Mj. Berlinger et al., RESISTANCE MECHANISMS OF LYCOPERSICON PENNELLII ACCESSIONS TO SPODOPTERA-LITTORALIS (BOISDUVAL) (LEPIDOPTERA, NOCTUIDAE), Journal of economic entomology, 90(6), 1997, pp. 1690-1696
Resistance mechanisms of 5 Lycopersicon pennellii (Corr.) D'Arcy acces
sions to Spodoptera littoralis (Boisduval) were compared with that of
2 commercial cultivars of L. esculentum with the ultimate intent af us
ing L. pennellii as a source of resistance to be incorporated into L.
esculentum. First instars were trapped by the sticky exudate which cov
ered the leaf surface of L. pennellii, but 2nd-5th instars overcame th
is physical barrier. Second and 3rd instars were influenced by an extr
actable substance present within, but not on, L. pennellii leaves. whi
ch had effects similar to juvenile hormone. The L. pennellii accession
Sisicaya 751 had the highest apparent level of this juvenile hormone-
like activity among those tested. Leaf feeding or incorporation of mat
erial from hexane or acetone extracts of L. pennellii leaves into arti
ficial diet or application of extracts directly to larvae caused high
larval mortality, adult morphological deformation. male sterility and
inhibited oviposition. Large larvae (4th and 5th instars) were not aff
ected by this juvenile hormone-like substance. Collectively, the data
suggest that certain accessions of L. pennellii could serve as sources
of resistance to S. littoralis which could be incorporated into an L.
esculentum background.