Biology of Sitotroga cerealella (Oliv.) (Lepidoptera: Gelechiidae) reared on five corn (maize) genotypes
ABSTRACT Laboratory experiments under controlled conditions of 30 ± 1 °C, 60 ± 10% r.h. and 14 h photophase were performed to study the biology of Sitotroga cerealella (Oliv.) reared on five natural diets of different corn (maize) genotypes. S. cerealella reared on the shrunken2 genotype displayed the longest developmental time (43.5 d) and the lowest fecundity (85.2 eggs/female). Although the egg to adult developmental time (40.2 d) of S. cerealella reared on sugary-opaco2 did not differ significantly from those on normal, opaco2 and sugary, the survival of the pre-imaginal stage (42.2%) was significantly reduced on this genotype. Significant differences were not found between the number of eggs hatched from females reared on these genotypes. The egg hatch ranged from 86.8 to 95.3% for the shrunken2 and opaco2 genotypes, respectively. Further rearing studies to determine the effects of these genotypes on the biology of S. cerealella are needed, since significant differences were not observed in the data from two successive generations.
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ABSTRACT: Relative resistance of paddy varieties to the Angoumois grain moth, Sitotroga cerealella was investigated in the laboratory at a temperature of 28 ± 1.0°C and relative humidity of 65 ± 1.5%. The study was carried out on Indian Agricultural Research Institute (IARI), New Delhi, India varieties and a Taiwan variety. The larvae of S. cerealella were allowed to feed and developed inside the grain while adults did not feed. Results showed that the performance of S. cerealella was least in T (N)-1 (Taichung Native-1), with the longest developmental time (26.3 days) and egg to adult survival of 38% making the variety the most resistant. The performance was best in Pusa 44 with the shortest developmental time (23.0 days) and egg to adult survival of 68.7% making the variety the least resistant. The heaviest females and males with 4.04 g and 2.38 g, respectively, were reared on Pusa sugandh 3, which are large seeds. Moths reared on T (N)-1 had the lowest weights for males and females. Unmated females lived longer than their mated counterparts while females generally lived longer than males. Fecundity was highest (164.2 eggs/female) in Pusa 44 and lowest (108.1 eggs/female) in T (N)-1. Hatchability ranged from 81.2% in T (N)-1 to 96.2% in Pusa 834. Generally, grain characters tested in this study influenced moth herbivore performance but the influence was not significant except for grain width which appeared to be the most important trait. With advances in biotechnology, it is possible to transfer desirable characters to other varieties to improve their resistance to S. cerealella and other stored products insects. However, care must be taken since this could change the grains susceptibility to some pests affecting pest-host relationships. Key wordspaddy- Sitotroga cerealella -resistance-emergence-fecundity-hatchabilityBiologia 65(2):333-337. · 0.51 Impact Factor