Demand-Driven Technologies for Sustainable Maize ... - IITA

264Table 5. Larval feeding responses of S.calamistis to eight maize genotypes.MaizegenotypesS5 9-1S5 11-1S5 27-1S5 27-3Tzmi 103Tzi 4001S5 20-2Tzmi 407Leaf area (sq.cm) eaten by 10fi rst instar larvae(Mean ± s.e.)*2.18 ± 0.35 ab1.86 ± 0.19 ab2.52 ± 0.38 a2.07 ± 0.40 ab1.47 ± 0.27b2.34 ± 0.29 ab1.97 ± 0.29ab1.87 ± 0.29abVolume (cu.cm) ofstem eaten by a singlethird instar larva(Mean ± s.e.)3.49 ± 0.62 ab4.72 ± 1.05ab3.40 ± 0.96 ab4.92 ± 1.63a3.70 ± 0.75ab3.03 ± 0.83 ab2.16 ± 0.43 b4.70 ± 0.60 abMean weight of stemtissues consumed bya single third instarlarva (Mean ± s.e.)0.64 ± 0.16 cd0.83 ± 0.08 bcd0.47 ± 0.10 d0.89 ± 0.19 bcd0.79 ± 0.17 bcd1.25 ± 0.13 ab1.00 ± 0.07 bc1.68 ± 0.32 a* Means within a column followed by the same letter are not significantly different (P>0.05, LSD)recovered from the plants, and majority of those recovered were in thepupal stage (Table 4). The mean percentage of tunnelling estimatedwas also low for all genotypes.Larval feeding on leaf and stem segmentsThe leaf area consumed by the fi rst instar larvae was signifi cantlyhigher on the resistant S5 27-1 than on the moderately resistant Tzmi103 (Table 5). No signifi cant differences were observed in leaf areaconsumed between the other genotypes. The volume of stem consumedby the third instar larvae was signifi cantly higher on the resistant S5 27-3 than on the susceptible S5 20-2 (Table 5). No signifi cant differenceswere recorded between the other genotypes. The mean weight of thestem tissues consumed by third instar larvae was signifi cantly higheron the susceptible Tzmi 407 than on all the resistant and moderatelyresistant genotypes, and the susceptible S5 20-2 (Table 5). However,the relative weight of food consumed by these larvae was higher on theresistant S5 11-1 than on the other genotypes (Table 6). In addition, asignifi cant difference in terms of the weight of feces collected from thethird instar larvae fed on the different genotypes was found betweenthe resistant S5 11-1 and the resistant S5 27-1(Table 6).Food utilizationThe stem consumption indices of the third instar larvae were loweron the resistant genotypes than on the susceptible ones, althoughtheir growth rates were not different (Table 7). A higher approximatedigestibility (AD), indicating the percentage of ingested food that wasdigested, was obtained on susceptible than resistant genotypes (Table7). On the contrary, values obtained for the effi ciency of conversion ofdigested food to body substance (ECD) and the effi ciency of conversionof ingested food to body substance (ECI) were lower on the susceptiblethan the resistant genotypes (Table 7).