Entomology and Plant Pathology

Sesame (Sesamum indicum L.), the “Queen of oil seeds” is being infected with pathogens, i.e., fungi, bacteria, virus and nematodes. Fusarium oxysporum sp. sesami (Zap.), is one of the fiercest pathogens causing severe economic losses on sesame. This work aimed to evaluate the impact of the cultivation of some preceding crops and seed inoculation with antagonistic predominant rhizospheric bacteria and actinomycetes on the incidence and development of Fusarium damping-off and wilt disease. Results showed that the lowest pre and/or post-emergence damping-off and wilt of sesame were recorded after onion and garlic, followed by wheat compared to clover in both the 2019 and 2020 seasons. In vitro, soil extracts from plots where onion and garlic have been cultivated slightly decreased the conidia germination and mycelium radial growth of F. oxysporum. The numbers of sesame rhizospheric F. oxysporum and fungi were lower after the cultivation of onion and garlic than those after wheat and clover. However, the numbers of actinomycetes and bacteria were higher in the onion, garlic, and clover rhizosphere than wheat. Among all isolated bacteria and actinomycetes associated with sesame roots cultivated after preceding plants, the Tricoderma viride and Bacillus subtilis (isolate No.3) profoundly reduce F. oxysporum mycelial growth in vitro. When sesame seeds were inoculated with Tricoderma viride, Bacillus subtilis, Streptomyces rochei and Pseudomonas fluorescens, the disease incidence of damping-off and wilt significantly decreased in the greenhouse and field trials conducted in both tested growing seasons, also had highly significant on plant health and growth parameters. Therefore, the current study suggested that using the preceding onion and garlic plants could be used for eco-friendly reduction of damping-off and wilt disease of sesame.

Food security (a pressing issue for all nations) faces a threat due to population growth, land availability for growing crops, a changing climate (leading to increases in both abiotic and biotic stresses), heightened consumer awareness of the risks related to the use of agrichemicals, and also the reliance on depleting fossil fuel reserves for their production. Legislative changes in Europe mean that fewer agrichemicals will be available in the future for the control of crop pests and pathogens. The need for the implementation of a more sustainable
agricultural system globally, incorporating an integrated approach to disease management, has never been more urgent. To that end, the Valorizing Andean Microbial Diversity (VALORAM) project (http://valoram.ucc.ie), funded under FP7, examined the role of microbial
communities in crop production and protection to improve the sustainability, food security, environmental protection, and productivity for rural Andean farmers. During this work, microbial volatile organic compounds (mVOCs) of 27 rhizobacterial isolates were identified using gas chromatography/mass spectrometry (GC/MS), and their antifungal
activity against Rhizoctonia solani was determined in vitro and compared to the activity of a selection of pure volatile compounds. Five of these isolates, Pseudomonas palleroniana R43631, Bacillus sp. R47065, R47131, Paenibacillus sp. B3a R49541, and Bacillus simplex M3-4 R49538 trialled in the field in their respective countries of origin, i.e., Bolivia, Peru, and Ecuador, showed significant increase in the yield of potato. The strategy followed in the VALORAM project may offer a template for the future isolation and determination of putative biocontrol and plant growth-promoting agents, useful as part of a low-input integrated pest management system.

Chili (Capsicum annuum L.) is an economically important and widely cultivated crop of India. Chilli leaf curl virus is one of the major limiting factors in chili production, which decreases yield significantly. The experiment was carried out in one hundred fifty villages randomly selected in eastern Uttar Pradesh viz, Sultanpur and Faizabad districts during 2014 and 2015 from March to May each year. The highest leaf curl incidence was noticed in Sewra (67.39 %) followed by Hasuimukundpur (65.22%) and Etwara (64.07%) in 2014, whereas in 2015, it was found maximum in Sewra (61.44%), Hasuimukundpur (59.79%) and Isawli (57.07%). In case of block wise, the maximum incidence was found

Forests play a vital role in Nepalese rural communities, which rely on them for firewood, employment, additional meals, and good health to sustain and improve their lifestyles. It has contributed to the Nepalese farming system. Soil helps in regulating ecological processes like nutrient uptake, decomposition, and water availability in the forest. Nepal's annual soil loss ranges from 2-105 t ha-1 with 34% water-induced erosion, 60% mass wasting (geological erosion), and 3 % by wind erosion. Forest soil requires various management and conservation practices to minimize the exploitation of forest lands. Hence, this article explains the ongoing soil conservation approaches like Afforestation, Agroforestry, and community forest management in Nepal. This article can also be the roadmap for the formulation of appropriate policies in soil conservation, and indirectly in maintaining sustainability in the ecology.

Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) Mediterranean (Q biotype) is a major pest of tomato (Solanum lycopersicum L.; Solanaceae) globally. To our knowledge, no whitefly resistant cultivar has been released commercially, and breeding programs are hampered by the lack of resistance sources to this insect which are related closely to the cultivated tomato. Two non-free-choice experiments on B. tabaci with 22 landrace (S. lycopersicum) and wild tomato (S. lycopersicum var. 'cerasiforme') populations from Mexico were performed to find sources of antibiosis resistance to this insect. Plants were infested with 20 insects per 1 leaflet of each plant using plastic micro-cages. In both assays, the number of adults and eggs were counted at 4 d post infestation, the number of nymphs (12 d post infestation), new adults, and non-glandular trichomes at 28 d post infestation. The highest B. tabaci resistance was detected in the UTC-SV13 population followed by UTC-SV12, UTC-SV1, and UTC-SV3 with a range of 15.0 to 20.0 dead adults, 0.0 to 16.5 eggs, 0.0 to 12.6 nymphs, 0.0 to 9.7 new adults per leaflet, and with a reproduction index of 0.0 to 21.7. Ten populations showed an intermediate level of resistance significantly lower in the number of dead adults, eggs, nymphs, new adults, and reproduction index compared to the commercial cultivar ('Bonny Best') used as the standard. The remaining 8 genotypes and the commercial cultivar were fully susceptible to B. tabaci. The number of non-glandular trichomes correlated significantly with the number of eggs, nymphs, and new adults emerging from the infested plants, suggesting that the density of non-glandular trichomes is favorable for whitefly reproduction. Those genotypes with moderate to high levels of resistance to B. tabaci are potential candidates for developing commercial tomato cultivars with some resistance levels to this insect.
Resumen Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) Mediterranean (biotipo Q) es una importante plaga del tomate (Solanum lycopersicum L.; Solanaceae) a nivel mundial. Hasta donde sabemos, ningún cultivar resistente a la mosca blanca ha sido liberado comercialmente y los programas de mejoramiento se ven obstaculizados por la falta de fuentes de resistencia a este insecto estrechamente relacionadas con el tomate cultivado. Se realizaron dos experimentos de no libre elección sobre B. tabaci con 22 poblaciones de tomates criollos (S. lycopersicum) y tomates silvestres (S. lycopersicum var. 'cerasiforme') de México para encontrar fuentes de resistencia tipo antibiosis a este insecto. Se infestaron las plantas con 20 insectos por 1 foliolo de cada planta utilizando microjaulas de plástico. En ambos ensayos se contó el número de adultos y huevos a los 4 d post infestación, el número de ninfas (12 d post infestación), nuevos adultos, y tricomas no glandulares a 28 d post infestación. La mayor resistencia a B. tabaci se detectó en la población UTC-SV13, seguida de UTC-SV12, UTC-SV1, y UTC-SV3 con un rango de 15,0 a 20,0 adultos muertos; 0,0 a 16,5 huevos; 0,0 a 12,6 ninfas; 0,0 a 9,7 adultos nuevos por hoja; y con un índice de reproducción de 0,0 a 21,7. Diez poblaciones mostraron un nivel intermedio de resistencia significativamente menor en el número de adultos muertos, huevos, ninfas, nuevos adultos y índice de reproducción en comparación con el cultivar comercial ('Bonny Best') utilizado como el estándar. Los 8 genotipos restantes y el cultivar comercial fueron totalmente susceptibles a B. tabaci. El número de tricomas no glandulares se correlacionó significativamente con el número de huevos, ninfas, y nuevos adultos que emergieron de las plantas infestadas, lo que sugiere que la densidad de tricomas no glandulares es favorable para la reproducción de la mosca blanca. Los genotipos con niveles de resistencia moderados a altos a B. tabaci son candidatos potenciales para desarrollar cultivares comerciales de tomate con algún nivel de resistencia a este insecto.

Whitefly is a known pest of economic importance in the cassava production systems of Africa. This pest has been reported to cause losses to cassava through direct feeding damage as well as vectoring cassava mosaic disease (CMD) and cassava brown streak disease (CBSD). Serangium parcesetosum is a known predator of whitefly (Bemisia tabaci) and previous screenhouse and laboratory studies reported that temperature affected the reproduction and survival of this predator. However, these findings lacked precision since they did not depict the field situation. In that regard, it was imperative to initiate a study to help understand the influence of abiotic factors especially temperature and rainfall on the population of S. parcesetosum in the cassava growing fields of Uganda. The study was conducted in two agro-ecological zones of Uganda, namely; North Western Savannah Grassland (Lira) and the Kyoga Plains (Kamuli) in the first rains of 2017. Results revealed that temperature caused an increment of 3.5%, 9.1% (Kamuli) and 1.1%, 1.8% (Lira) for mean adult and larvae S. parcesesotum per plant respectively. On the contrary, rainfall caused a decrease in the population of S. parcesesotum in Lira. Generally, the effect of both temperature and rainfall on the predator population in the field was minimal.
Keywords: Pest; Predator; Vector; Abiotic factors