Comparing the Effectiveness of Garlic (Allium sativum L.) and Hot Pepper (Capsicum frutescens L.) in the Management of the Major Pests of Cabbage Brassica oleracea (L.)

Abstract

<p>The use of chemical insecticides in crop production has resulted in increased food production in Africa, but their use has resulted in the destruction of beneficial organisms and development of resistance by some insects to the insecticides. The effectiveness of garlic <em>Allium sativum</em> and hot pepper, <em>Capsicum frutescens</em> in controlling the pests of cabbage, <em>Brassica oleracea</em> was evaluated. These botanicals were compared with a standard chemical insecticide Attack® (Emamectin benzoate). The experiment was conducted in a randomized complete block design, with 3 treatments and a control, each of which was replicated 3 times. <em>Plutella xylostella, Brevicoryne brassicae, Hellula undalis</em> and <em>Trichoplusia ni</em> were found on cabbage plants. Significantly fewer of them were found on the treated plants than the control plants. The use of the plant extracts resulted in a reduction in mortality ranging from 10.76% to 55.94%. Fewer natural enemies of <em>B. brassicae</em> were sampled on the insecticide-sprayed plots than the garlic and pepper-sprayed plots. The cost of protecting cabbage plants from insect infestation using Attack was higher than the botanicals. Garlic-treated plots recorded the highest cost: benefit ratio of 1:16 while Attack®-treated plots recorded the least of 1: 9.2. The control effects of the botanicals compared favourably with that of the chemical insecticides. Thus these botanicals can be used as substitutes to chemical insecticides.</p>

Efficacy of homemade botanical insecticides based on traditional knowledge. A review

“…In field application trials, garlic aqueous extracts resulted in a varying level of control of hemipteran pests (Bahar et al 2007;Baidoo and Mochiah 2016;Fening et al 2013;Oparaeke et al 2007;Said et al 2015), lepidopteran pests (Baidoo and Mochiah 2016;Fening 2013;Oparaeke et al 2007) as well as mites (Attia et al 2011) (Table 1). Results were not significantly different in 3 out of 9 trials (Table 2), yet, in 1 trial, the 2 synthetic pesticides used as a positive control had no significant effect either.…”

“…In field application trials, chili pepper aqueous extracts have been used to control hemipteran pests (Amoabeng et al 2013;Baidoo and Mochiah 2016;Fening et al 2013Fening et al , 2014, lepidopteran pests (Amoabeng et al 2013;Baidoo and Mochiah 2016;Fening et al 2013Fening et al , 2014Okrikata et al 2016), and thysanopteran pests (Fening et al 2014), yet the results obtained were inconsistent. Chili pepper aqueous extracts were superior to negative controls in 5 out of 10 instances.…”

Cabbage Production in West Africa and IPM with a Focus on Plant-Based Extracts and a Complementary Worldwide Vision

“…In total, 19 plant species representing 12 families have been reported: Anacardium occidentale L. (Anacardiaceae) [118]; three Asteraceae species (Ageratum conyzoides L., Chromolaena odorata L. and Synedrella nodiflora (L.) Gaertn.) [65,119,120]; one Caricaceae species (Carica papaya L.) [121][122][123]; two Euphorbiaceae (Jatropha curcas and Ricinus communis) [38,65,119,124]; three Lamiaceae species (Crataeva religiosa, Hyptis suaveolens and Ocimum gratissimum) [65,118,[124][125][126][127]; one Leguminosae/Fabaceae (Cassia sophera) [65]; one Liliaceae (Allium sativum) [128,129];…”

“…one Meliaceae (Azadirachta indica) [25,52,62,71,93,[120][121][122][123][130][131][132][133][134][135][136][137]; two Myrtaceae (Callistemon viminalis and Melaleuca leucadendron) [126]; one Poaceae (Cymbopogon schoenanthus (L.) Spreng.) [138]; one Rutaceae species (Zanthoxylum xanthoxyloides) [118] and two Solanaceae (Capsicum frutescens and Nicotiana tabacum) [65,119,128,129,139,140]. The plant parts used to prepare the different extracts are the leaves, fruits and seeds.…”

“…The plants from which extracts can be prepared on the farm are often available locally, often at no cost [242], which makes the end product cheaper than synthetic insecticides. Some of these plants are crop species, such as A. sativum, Capsicum frutescens, C. papaya or O. gratissimum [65,118,[121][122][123][124][125][126][127][128][129], whose use on another food crop can therefore be considered a sensible option, guaranteeing the safety of the produce for consumers. Plant parts of other species increasingly cultivated in several African countries are easily purchased in large quantities, in particular Anacardium occidentale [118] and the two oil-producing Euphorbiaceae R. communis and Jatropha curcas, already reported as a promising biofuel plant [38,65,119,124].…”