability of resistance was also studied by testing seventeen
generations of resistant beetles after the selection pressure was remo
ved. When the selection pressure was removed, the resistance level of
the selected colony decreased after five generations. The resistance l
ever did not decrease further when the selection was removed for >12 g
enerations.