Effectiveness of Bacillus thuringiensis (Bt) against sucking and chewing pests on cabbage (Brassica oleracea).

Abstract

Cabbage (Brassica oleracea var. capitata) is a leafy vegetable belonging to the Brassicaceae family, known for its dense, edible head composed of overlapping leaves (Šamec, Pavlović, & Salopek-Sondi, 2016). It is grown in various colors, including green, red, and purple, and can be consumed raw, cooked, or preserved. Cabbage is valued for its high nutritional content, providing essential vitamins such as vitamin C and K, dietary fiber, and various antioxidants that contribute to a healthy diet (Šamec, Pavlović, & Salopek-Sondi, 2016). It was introduced to Uganda during the British colonial period, specifically in the year 1943 in Kabale, a region in southwestern Uganda, amidst a severe famine caused by adverse weather conditions and the impacts of World War II. The famine had left many local communities, particularly the Bakiga people, struggling for food as their traditional crops failed due to heavy rains and soil erosion (Patra, et al., 2023). .Due to the ideal conditions in East Africa that resembled its natural habitat where it originated, cabbage rapidly adapted to the climate of Uganda, especially in the cooler highland regions where it flourished which was further enhanced by teaching local farmers new farming methods and crop management strategies (Gerszberg, 2018). According to Gerszberg (2018) and Šamec, et al., (2016), the introduction of cabbage was a part of a bigger agricultural strategy and colonial-era agricultural extension agencies encouraged Ugandan farmers to grow cabbage providing additional support for further introduction. Cabbage is classified under the Brassicaceae family, also referred to as the mustard family, which also includes other crops that are significant to the economy, such as kale, broccoli, and cauliflower (Gerszberg, 2018). Cabbage is classified scientifically as follows: Kingdom: Plantae Family: Brassicaceae Genus: Brassica Species: Brassica oleracea Variety: capitata Cabbage is further divided according to the shape and composition of the head. The popular varieties of cabbage, such as red, green, and Savoy cabbage, are grouped together under the capitata genus and are identified by the shape, color, and texture of their leaves (Warwick, 2010). Jabeen (2020) documented that the Brassicaceae family, which includes the cabbage (Brassica oleracea var. capitata), is a vital component of diets all over the world because of its diverse range of crops and high nutritional content. Other important members of this family are kale (Brassica oleracea var. sabellica), which has high levels of vitamins A, C, and K; broccoli (Brassica oleracea var. italica), which is prized for its green flower heads and richness in vitamins C and K; and cauliflower (Brassica oleracea var. botrytis), which is eaten for its edible white or colorful flower heads. While turnips (Brassica rapa subsp. rapa) and radishes (Raphanus sativus) are root vegetables known for their culinary variety and nutritional depth, Brussels sprouts (Brassica oleracea var. gemmifera) are tiny cabbage-like vegetables,Bok choy (Brassica rapa subsp. chinensis), also known as Chinese cabbage, is a mainstay in Asian cuisines with its soft stems and leaves, mustard greens (Brassica juncea) have a spicy flavor and are rich in vitamins. Vitamins A, C, and K are abundant in collard greens (Brassica oleracea var. acephala), which are commonly used in Southern America (Jabeen, 2020). These crops are vital for their dietary value combined with their health-promoting qualities, such as high glucosinolate and other bioactive chemical levels that may lower the risk of cancer which makes the Brassicaceae family crops essential for both agriculture and human nutrition due to their wide variety of tastes, textures, and growth patterns (Abbott, 2024). Cabbage is mostly grown in the cooler highland regions of Uganda due to the ideal climate with the major cabbage-producing areas being southwestern districts of Kabale, Kisoro, Rukungiri, and Ntungamo, as well as the high-altitude areas of Mbale, Kapchorwa, and the slopes of Mount Elgon in the eastern part of the country. These regions offer moderate temperatures and fertile, well-drained soils, which are conducive to cabbage growth (Šamec, Pavlović, & Salopek-Sondi, 2016). Central districts like Mukono, Wakiso, and parts of the Luwero Triangle also contribute to cabbage production, especially where irrigation is used to supplement rain. Uganda's total cabbage production capacity is estimated to be between 100,000 to 120,000 metric tons per year however it significantly varies due to factors such as weather variability, pest pressure, and access to agricultural inputs. The average yield per hectare ranges from 15 to 30 tons under optimal conditions that include good farming practices, quality seed varieties, and adequate pest and disease management (Patra, et al., 2023). Cabbage is an important vegetable in Uganda due to its nutritional, economic, and agricultural importance, it is a vital source of essential vitamins particularly vitamin C and K, as well as dietary fiber, which contribute to a balanced diet addressing common dietary deficiencies (Gerszberg, 2018). Cabbage is of great economic importance to many smallholder farmers offering a steady income and contributing to rural livelihoods because it has a relatively short growing cycle allowing farmers to harvest multiple times within a year. It is versatile in culinary uses, making it a staple in Ugandan cuisine which ensures its steady demand in local markets thus supporting food security by diversifying crop production and offering an alternative to staple crops that may be less resilient to climate fluctuations (Gerszberg, 2018). Cabbage yield is significantly affected by both abiotic and biotic factors. Abiotic factors include temperature, water availability, soil quality, and nutrient levels (Šamec, Pavlović, & Salopek-Sondi, 2016). Cabbage grows well in cool temperatures between 15-20°C because excessive heat leads to poor head formation and premature bolting and water stress from drought or waterlogging adversely impacts cabbage growth and yield. Adequate nutrient supply is crucial, as deficiencies in essential elements like nitrogen, phosphorus, and potassium can lead to reduced plant vigor and lower yields (Patra, et al., 2023). Biotic factors involve pests and diseases with common cabbage Pests being aphids, beetles, whiteflies cabbage loopers, and diamondback moths that cause significant damage by feeding on leaves and heads, which reduces the crop's marketability and yield and common diseases like black rot, downy mildew, and clubroot can lead to severe crop loss if not managed effectively (Gerszberg, 2018). Cabbage yields are significantly impacted by biotic variables, especially pests. Lepidopterans and non-lepidopterans being the main pests that feed destructively on cabbage leaves, such cabbage loopers (Trichoplusia ni) and diamondback moths (Plutella xylostella), are known to cause large yield losses (Gerszberg, 2018). These larvae have the capacity to severely defoliate plants and impair their capacity for efficient photosynthetic processes. Non-lepidopteran pests include beetles, white flies, cutworms (Agrotis spp.), and aphids (Aphis spp.). Aphids spread plant viruses leaving behind sticky honeydew deposits that draw sooty mold and injure plants .Effective pest management techniques are necessary to reduce the negative impacts of insect damage (Gerszberg, 2018). Farmers combine traditional and modern methods for controlling pests in cabbage crops and maximize production (Šamec, Pavlović, & Salopek-Sondi, 2016). Crop rotation and field sanitation are examples of cultural practices that assist decrease pest habitats and increase plant resistance. Handpicking and row coverings are examples of physical controls that directly control pest populations (Patra, et al., 2023). Biological controls make use of microbial insecticides like Bacillus thuringiensis (Bt), which targets specific pests without harming beneficial insects, and natural predators like ladybugs. When chemical controls are required, Bt insecticides are frequently selected for controlling lepidopterans (Gerszberg, 2018). In order to provide a sustainable and successful approach to pest control that minimizes the use of pesticides and their negative effects on the environment, Integrated Pest Management (IPM) integrates these techniques while monitoring and real-time data (Liu, Alemán-Báez, Visser, & Bonnema, 2024).