Insects of the genus Sitophilus are among the most destructive pests in rice storage, and the best strategy to control it is to use resistant genotypes. In this study, 26 upland rice elite lines were evaluated for Sitophilus weevil reaction on grain weight. The seeds were placed in plastic recipients stored in a room with temperature and lightning simulating a warehouse environment. The number of living weevils and the grain weight were obtained in two evaluations, one 35 days after storage, and the other 35 days after infestation. The lines differed statistically for number of living weevils and for grain weight in both evaluations. The correlations between these two characters were - 0.99 and - 0.47 for the first and the second evaluation (P < 0.05), respectively. The lines BRS Pepita, AB 112089 and AB 112090 were the most susceptible. Seventeen of the twenty-six elite lines were resistant in both evaluations and could be successfully used in upland rice breeding programs.
Rice (Oryza sativa L.) is one of the most cultivated crops in the world and an excellent source of carbohydrates and protein of human feeding. It is consumed by more than half of the world’s population and it is especially important in development countries such as Brazil, playing a strategic role in economic and social politics [
The world rice production was nearly 724 millions of tons in 2014 [
According to Campos [
The incidence of storage grain pests can start on the field, during seeds’ development and maturing, or after harvesting, during storage, when environmental is favorable or when there is no insect control. Among the storage grain pests, the weevils of Sitophilus genus (Coleoptera: Curculionidae) deserve special attention due to their importance in rice crop, reducing around 20% of yield production when there is no control of this pest or when the cultivar is susceptive [
The best strategy to control rice weevil is to use resistant lines, because it reduces the use of insecticide, the costs of production and grain contamination [
The experiment was carried out at the Federal University of Mato Grosso (UFMT), Sinop-MT, Brazil (11˚51'49"S, 55˚28'57"W). Twenty-six inbred lines from the Upland Rice Breeding Program from “EMBRAPA” (Empresa Brasileira de Pesquisa Agropecuária) were evaluated for grain weight and number of living Sitophilus weevils following a completely randomized design with five replications. These lines were the ones with best performance for several agronomic traits in the field trials carried out by the Brazilian Upland Rice Breeding Program. The plot consisted of a plastic recipient (500 mL) containing 250 grams of freshly harvested seeds for each genotype. Little holes were made on the cover to allow gases passage, and the recipients were stored in a room with lightening and temperature simulating a warehouse environment (30˚C - 32˚C).
A first evaluation was performed 35 days after storing in order to determinate the level of infestation from the field. The procedure consisted of the counting of the number of living Sitophilus weevils and plots weighting. Then, the plots were treated with the insecticide Gastoxin® and any speck was cleaned. A 200 grams sample of each plot was infested with ten adults Sitophilus weevils and returned to storage. A second evaluation was performed 35 days after infestation using the same procedure described before.
Analyses of variance were computed using the statistical software SAS [
Highly significant differences (P < 0.05) among genotypes were detected for both characteristics. All experimental accuracies were higher than 84%, indicating high experimental precision [
The number of living weevils and grain weight from both evaluations and the Scott-Knott test result are presented in
Considering the second evaluation, performed after the provoked infestation, seven of the 26 genotypes had a high level of infestation, with more than 100 weevils (
Genotypes | LW11 | GW11 | LW21 | GW21 | Lost (%) |
---|---|---|---|---|---|
Chorinho | 3.60 a | 250.00 a | 14.40 a | 200.00 a | 0 |
AB 072007 | 21.80 a | 250.00 a | 41.80 a | 190.60 a | 4.7 |
AB 072044 | 0.60 a | 250.00 a | 13.40 a | 199.00 a | 0.5 |
AN Cambará | 6.00 a | 250.00 a | 73.60 a | 198.00 a | 1 |
Carolino | 0.60 a | 250.00 a | 5.80 a | 200.00 a | 0 |
AB 112093 | 5.20 a | 250.00 a | 6.40 a | 186.80 b | 6.6 |
BRS CIRAD 302 | 0.40 a | 250.00 a | 0.40 a | 200.00 a | 0 |
AB 072063 | 0.20 a | 250.00 a | 17.40 a | 200.00 a | 0 |
BRS Primavera | 0.20 a | 250.00 a | 39.60 a | 199.00 a | 0.5 |
BRS Esmeralda | 0.00 a | 250.00 a | 12.20 a | 179.80 b | 10.1 |
AB 112108 | 3.00 a | 250.00 a | 8.60 a | 200.00 a | 0 |
AB 072085 | 16.00 a | 250.00 a | 20.40 a | 195.20 a | 2.4 |
AB 072047 | 6.40 a | 250.00 a | 121.80 b | 198.40 a | 0.8 |
BRS Pepita | 232.00 c | 246.00 b | 154.20 b | 181.00 b | 9.5 |
AB 112092 | 7.40 a | 250.00 a | 0.80 a | 196.20 a | 1.9 |
BRS Sertaneja | 0.20 a | 250.00 a | 12.00 a | 200.00 a | 0 |
AB 072041 | 0.20 a | 250.00 a | 5.60 a | 200.00 a | 0 |
AB 112089 | 236.20 c | 245.60 b | 175.20 b | 182.00 b | 9 |
AB 082022 | 1.00 a | 250.00 a | 122.40 b | 198.60 a | 0.7 |
H5 | 10,20 a | 250.00 a | 75.60 a | 197.80 a | 1.1 |
AB 112090 | 193.20 b | 246.20 b | 130.40 b | 169.00 c | 15.5 |
AB 072035 | 3.60 a | 250.00 a | 61.20 a | 199.20 a | 0.4 |
AB 072001 | 43.60 a | 249.60 a | 107.40 b | 191.40 a | 4.3 |
AB 1120172 | 10.00 a | 250.00 a | 53.00 a | 198.20 a | 0.9 |
AB 072083 | 0.00 a | 250.00 a | 15.00 a | 200.00 a | 0 |
AB 082021 | 3.60 a | 250.00 a | 179.00 b | 193.80 a | 3.1 |
Mean | 30.97 | 249.51 | 56.45 | 194.39 | |
Accuracy (%) | 98.48 | 91.93 | 84.76 | 93.58 |
1Means followed by the same latter in the column do not differ significantly by the Scott-Knott test with a probability of 95%.
*Corresponding author.
It is important to emphasize that most of the lines evaluated in this study are elite lines from advanced generations of the EMBRAPA Upland Rice Breeding Program, in which some are candidates to became new commercial cultivars, with good agronomic traits and grain quality. Since most of the lines showed resistance to weevil attack, they can be successfully used in programs aiming to obtain new cultivars to the MatoGrosso state, especially the ones that showed lower percentage of losses in productivity, like the lines “Chorinho”, “Carolino”, “AB072063”, “AB112108” and “BRS Sertaneja”.
According to Gallo et al. [
Puzzi [
The correlations between the number of living weevils and grain weight were significant (P < 0.05), negative and with large magnitude, −0.99 for the first evaluation and −0.47 for the second evaluation. These results suggest an important association between these characters, as the higher the weevil infestation, the higher the loss on grain weight.
According to the evaluations of the number of living weevils and the effect of the infestation on grain weight, it is possible to infer that the most susceptible lines are “BRS Pepita”, “AB 112089” and “AB 112090”. Seventeen of the twenty-six elite lines are resistant in both evaluations and can be successfully used by upland rice breeding programs in order to obtain new cultivars to Mato Grosso State, Brazil.
Flávia BarbosaSilva Botelho,Marcela PedrosoMendes,Rodrigo Teixeira deCarvalho Botelho,Adriano TeodoroBruzi,Cinthia SouzaRodrigues,NatáliaBotega Alves,Heloisa Oliveirados Santos, (2015) Sitophilus Weevil Reaction in Upland Rice Elite Lines. American Journal of Plant Sciences,06,1916-1919. doi: 10.4236/ajps.2015.612192