The efficacy of Tephrosia vogelii and Azadirachta indica leaf extract combinations against fall Armyworm, Spodoptera frugiperda, in Maize.

Abstract

Spodoptera frugiperda is an economical pest affecting Uganda’s agriculture. These pests are voracious feeders, polyphagous in nature and mostly affect the cereal crops such as maize and wheat which is the staple food of Africa and Uganda in particular, thus pause a threat to Africa’s food security. Ugandan farmers largely depend on synthetic pesticide to control FAW, however these have negative impacts on the environment such as water pollution, death of beneficial organisms such as bees, and development of pesticide resistance, and are toxic to human beings and the aquatic life. The aim of this study was to evaluate the bioactivity of Tephrosia vogelii and Azadirachta indica leaf extracts as botanicals against Spodoptera frugiperda under laboratory conditions. The selected botanicals were subjected to phytochemical screening to examine presence of pesticide phytochemical groups of namely; flavonoids, saponnins, terpenoids, alkaloids, tannins and glycosides as highlighted by different literature Fourth instar larvae were collected from established fields in south western Uganda where there was no application of pesticides before and then n transferred to the biology laboratory of Mbarara University of Science and Technology under the faculty of science where they were reared to obtain enough study populations(second instar generation). Aqueous plant extracts were applied in varying combinations as treatments, the percentage mortality rates were recorded at 12 hours interval for 48 hours after treatment. Sterile tap water and cypermethrin were used as negative and positive controls respectively. The tested treatments of the botanicals were mixed in a combination of T.vogelii & A. indica powder extract weight per volume respectively, where treatment A(20g:10g), B(10g:20g), C(15g:15g), D(30g T.vogelii only) & E(30g A. indica only) and a positive control of cypermethrin. Results showed that treatments A, D and the positive control had a higher percentage mortality (> 50%, p > 0.05) after 48hours of application compared to treatments B, C and E that had a lower percentage mortality below (< 50%, p < 0.05). The botanical treatments that showed higher mortality percentage against FAW larvae contained more of the T.vogelii extract, this can be used as an extract in most of the botanicals against the FAW larvae. As an alternative, smallholder farmers can include botanicals in their integrated pest management systems around Uganda and East Africa at large conditions in Ethiopia and elsewhere in Africa.