Damage and Loss Caused by the Larger Grain Borer Prostephanus truncatus

An overview of information on damage caused by the larger grain borer is provided, including details of early studies examining commodities that might be attacked and the importance of LGB field infestations in relation to storage losses. In addition, examples are given from published information on the weight losses that can result from LGB infestation in maize and cassava, with case studies. Problems in applying conventional methods of loss assessment to commodities attacked by LGB are highlighted, to suggest the need to develop alternative techniques. Experiences in developing and applying novel approaches to loss assessment for LGB are reported. Examples are also given to show how loss and damage estimates have been used to describe the impact of the pest on farmers, and on local, regional and international grain trading.     

Biological Control of the Larger Grain Borer, Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae)

Biological control was first considered shortly after the accidental introduction of Prostephanus truncatus in Africa in the early 1980's. This article reviews first the history of the biological control efforts with a focus on the results and recommendations of the initial international meetings and foreign exploration projects, followed by a discussion of the more important biocontrol agents, in particular the histerid Teretrius nigrescens. Since the release of T. nigrescens in Africa a number of techniques have been employed by different research groups to measure the effect of the natural enemy on P. truncatus, including pheromone trapping, field experiments, gut analysis grain store surveys, simulation modelling, and statistical and economic analysis the conclusions of these various studies have been largely equivocal, and the results of studies with recent data suggest that uncertainty is growing. Further resources and time are needed both for a proper evaluation and for the further development of control strategies compatible with biological control.     

The Biology of the Larger Grain Borer, Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae)

After about 25 years of intensive research a substantial moment of information has accumulated on the basic biology of Prostephanus truncatus in stored products. This article reviews the literature on the geographical distribution, biotypes, symbiotic associations, mating and flight behaviour, oviposition, and development on both agricultural and non-agricultural hosts. The current knowledge about the nutritional biology (including the role of symbionts) and host finding behaviour (including the inter-linked roles of plant chemicals and the insect's own pheronones) are highlighted as research areas which deserve future attention. In addition, few studies have been conducted to determine the extent to which the biology of P. truncatus permits it to survive and reproduce in non-agricultural environments. These areas of study should be pursued as possible routes to providing more effective integrated pest managements strategies for the larger grain borer.     

Chemical,Physical and Cultural Control of <Emphasis Type="Italic">Prostephanus truncatus</Emphasis>

Since its introduction into Africa 25 years ago, approaches to the management of the larger grain borer at farm level have gone through many changes. This article reviews the literature on chemical and non-chemical protection of maize and cassava after harvest from the perspective of the small-scale farmer during this period. The influence of traditional store design on Prostephanus truncatus and the history of changes in the use of post-harvest chemicals are described. Synthetic and non-synthetic chemicals, host plant resistance, store design, fumigation, plant products, inert dusts and thermal disinfestation all have a role to play. Attention is also given to the ways in which farmers in sub-Saharan Africa coped with the introduction of and damage caused by Prostephanus truncatus. Given the expense, poor distribution and health concerns of the use of synthetic chemicals, emphasis should be placed on the integration of low cost and low impact methods that could provide adequate control of this important post-harvest pest.     

A review of investigations to improve pest managemet of stored maize in smallholder farms in Kenya

A 4-year project in Kenya to develop management strategies for the larger grain borer (Prostephanus truncatus) in smallholder maize stores is described. The entomological investigations included behavioural and ecological studies of pest activity in experimental and farmers' maize stores and the natural environment, the use of insecticides to protect maize stored as grain and cobs and the release of a biological control agent. The latter was a predatory beetle; this marks the first release of a biological control agent against a storage pest in East Africa. The operation of a national trapping network to assess the extent and future spread of the pest and predator and target control campaigns is outlined. Recommendations for the control of the stored product pests, resulting from these investigations, were tested for likely adoption and modification in the light of socioeconomic surveys and a cost-benefit analysis. A decision tree approach to managing stored product pests is suggested which allows extension workers and farmers to decide the necessity of pesticide application when assessing how best to protect stored maize.     

Ecological Studies on the Larger Grain Borer, Prostephanus truncatus (Horn) (Col.: Bostrichidae) and their Implications for Integrated Pest Management

In this article, we review studies of the ecology of the larger grain borer, Protephanus truncatus, both outside and within the maize storage systems. Laboratory studies have shown that P. truncatus can breed on a wide range of woody substrates (branches, roots, and seeds). Pheromone trap catches in different habitats strongly suggest that P. truncatus is well-established in certain non-agricultural environments, presumably breeding in dead or dying wood. In Meso-America, West and East Africa, P. truncatus reproduction in the field has been documented in branches ring-barked by cerambycid beetles. Within a maize store, P. truncatus densities can increase from very small initial colonies of probably less than 200 individuals to densities in excess of 1000 beetles per kg after about 4–6 months of storage. Insect parasitoids are very often found in smallholders' grain stores attacked by P. truncatus, but they do not contribute significantly to population regulation. Declines in maize store population levels in Benin from 1993 to 1996, and in adult abundance in pheromone traps in the natural environment in Kenya, have been attributed to predation by the introduced predator, Teretrius nigrescens, but in recent years pheromone trap catches in West Africa suggest that the situation may be complex. Several environmental factors, notably temperature, humidity, and daylength, and their interactions, have been correlated with P. truncatus flight activity, as well as, in West Africa, the emptying of maize stores. Laboratory experiments have shown food quality also affects flight activity. Factors terminating dispersal and flight are most likely attraction to the male-released aggregation pheromone. Short range attraction to plant volatiles has also been recorded. In Africa the highest densities of P. truncatus tend to occur in humid lowlands, which contrasts with the situation in meso-America where P. truncatus tend to occur in greatest numbers in cooler upland regions. Pheromone trap catches can be significant predictors of the risk of stores becoming infested. Coupled with the development of a rule-based model of flight activity, these studies may offer the prospect of predicting the risk of store infestation based upon temperature and humidity measurements.     

Ten years after the arrival in Ghana of Larger Grain Borer: Farmers' responses and adoption of IPM strategies

Small-scale on-farm storage of maize in Africa is changing, in part due to shifts in the threat from insect pests. A questionnaire survey of 242 households in four closely situated districts in the Volta Region of Ghana, where Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) arrived ten years ago, was used to show how maize storage practices have changed over the last five years. The survey included asking farmers about changing use of contact insecticides in maize storage in order to guide research and future recommendations. We found high uptake of recommendations developed by a project for reducing Larger Grain Borer damage. Farmers are being pro-active in preventing extensive damage from this pest by replacing the wood of their storage structures, increasing inspection of maize in their stores, and increasing their use of grain protectants. There were differences in post-harvest practices according to district, ethnic group and gender. Grain protectants (traditional methods or commercially available products) were used by 45% of farmers. Cost was the most often cited constraint to the use of recommended commercial products. Farmers reported that their three most important sources of information on maize storage were the agricultural extension services, radio programmes and local networks of friends, family and fellow farmers.     

The integrated control concept and its relevance to current integrated pest management in California fresh market grapes

The foundation of an integrated pest management program involves valid treatment thresholds, accurate and simple monitoring methods, effective natural controls, selective pesticides and trained individuals who can implement the concept. The Integrated Control Concept written by Stern, Smith, van den Bosch and Hagen elucidated each of these points in an alfalfa ecosystem. Alfalfa hay (Medicago sativa L.) has a low per acre value, requires little hand labor and is primarily marketed in the USA. In contrast, fresh market table grape (Vitis vinifera L.) has a high per acre value, requires frequent hand labor operations, suffers unacceptable cosmetic damage and is marketed throughout both the USA and the world. Each of the components of a working IPM program is present in table grape production. Marketing grapes to foreign countries presents special problems with pests considered invasive and where residue tolerances for some selective insecticides are lacking. However, fresh market grape farmers are still able to deal with these special problems and utilize an IPM program that has resulted in a 42% reduction in broad‐spectrum insecticide use from 1995 to 2007. Copyright © 2009 Society of Chemical Industry     

Responding to Economic Crisis in Sub-Saharan Africa: New Farmer-Developed Pest Management Strategies in Cocoa-Based Plantations in Southern Cameroon

Cocoa is a key or source of income and poverty reduction in the humid forest of Southern Cameroon. Cameroon like other African countries went through a major economic crisis in the early 1980s with a decline in international commodity prices and significant changes in macroeconomic policies. Structural adjustment reforms following the economic crisis led to removal of fertilizers and pesticides subsidies, cocoa price liberalization and the overall withdraw of Government interventions from the cocoa sub-sector. Cocoa input price increases have been compounded by the devaluation of the CFA Franc, which doubled the prices of the imported pesticides which were considered key to the control of cocoa pests. This overall economic shock led to changes in cocoa producer's production decisions as a response to minimize cost. Among the changes the use of alternatives to imported chemicals for cocoa pest control. Farmers responded to the high prices of pesticides by developing, from local botanical knowledge and pest management strategies, which include plant extracts and plant extracts mixed with pesticides at different proportions. This is a major decision given the importance of imported chemical in the cost of production of cocoa. Valuable indigenous knowledge from farmers could be used also as an effective support system for communicating and diffusing modern knowledge and technologies to farmers. The paper describes the farmer knowledge-based alternatives to chemical pesticides for pest control in cocoa fields as a response to high pest control costs. Pest management specialists are urged to take advantage of this shift in practice and assess their effectiveness for further use. Two sets of questions are posed: (1) were the conventional insecticides, with all their problems, really necessary? and (2) are the materials derived from locally grown plants effective pest management agents or are they, in some way, placebos?     

The bionomics of the African armyworm Spodoptera exempta in relation to its status as a migrant pest

A multidisciplinary study was undertaken on the bionomics of the African armyworm in eastern Africa as a basis for the development of control strategies for this important pest of cereal crops and pastures. Relevant findings from studies on seasonal distribution, migration, field infestations and population cycles are reviewed in relation to understanding the causes for the onset and spread of armyworm outbreaks. It is concluded that the onset of the first outbreaks of an armyworm epidemic is caused by oviposition at high density by moths concentrated by wind convergence at storm outflows. The sources of these moths seem to be low-density populations which survive from one season to the next at sites receiving unseasonable rainfall. Some areas in Tanzania and Kenya are particularly prone to early outbreaks which are potentially critical for the initiation of a subsequent spread of outbreaks downwind throughout eastern Africa. These areas have low and erratic rainfall, and are near the first rising land inland from the coast. Below average rainfall prior to the development of outbreaks increases the probability of their occurrence. Their subsequent spread is enhanced by storms downwind which concentrate moths in flight and by sunshine during caterpillar development. Persistent wet weather reduces the spread of outbreaks. This study demonstrates the importance and value of developing and implementing a long-term monitoring system over a large region, in this case in Africa, not only for the generation of data used by the forecasters for the prediction and location of possible outbreaks, but also for obtaining a clearer understanding of the epidemiology of a highly mobile pest.     

<Emphasis Type="Italic">Anascirtothrips arorai</Emphasis> bhatti (Thysanoptera: Thripidae): A new thrips for Israel

Anascirtothrips arorai was discovered for the first time in the Palearctic region and in new niches: inside fig fruits and in the galls ofGynaikothrips ficorum. http://www.phytoparasitica.org posting May 4, 2007     

Integrated Soybean Pest Management in Micro River Basins in Brazil

A Soybean IPM system was deployed in large, continuous river basin areas. The system was designed to improve the productivity of the rural environment by restoring balance among pests and their natural enemies. The system was developed with the active participation of various governmental, industrial and academic institutions, and it was based on the main approaches utilized by the EMBRAPA soybean IPM program referred here as IPM-Soybean.The work of IPM-Soybean in microbasins is being implemented in five counties in Paraná state (Campo Mourão, Mamborê, Missal, Cambé and Toledo) in an area of approximately 18,020ha of soybean involving 343 producers at various stages of implementation. The results obtained in the Rio do Campo basin in Campo Mourão, after four years of IPM-Soybean, showed drastic changes in pest control practices. Mean number of insecticide applications per cropping year in the river basin fell from 2.8 (1993/94 season) to 1.23 four seasons later. Biological control of the velvetbean caterpillar, Anticarsia gemmatalis, by Baculovirus anticarsia increased 57%, from 205ha treated with this biological product in the 1993/94 season to 2730ha in 1998. A mean of about 300,000 Trissolcus basalis (Wollaston) adults were released per year to control soybean stink bugs. As a consequence of the parasitoid release and the use of more selective insecticides, the number of insecticide applications to control stink bugs was significantly reduced. After two soybean seasons with IPM-Soybean in the river basin, mean applications for stink bugs decreased from 0.81 before the program started to 0.09 in 1996. The mean number of applications in the region and the state respectively were 9.20 and 11.44 times greater. In 1997 and 1998, the results again showed very low population densities of stink bugs in the river basin area, with a consequent reduction in insecticide applications for the control of these pests. Furthermore there was a substantial improvement in the range of products used in this area for soybean pest control. Broad spectrum products, used in 97.5% of the applications before start of IPM-Soybean (1993/94), were replaced with more selective products, especially biologicals and growth regulators. The latter had rarely been used by the river basin producers before the study (0.6% of the applications), but they accounted for 35.8% of the applications after four seasons with IPM-Soybean. IPM-Soybean developed in river basins has resulted in a more stable control system that, in turn, provides greater long-term equilibrium between the pests and the natural enemies populations in these soybean producing areas.     

A Review on Options for Management of Cowpea Pests: Experiences From Uganda

More than 100 field pests of cowpea (Vigna unguiculata L. Walp.) can be found in most of the crop production agroecologies in Africa, but four of these – aphids (Aphis craccivora Koch), flower thrips (Megalurothrips sjostedti Trybom), the legume pod borer (Maruca vitrata Fab. Syn. Maruca testulalis Geyer) and pod sucking bugs – are commonly encountered and are of economic importance in Uganda. The diverse cowpea pest complex dictates that a single control strategy is unlikely to produce satisfactory control.Earlier field studies done in eastern and northern parts of Uganda demonstrated that close spacing (30 × 20cm) effectively reduces aphid infestation (early season pest) but seems to promote thrips, legume pod borers and pod bugs infestation. The other option for management of early season pests and nematodes is seed dressing, especially with carbofuran (Furadan 5G). Late season pests are more effectively controlled by the use of foliar sprays, the type of pesticide depending on the pest profile. Intercropping also offers remedial control, but the crop combination must consider the pest profile, cowpea/sorghum intercrop being effective against aphids and thrips, and cowpea/greengram against legume pod borers and pod sucking bugs. Selected combinations of agronomic, chemical and cultural control measures (Integrated Pest Management), especially when combined with early planting, offer better management options than the use of sole treatments. The success of these packages is highly dependent on the degree and level of farmer involvement and to what extent they are tailored to meet his/her production goals.     

草地贪夜蛾到底有多“贪”

草地贪夜蛾Spodoptera frugiperda被认为是世界上最具破坏性的害虫之一。其巨大的破坏性主要源于其具有贪吃、贪育、贪婪、广适、耐药等特性。治"贪"就是要利用它的贪性发展出一系列的治理措施和技术,使得其贪性难以发挥,将其种群密度控制在经济为害水平以下,以保障作物生产和生态安全。     

Horizontal resistance: core to a research breakthrough to combat Striga in Africa

The parasltie flowering plants, Striga species, represent the largest biological constraint to cereal and legume crop production in sub-Saharan Africa. Eighty-three percent of Striga worldwide (35 species) occurs in Africa. Among them, Striga hermonthica causes the greatest damage. The IITA's scientists began research on breeding maize for horizontal resistance to Striga in 1982. By 1995 a comprehensive approach to combat Striga on maize had been developed and demonstrated. This included the development of a simple field infestation technique, the discovery of durable resistance genes, genetic studies of resistance genes and the formation of many resistant varieties (hybrids and synthetics) with high grain quality, high grain and stover yields and a combined resistance to major biotic and abiotic stresses. Multilocation testing and subsequent seed multiplication of the resistant varieties was carried out by national programmes in Benin, Burkina Faso, Cameroon, the Ivory Coast, Ethiopia, Ghana, Nigeria, and Togo. Striga-resistant maize varieties show horizontal resistance not only to S. hermonthica, but also to another species, Striga asiatica. Based on the results of a 15 year research, an integrated approach using resistant varieties and cereal-legume intercropping or rotation is recommended as a sustainable and permanent solution to combat Striga in Africa. This horizontal resistance package, with a combined resistance to other biotic stresses, could be applicable not only to Striga problems in other crops such as sorghum, millet, rice and cowpea, but also to other parasitic weeds, such as Orobanche species. This paper reviews and discusses why, approximately a century's research work on parasitic weeds, has not led to a major research breakthrough.     

Response of two lacewing species to biorational and broad-spectrum insecticides

Green lacewings, includingChrysoperla rufilabris (Burmeister) andCeraeochrysa cubana (Hagen), are predators of small, soft-bodied insects including whiteflies. The silverleaf whitefly,Bemisia argentifolii Bellows & Perring [formerlyB. tabaci (Gennadius) strain B], is an important pest of agronomic, vegetable and ornamental crops. Practical use of these lacewings as biological control agents would be facilitated by better understanding of their responses to both biorational (selective) and broad-spectrum insecticides. The topical and residual toxicity of azadirachtin (Azatin-EC^TM), insecticidal soap (M-Pede^TM), paraffinic oil (Sunspray Ultra-Fine Spray Oil^TM) and the pyrethroid bifenthrin (Brigade^TM) to eggs, larvae and adults of the lacewings were studied in the laboratory. Larvae ofC. cubana were much more tolerant to residues of bifenthrin than wasC. rufilabris and were somewhat more tolerant to topically applied soap. At normal field concentrations, azadirachtin (0.005%, by wt a.i.), paraffinic oil (1.0% by volume) and soap (1.0% by volume) were not toxic to larvae or adults of either species either topically or residually. Oil was toxic topically to eggs but azadirachtin and soap were not. Bifenthrin was toxic topically and residually to larvae and adults but was not so toxic to eggs as was oil. Thus, selectivity of all materials tested was relative to lacewing species and lifestage. The relative tolerance to insecticide residues exhibited byC. cubana larvae may be related to its trash-carrying habit, suggesting that use of trash-carrying chrysopids in place of non-trash carriers for augmentative biological control would increase options for non-disruptive chemical intervention when necessary.     

Tackling fall armyworm (Spodoptera frugiperda) outbreak in Africa: an analysis of farmers’ control actions

Abstract

Since its emergence in Africa in 2016, fall armyworm (FAW) has spread rapidly and poses a severe threat to the food security and livelihood of millions of smallholder farmers in the continent. Using survey data from Ghana and Zambia, we examined FAW prevention and control methods implemented by farm households and their impacts on maize output and household consumption of self-produced maize. The main control methods used included pesticide application and handpicking of larvae, while access to information on FAW was a key driver behind the implementation of the control methods. Results from an endogenous switching regression showed that the implementation of a FAW management strategy significantly enhanced maize yield and households’ own maize consumption. When disentangling the impacts of the main control methods, we found that the combination of pesticide application and handpicking of larvae produced the highest yield gain of 125%. We concluded that the current interventions put in place by farmers to tackle FAW infestations are providing positive outcomes, but successful management of the pest will require more actions, including raising awareness to enhance the adoption of control interventions and exploring other control options.     

甜玉米与木薯间套作对二斑叶螨的生态调控效果

为生态调控我国木薯主产区主要外来入侵害虫二斑叶螨Tetranychus urticae,以甜玉米YT29和食用木薯品种SC9 （抗虫）及工业原料木薯品种SC205 （感虫）为供试材料,系统开展甜玉米与这2种木薯间套种对二斑叶螨调控效果的研究。结果表明,二斑叶螨对SC9表现出非适宜性,而对YT29和SC205表现出适宜性。取食SC9的二斑叶螨各虫态发育历期均显著长于取食YT29和SC205的,幼螨-后若螨死亡率显著高于取食YT29和SC205的,雌、雄成螨寿命显著短于取食YT29和SC205的,单雌产卵量、卵孵化率和雌性百分率均显著低于取食YT29和SC205的,但取食YT29和取食SC205的二斑叶螨的发育和繁殖之间无显著差异。4/YT29-2/SC9间套作模式对二斑叶螨的生态调控效果最好,不仅3年螨害指数显著低于SC9单作、 SC205单作及2/YT29-2/SC205间套作模式,而且其3年平均产量达39.1 t/hm²,显著高于SC9单作 （32.1 t/hm²）、 4/YT29-2/SC205间套作模式（20.5 t/hm²）和SC205单作（12.0 t/hm²）的平均产量。表明甜玉米与抗虫木薯品种间套作模式具有调控虫害、增产的作用,可以在我国木薯种植区大面积推广应用。