Contents - Faperta

Mechanisms and Inheritance of Resistance to Insect Pests 139
Oilseeds
Resistance in soybean to defoliating insects is polygenic. Heritability estimates for resistance
to the cabbage looper, T. ni (Luedders and Dickerson, 1977) and E. varivestis (Sisson
et al., 1976) suggest quantitative inheritance. The F2 plants from a cross between the parents
resistant and susceptible to the soybean looper, P. includens also exhibit partial dominance
or a quantitative inheritance (Kilen, Hatchett, and Hartwig, 1977). Johnson and
Beard (1977) observed that a phytomelanin (achene) layer conferring resistance to sunfl
ower moth, Homoeosoma electellum (Hulst.), in different Helianthus species is inherited as a
dominant trait.
Alfalfa
A single dominant gene in alfalfa, Medicago sativa L., and sweet clover, Melilotus infesta
Guss., controls resistance to the pea aphid, A. pisum (D.V. Glover and Stanford, 1966), and
the sweet clover aphid, Therioaphis riehmi (Bomer) (Manglitz and Gorz, 1968). Resistance to
spotted alfalfa aphid, Therioaphis maculata (Buckton), is controlled by several genes (E. Glover
and Melton, 1966), indicating that resistance is quantitative. Combining ability effects in
alfalfa for resistance to E. fabae are signifi cant and additive in nature (Soper, Mcintosh, and
Elden, 1984; Elden, Elgin, and Soper, 1986).
Potato
Resistance to the green peach potato aphid, Myzus persicae (Sulzer) in cultivated and wild
Solanum species is expressed as a partially dominant trait (Sams, Lauer, and Radcliffe,
1976). One dominant gene controls glandular trichome-mediated resistance to M. persicae
in Solanum tarijense Hawkes and S. berthaultii Hawkes, but in S. phureja ( Juz et Buk.) S.
berthaultii crosses, two genes control the expression of resistance (R.W. Gibson, 1979).
Resistance to M. persicae is mediated by a complex interaction between trichome density
and droplet size of exudates, and is a quantitatively inherited trait (Mehlenbacher,
Plaisted, and Tingey, 1983, 1984). Resistance to potato tuber moth, P. operculella, has been
derived from Solanum sparsipilum (Bitter) Juz. & Buk., and is controlled by a few major
genes (Ortiz et al., 1990).
Grain Legumes
Resistance in Lima bean, Phaseolus lunatus L., to the leafhopper, Empoasca kraemeri Ross &
Moore, is due to the quantitative effect of several genes, and is inherited as a recessive trait
(Lyman and Cardona, 1982). Both additive and dominant gene effects are responsible for
E. kraemeri resistance in cultivars of the common bean, Phaseolus vulgaris L. (Kornegay and
Temple, 1986). Inheritance of hooked trichomes is complex, and is controlled by additive,
dominant, and epistatic gene effects (Park et al., 1994). There is also evidence for transgressive
segregation (levels of resistance greater than that of the resistant parent) in some
progenies from crosses between resistant and susceptible bean cultivars. Resistance in
wild strains of P. vulgaris to Zabrotes subfasciatus (Boheman) is controlled by the toxic seed
protein, arcelin. The presence of arcelin is inherited as a dominant trait (Romero Andreas,
Yandell, and Bliss, 1986; Kornegay, Cardona, and Posso, 1993). Resistance to bean weevil,
Acanthoscelides obtectus (Say), is derived from a wild Phaseolus accession, and is inherited as
a complementary effect of two recessive genes (Kornegay and Cardona, 1991). Resistance