Biological control of the cassava mealybug, Phenacoccus manihoti (Hom., Pseudococcidae) by Epidinocarsis lopezi (Hym., Encyrtidae) in West Africa, as influenced by climate and soil

Neuenschwander, Peter; Hammond, W. N. O.; Ajuonu, O.; Gado, Aishatu Adamu; Echendu, N.; Bokonon-Ganta, Aimé H.; Allomasso, R.; Okon, Iniobong E.

doi:10.1016/0167-8809(90)90122-t

Cited by 39 publications

(27 citation statements)

References 15 publications

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“…The plant can sustain large numbers of CM, but high densities and decreased plant vigour affect CM size, survivorship and fecundity (Gutierrez et al 1988a). Generalist hyperparasitoids do not appear to affect CM control by E. lopezi (Neuenschwander & Hammond 1988;Neuenschwander et al 1989Neuenschwander et al , 1990Goergen & Neuenschwander 1992) and their effect is included in the model as a density-dependent function. Generalist hyperparasitoids do not appear to affect CM control by E. lopezi (Neuenschwander & Hammond 1988;Neuenschwander et al 1989Neuenschwander et al , 1990Goergen & Neuenschwander 1992) and their effect is included in the model as a density-dependent function.…”

Section: Cassava Systemmentioning

confidence: 99%

Factors Affecting Biological Control of Cassava Mealybug by Exotic Parasitoids: A Ratio-Dependent Supply-Demand Driven Model

Gutiérrez¹,

Neuenschwander²,

Alphen³

1993

The Journal of Applied Ecology

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. Summary 1. A unified ratio-dependent supply-demand driven tritrophic model of the cassava (Manihot esculenta Crantz) system was compared to field data, and then used to explore the basis for the successful control of cassava mealybug (CM, Phenacoccus manihoti Mat. -Ferr.) in Africa by the exotic parasitoid Epidinocarsis lopezi (DeSantis). The causes for the failure of the related parasitoid E. diversicornis (Howard) to establish were examined. 2. Among the important findings are: (i) the functional and numerical responses of either parasitoid alone are insufficient to explain the observed dynamics of the mealybug; (ii) rainfall and its enhancement of the fungal pathogen Neozyites fumosa suppress CM numbers sufficiently during the wet season so that the parasitoid E. lopezi, with its efficient search, can regulate CM density at low levels during the dry season; (iii) weather and soil factors (e.g. nitrogen and water) affect plant growth rates directly, and CM size and number dynamics and parasitoid sex ratios indirectly; (iv) the effects of host-size dynamics on sex ratios favour E. lopezi over E. diversicornis; (v) the importance of low rates of parasitoid immigration for the successful regulation of CM is demonstrated; (vi) the higher host-finding capacity of E. lopezi enhances its dominance over E. diversicornis; but (vii) the sway of E. lopezi in cases of multiple parasitism causes the competitive displacement of E. diversicornis from the system during periods when few hosts are available and/or when weather-induced plant stress decreases host size, favouring a stronger male-biased sex ratio in E. diversicornis than in E. lopezi. 3. This modelling paradigm allows the richness of the observed biology to be incorporated with relative ease.

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Section: Cassava Systemmentioning

confidence: 99%

Factors Affecting Biological Control of Cassava Mealybug by Exotic Parasitoids: A Ratio-Dependent Supply-Demand Driven Model

Gutiérrez¹,

Neuenschwander²,

Alphen³

1993

The Journal of Applied Ecology

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“…All factors subject to strong feedbacks were excluded, as discussed by Neuenschwander et al (1990). For the final analysis, factors contributing significantly (P= 0.05) were retained (though in one case a P-value of 0.059 was accepted).…”

Section: Discussionmentioning

confidence: 99%

Impact of Two Accidentally Introduced Encarsia Species (Hymenoptera: Aphelinidae) and Other Biotic and Abiotic Factors on the Spiralling Whitefly Aleurodicus dispersus (Russell) (Homoptera: Aleyrodidae), in Benin, West Africa

D'almeida¹,

Lys²,

Neuenschwander³

et al. 1998

Biocontrol Science and Technology

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In early 1993, the spiralling whitefly, Aleurodicus dispersus (Russell), was observed in Benin for the first time, inflicting damage to ornamental and shade trees and cassava. The parasitoids Encarsia ?ha it iensis Dozier and E. guadeloupae Viggiani were observed in the second half of 1993. They were known to have the same host in the Pacific region, and were thought to have been introduced accidentally. The impact of these parasitoids was quantified using four surveys from 1993 to 1995 (on 2541 trees in 537 localities) and by population studies on guava. In 1993, A. dispersus occurred mostly in towns in the southern part of Benin; penetration into farmland was observed later. E. ?haitiensis was more abundant and widespread than E. guadeloupae, and by 1995 it had been recovered from most (84%) of the infested localities. On guava trees, the annual peaks of A. dispersus population declined by ca. 80% between 1993 and 1996. During the same period parasitism rates increased. Econometric multiple regression analyses based on 996 infested trees demonstrated that A. dispersus population densities, the proportion of infested trees and damage scores all declined significantly with increasing duration of the presence of the parasitoids, indicating their impact. Other variables were also significantly related to A. dispersus levels.

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“…Plant vigour enhancement due to fertilizer use has been explained as the cause behind ability of plants to withstand pests and diseases (Neuenschwander et al, 1990;Satti, 2012). The effect of NPK fertilizer application on pests and disease incidences and severity in the trials varied depending on site and cultivar.…”

Section: Discussionmentioning

confidence: 99%

Effect of modified spacing arrangements, fertilizer use and legume intercrop on prevalence of cassava brown streak disease in Western Kenya

Ememwa¹,

Wéré²,

Ogemah³

et al. 2017

Afr. J. Agric. Res.

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Cassava is an important food security crop in Western and Coastal counties of Kenya. As a food security crop, it is continuously cultivated with minimal inputs. Its production is constrained by factors like declining soil fertility, poor agronomic practices, pests and diseases. Cassava brown streak disease (CBSD) is a viral infection attacking the cassava crop causing yield losses of up to 100%. The current study was intended to determine the effect of planting technologies on the prevalence of CBSD in two agro-ecological zones of Western Kenya: lower midland (LM1) and upper midland (UM1). Various spacing arrangements, four fertilizer regimes, legume intercrop and improved cassava cultivars were tested in a randomised complete block design (RCBD) with each site as a replicate. Data was collected on pathogen population and disease incidences and severity, and cassava and legumes yields. Results showed no effect of modified spacing and legume intercrop on CBSD incidence. However, incidences varied by cassava cultivar (9 to 59%) and fertilizer application (3 to 41%). Low CBSD incidences (3 to 16%) were observed over time in management strategies involving fertilizer NPK 17:17:17 suggesting that vigour enhancement may have contributed to low CBSD incidences. Low incidence of CBSD on improved cultivars indicates that CBSD can be mitigated through crop improvement technologies such as breeding for resistance to diseases. Intercropping cassava with beans and modification of spacing did not demonstrate an effect on CBSD incidence. However, 2 m× 0.5 m spacing arrangement can compensate for rising land pressure in Western Kenya and areas facing similar problem.

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Biological control of the cassava mealybug, Phenacoccus manihoti (Hom., Pseudococcidae) by Epidinocarsis lopezi (Hym., Encyrtidae) in West Africa, as influenced by climate and soil

Cited by 39 publications

References 15 publications

Factors Affecting Biological Control of Cassava Mealybug by Exotic Parasitoids: A Ratio-Dependent Supply-Demand Driven Model

Factors Affecting Biological Control of Cassava Mealybug by Exotic Parasitoids: A Ratio-Dependent Supply-Demand Driven Model

Impact of Two Accidentally Introduced Encarsia Species (Hymenoptera: Aphelinidae) and Other Biotic and Abiotic Factors on the Spiralling Whitefly Aleurodicus dispersus (Russell) (Homoptera: Aleyrodidae), in Benin, West Africa

Effect of modified spacing arrangements, fertilizer use and legume intercrop on prevalence of cassava brown streak disease in Western Kenya

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