M. Taylor et al., GENOME SIZE AND ENDOPOLYPLOIDY IN PYRETHROID-RESISTANT AND SUSCEPTIBLE STRAINS OF HELIOTHIS-VIRESCENS (LEPIDOPTERA, NOCTUIDAE), Journal of economic entomology, 86(4), 1993, pp. 1030-1034
Heliothis virescens (F.) males have a haploid genome size of 403.6 (2.
3 +/- SD) million nucleotide pairs (Mnp), which is very close to that
reported for tissues of other Lepidoptera (456-485 Mnp). Octaploid cel
l types were present in various abundances in all tissues examined, an
d thus may derive from a common tissue such as epithelial tissue. Extr
emely (i.e., 10(4)- to 10(5)-fold) polyploid nurse or silk gland cells
are known in other Lepidopters. However, attempts to analyze salivary
glands of H. virescens, which might also be highly polyploid, were no
t successful. Cells of higher ploidy were not found in any of the tiss
ues examined. Incomplete duplication of higher ploidy cells was found
in both fat body and Malpighian tubules. The cells of the Malpighian t
ubules were found to be inflated in DNA content relative to other tiss
ues, for reasons unknown. Nuclei were analyzed from larvae of both a p
yrethroid-resistant and a susceptible strain of H. virescens. Differen
ces in DNA contents between strains were sex specific and were not con
sistent with the hypothesis that large-scale DNA amplification contrib
utes to pyrethroid resistance in the RR strain.