Thierry Hance

Catholic University of Louvain | UCLouvain · Earth and Life Institute

Dependence on multiple nutritional endosymbionts has evolved repeatedly in insects feeding on unbalanced diets. However, reference genomes for species hosting multi-symbiotic nutritional systems are lacking, even though they are essential for deciphering the processes governing cooperative life between insects and anatomically integrated symbionts....

Pentalonia nigronervosa Coquerel (Hemiptera: Aphididae) is the vector of the Banana Bunchy Top Virus (BBTV), the most serious viral disease of banana (Musa spp.) in the world. Before acquiring the virus, the vector is more attracted to infected banana plants in response to the increased emissions of volatile organic compounds (VOCs). Here, we test...

The coffee aphid Toxoptera aurantii (Boyer de Fonscolombe) (Hemiptera: Aphididae) causes direct feeding injuries and vectors the coffee ringspot virus (CoRSV) (Mononegavirales: Rhabdoviridae), which is more damaging to coffee plants. Coffee farmers have controlled this pest using synthetic pesticides. However, chemical control is ineffective and so...

Pentalonia nigronervosa Coquerel ( Hemitera: Aphididae ) is the vector agent of Banana Bunchy Top Virus (BBTV), the most serious viral disease of banana ( Musa spp) in the world. Before acquiring the virus, the vector is more attracted to infected banana plants thanks to increased emissions of volatile organic compounds (VOCs). Here, we test the hy...

Bioconversion using insects is a promising strategy to convert organic waste (catering leftovers, harvest waste, food processing byproducts, etc.) into biomass that can be used for multiple applications, turned into high added-value products, and address environmental, societal and economic concerns. Due to its ability to feed on a tremendous varie...

Viral diseases can change plant metabolism, with potential impacts on the quality of the plant's food supply for insect pests, including virus vectors. The banana aphid, Pentalonia nigronervosa Coquerel, is the vector of the Banana bunchy top virus (BBTV), the causal agent of Banana bunchy top disease (BBTD), the most devastating viral disease of b...

Insects have evolved diverse strategies to resist extreme high temperatures (EHT). The adaptive value of such strategies has to be evaluated when organisms experience multiple EHT events during their lifetime, as predicted in a changing climate. This is particularly the case for associations with facultative microbial partners involved in insect he...

Parasitoids represent the third trophic level in plant-insect food webs. They develop in or on herbivorous insects at the second trophic level, which in turn feed on plants that constitute the first trophic level. This food web system might be affected by agricultural landscape and practices. We studied the phenology and population density of Aphis...

Apples and pears are among the most widely cultivated fruit species in the world. Pesticides are commonly applied using ground sprayers in conventional orchards; however, most of it will not reach the target plant, increasing the contamination of nontarget organisms such as natural predators, pollinators, and decomposers. Trunk injection is an alte...

Knowledge of the reproductive biology parameters of a parasite on its insect hosts is necessary for successful mass rearing and augmentative release. Here, we examine the fitness-related traits and life-history parameters of the parasitoid Bracon hebetor living on two hosts Ephestia kuehniella and Corcyra cephalonica. Results showed that ovipositio...

Climate warming is considered to be among the most serious of anthropogenic stresses to the environment, because it not only has direct effects on biodiversity, but it also exacerbates the harmful effects of other human‐mediated threats. The associated consequences are potentially severe, particularly in terms of threats to species preservation, as...

Mass releases of two parasitoid species, Aphidius matricariae and Ephedrus cerasicola, may provide an alternative measure to pesticides to control the rosy apple aphid Dysaphis plantaginea in organic apple orchards. As an exploratory study, we tested if the presence of flower strips between apple tree rows could improve the action of three early pa...

Understanding the thermal tolerance of insect herbivores and their natural enemies is crucial for biological control programs. The rosy apple aphid Dysaphis plantaginea is one of the most problematic pests of apple orchards, causing economic losses of up to 30% due to damage to fruits. Dysaphis plantaginea is highly adapted to low temperature, enab...

Dependence on multiple nutritional bacterial symbionts forming a metabolic unit has repeatedly evolved in many insect species that feed on nutritionally unbalanced diets such as plant sap. This is the case for aphids of the subfamilies Lachninae and Chaitophorinae, which have evolved di-symbiotic systems in which the ancient obligate nutritional sy...

Dependence on multiple nutritional bacterial symbionts forming a metabolic unit has repeatedly evolved in many insect species that feed on nutritionally unbalanced diets such as plant sap. This is the case for aphids of the subfamilies Lachninae and Chaitophorinae, which have evolved di-symbiotic systems in which the ancient obligate nutritional sy...

Coffea (Gentianales: Rubiaceae) is an economic plant considering its production income and the number of people that depend on it for their daily livelihoods. Tropical regions predicted to face severe challenges related to climate change impacts often grow coffee. Like other crops, coffee benefits from many ecosystem services, mainly regulating and...

Multipartner nutritional endosymbioses have evolved many times in insects. In Chaitophorinae aphids, the eroded metabolic capabilities of the ancient obligate symbiont B. aphidicola are complemented by those of more recently acquired symbionts.

The MODIRISK project studied mosquito biodiversity and monitored and predicted biodiversity changes, to actively prepare to address issues of biodiversity change, especially invasive species and new pathogen risks. This work is essential given continuing global changes that may create suitable conditions for invasive species spread and the (re-)eme...

Alternatives to pesticides to control the rosy apple aphid, Dysaphis plantaginea, are being developed. Natural enemies usually arrive too late after the first aphid infestation to provide effective control. This study tested effects of mass release of two parasitoid species, Aphidius matricariae and Ephedrus cerasicola, on the numbers of aphid colo...

Symbioses are significant drivers of insect evolutionary ecology. Despite recent findings that these associations can emerge from environmentally derived bacterial precursors, there is still little information on how these potential progenitors of insect symbionts circulate in trophic systems. Serratia symbiotica represents a valuable model for dec...

The palm weevils, Rhynchophorus, have last stage larvae that are highly appreciated by the population of the Democratic Republic of Congo. The population has a poor knowledge of the adult of this insect. We initiated this work to contribute to a better knowledge of the species of Rhynchophorus in the region and, to know their population dynamics. T...

Intensive agriculture has profoundly altered biodiversity and trophic relationships in agricultural landscapes, leading to the deterioration of many ecosystem services such as pollination or biological control. Information on which spatio-temporal factors are simultaneously affecting crop pests and their natural enemies is required to improve conse...

Mass releases of two parasitoid species, Aphidius matricariae and Ephedrus cerasicola, may provide an alternative measure to pesticides to control the rosy apple aphid Dysaphis plantaginea in organic apple orchards. As a proof of concept study, we tested if the presence of flower strips between apple tree rows could improve the action of three earl...

Although synthetic pesticides are still used to control insect pests, greater efforts have been made to develop healthier and more environmentally friendly pesticides. Because of their insecticidal properties, botanical essential oils (EOs) are considered as promising alternatives to the use of synthetic insecticides. However, little is known about...

Background Pulsed ultraviolet (UV)-C light sources, such as excimer lasers, are used in emerging non-thermal food-decontamination methods and also have high potential for use in a wide range of microbial decontamination applications. The acaricidal effect of an experimental UV-C irradiation device was assessed using female adults and eggs of a mode...

Effect of thermal stress on the expression of traits modulated by aphid endosymbionts: a meta-analysis The ecology and evolution of many insect species are studied through the lens of their mutualistic associations with various microorganisms. Beneficial microbes have shaped the life histories and evolutionary trajectories of their hosts, providing...

Temperatures experienced by insects during their adult life often differ from developmental temperatures. Yet, developmental thermal acclimation can play an important role in shaping physiological, morphological, and behavioral traits at the adult stage. We explored how three rearing temperatures (10, 20, and 28 °C) affected host-foraging behaviors...

Temperature influences the ecology and evolution of insects and their symbionts by impacting each partner independently and their interactions, considering the holobiont as a primary unit of selection. There are sound data about the responses of these partnerships to constant temperatures and sporadic thermal stress (mostly heat shock). However, th...

Essential oils (EOs) have been long known for their lethal effects on pests when topically applied or delivered by fumigation on the stored crops. However, their potential disturbance of insect pest colonization on their host plant remains little studied. EOs can cause escape behaviors due to their repellent volatile organic compounds (VOCs) or pre...

Herbivore-induced plant volatiles constitute the first indicators of insect host presence, and these can affect the foraging behavior of their natural enemies. The density of insect hosts may affect the nature and concentration of these plant-induced volatiles. We tested the impact of infestation density (low, intermediate, and high) of the pea aph...

Testing fluctuating rather than constant temperatures is likely to produce more realistic datasets, as they are ecologically more similar to what arthropods experience in nature. In this study, we evaluated the impact of three constant thermal regimes (7, 12, and 17 °C) and one fluctuating thermal regime (7–17 °C with a mean of 12 °C) on fitness in...

Improved methods of integrated pest management of the pear psyllid Cacopsylla pyri (L.), the primary pest of pear in Europe and North America, are needed. Trechnites insidiosus (Crawford) is the most abundant parasitoid of C. pyri in pear orchards, where it is present early in the psyllid infestation period. However, little is known about its gener...

Alternative measures to pesticides to control the rosy apple aphid Dysaphis plantaginea are being developed. Naturally occurring predators and parasitoids often fail to reduce aphid abundance below the economic threshold in orchards, because they are active too late after the aphid first infestation. We tested the efficiency of mass release of two...

Developmental temperature plays important roles in the expression of insect traits through thermal developmental plasticity. We exposed the aphid parasitoid Aphidius colemani to different temperature regimes (10, 20, or 28 °C) throughout larval development and studied the expression of morphological and physiological traits indicator of fitness and...

Background While pulsed UV-C light sources such as excimer lasers are used in emerging non-thermal food decontamination method, they also have a high potential for a wide range of other microbial decontamination applications. The acaricidal effect of an experimental UV-C irradiation device was assessed using two-spotted spider mite female adults Te...

Banana plants are affected by various viral diseases, among which the most devastating is the "bunchy top", caused by the Banana bunchy top virus (BBTV) and transmitted by the aphid Pentalonia nigronervosa Coquerel. The effect of BBTV on attraction mechanisms of dessert and plantain banana plants on the vector remains far from elucidated. For that,...

Secondary metabolites are central to understanding the evolution of plant-animal interactions. Direct effects on phytophagous animals are well-known, but how secondary consumers adjust their behavioral and physiological responses to the herbivore's diet remains more scarcely explored for some metabolites. Caffeine is a neuroactive compound that aff...

Many insect species are associated with bacterial partners that can significantly influence their evolutionary ecology. Compared to other insect groups, aphids harbor a bacterial microbiota that has the reputation of being poorly diversified, generally limited to the presence of the obligate nutritional symbiont Buchnera aphidicola and some faculta...

We sampled the mites present on individuals of Rhynchophorus phoenicis collected at different sites in the Kisangani region of the Democratic Republic of the Congo. Two species belonging to two families (Uroactiniidae and Urodinychidae) were identified: Centrouropoda almerodai and Uroobovella phoenicola. This is the first time that C. almerodai has...

Pear cultivation accounts for a large proportion of worldwide orchards, but its sustainability is controversial because it relies on intensive use of pesticides. It is therefore crucial and timely to find alternative methods to chemical control in pear orchards. The psyllids Cacopsylla pyri and Cacopsylla pyricola are the most important pests of pe...

Mutualistic associations between insects and heritable bacterial symbionts are ubiquitous in nature. The aphid symbiont Serratia symbiotica is a valuable candidate for studying the evolution of bacterial symbiosis in insects because it includes a wide diversity of strains that reflect the diverse relationships in which bacteria can be engaged with...

Banana trees are affected by various viral diseases, among which the most devastating is the "bunchy top", caused by the Banana bunchy top virus (BBTV), vectorized by the aphid Pentalonia nigronervosa Coquerel. The host-virus-vector relationship still remains to be precisely studied. In order to clarify the effect of BBTV on recognition mechanisms...

Secondary metabolites are central to understanding the evolution of plant-animal interactions. Direct effects on phytophagous animals are well-known, but how secondary consumers adjust their behavioral and physiological responses to the herbivore’s diet remains quite scarcely explored for some metabolites. Caffeine is a neuroactive compound that af...

The European project Proverbio, supported by the Interreg program, focuses on the rosy apple aphid Dysaphis plantaginea one of the most problematic pests of apple orchards, with economic losses up to 30% of fruits. This aphid species shows high adaptation to low temperature and appears very early in the season, before the presence of natural enemie...

Bacterial symbioses are significant drivers of insect evolutionary ecology. However, despite recent findings that these associations can emerge from environmentally derived bacterial precursors, there is still little information on how these potential progenitors of insect symbionts circulates in the trophic systems. The aphid symbiont Serratia sym...

The use of conventional pesticides is debated because of their multiple potential adverse effects on non-target organisms, human health, pest resistance development and environmental contaminations. In this setting, this study focused on developing alternatives, such as trunk-injected essential oil (EO)-based biopesticides. We analysed the ecophysi...

Numerous cases of evolutionary trait loss and regain have been reported over the years. Here, we argue that such reverse evolution can also become apparent when trait expression is plastic in response to the environment. We tested this idea for the loss and regain of fat synthesis in parasitic wasps. We first show experimentally that the wasp Lepto...

The European crabapple Malus sylvestris, a crop wild relative of Malus domestica, is a major contributor to the cultivated apple genome and represents a potential source of interesting alleles or genes, particularly pest resistance traits. An original approach was used to explore the trophic interaction between M. sylvestris populations and its pes...

CONTEXT The COVID-19 pandemic, caused by the SARS-CoV-2 virus, has affected global agricultural chains and intensified the issue of food insecurity worldwide. OBJECTIVE We propose a short retrospective of the reported effects of the COVID-19 pandemic from its beginning in March 2020 in Europe, on orchard management and harvest, sales and agricultu...

The granary weevil Sitophilus granarius is a stored product pest found worldwide. Environmental damages, human health issues and the emergence of resistance are driving scientists to seeks alternatives to synthetic insecticides for its control. With low mammal toxicity and low persistence, essential oils are more and more being considered a potenti...

Pear is one of the most important fruit crops of temperate regions. The control of its mains pest, Cacopsylla pyri , is still largely based on the use of chemical pesticides, with all that this implies in terms of negative effects on the environment and health. Within the context of integrated pest management, innovative and ecologically sustainabl...

Natural plant extracts, especially essential oils, are used largely against plant pests. The aim of this study was to investigate the bio-insecticidal effect of chemical extracts of three plants, Mentha pulegium L. (Lamiales: Lamiaceae), Lavandula stoechas L. (Lamiales: Lamiaceae) and Ruta chalepensis L. (Sapindales: Rutaceae) collected from Tunisi...

Dollo's law of irreversibility states that once a complex adaptation has been lost in evolution, it will not be regained. Recently, various violations of this principle have been described. Here, we argue that the logic underlying Dollo's law only applies to traits that are constitutively expressed, while it fails in case of 'plastic' traits that a...

Diapause is an adaptation that insects have evolved to synchronize their life cycle with that of seasonal climatic changes and resources availability. However, cues for its induction are not always clear and, in some cases, a maternal effect may be involved. At the population level, just a part of the individuals may exhibit diapause with important...

Like many insects, aphids (Hemiptera: Aphididae) can host a wide diversity of symbiotic bacteria that can be important drivers of their evolutionary ecology. In addition to the nutritional obligate symbiont Buchnera aphidicola, these phloem-sap feeding insects can host various facultative symbionts whose functional diversity depends on complex inte...

Serratia symbiotica , one of the most frequent symbiont species in aphids, includes strains that exhibit various lifestyles ranging from free-living to obligate intracellular mutualism. Here, we report the draft genome sequences of two strains, namely, 24.1 and Apa8A1, isolated from aphids of the genus Aphis , consisting of genome sizes of 3,089,09...

Transgenerational effects act on a wide range of insects' life-history traits and can be involved in the control of developmental plasticity, such as diapause expression. Decrease in or total loss of winter diapause expression recently observed in some species could arise from inhibiting maternal effects. In this study, we explored transgenerationa...

Associations between symbiotic microorganisms and animals are ubiquitous and hosts may benefit from hosting microbial communities through enhanced protection to environmental stresses or resource exploitation. Like many insects, aphids are hosts of a wide diversity of heritable symbionts that can be important drivers of their evolutionary ecology....

Many plants require animal pollinators for successful reproduction; these plants provide pollinator resources in pollen and nectar (rewards) and attract pollinators by specific cues (signals). In a seeming contradiction, some plants produce toxins such as alkaloids in their pollen and nectar, protecting their resources from ineffective pollinators....

There are three possible scenarios regarding interacting populations within biological control programs. It is possible that the interaction does not lead to different outcomes from those in which each population is released individually. However, the interaction of two populations/species may increase the impact of the biocontrol, in which case it...

Effects of plants on herbivores can cascade up the food web and modulate the abundance of higher trophic levels. In agro-ecosystems, plant viruses can affect the interactions between crops, crop pests, and natural enemies. Little is known, however, about the effects of viruses on higher trophic levels, including parasitoids and their ability for pe...

Many insects engage in symbiotic associations with diverse assemblages of bacterial symbionts that can deeply impact on their ecology and evolution. The intraspecific variation of symbionts remains poorly assessed while phenotypic effects and transmission behaviors, which are key processes for the persistence and evolution of symbioses, may differ...

Sexual dimorphism, particularly at the level of sensory and locomotor organs, is usually attributed to sexual selection. Antennae are notably developed in males of species that need to detect a sex pheromone at low concentration or at long distance. In addition to their role in intrasexual selection, antennae can be seen as important ornaments in i...