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Simple Summary: Bean leaf beetles (BLBs) are significant pests in Uganda, damaging crops such as beans and cowpeas, leading to substantial yield losses. They exhibit preferential feeding behaviour, targeting specific crops over others. Understanding these preferences can form the basis for identifying a potential trap crop that can be used to manage the pest at a low cost in a sustainable manner. A field study was conducted to determine the feeding preference of BLBs on various host crops among those commonly cultivated in Uganda, across different locations and seasons. This study was conducted in Arua and Lira districts in the first and second rainy seasons of 2018. Seven BLB host crops, i.e., common bean, cowpea, greengram, soybean, groundnuts, okra and roselle (locally known as malakwang), were selected for the study. The results showed that cowpea exhibited the highest abundance of BLBs among all crops and it had a high amount of foliar damage as well. Thus, it was selected as the most preferred host crop and can be recommended as a trap crop for managing Ootheca spp. With respect to locations and seasons, the pest was more abundant in Arua than in Lira and more abundant in 2018A than 2018B across all locations. The bean leaf beetle (BLB) (Ootheca spp.) is a polyphagous pest causing significant yield losses in Uganda, particularly in the Northern and Eastern regions on various hosts plants. Despite its polyphagous behaviour, the BLB exhibits preferential feeding, offering an opportunity for targeted pest management. This study explored its feeding preferences across seven crops: common bean, cowpea, greengram, okra, roselle (malakwang), groundnuts, and soybean. This study was conducted in Arua and Lira districts using a randomized complete block design for two rainy seasons (2018A and 2018B). The results showed significant differences in BLB abundance and foliar damage among host crops, locations, days after planting and seasons. Cowpea was the most preferred crop while groundnuts was the least preferred. Therefore, cowpea can be recommended for use as a trap for managing Ootheca spp. in gardens where it is not the main crop. There was a higher pest abundance in Arua than in Lira. There was also a higher pest abundance in 2018A than in 2018B. These findings highlight the importance of understanding BLB's feeding preferences for implementing effective IPM strategies, emphasizing the potential role of trap cropping, especially with cowpea, to minimize BLB damage in resource-constrained agricultural settings. [ABSTRACT FROM AUTHOR]

Keywords: Chrysomelidae; Phaseolus vulgaris; common bean; cowpea beetle; Ootheca mutabilis; defoliation; foliage beetle; immature life stages EN Chrysomelidae Phaseolus vulgaris common bean cowpea beetle Ootheca mutabilis defoliation foliage beetle immature life stages N.PAG N.PAG 14 09/27/22 20220901 NES 220901 1. The higher abundance of adult BLBs on cowpea than on common bean and soybean indicates that cowpea is the most preferred host, followed by common bean. Similarly, the mean number for below-ground adults was higher on cowpea than on common bean and soybean, but the number of adults recovered in cowpea was not different from that on common bean (Table 2). 3.5. The preference of cowpea over common bean suggests that the crop can be used as a trap against bean leaf beetles in common bean fields. [Extracted from the article]

Simple Summary: Bean leaf beetles (Ootheca spp.) (Coleoptera: Chrysomelidae) are a major pest of the common bean (Phaseolus vulgaris L.) in Africa, attacking the roots, leaves, floral parts, and young pods, and reducing grain yields significantly. However, there is no comprehensive program for managing bean leaf beetles. In Uganda, farmers typically try to reduce pest impacts by delaying bean crop sowing, and to a lesser extent, using insecticides, but there is no information on the impact of delayed planting and insecticide application on bean leaf beetles. We conducted a study to assess the effects of planting timing and insecticide spray regimes on bean leaf beetle abundance, foliar damage, and common bean grain yield in three agro-ecological zones. Bean leaf beetle abundance was highest in mid-planting compared to late and early planting, while foliar damage was highest in late planting in two of the three agro-ecological zones. However, marketable grain yield was highest in early-planted plots in all three agro-ecological zones. Insecticide application reduced foliar damage and increased marketable grain yield, with a combination of soil drench and foliar spray resulting in significantly less foliar damage and higher grain yield. Marketable grain yield was higher when insecticides were combined with early planting in all agro-ecological zones. Bean leaf beetles (Ootheca spp.) (Coleoptera: Chrysomelidae) are one of Africa's most important pests of the common bean (Phaseolus vulgaris L.). Roots, leaves, floral parts, and young pods are all attacked, leading to a considerable loss in grain yield. In Uganda, there are no comprehensive prescribed management strategies for bean leaf beetles, but farmers typically try to control the pest by delaying bean crop sowing, and to a lesser extent, using insecticides. Although farmers have consistently implemented the two approaches, there is no information on the effects of the approaches in Uganda. To assess the impact of planting timing and insecticide spray regimes on bean leaf beetle populations, concomitant foliar damage, and grain yield, we set up trials in three agro-ecological zones with known presence of the beetles during the second rainy season of 2016 (2016) and the first rainy season of 2017 (2017). The first planting, coinciding with early planting, was conducted within one week after the onset of rains. The second planting, coinciding with mid planting, followed two weeks later, while the third planting, considered late planting in this study, was conducted one month after the second planting. A foliar application of cypermethrin commencing at 7 days after emergence (DAE), 14 DAE, 21 DAE, 28 DAE, and 35 DAE; a soil drench of imidacloprid at planting combined with a foliar spray starting at 7 DAE; and an untreated control were among the insecticide spray regimes evaluated. Higher bean leaf beetle abundance was recorded from mid-planting, while higher foliar damage was recorded from late planting in two of the three agro-ecological zones. However, higher marketable grain yield was recorded from early planting in all agro-ecological zones, suggesting that delayed planting may not be beneficial. Insecticide application reduced foliar damage and increased marketable grain yield, with a combination of soil drench and foliar spray resulting in much less foliar damage and, as a result, higher grain yield. However, this did not result in economic benefits. Furthermore, marketable grain yield was higher when insecticide spray regimes were combined with early planting in all agro-ecological zones during both seasons. Our findings suggest that the common bean should be planted early and that the control of the bean leaf beetle should target both the adults and the juvenile stages in the soil. Therefore, there is a need for farmers to be able to access less-expensive soil treatments. [ABSTRACT FROM AUTHOR]

Simple Summary: The bean leaf beetle (Ootheca mutabilis) has lately emerged as a major bean pest in Uganda, causing devastating crop losses. Despite its importance, little is known about its population genetic structure. We developed microsatellite DNA markers and combined them with partial mito-chondrial cytochrome oxidase subunit I gene sequences as a marker to examine the spatial pop-ulation genetic structure of 86 O. mutabilis samples from 16 populations. We developed a set of five highly polymorphic microsatellite DNA markers. From both types of markers, nearly all the genetic variation occurred within populations and there was no evidence of genetic differentiation in both markers. There was no isolation by distance between geographical and genetic distances for both markers except in one of the agro-ecological zones for mtCOI data. This information will assist in the design of O. mutabilis control strategies. Bean leaf beetle (BLB) (Ootheca mutabilis) has emerged as an important bean pest in Uganda, leading to devastating crop losses. There is limited information on the population genetic structure of BLB despite its importance. In this study, novel microsatellite DNA markers and the partial mitochondrial cytochrome oxidase subunit I (mtCOI) gene sequences were used to analyze the spatial population genetic structure, genetic differentiation and haplotype diversity of 86 O. mutabilis samples from 16 (districts) populations. We identified 19,356 simple sequence repeats (SSRs) (mono, di-, tri-, tetra-, penta-, and hexa-nucleotides) of which 81 di, tri and tetra-nucleotides were selected for primer synthesis. Five highly polymorphic SSR markers (4–21 alleles, heterozygosity 0.59–0.84, polymorphic information content (PIC) 50.13–83.14%) were used for this study. Analyses of the 16 O. mutabilis populations with these five novel SSRs found nearly all the genetic variation occurring within populations and there was no evidence of genetic differentiation detected for both types of markers. Also, there was no evidence of isolation by distance between geographical and genetic distances for SSR data and mtCOI data except in one agro-ecological zone for mtCOI data. Bayesian clustering identified a signature of admixture that suggests genetic contributions from two hypothetical ancestral genetic lineages for both types of markers, and the minimum-spanning haplotype network showed low differentiation in minor haplotypes from the most common haplotype with the most common haplotype occurring in all the 16 districts. A lack of genetic differentiation indicates unrestricted migrations between populations. This information will contribute to the design of BLB control strategies. [ABSTRACT FROM AUTHOR]

Simple Summary: Bean leaf beetles (Ootheca spp.) (Insecta: Coleoptera: Chrysomelidae) were originally thought to be minor pests of the common bean in Uganda, with only reports coming from the north. The beetles have already expanded to other locations, prompting farmers to postpone bean planting in order to avoid their damaging effects. The species that do exist in Uganda, however, are poorly documented. Furthermore, little is known about the factors that influence bean leaf beetle population dynamics and dispersion across the country. We conducted surveys to determine the species and relative abundance of bean leaf beetles, as well as the factors that control their population dynamics. We recovered 12 genera of leaf beetles on common bean from the sampled agro-ecological zones in Uganda. Only three species belong to the genus Ootheca (O. mutabilis, O. proteus and O. orientalis) in the surveyed locations of Uganda. Ootheca mutabilis is the most common of the three species, accounting for 70% of the total. The most infested agro-ecological zone is the Northern Moist Farmlands, whereas the least infested is the Southwestern Highlands. Our findings provide a foundation for assessing the importance of Ootheca species as common bean pests in Uganda. Bean leaf beetles (Ootheca spp.) (Insecta: Coleoptera: Chrysomelidae) are one of Africa's most destructive pests of common bean and other leguminous crops. The beetles are widely distributed in Africa where they are estimated to cause annual crop yield losses of 116,400 tons of crop yields in sub-Saharan Africa. Despite their importance, little is known about the distribution, relative abundance and damage caused by bean leaf beetles in Uganda. As a result, the development of effective management methods has been hampered. We conducted surveys in six key Ugandan agro-ecological zones to determine the species distribution and relative abundance of bean leaf beetles. Findings indicate that leaf beetles belonging to 12 genera are present, including members of the genera Afrophthalma Medvedev, 1980, Buphonella Jacoby, 1903, Chrysochrus Chevrolat in Dejean, 1836, Diacantha Dejean, 1845, Exosoma Jacoby, 1903, Lamprocopa Hincks, 1949, Lema Fabricius, 1798, Nisotra Baly, 1864, Neobarombiella Bolz and Wagner, 2012, Ootheca Dejean, 1935, Parasbecesta Laboissière, 1940, and Plagiodera Dejean, 1835. We identified only three species belonging to the genus Ootheca: O. mutabilis, O. proteus, and O. orientalis. Seventy percent of all the beetles collected were O. mutabilis and these were present in all agro-ecological zones studied. The Northern Moist Farmlands (21.9%), West Nile Farmlands (12.9%), Central Wooded Savanna (4.4%) and Southern and Eastern Lake Kyoga Basin (1.4%) were the only agro-ecological zones where O. proteus was found. Only one specimen of O. orientalis was found at a single site in the Central Wooded Savanna. The Northern Moist Farmlands had a significantly (p < 0.05) higher bean leaf beetle density than the West Nile Farmlands and Southwestern Highlands. Similarly, the Northern Moist Farmlands had the highest beetle foliar damage per plant (1.15 ± 0.05), while the Southwestern Highlands had the lowest (0.03 ± 0.02). We provide the first information on Ootheca species distribution, abundance and damage in Uganda. Our findings provide a foundation for assessing the importance of Ootheca spp. as common bean pests in Uganda. [ABSTRACT FROM AUTHOR]