Spotted stem borer, Chilo partellus (Swinhoe) is a serious pest of maize, Zea mays L. The mechanisms (antibiosis, antixenosis and tolerance) and bases of resistance to this pest have been investigated in India. Many materials were evaluated for antibiosis and about 20 were reported to manifest this mechanism of resistance. Among these, seven maize materials, namely, Antigua Gr. 1, A1 x Antigun Gr. 1, Antigun Compuesto, Ganga 5, J 22, J 605 and Mex. 17 manifested a higher level of antibiosis. The use of plant materials this germplasm, as food for rearing C. partellus, adversely affected some vital parameters of the insect's biology. It reduced larval survival, larval and pupal weight, fecundity and egg viability, prolonged the larval and pupal period, and ultimately reduced the progeny of the pest. A cumulative effect of antibiosis was also observed. Among different plant parts, minimum antibiosis was recorded in ears and maximum in the tassel. Antibiosis was observed to develop and become operative when the plants were 10-15 days old and it increased with plant age. Antixenosis for oviposition occurred in Antigua Gr. 1, A1 x Antigua Gr. 1, Ageti 76, Caribbean Flint Composite and Cuba 11l. The 4-week old plants were less preferred than 2-week old plants. Antigua Gr. 1 and A1 x Antigua Gr. 1 exhibited both antibiosis and antixenosis. Among nine maize varieties tested for tolerance, Vijay ZFS3 appeared to possess this mechanism. Some chemical constituents of maize plants were evaluated in relation to the level of resistance. The germplasm having higher resistance, compared to those possessing lower resistance, had higher contents of silica and iron but lower nitrogen, phosphorous, potash and sugar. Furthermore, the studies showed that the resistance may be due to some toxins. The implications of the results obtained on mechanisms and bases of resistance are discussed.

English

9711|AGRIS 9702

Jose Juan Caballero

CIMMYT Publications Collection