Effect of the rice-Vigna radiata cropping system on the management of insect pests of rice and mung bean in a smallholder farming environment in Tshilenge, Kasaï-Oriental.

Abstract

The present study evaluates the effect of a rice-Vigna radiata cropping system on the phytosanitary status of Oryza sativa and Vigna radiata (mung bean) in a smallholder farming environment in Tshilenge, village of Bena-ntanda (-6.130199, 23.432759 and 621m). To this end, a field experiment was conducted using a Fisher completely randomized block design. In this design, in pure stands, Vigna (yellow and green cultivars) and rice (Nerica 4 variety) were sown at spacings of 0.20 m x 0.20 m with two seeds (Vigna) and four grains (rice) per hole, respectively. In intercropping, rice was sown one month before Vigna at spacings of 0.40 m x 0.20 m (4 grains per hole) while for Vigna, spacings were 0.30 m x 0.20 m (2 seeds per hole). After the experiment, the phytosanitary status within the rice-Vigna radiata system indicated, for mung bean, three identified insect pests, namely: Leptocorisa oratorius, Lasius niger, and Leptoglossus phyllopus. These insect pests were abundant in pure stands than in intercropped stands, except for Lasius niger where the sanitary situation was almost similar in both cases. The overall infestation incidence was higher in monoculture (25 and 25.7%, for the green and yellow mung bean varieties respectively) than in intercropping for the same cultivars (15.4 and 16.6%, for green and yellow mung bean respectively). Whereas for rice cultivation, four insect pests were recorded: Leptocorisa oratorius, Lasius niger, Aulacopha indica, and Mantis religiosa. Leptocorisa oratorius and Aulacopha indica were more abundant in monoculture than in intercropping. For Lasius niger, their count was the same in monoculture and intercropping. On the other hand, Mantis religiosa (praying mantis) was rare in monoculture but present in intercropped plots. Overall, the infestation incidence was higher in monoculture (28.5%) than in intercropping (16.6 and 17.4%, for yellow and green mung bean respectively). These results demonstrate that rice-mung bean intercropping within the rice-Vigna radiata cropping system allows for better management of field infestation by insect pests without the use of synthetic pesticides.