Peter Neuenschwander

Peter Neuenschwander
Consultative Group on International Agricultural Research | CGIAR · International Institute of Tropical Agriculture

PhD

About

136
Publications
32,474
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
4,156
Citations
Additional affiliations
January 1983 - present
International Institute of Tropical Agriculture
Position
  • emeritus scientist
Description
  • since 1983 in different functions

Publications

Publications (136)
Article
Biodiversity loss and invasive species are exacting negative economic, environmental and societal impacts. While the monetary aspects of species invasion have been well-assessed, their impacts on human and social livelihood outcomes routinely remain obscure. Here, we empirically demonstrate several important human health and demographic consequence...
Preprint
Full-text available
As prominent features of the Anthropocene, biodiversity loss and invasive species are exacting serious negative economic, environmental and societal impacts. While the monetary aspects of species invasion are reasonably well assessed, their human and social livelihood outcomes often remain obscure. Here, we empirically demonstrate the (long-term) h...
Chapter
Under relentless global population growth the key challenge is to increase agricultural production while preserving biodiversity and reducing the pressure on ecosystems and natural resources. As a first step, the development of sustainable agricultural practices requires thorough understanding of all biodiversity components and their interlinkages...
Chapter
This chapter reviews control methods for the main pests affecting fruit and other tree crops. It describes the use of classical biological control for mango, papaya, cacao, coconut and citrus. Mango mealybug, Rastrococcus invadens, has been controlled with great success across West and Central Africa by two parasitoids. On papaya, the spiralling wh...
Article
Full-text available
Biological control, a globally-important ecosystem service, can provide long-term and broad-scale suppression of invasive pests, weeds and pathogens in natural, urban and agricultural environments. Following (few) historic cases that led to sizeable environmental up-sets, the discipline of arthropod biological control has—over the past decades—evol...
Preprint
Biological control constitutes one of the world’s prime ecosystems services, and can provide long-term and broad-scale suppression of invasive pests, weeds and pathogens in both natural and agricultural environments. Following (very few) widely-documented historic cases that led to sizeable environmental up-sets, the discipline of insect biological...
Preprint
Full-text available
Biological control constitutes one of the world’s prime ecosystems services, and can provide long-term and broad-scale suppression of invasive pests, weeds and pathogens in both natural and agricultural environments. Following (very few) widely-documented historic cases that led to sizeable environmental up-sets, the discipline of insect biological...
Article
Full-text available
In a twenty-year effort at Drabo, southern Benin, small remnant forests, young fallow and agricultural fields were linked and rehabilitated to develop a 14 ha forest reserve. Forest regrowth was encouraged by managing the natural growth of the local fallow vegetation and by bringing in seeds and other propagules from forest islands of Benin. The su...
Article
Full-text available
The management schemes of four rain forest patches in southern Benin and southwestern Nigeria, which led to the successful protection of numerous threatened plants and animals over the last 20 plus years, are analysed. Since climatic conditions are similar, tree composition depends largely on different availability of water and documented biodivers...
Article
Full-text available
Papaya mealybug (PM), Paracoccus marginatus, was first detected on the African continent towards the end of 2009 when outbreaks were causing severe damage in papaya orchards near Accra in Ghana1. In a spectacular spread, PM had previously invaded most tropical regions of the world within only two decades. Although first samples had been collected i...
Book
Full-text available
Biological control is a significant component of integrated pest management programs around the world. However, uncertainty about the risk of unanticipated effects on non-target organisms is one of the major concerns surrounding the release of biological control agents. This brief has been prepared with the intention of: • aiding scientists within...
Book
Full-text available
The information needed for implementing nature protection in Benin is sparse and scattered. This volume for the first time presents information in 33 chapters covering rare and threatened plants, insects, fishes, antelopes, large cats, etc. The status of over 550 species is evaluated according to IUCN criteria and their local names, short descripti...
Article
Under the conditions of a mass-trapping experiment with 2 yellow sticky traps (YT)/small tree, 16 times as many parasitoids and predators as Dacus oleae (Gmel.) were caught. If only known parasitoids and predators of the main olive pest insects D. oleae, Saissetia oleae (Oliv.), Prays oleae Bern., and Aspidiotus nerii Bouché were considered, this r...
Article
The capability of Epidinocarsis lopezi (De Santis) (Hymenoptera: Encyrtidae) to control the cassava mealybug (CM) Phenacoccus manihoti Mat.-Ferr. (Homoptera: Pseudococcidae) was investigated in Nigeria using physical and chemical exclusion experiments. In two sleeve cage experiments CM populations, about 2 months after artificial infestation, were...
Article
In uninfested fields, 80 cassava tips were artificially infested with 0, 1, 2, 4, 8, 16, 32, or 64 third instars, and 20 or 100 eggs of cassava mealybug, Phenacoccus manihoti Matile-Ferrero (Hom., Pseudococcidae). Another 80 uninfested tips served as a control. Tips were arranged in a circle of 28 m diameter, in the centre of which the following ex...
Chapter
Full-text available
In Benin, insects are found in all ecosystems, whereby the species richness is greatest in the rainforest relicts in the south. The biogeographical situation is of particular interest: Benin lies in the relatively dry zone called Dahomey Gap, which is situated between the two more humid forest blocks in the East and the West. The composition of the...
Article
Full-text available
In December 2009, the Plant Protection and Regula-tory Services Directorate (PPRSD), Accra, Ghana requested assistance from the International Insti-tute of Tropical Agriculture (IITA) in Benin for the identification of an unknown mealybug that was severely threatening papaya in orchards at Nsawam in the Eastern Region and Bawjiase in the Central Re...
Chapter
Full-text available
In the year 2000 the German Federal Ministry of Education and Research initiated the major German-African project BIOTA (Biodiversity Transect Analysis) West. Over 150 botanists, zoologists, meteorologists, remote sensing specialists, geographers, economists and ethnologists collected full data sets on biodiversity and important influencing factors...
Article
Full-text available
The spiraling whitefly Aleurodicus dispersus (Russell) is an insect pest that causes substantial damage to ornamental plants, shade trees and food crops. It was first observed in Benin in 1993. Two host specific parasitoids, Encarsia dispersa and E. guadeloupae, fortuitously introduced with its host, were recovered in the second half of 1993 in Sou...
Article
Though studies in biological control belong to the best documented research in ecology the actual decision to release a beneficial organism is often influenced by diffuse fears of anything foreign. Yet, agriculture is largely based on exotics; others remain inconspicuous and integrate themselves without problems into the existing ecosystems; and on...
Article
From 1975 to 1979 the population dynamics of Saissetia oleae were followed on olive trees, the only important host of this scale in Crete, by monthly recordings of population numbers, parasitization rates, climatological data, and effects of insecticide applications. Outbreaks, i. e. high scale densities, were frequent mainly in humid regions of th...
Article
During the past six years, the South-American encyrtid wasp Epidinocarsis lopezi (De Santis) was released from the ground and from the air in about 100 areas in Africa for the biological control of the cassava mealybug (CM) Phenacoccus manihoti Mat.-Ferr. It was established in all release sites and, in 1988, occurred in 18 African countries over 1....
Article
The crop loss which is directly attributable to D. oleae larvae is assessed for the two major oil varieties, Tsounati and Koroneiki, in Crete, Greece at harvest time and following different periods of outdoor storage of the harvested olives before milling. Loss through preharvest fruit drop is not considered here. The amount of pulp directly consum...
Article
The experiments were carried out on two varieties of olive trees under irrigated and non irrigated conditions in Crete, Greece. Fruit drop, as it is caused by D. oleae, was simulated by picking up to 50% of all olives in either August or September from entire trees or from marked branches. From August up to harvest in November-December, olives on t...
Article
The spatial dispersion pattern and the intracanopy distribution of the mango mealybug, Rastrococcus invadens Williams, were assessed during one year in a small mango plantation, in order to develop sampling plans and facilitate sampling in mango trees. Mean number of mango mealybugs per leaf differed significantly between trees for most sampling da...
Article
Full-text available
The efficiency of natural enemies, especially the exotic parasitoid Epidinocarsis lopezi (De Santis) and the indigenous predator Exochomus troberti Mulsant, in reducing populations of the cassava mealybug (CM), Phenacoccus manihoti Mat.-Ferr., was studied through exclusion experiments. In the physical exclusion experiment lasting 52 days, CM number...
Article
Full-text available
We assessed the effect of two biological control agents, the mirid Eccritotarsus catarinensis (Carvalho) and the weevil Neochetina eichhorniae (Warner), singly or in combination, on the competitive ability of their host plant, water hyacinth, Eichhornia crassipes (Mart.) Solms-Laub., grown in a screen house, in competition with another aquatic plan...
Article
Over several years, the fruits of a total of 40 olive varieties were exposed to D. oleae females in the laboratory in two types of choice experiments. Oviposition was related to several physical factors, which were also tested individually in more detail on fewer varieties. Susceptibility of olives to olive fly attack increased with the size of the...
Article
The survey was conducted on cultivated olives in the south-western Cape Province, and on several wild olive species in the Cape Province and Transvaal from March to May 1981. Though Dacus oleae (Gmel.) was found in all areas, its occurrence on wild olive trees (Olea europaea africana only) was irregular. On wild olives, mortality of eggs and young...
Article
Full-text available
Taxonomy: Earliest descriptions of Pistia stratiotes L. (Araceae) were by the ancient Egyptians and by the Greek philosophers Dioscorides and Theophrastus. This plant has also been mentioned by Plinius (Stoddard, 1989). According to Bogner and Nicolson (1991) P. stratiotes is the solitary member of the subfamily Pistioidea in Araceae. However, USDA...
Conference Paper
Full-text available
Cassava is well recognized for its capacity to address food needs of vulnerable communities in unstable environments in SSA. IITA and colleagues in African NARS, in collaboration with CIAT and ARIs have played leading roles in the development of improved cassava varieties which are disease and pest resistant, early maturing, and high yielding. Thro...
Article
Full-text available
. 1In cassava fields in Africa, population sex ratios of Epidinocarsis fopezi vaned from 0.44 (males to total parasitoids) at low host densities to highly male-biased ratios of 0.70 at high host densities.2This variability is caused by the difference in allocation of sons and daughters to hosts of different sizes, through the following mechanisms:...
Article
Full-text available
There has been some debate recently about the cause of the decline of water hyacinth on Lake Victoria. While much of this evidence points to classical biological control as the major factor, the El Niño associated weather pattern of the last quarter of 1997 and the first half of 1998 has confused the issue. We argue first that the reductions in wat...
Article
Full-text available
Water hyacinth (Eichhornia crassipes (Mart.) Solms-Laub.) remains a problem waterweed worldwide, for which biological control offers a sustainable solution. Under laboratory conditions, we investigated the interaction between two established weevil species Neochetina eichhorniae (Warner), Neochetina bruchi Hustache and the mirid Eccritotarsus catar...
Article
Full-text available
Since 1999, four specific weevils (Coleoptera, Curculionidae) were released in the Republic of Congo against three exotic floating water weeds: Neochetina eichhorniae Warner and N. bruchi Hustache against water hyacinth, Neohydronomus affinis Hustache against water lettuce, and Cyrtobagous salviniae Calder and Sands against water fern. Recoveries o...
Article
Full-text available
Discusses cassava mealybug Phenacoccus manihoti and cassava green mite Mononychellus tanajoa, both of which - following introduction to Africa in the early 1970s - have spread at a rapid pace to threaten crops. The spread of both pest species in Africa is outlined, and the subsequent search for organisms with potential for biological control is rep...
Article
Full-text available
Between 1991 and 1993, two weevils species, Neochetina eichhorniae (Warner) and N. bruchi Hustache (Col.: Curculionidae), were released at several localities on the Ouémé and Zou River systems in Benin for biological control of water hyacinth, Eichhornia crassipes. In Benin, N. eichhorniae became the dominant and ubiquitous species, whereas N. bruc...
Article
Full-text available
The weevil Neohydronomus affinis Hustache (Coleoptera: Curculionidae) of Neotropical origin was imported into Benin in 1993 and released in 1995 for the biological control of water lettuce Pistia stratiotes L. (Araceae). After the release of N. affinis in water bodies linked to the Mono River system, southwestern Benin, larval mines characteristic...
Article
Full-text available
A biological control program of water hyacinth was undertaken in Southern Benin between 1991 and 1993. It consisted of the release of three natural enemies, two weevil species and one moth, that feed exclusively on water hyacinth. In 1999, a survey of 365 men and women from 192 households in 24 villages in the target area, using participatory and q...
Article
Full-text available
Cassava is called Africa's food insurance because it gives stable yields even in the face of drought (Fig. 1), low soil fertility and low intensity management. It can remain in the soil until needed, spreading out food supply over time, helping families through the hungry time each year when seasonal harvests run out and, helping people avert the t...
Chapter
This book contains 24 chapters containing case studies and research papers on the biological control of pests by naturally occurring agents, exotic agents or by seasonal manipulation in Africa. This book will be of interest to those working in the areas of crop protection, entomology and pest management. An index of terms and species found in the b...
Chapter
Full-text available
This book contains 24 chapters containing case studies and research papers on the biological control of pests by naturally occurring agents, exotic agents or by seasonal manipulation in Africa. This book will be of interest to those working in the areas of crop protection, entomology and pest management. An index of terms and species found in the b...
Chapter
This book presents experiences and successful case studies of integrated pest management (IPM) from developed and developing countries and from major international centres and programmes. It contains 39 chapters by many contributors addressing themes such as: emerging issues in IPM, including biotechnology, pesticide policies and socioeconomic cons...
Article
Mango mealybug, an exotic pest of mango, was first observed in Benin in 1986. In a biological control programme, natural enemies were successfully released in the following years. The present study is the first attempt to measure the impact of the biological control of mango mealybug over a large area, through a survey of mango producers. Most prod...
Article
Full-text available
South Eastern Ghana and the south of Togo and Benin constitute a bio-geographically remarkable area, called the Dahomey Gap, whose entomological fauna is still little known despite its unique features. The geographical barrier separating this region from the two forest blocks with wetter climates, in the east and the west, is more strongly marked i...
Article
Full-text available
Among several natural enemies introduced to combat the cassava mealybug, Phenacoccus manihoti (Homoptera: Pseudococcidae), the neotropical parasitoid Apoanagyrus (Epidinocarsis) lopezi (Hymenoptera: Encyrtidae) was the most successful. It established in 26 African countries, causing a satisfactory reduction in the population density of P. manihoti...
Article
Full-text available
Pest populations of the cassava mealybug Phenacoccus manihotiMat.-Ferr. (Homoptera; Pseudococcidae) were reduced successfully by the biological control agent Apoanagyrus (Epidinocarsis) lopezi De Santis (Hymenoptera: Encyrtidae) throughout most of sub-Saharan Africa. The economics of the project were evaluated based on data from field trials, socio...
Chapter
This book contains 11 chapters by 35 contributors, which are noticed elsewhere. The papers were presented at an international symposium held in Montpellier, France, on 17-20 October 1999.
Article
Full-text available
The metapopulation dynamics of the African cassava food web is explored using a physiologically based tritrophic model. The interacting species are cassava, cassava mealybug and its natural enemies (two parasitoids, a coccinellid predator and a fungal pathogen), and the cassava greenmite and its natural enemies (two predators and a fungal pathogen)...
Article
Full-text available
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 ?haitiensis 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,...
Article
The effect of fertilizer and mulch across trophic levels of the cassava ecosystem, i.e., the plant, the cassava mealybug (CM), the encyrtid wasp Apoanagyrus lopezi and its hyperparasitoids, was studied in two field experiments planted in southern Benin. Several cassava cultivars with different branching patterns and varying susceptibility to the ca...
Article
Abstract The coccinellid Hyperaspis notata Mulsant was introduced into Africa for the biological control of the cassava mealybug, Phenacoccus manihoti Matile-Ferrero. Two cohorts of strains, one originating from Southern Brazil and Paraguay feeding on P. manihoti, and one from Colombia feeding on Phenacoccus herreni Cox & Williams were studied at d...
Article
The coccinellid, Hyperaspis notata Mulsant, is associated with the mealybugs Phenacoccus manihoti Mat.-Ferr. and P. herreni Williams, on cassava in southern Brazil and the highlands of Colombia. Brought to Africa to help control the accidentally introduced P. manihoti, its range of target prey and plant food sources as well as its performance under...
Article
Full-text available
Techniques for evaluating biological control of cassava mealybug (Phenacoccus manihoti Matile-Ferrero), mango mealybug (Rastrococcus invadens Williams), and spiralling whitefly (Aleurodicus dispersus Russell) are described. In each case, two exotic hymenopterous parasitoids were introduced. Alone or together, they brought the pests under control, w...
Article
Full-text available
The competition between Gyranusoidea tebygi Noyes and Anagyrus mangicola Noyes (both Hymenoptera: Encyrtidae), exotic parasitoids of the mango mealybug, Rastrococcus invadens Williams (Homoptera: Pseudococcidae) was studied in the laboratory. No significant differences were found in the way each parasitoid species examined, attacked, stung, and ovi...
Article
Full-text available
Host stage selection and sex allocation by Gyranusoidea tebygi Noyes (Hym,, Encyrtidae) were studied in choice and no-choice experiments in the laboratory. The parasitoid reproduced on first, second, and third instars of the mango mealybug, Rastrococcus invadens Williams (Hem., Pseudococcidae), and it avoided hosts that were already parasitized. Ho...
Article
Full-text available
Host stage selection and sex allocation behaviors by Anagyrus mangicola Noyes were studied in choice and no-choice experiments in the laboratory. All host instars of the mango mealybug (MM), Rastrococcus invadens Williams (Hem., Pseudococcidae), were parasitized. First instars were less often encountered, seldom stung, and parasitized. They were, h...
Article
Full-text available
Life table data for Rastrococcus invadens and its introduced natural enemy Gyranusoidea tebygi were obtained in the field and in the laboratory. The mealybug population's potential rate of increase ranged from 0.066/day to 0.078/day. The potential for increase of the parasitoid was double that of its host. Seasonal fluctuations in abundance of R. i...
Article
Full-text available
The distribution of Rastrococcus invadens among different host plants and the impact of the mealybug on mango growth were investigated on 2067 trees in three surveys across all the ecological zones of Benin. The first survey started in 1989, less than 1 year after the first release of the exotic parasitoid Gyranusoidea tebygi. Within 3 years, G. te...