African nightshade (Solanum scabrum Miller) is a vegetable, widely distributed
throughout the tropics including East Africa. It is an important vegetable in Kenya but
consumer demands have not been met due to low yields and partly due to attack by
Aphis fabae Scopoli. The aphids cause serious damage through sucking plant cell sap
from phloem leaving the plant weakened, dehydrated, stunted in growth and eventually
under heavy infestation the leaves curl making the vegetables unattractive to consumers.
Synthetic insecticides have been used but the aphids developed resistance. They are also
a risk to human health and they kill important non-target organisms e.g. predators,
parasites and pollinators. These reasons have led to the quest for use of extracts from
plants to control aphids. The objective of this study was to evaluate the efficacy of leaf
extracts of Artemisia annua Linn. and Thevetia peruviana (Pers.) Schumann for the
control of A. fabae infesting S. scabrum, its yield output and impact of extracts on nontarget
organisms during short and long rain season from September to December 2015
and from March to July, 2016 respectively. Field experiments were carried out in
Masinde Muliro University of Science and Technology’s Main Campus farm. A
randomized complete block design (RCBD) of six treatments and three replicates was
used. The treatments used were A. annua 0.5%, A. annua 1%, T. peruviana 0.15%, T.
peruviana 0.3%, Albaz 10 EC insecticide and water. The African nightshade (S.
scabrum) used as test crop and seeds were obtained from Kenya Seed Company. A.
annua and T. peruviana leaves were each obtained from two farm each. The S. scabrum
plants were sprayed thrice at an interval of two weeks. Parameters collected were A.
fabae population density, leaf damage caused by aphids, plant height (cm), leaf width
(cm), number of flowered plants per plot, number of plants with formed fruits per plot,
number of plants with ripened fruits per plot and total weight of fresh and dry leaves,
stems and seeds (Kgs) per plot and diversity of non-target organisms. Results showed
that leaf extracts of A. annua 1% concentration significantly (p< 0.0001) reduced the
aphid population density, had significantly higher mean weight per plot of dry leaves
(0.60, 0.63 kg per plot), stems (2.62, 2.97 kg per plot) and seeds (1.36, 1.57 kg per plot)
and lower number of damaged leaves per plot (24.67, 15.00) for short and long rains
respectively. Leaf extracts of A. annua 0.5% concentration had significantly (p< 0.0001)
the highest aphid population density per plot, the lowest mean weight per plot of dry
leaves (0.38, 0.41 kg per plot), stems (1.82, 1.91 kg per plot) and seeds (0.92, 1.07 kg
per plot) and highest number of damaged leaves per plot (49.33, 36) for short and long
rains respectively when compared to those treated with leaf extracts. Plots treated with
leaf extracts of A. annua 0.5% and T. peruviana 0.15% recorded higher population of
bees, beetles and black ants. Plots treated with leaf extracts of A. annua 1% and T.
peruviana 0.3% recorded lower population of bees, beetles and black ants. The results of
this study indicated that leaf extracts of T. peruviana 0.3% and A. annua 1% had the
potential to for control of A. fabae infesting S. scabrum while leaf extracts of A. annua
0.5% and T. peruviana 0.15% conserved non-target organisms.
, I & Amolo, E (2021). Efficacy Of Leaf Extracts Of Artemisia Annua And Thevetia Peruviana Against Aphis Fabae And Non-Target Organisms On Solanum Scabrum. Afribary. Retrieved from https://afribary.com/works/efficacy-of-leaf-extracts-of-artemisia-annua-and-thevetia-peruviana-against-aphis-fabae-and-non-target-organisms-on-solanum-scabrum
, Imbaya and Elisheba Amolo "Efficacy Of Leaf Extracts Of Artemisia Annua And Thevetia Peruviana Against Aphis Fabae And Non-Target Organisms On Solanum Scabrum" Afribary. Afribary, 07 May. 2021, https://afribary.com/works/efficacy-of-leaf-extracts-of-artemisia-annua-and-thevetia-peruviana-against-aphis-fabae-and-non-target-organisms-on-solanum-scabrum. Accessed 23 Mar. 2023.
, Imbaya, Elisheba Amolo . "Efficacy Of Leaf Extracts Of Artemisia Annua And Thevetia Peruviana Against Aphis Fabae And Non-Target Organisms On Solanum Scabrum". Afribary, Afribary, 07 May. 2021. Web. 23 Mar. 2023. < https://afribary.com/works/efficacy-of-leaf-extracts-of-artemisia-annua-and-thevetia-peruviana-against-aphis-fabae-and-non-target-organisms-on-solanum-scabrum >.
, Imbaya and Amolo, Elisheba . "Efficacy Of Leaf Extracts Of Artemisia Annua And Thevetia Peruviana Against Aphis Fabae And Non-Target Organisms On Solanum Scabrum" Afribary (2021). Accessed March 23, 2023. https://afribary.com/works/efficacy-of-leaf-extracts-of-artemisia-annua-and-thevetia-peruviana-against-aphis-fabae-and-non-target-organisms-on-solanum-scabrum