Essais de lutte biologique contre la Cochenille du manioc au Gabon: I. — Établissement, dispersion du parasite exotiqueEpidinocarsis lopezi [Hym.: Encyrtidae] et déplacement compétitif des parasites indigènes

Boussienguet, J.; Neuenschwander, Peter; Herren, H. R.

doi:10.1007/bf02377952

Cited by 11 publications

(3 citation statements)

References 12 publications

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“…Bennett (1993) reported the displacement of Pseudhomalopoda prima Girault (Hymenoptera: Encyrtidae), a local opportunist parasitoid of the introduced scale Chrysomphalus anoidum (Linnaeus) (Homoptera: Diaspididae), after the introduction of Aphytis holoxanthus DeBach (Hymenoptera: Aphelinidae), an exotic specialist parasitoid, to California. In West Africa, Anagyrus niombae Boussienguet (Hymenoptera: Encyrtidae) (Boussienguet, 1988) and other species of Anagyrus adapted to the introduced cassava mealybug but were displaced after the introduction of Apoanagyrus lopezi (DeSantis) (Hymenoptera: Encyrtidae), a host-specific cassava mealybug parasitoid from South America (Bassiangama et al, 1989;Boussienguet et al, 1991). Nevertheless, the speed of the displacement in the present case was surprising; it was almost complete when parasitism by D. semiclausum was still y = -0.065x + 5.5078, R 2 = 0.1859, p = 0.0001 y = -0.1314x + 5.5415, R 2 = 0.526, p < 0.0001 moderate and many unparasitized diamondback moth larvae were available.…”

Section: Discussionmentioning

confidence: 99%

Impact of an exotic parasitoid onPlutella xylostella(Lepidoptera: Plutellidae) population dynamics, damage and indigenous natural enemies in Kenya

Löhr

Gathu

Kariuki

et al. 2007

Bull. Entomol. Res.

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Diadegma semiclausum (Hellén) (Hymenoptera: lchneumonidae), an exotic diamondback moth parasitoid, was released in two pilot areas (Werugha in Coast Region and Tharuni in Central Province) in Kenya. Fifteen month before release, observations on the diamondback moth, Plutella xylostella (Linnaeus), and local natural enemy population dynamics and pest damage were initiated in both areas and continued for three years after release. The P. xylostella population was bimodal with higher records during dry seasons. At Werugha, the peak population of P. xylostella was 16.8 per plant (October 2001); at Tharuni it was 12.8 (February 2002). Populations at Werugha declined from three months after release and decreased from 5.4 per plant (before release) to 0.8 (year 3 after release). Concurrently, average damage (1.9 to 1.5) (on a 0-5 scale), proportion of attacked plants (72 to 31%) and proportion of plants in damage group >2 (plants with head damage) decreased (21.4 to 5.3%), while total parasitism increased from 14.4 (before) to 52.5% (year 3 after release, 90% due to D. semiclausum). At Tharuni, D. semiclausum was only recovered 3 months after release. Average populations of P. xylostella declined from 5.9 per plant (before release) to 2.4 (year 3 after release) and damage scores from 2.3 to 1.7. The proportion of plants in damage group >2 declined from 39.7 to 4.5% while overall parasitism increased from 4.2 to 40.6% (98.3% by D. semiclausum). Four species of indigenous parasitoids (Diadegma mollipla (Holmgren), Oomyzus sokolowskii (Kurdjumov), Apanteles sp. and Itoplectis sp., all primary parasitoids) were almost completely displaced by D. semiclausum. Possible reasons for the different parasitoid development between the two release areas and the displacement of the indigenous species are discussed.

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Section: Discussionmentioning

confidence: 99%

Impact of an exotic parasitoid onPlutella xylostella(Lepidoptera: Plutellidae) population dynamics, damage and indigenous natural enemies in Kenya

Löhr

Gathu

Kariuki

et al. 2007

Bull. Entomol. Res.

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“…But its local production is not enough. Indeed, the cassava production in Gabon remains yet insufficient, because of several reasons, namely the lack of technical knowledge by farmers to manage larger fields, the pests and diseases [4][5][6][7]. Indeed, cassava plants are subjected to pests and diseases at all stages of their vegetative cycle and on roots, leaves and stems.…”

Section: Introductionmentioning

confidence: 99%

Occurrence, Distribution and Farmers' Perceptions of Cassava Diseases in Gabon, Central Africa

Armel,

Dyana,

Armel

et al. 2023

ARJA

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Aims: In order to identify and assess the level of cassava diseases in farms present in Gabon, disease surveys were carried out across the country in 2021 and 2022. Methodology: The method used is based on administration of questionnaire to cassava growers, supplemented by the recognition of disease symptoms on 30 randomly selected plants in farms. Results: Some 201 cassava growers were interviewed, 84.04% (n=169) of them were women and 15.92% (n=32) men. Nearly 65.41% of the farmers interviewed had a primary school education and were aged between 51 and 55. The majority of these producers had farming as their main activity (89.73%). The results showed the occurrence of five cassava diseases in the study area: cassava mosaic (Im = 60.22%; Sm = 2.95), anthracnose (Im = 19.45%; Sm = 3), leaf necrosis (Im= 9.95%; Sm = 2.71), bacteriosis (Im = <1%; Sm = 3), and root rot (Im = <1%; Sm = 2.61). Among these diseases, mosaic was the most frequently observed in the provinces surveyed. Its incidence was lowest in Estuaire (38.40%) and highest in Ogooué-Ivindo (71.36%) and Ogooué-Maritime (71.76%). Anthracnose incidence was lowest in Moyen-Ogooué (4.05%) and highest in Haut-Ogooué (36.50%). For leaf necrosis, Woleu-Ntem (0.71%) and Ogooué-Ivindo (31.11%) recorded the lowest and highest incidence respectively. Conclusion: In order to control these cassava diseases, it is important to initiate and implement awareness campaigns and training workshops for growers to encourage them to adopt good farming practices.

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“…As many as 100 000 insect species have been reported from the area, but Miller and Rogo (2002) suggest that species richness could exceed 600 000 species. In Gabon, a central-African country which is still covered by 80% of tropical rainforests, insect inventories have only considered butterflies (vande Weghe 2010), a few groups with limited number of species such as Mantodea (Roy 1973;Moulin 2018), Lucanidae (Maes and Pauly 1998), or Apoidae (Pauly 1998), and groups with specific economical and (or) agronomical importance such as Pseudococcidea (Hemiptera) and their parasitoids (Boussienguet et al 1991). A few studies have also targeted terrestrial arthropod assemblages along human disturbance gradients (Basset et al 2004(Basset et al , 2008.…”

Section: Introductionmentioning

confidence: 99%

Characterization and comparison of poorly known moth communities through DNA barcoding in two Afrotropical environments in Gabon

Delabye

Rougerie

Bayendi

et al. 2019

Genome

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Biodiversity research in tropical ecosystems—popularized as the most biodiverse habitats on Earth—often neglects invertebrates, yet invertebrates represent the bulk of local species richness. Insect communities in particular remain strongly impeded by both Linnaean and Wallacean shortfalls, and identifying species often remains a formidable challenge inhibiting the use of these organisms as indicators for ecological and conservation studies. Here we use DNA barcoding as an alternative to the traditional taxonomic approach for characterizing and comparing the diversity of moth communities in two different ecosystems in Gabon. Though sampling remains very incomplete, as evidenced by the high proportion (59%) of species represented by singletons, our results reveal an outstanding diversity. With about 3500 specimens sequenced and representing 1385 BINs (Barcode Index Numbers, used as a proxy to species) in 23 families, the diversity of moths in the two sites sampled is higher than the current number of species listed for the entire country, highlighting the huge gap in biodiversity knowledge for this country. Both seasonal and spatial turnovers are strikingly high (18.3% of BINs shared between seasons, and 13.3% between sites) and draw attention to the need to account for these when running regional surveys. Our results also highlight the richness and singularity of savannah environments and emphasize the status of Central African ecosystems as hotspots of biodiversity.

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Essais de lutte biologique contre la Cochenille du manioc au Gabon: I. — Établissement, dispersion du parasite exotiqueEpidinocarsis lopezi [Hym.: Encyrtidae] et déplacement compétitif des parasites indigènes

Cited by 11 publications

References 12 publications

Impact of an exotic parasitoid onPlutella xylostella(Lepidoptera: Plutellidae) population dynamics, damage and indigenous natural enemies in Kenya

Impact of an exotic parasitoid onPlutella xylostella(Lepidoptera: Plutellidae) population dynamics, damage and indigenous natural enemies in Kenya

Occurrence, Distribution and Farmers' Perceptions of Cassava Diseases in Gabon, Central Africa

Characterization and comparison of poorly known moth communities through DNA barcoding in two Afrotropical environments in Gabon

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