Pathogenicity of isolates of Beauveria bassiana to the banana weevil Cosmopolites sordidus

Bananas constitute a major staple food crop for millions of people in developing countries, providing energy as well as important vitamins and minerals. Itfs production in Kenya has been on the decline due to, among other factors, pests and disease of which the banana weevil, Cosmopolites sordidus, is the most important. The aim of this study was to screen ten isolates of the entomopathogenic fungus Beauveria bassiana for pathogencity against C.sordidus. Twenty weevils were inoculated with the fungus by dipping them into a fungal suspension containing 1x108 conidia ml-1 for 11 seconds. The suspension was then drained out and pieces of banana corm introduced as food for the weevils. All the ten isolates of B. bassiana tested were found to be pathogenic to adult banana weevil  causing mortalities of between 20]50% by 40 days post exposure. ICIPE 273 was the most pathogenic isolate killing 50% of adults, followed by M313 at 36% and M207 at 30%. Isolates KE300, M221, ICIPE 50, M573, M618, M470 and ICIPE 279 killed less than 30% of the weevils, ICIPE 279 was the least pathogenic isolate to the adult C. sordidus killing 6% of the inoculated weevils. The dead weevils were incubated in sterile moist filter papers in Petri dishes for two weeks and fungal mycelia was observed on the surface of the weevils starting from intersegmental junctions. Mortality caused by fungus was confirmed by microscopic examination. Since isolate ICIPE 273 has reasonable pathogenicity to C. sordidus and  field/screenhouse studies are recommended to validate the findings.Key words: biocontrol, entomopathogens, pest managemen

Pathogenicity of Metarhizium anisopliae (Metch) Sorok and Beauveria bassiana (Bals) Vuill to adult Phlebotomus duboscqi (Neveu-Lemaire) in the laboratory

Background & objectives: Biological control of sandflies using entomopathogenic fungi is a possible alternativeto the expensive synthetic chemical control. It is potentially sustainable, less hazardous, and relatively inexpensiveand merits further investigations. The objective of this study was to identify the most pathogenic fungal isolate(s)to sandflies in the laboratory.Methods: Isolates of entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana were screenedfor their pathogenicity against Phlebotomus duboscqi. Adult flies were contaminated using the technique describedby Migiro et al (2010). Briefly, flies were exposed to 0.1 g of dry conidia evenly spread on a cotton velvet clothcovering the inner side of a cylindrical plastic tube (95 mm long × 48 mm diam). In all 25 sandflies weretransferred into the cylindrical tube and allowed to walk on the velvet for one minute, after which they weretransferred from the velvet into the cages in Perplex. Insects in the control treatments were exposed to fungusfree velvet cloth before being transferred into similar cages. The treatments were maintained at 25 ± 2°C,60–70% RH and 12L: 12D photoperiod. The experiment was replicated 5 times. The most pathogenic isolateswere selected for further studies.Results: A total of 19 isolates were screened against adult sandflies in the laboratory. Mortality in the controlswas approximately 16.8 ± 1.7 %. All the isolates were found to be pathogenic to P. duboscqi. Mortality rangedbetween 76.8 and 100% on all the fungal isolates tested. The lethal time taken to 50% (LT50) and 90% (LT90(mortality ranged from 3.0–7.8 days and from 5.3–16.2 days, respectively. The virulent isolates, causing mortalitiesof 97.5–100%, were selected for further studies.Interpretation & conclusion: The high susceptibility of sandflies to entomopathogenic fungi suggests that fungiare potential alternatives to chemical control methods. We conclude that application of entomopathogenic fungicould result in acute mortalities of sandflies and reduction of parasite transmission and subsequently, reductionof leishmaniasis risk. This method of biological control has great potential as a new strategy for leishmaniasiscontro

Optimizing Western Flower Thrips Management on French Beans by Combined Use of Beneficials and Imidacloprid

Western flower thrips (WFT), Frankliniella occidentalis (Pergande), is an important pest of vegetable crops worldwide and has developed resistance to many insecticides. The predatory mites Neoseiulus (=Amblyseius) cucumeris (Oudemans), the entomopathogenic fungus Metarhizium anisopliae (Metsch.), and an insecticide (imidacloprid) were tested for their efficacy to reduce WFT population density and damage to French bean (Phaseolus vulgaris L.) pods under field conditions in two planting periods. Metarhizium anisopliae was applied as a foliar spray weekly at a rate of one litre spray volume per plot while imidacloprid was applied as a soil drench every two weeks at a rate of two litres of a mixture of water and imidacloprid per m(2). Neoseiulus cucumeris was released every two weeks on plant foliage at a rate of three mites per plant. Single and combined treatment applications reduced WFT population density by at least three times and WFT damage to French bean pods by at least 1.7 times compared with untreated plots. The benefit-cost ratios in management of WFT were profitable with highest returns realized on imidacloprid treated plots. The results indicate that M. anisopliae, N. cucumeris, and imidacloprid have the potential for use in developing an integrated pest management program against WFT on French beans.BMZ/GIZ/07.7860.5-001.0

Integrated Management of Aphis craccivora in Cowpea Using Intercropping and Entomopathogenic Fungi under Field Conditions

Cowpea aphid, Aphis craccivora, is a major cowpea pest. Cowpea–cereal intercrop alone does not effectively manage the pest. Use of pesticides in intercrop leads to health and environmental risks. Fungal-based biopesticides offer a better option because they are environment- and consumer-friendly. This study assessed the combined effect of Metarhizium anisopliae ICIPE 62 and cowpea–maize intercrop against A. craccivora under six treatments: (1) untreated cowpea monocrop, (2) untreated cowpea–maize intercrop, (3) cowpea monocrop + ICIPE 62, (4) cowpea–maize intercrop + ICIPE 62, (5) cowpea monocrop + Duduthrin insecticide, and (6) cowpea–maize intercrop + Duduthrin during three seasons (long rainy/cold and dry/short rainy). In the cold and dry season, cowpea–maize intercrop treated with ICIPE 62 recorded the lowest infestation/cowpea damage, whereas the leaf yield was comparable to cowpea monocrop treated with ICIPE 62. In the short rainy season, the cowpea–maize intercrop treated with ICIPE 62 recorded the lowest infestation/damage, whereas leaf yield was similar to cowpea–maize intercrop treated with ICIPE 62 in the cold and dry season. Duduthrin in monocrop and intercrop did not reduce aphid infestation/cowpea damage levels in all the seasons. Although the efficacy of M. anisopliae ICIPE 62-based biopesticide could be affected by seasons, it successfully controlled aphid population in cowpea–maize intercrop under field conditions without affecting aphid-associated natural enemies.Peer Reviewe

Screening for attractants compatible with entomopathogenic fungus Metarhizium anisopliae for use in thrips management

Several thrips attractants were screened for compatibility with Metarhizium anisopliae (Metchnikoff) Sorokin (Hypocreales: Clavicipitaceae) and a subset of these for attraction to Megalurothrips sjostedti Trybom  (Thysanoptera: Thripidae). Conidial germination and germ tube length of M. anisopliae were used as  indicators of its compatibility with thrips attractant. Conidial germination and germ tube length differed significantly according to volatiles of different attractants. The highest conidial germination (76.5±3.5%) and longest germ tube length (130.3±13.4 μm) were recorded in the control, followed by methyl anthranilate (63.8±3.8%; 103.8±8.4 μm), cis-jasmone (61.8±5.9%; 93.8±14.4 μm) and  transcaryophyllene (57.7±6.5%; 96.3±15.5 μm) which were found compatible with M. anisopliae. A  Pearson correlation test indicated a significant positive correlation between conidial germination and germ tube length (r =0.6; P<0.0001). The attraction of M. sjostedti to selected thrips attractant also varied significantly among the attractants. Under field conditions, methyl anthranilate was equally attractive to M. sjostedi as Lurem-TR and could be recommended as a thrips attractant that can be combined with M. anisopliae in autoinoculation devices for potential control of M. sjostedti.Key words: Semiochemicals, conidial germination, germ tube length, Megalurothrips sjostedti, attraction,persistence, field

Development of an attract-and-infect system to control Rhynchophorus ferrugineus with the entomopathogenic fungus Beauveria bassiana

This is the peer reviewed version of the following article: Dembilio, Ó. , Moya, P. , Vacas, S. , Ortega‐García, L. , Quesada‐Moraga, E. , Jaques, J. A. and Navarro‐Llopis, V. (2018), Development of an attract‐and‐infect system to control Rhynchophorus ferrugineus with the entomopathogenic fungus Beauveria bassiana. Pest. Manag. Sci, 74: 1861-1869., which has been published in final form at http://doi.org/10.1002/ps.4888. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving[EN] BACKGROUNDA new Beauveria bassiana-based attract and infect device (AID) to control Rhynchophorus ferrugineus Olivier (Coleoptera: Curculionidae) was developed. The virulence and persistence of the fungal formulation used in the AID were evaluated in the laboratory. Semi-field and field trials were carried out to validate the results and establish the potential of this device as a control tool. RESULTSIn laboratory conditions, a 50% lethal time (LT50) of 4.33 days was obtained when adults (7-10 days old) were exposed to the inoculation tunnel (IT) containing 1 x 10(10) conidia g(-1) in an oil-based fungal formulation. This formulation maintained conidium viability at 50% for up to 2 months. Moreover, when adults were exposed to 2.5-month field-aged ITs, mortality still reached 50% 40 days after exposure. In addition, no differences were observed between ITs aged in early spring and those aged in summer, suggesting that the fungal formulation is not strongly affected by environmental factors in Mediterranean basin conditions. Semi-field assays showed that the device allowed an easy transit of weevils through the IT, which were effectively attracted and infected. Using the AIDs in 4-ha plot field trials, a reduction of >50% in the percentage of infested sentinel palms was obtained. CONCLUSIONBased on the results obtained in terms of the efficacy and persistence of this new AID in the field and its potential in reducing R. ferrugineus populations and palm infestation, this device could become a key tool for the management of R. ferrugineus. (c) 2018 Society of Chemical IndustryWe wish to thank Manuel Piquer, Juan Argente and Carlos Campos for their assistance with many parts of this work, Cuca Orero for providing the trial field at Sagunt, and Jose Sancho from Sansan Prodesing SL for providing prototype solutions for the infective trap. The research that has led to these results received funding from the 7th European Union Framework Programme with Grant Agreement no. FP7 KBBE 2011-5-289566 (PALM PROTECT).Dembilio, O.; Moya Sanz, MDP.; Vacas, S.; Ortega-García, L.; Quesada-Moraga, E.; Jaques, J.; Navarro-Llopis, V. (2018). Development of an attract-and-infect system to control Rhynchophorus ferrugineus with the entomopathogenic fungus Beauveria bassiana. Pest Management Science. 74(8):1861-1869. https://doi.org/10.1002/ps.4888S1861186974

Endophytic Colonization of Onions Induces Resistance Against Viruliferous Thrips and Virus Replication

In agricultural ecosystems, insect pests, pathogens, weather patterns, and reduced soil fertility pose major challenges to crop productivity and are responsible for significant yield losses worldwide. Iris yellow spot virus (IYSV) vectored by Thrips tabaci Lindeman, is a major hindrance to onion production in eastern Africa. Control measures often rely on insecticides with deleterious effects. Endophytes are one key alternative as they can play important roles in mediating induced systemic resistance. Hence, we examined the potential effect of endophytic fungus Hypocrea lixii (F3ST1) on feeding and replication of IYSV on endophyte-colonized (E+) and endophyte-free (E-) onion plants. For more precise assessment, replication was also tested using leaf disk bioassays and individual thrips. The number of feeding punctures was significantly lower in E+ as compared to E- plants. Disease level was significantly lower in E+ as compared to E- plants for four weeks post-exposure to thrips. IYSV replication was reduced by 2.5-fold in endophytic treatment on both whole plant and leaf disk assays. Thrips tabaci showed 2 times higher feeding activities on endophyte-free onion leaf disks as compared to the endophyte-inoculated leaf disks. Our results suggest potential utility of the endophytes to reduce feeding damage and virus infection on onion plants. Further studies should be conducted to elucidate the secondary metabolites involved in such endophyte-thrips-virus mediated interaction and determine whether the interactions extend for this and other onion varieties and viruses under field conditions

The effect of a mass distribution of insecticide-treated nets on insecticide resistance and entomological inoculation rates of Anopheles gambiae s.l. in Bandundu City, Democratic Republic of Congo

Introduction: insecticide-treated nets (ITNs) remain the mainstay of malaria vector control in the Democratic Republic of Congo. However, insecticide resistance of malaria vectors threatens their effectiveness. Entomological inoculation rates and insecticide susceptibility in Anopheles gambiae s.l. were evaluated before and after mass distribution of ITNs in Bandundu City for possible occurrence of resistance. Methods: a cross-sectional study was conducted from 15th July 2015 to 15th June 2016. Adult mosquitoes were collected using pyrethrum spray catches and human landing catches and identified to species level and tested for the presence of sporozoites. Bioassays were carried out before and after distribution of ITNs to assess the susceptibility of adult mosquitoes to insecticides. Synergist bioassays were also conducted and target site mutations assessed using Polymerase chain reaction (PCR). Results: a total of 1754 female An. gambiae s.l. were collected before and after deployment of ITNs. Fewer mosquitoes were collected after the distribution of ITNs. However, there was no significant difference in sporozoite rates or the overall entomological inoculation rate before and after the distribution of ITNs. Test-mosquitoes were resistant to deltamethrin, permethrin, and Dichlorodiphenyltrichloroethane but susceptible to bendiocarb. Pre-exposure of mosquitoes to Piperonyl butoxide increased their mortality after exposure to permethrin and deltamethrin. The frequency of the Kinase insert domain receptor (kdr)-West gene increased from 92 to 99% before and after the distribution of nets, respectively. Conclusion: seasonal impacts could be a limiting factor in the analysis of these data; however, the lack of decrease in transmission after the distribution of new nets could be explained by the high-level of resistance to pyrethroid

Control of Pyrethroid-Resistant Chagas Disease Vectors with Entomopathogenic Fungi

Chagas disease, also known as American Trypanosomiasis, is the most relevant parasitic disease in Latin America, being a major burden that affects mostly poor human populations living in rural areas. The kissing-bugs of the Triatominae family transmit the parasite Trypanosoma cruzi by infectious blood-sucking; Triatoma infestans is the vector of major relevance in the southern Cone of South America. Current control strategies, heavily based on residual insecticide spraying, are threatened by the emergence of pyrethroid-resistant bug populations. Furthermore, ensuring the long-term and sustainable control of this overwhelming disease remains a major challenge. Here we show the utility of a simple, low-cost, biological control methodology against T. infestans bugs, regardless of their susceptibility to pyrethroid insecticides. It is based on the understanding of the initial contact interactions between a mycoinsecticide agent—the fungus Beauveria bassiana—and the host defense barrier, the bug cuticle. The proposed methodology is also supported by present data showing a relationship between the triatomine cuticle width and its hydrocarbon surface components, with insecticide resistance. These results will help to provide a safe and efficient alternative to overcome pyrethroid-resilience of these noxious bugs. A high transfer potential to immediate application in rural communities located in remote areas inaccessible to sanitary control teams, and to the control of other Chagas disease vectors as well, is also envisaged

Détermination des paramètres bioécologiques et entomologiques d’Anopheles gambiae sl dans la transmission du paludisme à Bandundu-ville, République Démocratique de Congo

Introduction: La présente étude a été menée à Bandundu-ville (RDC) en vue d'identifier les paramètres écologiques et entomologiques modulant la transmission du paludisme ainsi que leur tendance  saisonnière dans cette agglomération.Méthodes: Cette étude a été réalisée dans la période du 1er juin au 31 décembre 2011. Des prospections des gîtes larvaires d'anophèles avec récolte ont été réalisées, les paramètres physiques, physico-chimiques et environnementaux déterminés. La densité larvaire a été estimée selon une échelle de classes de densité, inspirée de la méthode de Carron pour chaque type de gîtes. Quarante-huit maisons ont été sélectionnées et prospectées pour la récolte des moustiques par pulvérisation intradomicilaire. L'identification des moustiques a été faite sur base des critères  morphologiques de Gilles et Demeillon. L'Indice sporozoïtique (Is) a été déterminé par le test ELISA CSP de Plasmodium falciparum à l'Institut National de Recherche Biomédicale selon le protocole de Robert  Wirtz. Les autres paramètres entomologiques comme la densité, le taux d'agressivité, le taux  d'inoculation entomologique (TIE) ainsi que l'indice de stabilité ont été déterminés selon le protocole de l'OMS. La régression linéaire a été réalisée au seuil de signification de 0,05 pour identifier les  déterminants de la densité larvaire. Résultats: Cent-sept gîtes larvaires ont été identifiés et caractérisés en 5 types (digues et puits d'eau, collections d'eau maraîchère et concasseurs moellons, marais Régie de distribution d'eau, marais le long des rivières et ruisseaux et flaques d'eau de pluies). La densité larvaire moyenne a été de 117,4±64,1. Quatre mille cinq cents quatre-vingthuit moustiques ont été capturés et identifiés, parmi lesquels 1.258 Anopheles gambiae sl avec une densité de 8,86, un taux d'agressivité de 1,55 piqûre par homme par nuit, l'Is de 5,6%, un TIE de 0,085 piqûre infectante par homme par nuit, l'espérance de vie moyenne d'anophèles de 16,4 jours et un indice stabilité de 6,512. L'analyse des  données a montré que la superficie des gîtes larvaires influençait significativement la densité larvaire (p<0,001). Par contre, la turbidité et la conductivité des gîtes influençaient négativement la densité  larvaire (p<0,05, IC 95%).Conclusion: Les diverses biotopes, la forte densité d'Anopheles gambiae sl , le TIE et l'indice de stabilité placent Bandundu-ville en zone endémique stable.Key words: Paramètres entomologiques, bioécologiques, anopheles gambia