Scientific publications
Pierre Stephan Elono Azang
Desiree Dounia
Leslie Carelle Mahanac Njiti
Pierre Ngassam
Joseph Lebel Tamesse
Champlain Djiéto-Lordon
Cyril Roméo Heumou
American Journal of BioScience
The study on the temporal fluctuation of populations and damage caused by <i>Leucinodes orbonalis</i> on African eggplant (<i>Solanum aethiopicum</i>) fruits was carried out in the forest region of South Cameroon from June 11 to September 22, 2018. It consisted of incubations of the attacked fruits in the laboratory for the study of <i>L. orbonalis</i> abundances and the evaluation of the damage caused by the same pest directly in the field and during each harvest; followed by the correlations with abiotic factors. The results showed that out of 331 incubated fruits for 06 harvests and 02 seasons of study, the average number of adults / fruit of <i>L. orbonalis</i> varied significantly from one harvest to another (F (5, 325) = 27.038, <i>p</i> <0.001) with a peak of 4.37 ± 0.66 individuals / fruit (N= 2) at the 2nd harvest (in August), and season to season (F (1, 329) = 15.002, <i>p</i> <0.001) with a peak of 3.22 ± 0.48 individuals / fruit (N=31) during the short dry season. Damage on <i>S. aethiopicum</i> fruits varied significantly from one harvest to another (F (5, 325) = 27.038, <i>p</i> <0.001) with a peak of 13.05 ± 4.10% in the first week of harvest in August. This damage did not change from one season to another (<i>p</i> <0.659). Means weight, length and diameter of an incubated fruit varied significantly from one harvest to another (F (5, 325) = 5,893; F (5, 325) = 7.71 and F (5, 325) = 7.84; <i>p</i> <0.001 respectively). The highest means weight, length and diameter were obtained at the 2nd and 3rd harvest with average values of 36.15 ± 6.87g and 40.20 ± 4.40g for the mean weight; 4.03 ± 0.30cm and 3.86 ± 0.15cm for the mean length and 4.15 ± 0.34cm and 4.12 ± 0.20cm for the mean diameter. Study revealed that the mean number of <i>L. orbonalis</i> per fruit had a significant positive correlation with mean weight (r=0.39, <i>p </i><0.01), mean length (r=0.40, <i>p </i><0.001) and mean diameter (r=0.41, <i>p </i><0.001) of attacked fruits and multiple regression equations of y=5.3302x+16.021, R<sup>2</sup>=0.8172; y=0.3103x+2.6544, R<sup>2</sup>=0.8194 and y=0.3684x+2.6037, R<sup>2</sup>=0.8664 of weight, length and diameter respectively. Field damage showed a positive and non-significant correlation with precipitation (r = 0.80, <i>p</i> <0.20) and a negative and non-significant correlation with mean temperature (r = -0.737, <i>p</i> <0.262) and mean relative humidity (r = -0.632, <i>p</i> <0.367). These results are of practical significance in designing appropriate strategies for <i>L. orbonalis</i> control in eggplant intercropping systems.
