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Ecosystem functions such as biological pest control are mediated by the richness and abundance of service providers i.e., biological control agents (BCAs), relative contributions of individual taxa and community structure. This is especially relevant in the native range of agricultural herbivores, where a speciose community of co-evolved BCAs can prevent them from attaining pest status. Here, we use a powerful graphical approach to assess the functional structure of BCA communities of the fall armyworm (FAW) Spodoptera frugiperda (Lepidoptera: Noctuidae) on maize in the Neotropics. Drawing upon a curated database of all-time field and laboratory studies, we graphed patterns in the functional contribution, abundance and niche breadth for a respective 69, 53 and 3 taxa of resident parasitoids, predators and pathogens. Regardless of varying taxon coverage and rigor of the underlying studies, functional structure follows a saturating relationship in which the first three taxa account for 90–98% of aggregate biological control function. Abundance-functionality matrices prove critically incomplete, as more than 80% of invertebrate taxa miss empirically derived efficiency metrics while associated FAW infestation data are scarce. Despite its methodological shortfalls and data gaps, our work pinpoints Chelonus insularis, several taxa of egg parasitoids, Doru spp. and Orius spp. as taxa with outsized (average) functionality and conservation potential. This is also exemplified by the highly variable aggregate function across studies, with dispersion indices of 1.52 and 2.14 for invertebrate BCAs. Our work underlines the critical importance of functional ecology research, networked trials and standardized methodologies in advancing conservation biological control globally.

Since 2016, the fall armyworm (FAW) Spodoptera frugiperda has spread over extensive areas of the tropics and subtropics, imperiling food security, economic progress and the livelihoods of millions of cereal farmers. Although FAW has received long-standing scientific attention in its home range in the Americas, chemical inputs feature prominently in its mitigation and biological control uptake is globally lagging. Here, building upon a quantitative review of the global literature, we methodically dissect FAW biological control science. Of the known entomopathogens (46), parasitoids (304) and predators (215) of FAW, approx. 40% have been subject to laboratory- or field-level scrutiny. Laboratory-level performance has partially been assessed for 14–18% of the above invertebrate taxa. Yet, organismal, geographic, methodological and thematic biases hamper efforts to relate in-field biodiversity to actual ecosystem service delivery. Often, single-guild ‘snapshot’ surveys are preferred over comprehensive bio-inventories or population dynamics appraisals, trophic interactions are wrongly inferred from co-occurrence, standard pest infestation metrics are lacking and natural enemy censuses are performed arbitrarily. Diurnal biota receive inordinate attention, while egg and pupal predation - the main biotic sources of mortality - are routinely overlooked. Multiple microbial and invertebrate biota are investigated with a view towards mass-rearing and augmentative release, but the basis for agent selection is often unclear. Lastly, conservation biological control receives marginal attention and cross-disciplinary engagement with the agroecology domain is lagging. We lay out several steps, including standardized methodologies, smart use of biodemographic toolkits, networked field trials and a fortification of its ecological underpinnings, to sharpen the science of (FAW) biological control and urge further momentum in its global implementation.

Abstract Microclimatic and macroclimatic data differ, and microclimatic data are most useful at short time intervals (30‐min scales rather than daily/monthly scales). We developed an end‐to‐end system to acquire such data at a high temporal resolution, transfer them to a server through an Internet of Things network using low‐cost technologies, and make them available with dynamic graphical visualizations and download capabilities. The system has been used for 2 years to monitor environmental variables in contrasting agroecosystems in France, Bolivia and Kenya. It has been proven to be reliable and supports the mismatch between macro‐ and microclimates. This low‐cost Internet of Things system can capture the microclimate in contrasting environments with accuracy comparable to commercial solutions, and great flexibility in data processing. It thus constitutes a possible solution in an academic context and has the potential to be used by a broad audience of scientists interested in capturing environmental variables in real time and at a high temporal frequency.

The fall armyworm (FAW), Spodoptera frugiperda, a pest of maize native to the Americas first reported in West and Central Africa in 2016, severely threatens maize production and food security in Sub-Saharan Africa. Native genetic resistance is one of the best methods of control of insect pests as it is contained in the seed making it more amenable for use by farmers compared to other interventions and it is also compatible with other integrated pest management (IPM) options. An intensive screening against FAW was carried out by artificial infestation in greenhouse conditions in Kenya between 2017 and 2018 on about 3000 inbred lines available in the germplasm collection of the International Maize and Wheat Improvement Center (CIMMYT). Among these lines, only four showed to be resistant to FAW, but the mechanisms of resistance are not yet known. The objective of this study was to determine the resistance mechanisms specifically non-preference and antibiosis to S. frugiperda in these four selected resistant inbred lines. The studies were conducted under laboratory and net house conditions in Kenya from April 2020 to November 2021. Non-preference was assessed estimating the feeding preference by counting the number of FAW neonates found on each leaf portion, silk portion and grain using binary and multiple choice methods under laboratory conditions, while antibiosis was assessed through the relative growth rate (RGR) and developmental time of FAW larvae on leaves, silks and grains under both laboratory and net house conditions. Among the four resistant maize inbred lines tested, two, namely CML71 and CKSBL10008, exhibited the highest level of antibiosis resistance on leaves. Under laboratory conditions, the larval RGR reduced from 13 mg/d on the most susceptible line to 8 mg/d on CML71. CML71 also showed a good non-preference on leaves compared to other tested lines. Only 6% of neonates choose to feed on CML71 whereas more than 10% choose to feed on the other lines (and 15% on the most susceptible) in multiple choice tests. The non-preference for feeding and lower RGR of larvae on CML71 suggest a biochemical involvement resistance to FAW. Through this study, CML71 is revealed as a highly promising line for use in breeding for native genetic resistance to FAW in tropical maize.

While many insects are in decline due to global warming, the effect of rising temperatures on crop insect pests is uncertain. A capacity to understand future changes in crop pest populations remains critical to ensure food security. Using temperature-dependent mathematical models of the development of four maize stemborers in temperate and tropical regions, we evaluated the potential impacts of different climate change scenarios on development time. While recognizing the limitations of the temperature-dependent development rate approach, we found that global warming could either be beneficial or detrimental to pest development, depending on the optimal temperature for the development of the species and scenarios of climate change. Expected responses range from null development to 1.5 times faster development than expected today. These results suggest that in the medium term, the studied species could benefit from global warming with an accelerated development, while in the long term, their development could either be delayed or accelerated, which may impact their dynamics with implications on maize cultivation.

Following its recent invasion of African countries, fall armyworm (FAW), Spodoptera frugiperda (Lepidoptera: Noctuidae), now co-exists with resident stemborers such as Busseola fusca (Lepidoptera: Noctuidae) and Chilo partellus (Lepidoptera: Crambidae) causing severe damage to maize crops. Due to niche overlap, interspecific interactions occur among the three species, but the mechanisms and degree remain unclear. In this study, we assessed plant-mediated intraspecific and interspecific interactions, predation in laboratory and semi-field settings, and larval field occurrence of S. frugiperda and the two stemborer species. Larval feeding assays to evaluate competitive plant-mediated interactions demonstrated that initial S. frugiperda feeding negatively affected subsequent stemborer larval feeding and survival, suggesting induction of herbivore-induced mechanisms by S. frugiperda, which deters establishment and survival of competing species. Predation assays showed that, at different developmental larval stages, second–sixth instars of S. frugiperda preyed on larvae of both B. fusca and C. partellus. Predation rates of S. frugiperda on stemborers was significantly higher than cannibalism of S. frugiperda and its conspecifics (p < 0.001). Cannibalism of S. frugiperda in the presence of stemborers was significantly lower than in the presence of conspecifics (p = 0.04). Field surveys showed a significantly higher number of S. frugiperda larvae than stemborers across three altitudinally different agroecological zones (p < 0.001). In conclusion, this study showed that the invasive S. frugiperda exhibited a clear competitive advantage over resident stemborers within maize cropping systems in Kenya. Our findings reveal some of the possible mechanisms employed by S. frugiperda to outcompete resident stemborers and provide crucial information for developing pest management strategies for these lepidopteran pests.

Fall armyworm (FAW), Spodoptera frugiperda J.E Smith, (Lepidoptera: Noctuidae) is a serious invasive pest of maize that has been established in Kenya since 2016. Little is known about its co-occurrence with resident stemborers, relative infestation and damage and how agronomic factors influence its infestation and damage in maize cropping systems across different agro-ecological zones. This study assessed FAW co-occurrence with resident stemborers, relative infestation and damage across three agro-ecological zones, and the effects of different agronomic practices on its infestation and damage in maize cropping systems in Kenya. A total of 180 maize farms were surveyed across three different agro-ecological zones. FAW infestation and damage was highest in lowlands compared to mid-altitude and high-altitude lands. Its population (eggs and larvae) dominated that of resident stemborers in maize fields. Maize grown under mixed cropping systems, with rainfed production and weeded frequently had low infestation and damage compared to those grown under monoculture, with irrigation and no weeding, respectively. Young vegetative maize plants were more infested and damaged compared to mature plants. Different maize varieties were found to have different infestation and damage levels with Pioneer having the least damage. These results demonstrate that agronomic practices play a role in influencing FAW infestation and damage in maize cropping systems. Further, the population of FAW is dominating that of stemborers in maize cropping systems in Kenya, four years after its invasion. Thus, agronomic practices need to be considered while designing sustainable agro-ecological-based management solutions for resource-constrained smallholder farmers.