Entomology and Plant Pathology

Global food security is vulnerable due to massive growth of the human population, changes in global climate, the emergence of novel/more virulent pathogens, and demands from increasingly discerning consumers for chemical-free, sustainably produced food products. Bacterium- based biological control agents (BCAs), if used as part of an integrated management system, may satisfy the above demands. We focus on the advantages, limitations, problems, and challenges involved in such strategies.

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.

Serangium parcesetosum is a predator of the whitefly (Bemisia tabaci), a major pest of cassava in Africa which causes crop yield reduction of up to 50% in susceptible cassava varieties as well as vectoring cassava mosaic disease (CMD) and cassava brown streak disease (CBSD). In order to explore the use of this predator in the sustainable management of this pest, a study was conducted to evaluate the population of Serangium parcesetosum 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 both mean adult and larvae Serangium parcesetosum per plant were more abundant in Kamuli (4.92 and 11.75) as compared to Lira (0.39 and 0.51) respectively. Location and cassava age emerged as the main drivers of whitefly population which directly influenced the Serangium parcesesotum population.

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

Physical control is one of the main approaches to crop protection against insects, the others being chemical, biological and cultural.). From theoretical and technical points of view, all of these approaches have limits that make them more or less suitable for control of a given pest. In practice, the relative merits of each approach are also weighed against numerous factors before an actual decision is made regarding the most appropriate methods to be implemented. A majority of agricultural commodities are protected using chemical control but ideally, all components and technologies should be blended optimally and harmoniously into an integrated pest management (IPM) program. Ideally integrated pest management should rely on an array of tactics. In reality, the main technologies in use are synthetic pesticides. Because of well documented problems with reliance on synthetic pesticides, viable alternatives are sorely needed. Physical controls can be classified as passive (e.g. trenches, fences, organic mulch, particle films, inert dusts and oils), active (e.g. mechanical, polishing, pneumatic, impact and thermal) and miscellaneous (e.g. cold storage, heated air, flaming, hot water immersion). Some physical methods such as oils have been used successfully or pre-harvest treatments for decades. Another recently developed method for pre-harvest situations is particle films. As we move from production to the consumer, legal constraints restrict the number of options available. Consequently, several physical control methods are used for post-harvest situations. Two noteworthy examples re the entoleter, an impacting machine used to crush all insect stages in flour and hot water immersion of mangoes, used to kill tephritid fruit fly immature in fruit. The future of physical control methods will be influenced by socio-legal issues and by new developments in basic and applied research.

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

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.

Two single nucleotide polymorphisms (SNPs) were detected in the internal transcribed spacer region of the nuclear ribosomal DNA (rDNA-ITS) of 21 Corynespora cassiicola isolates obtained from a number of Hevea clones grown in rubber plantations in Malaysia. The two SNPs correlated with the physiological races of the isolates. Database searches yielded another 28 C. cassiicola isolates from diverse hosts and geographical regions. With this inclusion, a total of seven SNPs and two indels in the rDNA-ITS region were detected from all 49 C. cassiicola isolates. The knowledge of intraspecific variability (SNPs and indels) could prove useful in the delineation of physiological races or pathotypes of this fungus.

Two single nucleotide polymorphisms (SNPs) were detected in the internal transcribed spacer region of the nuclear ribosomal DNA (rDNA-ITS) of 21 Corynespora cassiicola isolates obtained from a number of Hevea clones grown in rubber plantations in Malaysia. The two SNPs correlated with the physiological races of the isolates. Database searches yielded another 28 C. cassiicola isolates from diverse hosts and geographical regions. With this inclusion, a total of seven SNPs and two indels in the rDNA-ITS region were detected from all 49 C. cassiicola isolates. The knowledge of intraspecific variability (SNPs and indels) could prove useful in the delineation of physiological races or pathotypes of this fungus.

Two single nucleotide polymorphisms (SNPs) were detected in the internal transcribed spacer region of the nuclear ribosomal DNA (rDNA-ITS) of 21 Corynespora cassiicola isolates obtained from a number of Hevea clones grown in rubber plantations in Malaysia. The two SNPs correlated with the physiological races of the isolates. Database searches yielded another 28 C. cassiicola isolates from diverse hosts and geographical regions. With this inclusion, a total of seven SNPs and two indels in the rDNA-ITS region were detected from all 49 C. cassiicola isolates. The knowledge of intraspecific variability (SNPs and indels) could prove useful in the delineation of physiological races or pathotypes of this fungus. Abbreviations: BLAST (Basic local alignment search tool); ITS rDNA (Internal Transcribed Spacer region of the Ribosomal DNA); SNPs (Single Nucleotide Polymorphisms) Footnotes: Nucleotide sequence data reported are available in the GenBank databases under the accession number(s) from EU364535 to EU364555. Single nucleotide polymorphisms data reported are available in the dbSNP database (Build 130) under the submitter SNP (ss) accession numbers from ss105106974 to ss105106982

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.