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Introduction: Insect pests cause important crop production losses worldwide. Their distribution and movement are affected by climate and land use change and agriculture intensification. Site colonization by insect pests is dependent on pest dispersal capability, the availability of resources, the presence of competitors or predators, the weather conditions and the characteristics of the surrounding landscape. Movement of pests between the plots might be considered in pest management strategies to counterbalance the traditional plot oriented strategies. In this study, our objective was to provide evidence of the movement of the coffee berry borer (CBB), the most important pest in coffee cultivation, from neighboring coffee plantations to adjacent land uses at different time periods of the coffee production cycle. Methods: For 10 months we captured the CBB with funnel traps in 13 coffee plots that had an interface with forests, pastures, and abandoned coffee plantations in Costa Rica. At each interface, we established three transects with a minimum distance of 50 m between them, in the direction of the wind. Within each transect, we placed four traps 20 m apart. We fitted generalized linear mixed models to evaluate the relationship between CBB captures and the type of interface, the position of the trap, wind velocity, rainfall, temperature and relative humidity, and their interactions. Results: Our findings suggest that CBB moves into adjacent land uses when the coffee resource in the plot is limited. This effect varies according to the interface and the position of the trap. We also found an interaction between the interface and the position of the trap with the wind and relative humidity. Discussion: Our findings suggest that movement of the CBB partly depends upon the adjacent land uses. The forest creates a barrier to CBB movement and may prevent the transport of the CBB considering the action of the wind speed. The pasture may facilitate movement of the CBB thro

Climate change may impact the life cycle (e.g., number of annual generations) and distribution range of insect pests, increasing the risk of total crop losses and compromising the food sovereignty of smallholders. This has sparked interest in adaptive management that considers multiple spatial scales and the possible effects of climate change. Coffee berry borer (CBB; Hypothenemus hampei, Coleoptera: Curculionidae: Scolytinae) is a pest that affects coffee berries and causes the main economic loss for coffee farmers. The CBB management is difficult and usually focuses on the plot scale. We present an agent-based model that simulates the CBB dynamics, with a bottom-up approach that connects agents and entities to the whole system. The objective of the tool is to explore several CBB management scenarios considering multiple spatial scales (plant, plot, and surrounding landscape) as well as their environmental setting. The simulator was parameterized based on literature review, fieldwork and participatory workshops with farmers, technicians, and researchers from various institutions in Costa Rica and Nicaragua. The simulator includes information on CBB and coffee fruits dynamics, landscape context, main management practices and climatic conditions. The tool can be used to generate scenarios with different spatial configurations of the landscape (coffee- dominated, heterogeneous, or forest-dominated landscapes), coffee systems (with shade trees or full sun), as well as to evaluate management practices and climate parametrization. It is also a participatory simulation tool where management decisions can be virtually tested through interactive games. Thus, this tool aims to support technicians and farmers in exploring coordinated management alternatives at a landscape scale. This approach can be applied to evaluate pests in other crops and support farmers management decisions.

Seed size is a critical factor that can impact the regeneration process of plant populations. The objective of this study is to identify optimal seeds for the cultivation of two overexploited native forest species in Côte d'Ivoire, namely Khaya senegalensis (Desr.) A.Juss., 1830 and Parkia biglobosa (Jacq.) R.BR. ex G. Don, 1830. A total of 1080 seeds per species were evaluated for germination and seedling vigour in two distinct environments (dry and humid) in Côte d'Ivoire. The results demonstrated that, for Khaya senegalensis, larger seeds exhibited higher germination rates, whereas for Parkia biglobosa, smaller and medium-sized seeds showed better germination performance. However, regardless of species and study site, larger seeds consistently produced more vigorous seedlings. In this case, pretreatment tests on large seeds of Parkia biglobosa can potentially enhance their germination performance. Large seeds, ranging from 0.25–0.37 g in Khaya senegalensis and 0.2–0.32 g in Parkia biglobosa, appear to be the most suitable and best candidates for high-quality, high-performance seeds to optimise the cultivation of these species in Côte d'Ivoire. Distributing such seeds to farmers can contribute to the success of reforestation and agroforestry programs involving these target species in Côte d'Ivoire. These findings contribute to the sustainable management of the target species and can serve as a basis for restructuring forest regeneration policies in Côte d'Ivoire.

Adapting agricultural systems to face persistent environmental hazards is at the center of global concerns. In line with this, understanding and highlighting the structural characteristics of agroforestry systems could strengthen their resilience in terms of disease management. This study was conducted to evaluate the effect of shade on the intensity of citrus leaf and fruit spot disease caused by Pseudocercospora (PLFSD). Investigations to assess the effects of shade components on the incidence of PLFSD were carried out on 15-year-old tangerine trees in a cocoa-based agroforestry plot (Bokito) during four fruits seasons. Tangerines under the shade of large forest trees were compared to others located under full sunlight. A complementary experiment was conducted on young grapefruit plants in an orchard with mango and avocado groves in Foumbot. Three shading conditions, i.e., under avocado trees, under mango trees, and without shade, were explored. Data on shade and PLFSD incidence were collected and analyzed. Our findings show that PLFSD incidence was null on tangerine leaves from trees under shade compared to those under full sunlight. The same trends were observed in fruits under shade and under full sunlight. Disease incidence on grapefruit leaves was lower on trees under shade compared to those under full sunlight. In short, shade trees appear to constitute potential physical barriers to disease progression. This study also highlights disease spatial distribution as beyond 12 m of distance between neighboring trees, no spatial dependence of disease spread was observed. Management actions based on the distance between citrus trees and regulating shade are envisaged.

In perennial plants, the selection of new genotypes requires several years of evaluation to get a good estimate of the genetic value of the trees. The cocoa tree, which is cultivated for its seeds, produces continuously throughout the entire duration of exploitation of the plots, which can last up to 30 years. The genetic value of the trees' productivity over the entire harvesting period is therefore difficult to assess. In particular, how many years are needed to estimate the genetic value of the trees' productive capacity? To answer this question, the analysis of a trial comparing 42 clones in a statistical design with 4 blocks, located in Costa Rica, is proposed. The individual production of the 1187 trees in this trial was evaluated over 18 consecutive years. The first year of production is not a good predictor of cumulative production over 18 years with a genetic correlation of 0.68. It is necessary to have an accumulation of 4 years for the genetic correlation with the 18-year accumulation to be higher than 0.85, and an accumulation of 7 years for the genetic correlation with the 18-year accumulation to be higher than 0.90. Longitudinal data analysis allows for a better understanding of the links between production of the successive years. In this trial, the seventh year is a year of high production followed by a slight decrease in the eighth year. To determine an evaluation period that allows a good estimate of genetic value should therefore be based on the study of production kinetics. Indeed, it seems necessary to continue the evaluation of tree production until a high annual production that reveals the productive capacity of the genotypes. Studies on production kinetics also make it possible to envisage genetic improvement for better sustainability of cocoa trees to be proposed in appropriate cropping systems.

The role of agroforest systems in pathogen regulation through structural characteristics such as shade and tree diversity is recognized. However, few studies have examined the importance of these factors on the spread of diseases of associated fruit trees in agroforestry systems, especially cocoa-based agroforestry systems (CBAS). The aim of this study was to evaluate the effect of associated tree diversity and shade rate into CBAS on citrus Phytophthora foot rot disease (PFRD) intensity. The study was carried out in five citrus production basins of Cameroon, contrasted by ecology and rainfall regimes. A set of 33 CBAS plots was mapped and their species composition and vertical structure were determined. Field data were used to reconstruct CBAS in 3D with Shademotion 5.1.47 software. Using static simulations with shadow overlays, shade rate received by each citrus tree was calculated. Subsequently, citrus trees were grouped into three categories according to the shade rate they received: (i) full sun, with shade rate <30%; (ii) light shade with shade rate 30–70% and, (iii) dense shade, with shade rate >70%. PFRD intensity was determined by measuring the canker extent relatively to the citrus crown circumference. A significant difference in PFRD intensity was observed between the different shade rates. Citrus trees receiving no shade were significantly more attacked by PFRD than those receiving little shade or dense shade. The antagonistic effect of shade was demonstrated. At the expense of factors related to the specific composition of the CBAS, shade, temperature, relative humidity and rainfall were found to be the main factors explaining PFRD intensity in CBAS. This study shows that microclimatic alterations due to the biodiversity in tropical agroforestry systems contribute to sustainable pest management.

Avec ses grandes plantations industrielles, le changement climatique actuel fragilise fortement les systèmes agroécologiques de la Cote d'Ivoire. L'étude s'appuie sur des observations pluviométriques relevées à la station d'Abidjan, au pas de temps journalier et horaire. Elle cherche tout particulièrement à cerner comment les séquences sèches, ou pluvieuses, ont évoluées sous la contrainte du changement climatique actuel. Les premiers résultats de ce travail montrent clairement une diminution des séquences sèches. A l'échelle mensuelle, il faut cependant nuancer cette érosion des durées selon les moments de l'année. Ces tendances, globalement à la baisse, viennent contrarier les pratiques culturales de ces régions, qui impliquent de pouvoir conserver une partie du temps des moments suffisamment longs dépourvus d'humidité.

Studying spatial and temporal plant disease dynamics helps to understand pathogen dispersal processes and improve disease control recommendations. In this study, three cacao plots devoid of primary inoculum of Phytophthora megakarya (causal agent of cacao black pod rot disease) upon establishment in 2006 were monitored for presence of disease on a weekly basis from 2009 to 2016. Ripley's K(r) function, join count statistics and Fisher Exact test were used to analyse spatial and temporal disease dynamics. Disease distribution maps showed aggregated disease patterns in all plots although for the years of disease onset, exogenous primary infections were mostly randomly distributed. The K(r) function confirmed these results indicating that inoculum generally disperses only over short distances. Moreover, significant positive spatial autocorrelations showed that diseased trees were often clustered up to a distance of 3-9 m. Temporal disease progression was low, meaning that endogenous inoculum failed to establish itself which is partly explained by rigorous phytosanitation and partly by unfavourable microclimatic conditions for disease development. Since P. megakarya had difficulty establishing itself in the plots, proximity to already infected cacao plantations drove infection dynamics. Thus, isolation of newly established cacao plantations from infected ones and rigorous phytosanitation as a preventive strategy appears to be an effective approach to control black pod for newly established cacao plantations.

Cocoa is an important crop in Cameroon, where it is cultivated in different areas, including marginal areas, characterized by a rather low level of annual rainfall and marked dry seasons. In order to release cocoa varieties with a good level of adaptation to these marginal conditions, nine full-sib progenies, already released to farmers in other producing areas of the country, were assessed on twelve on farm cocoa plots, set up in 2006, in Mbam et Inoubou county, which is a forest–savannah transition zone. The traits assessed were mortality rate, yield and yield stability. Mortality rate and yield vary widely among trial plots and among progenies. Four out of the nine assessed progenies present a yield level significantly higher than the five others. The lowest level of yield stability (estimated by the contribution to total ecovalence) was observed in both the highest and the lowest yielding progenies. Recommendation for the large-scale release of these progenies to farmers of the county, and to other cocoa producing forest–savannah transition areas, are made, based on the results obtained from this study.