Up and to the light: intra- and interspecific variability of photo- and geo-tactic oviposition preferences in genus Trichogramma

Burte, Victor; Perez, Guy; Ayed, Faten Srarfi Ben; Groussier, Géraldine; Mailleret, Ludovic; Oudenhove, Louise van; Calcagno, Vincent

doi:10.24072/pcjournal.78

Cited by 4 publications

(7 citation statements)

References 31 publications

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“…T. cacoeciae is a strictly thelytokous species, whose females give birth to genetically identical daughters by clonal reproduction [ 17 ]. Insects were reared on UV-sterilised eggs of Ephestia kuehniella (the common laboratory host for trichograms, also used for sampling and experiments) with a 12:12 light:dark cycle, at temperatures switching between 25 and 19 °C, in order to get a development time of 14 days from host parasitism to adult emergence [ 32 ]. All individuals used for experiments were 24 h old and kept at 25 °C in a glass tube with water and honey as a facultative food source prior to experiments.…”

Section: Methodsmentioning

confidence: 99%

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When complex movement yields simple dispersal: behavioural heterogeneity, spatial spread and parasitism in groups of micro-wasps

et al. 2023

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Background Understanding how behavioural dynamics, inter-individual variability and individual interactions scale-up to shape the spatial spread and dispersal of animal populations is a major challenge in ecology. For biocontrol agents, such as the microscopic Trichogramma parasitic wasps, an understanding of movement strategies is also critical to predict pest-suppression performance in the field. Methods We experimentally studied the spatial propagation of groups of parasitoids and their patterns of parasitism. We investigated whether population spread is density-dependent, how it is affected by the presence of hosts, and whether the spatial distribution of parasitism (dispersal kernel) can be predicted from the observed spread of individuals. Using a novel experimental device and high-throughput imaging techniques, we continuously tracked the spatial spread of groups of parasitoids over large temporal and spatial scales (8 h; and 6 m, ca. 12,000 body lengths). We could thus study how population density, the presence of hosts and their spatial distribution impacted the rate of population spread, the spatial distribution of individuals during population expansion, the overall rate of parasitism and the dispersal kernel (position of parasitism events). Results Higher population density accelerated population spread, but only transiently: the rate of spread reverted to low values after 4 h, in a “tortoise-hare” effect. Interestingly, the presence of hosts suppressed this transiency and permitted a sustained high rate of population spread. Importantly, we found that population spread did not obey classical diffusion, but involved dynamical switches between resident and explorer movement modes. Population distribution was therefore not Gaussian, though surprisingly the distribution of parasitism (dispersal kernel) was. Conclusions Even homogenous asexual groups of insects develop behavioural heterogeneities over a few hours, and the latter control patterns of population spread. Behavioural switching between resident and explorer states determined population distribution, density-dependence and dispersal. A simple Gaussian dispersal kernel did not reflect classical diffusion, but rather the interplay of several non-linearities at individual level. These results highlight the need to take into account behaviour and inter-individual heterogeneity to understand population spread in animals.

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Section: Methodsmentioning

confidence: 99%

“…The two host distributions thus had on average the same host density (120 eggs in total per arena). In those treatments the parasitism status of each egg at the end of the experiment was recorded: the bottom paper sheet was stored for five days at 25 °C, after which parasitized hosts turned black and could be counted (see [ 29 , 32 ]).…”

Section: Methodsmentioning

confidence: 99%

When complex movement yields simple dispersal: behavioural heterogeneity, spatial spread and parasitism in groups of micro-wasps

et al. 2023

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“…T. cacoeciae is a strictly thelytokous species, whose females give birth to genetically identical daughters by clonal reproduction (Cônsoli et al, 2010). Insects were reared on UV-sterilised eggs of Ephestia kuehniella (the common laboratory host for trichograms, also used for sampling and experiments) with a 12:12 light:dark cycle, at temperatures switching between 25°C and 19°C, in order to get a development time of 14 days from host parasitism to adult emergence (Burte et al, 2022). All individuals used for experiments were 24 hour old and kept at 25°C in a glass tube with water and honey as a facultative food source prior to experiments.…”

Section: Methodsmentioning

confidence: 99%

“…The two host distributions thus had on average the same host density (120 eggs in total per arena). In those treatments the parasitism status of each egg at the end of the experiment was recorded: the bottom paper sheet was stored for five days at 25°C, after which parasitized hosts turned black and could be counted (see (Burte et al, 2022; Morel-Journel et al, 2016)).…”

Section: Methodsmentioning

confidence: 99%

When complex movement yields simple dispersal: behavioural heterogeneity, spatial spread and parasitism in groups of micro-wasps

Burte

Silva

Perez

et al. 2022

Preprint

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Understanding how behavioural dynamics, inter-individual variability and individual interactions scale-up to shape the spatial spread and dispersal of animal populations is a major challenge in ecology. For biocontrol agents, such as the microscopic Trichogramma parasitic wasps, an understanding of movement strategies is also critical to predict pest-suppression performance in the field.We experimentally studied the spatial propagation of groups of parasitoids and their patterns of parasitism. We investigated whether population spread is density-dependent, how it is affected by the presence of hosts, and whether the spatial distribution of parasitism (dispersal kernel) can be predicted from the observed spread of individuals.Using a novel experimental device and high-throughput imaging techniques, we continuously tracked the spatial spread of groups of parasitoids over large temporal and spatial scales (eight hours; and six metres, ca. 12,000 body lengths). We could thus study how population density, the presence of hosts and their spatial distribution impacted the rate of population spread, the spatial distribution of individuals during population expansion, the overall rate of parasitism and the dispersal kernel (position of parasitism events).Higher population density accelerated population spread, but only transiently: the rate of spread reverted to low values after four hours, in a “tortoise-hare” effect. Interestingly, the presence of hosts suppressed this transiency and permitted a sustained high rate of population spread. Importantly, we found that population spread did not obey classical diffusion, but involved dynamical switches between resident and explorer movement modes. Population distribution was therefore not Gaussian, though surprisingly the distribution of parasitism (dispersal kernel) was.Even homogenous asexual groups of animals were shown to develop behavioral heterogeneties over a few hours. Explorer individuals were responsible for most parasitism and dispersal, and determined spatial spread and density-dependent dispersal. We showed that simple Gaussian dispersal did not emerge from simple diffusion, but rather from the interplay of several non-linearities at individual level. This suggests expectations from classical diffusion theory may not hold generally to active dispersers. These results highlight the need to take into account behaviour and inter-individual heterogeneity to understand population spread in animals.

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“…All Parameters were estimated with Bayesian inference from non-informative priors (see Supplementary Information S.3.1 for details). From these estimations, both the number of black and white eggs (EggsB and EggsW) were predicted from the number of pixels for all patches (see Supplementary Information S.3.1 and Burte et al (2022) for prediction accuracy). The data available after this first step analysis were thus, for all the 310 patches: NbEggs, the total number of eggs (NbEggs = EggsB + EggsW) and NbB the number of parasitoid pupae NbB = EggsB).…”

Section: Pre-imaginal Survivalmentioning

confidence: 99%

Non-target effects of ten essential oils on the egg parasitoidTrichogramma evanescens

Oudenhove

Cazier

Fillaud

et al. 2022

Preprint

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Essential oils (EOs) are increasingly used as biopesticides due to their insecticidal potential. This study addresses their non-target effects on a biological control agent: the egg parasitoid Trichogramma evanescens. In particular, we tested whether EOs affected parasitoid fitness either directly, by decreasing pre-imaginal survival, or indirectly, by disrupting parasitoids' orientation abilities. The effect of Anise, Fennel, Sweet orange, Basil, Coriander, Oregano, Peppermint, Mugwort, Rosemary and Thyme EOs were studied on five strains of T. evanescens. Specific experimental setups were developed, and data obtained from image analysis were interpreted with phenomenological models fitted with Bayesian inference. Results highlight the fumigant toxicity of EOs on parasitoid development. Anise, Fennel, Basil, Coriander, Oregano, Peppermint and Thyme EOs are particularly toxic and drastically reduce the emergence rate of T. evanescens. Most EOs also affect parasitoid behavior: (i) Basil, Coriander, Oregano, Peppermint, Mugwort and Thyme EOs are highly repellent for naive female parasitoids; (ii) Anise and Fennel EOs can have repellent to attractive effects depending on strains; and (iii) Sweet orange, Oregano and Rosemary EOs have no detectable impact on orientation behavior. This study shows that EOs fumigation have non-target effects on egg parasitoids. This highlights the need to cautiously precise the deployment framework of biopesticides in an agroecological perspective.

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Up and to the light: intra- and interspecific variability of photo- and geo-tactic oviposition preferences in genus Trichogramma

Abstract: Oudenhove and Vincent Calcagno (2022) Up and to the light: intra-and interspecific variability of photo-and geo-tactic oviposition preferences in genus Trichogramma, Peer Community Journal, 2: e3.

Cited by 4 publications

References 31 publications

When complex movement yields simple dispersal: behavioural heterogeneity, spatial spread and parasitism in groups of micro-wasps

When complex movement yields simple dispersal: behavioural heterogeneity, spatial spread and parasitism in groups of micro-wasps

When complex movement yields simple dispersal: behavioural heterogeneity, spatial spread and parasitism in groups of micro-wasps

Non-target effects of ten essential oils on the egg parasitoidTrichogramma evanescens

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