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- The right banker plant for the right application: Comparison of three candidates for aphid biocontrol, barley (Hordeum vulgareL.), corn (Zea maysL.), and finger millet (Eleusine coracana (L.) Gaertn)Publication . Fauteux, Arlette; Fournier, Marc; Soares, António O.; Lucas, EricBACKGROUND In temperate regions, aphid biological control in greenhouses is mostly achieved by the regular release of biocontrol agents. Due to the rapid growth rate of the aphid population, biocontrol agents must be released frequently in order to be present before pest outbreaks and to act rapidly to prevent exceeding the economic threshold. Banker plants reduce these numerous releases by providing natural enemies with a high-quality environment to develop and reproduce. Optimally, banker plants should be easy to produce, resistant to environmental conditions, provide a large amount of suitable banker prey in order to produce a high number of biocontrol agents, and resist the herbivory pressure of the banker prey. The present study aimed to compare the value of three banker plant candidates of the Poaceae family under laboratory and greenhouse conditions: barley (Hordeum vulgare L.), finger millet (Eleusine coracana (L.) Gaertn), and corn (Zea mays L.). RESULTS Our results show that the three plants were suitable for different contexts. Finger millet yielded the biggest fresh plant biomass, supported the highest load of banker prey, and resisted aphid feeding longer than the other plant species. Corn was the cheapest to produce, and barley was the fastest to grow. CONCLUSIONS Overall, finger millet could be more fitted for long crop cycles, pests with rapid population growth rates, and voracious or fast-reproducing biocontrol agents. Meanwhile, barley and corn may be better suited for rapid crop cycles, pests with slow population growth rates, and biocontrol agents that are not too voracious or have low reproductive rates. © 2024 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
- Larval development and voracity of Eupeodes americanus (Diptera: Syrphidae): comparison of the focal prey Aphis gossypii (Hemiptera: Aphididae) and the banker prey Rhopalosiphum padi (Hemiptera: Aphididae)Publication . Fauteux, Arlette; Soares, António Onofre; Lucas, EricABSTRACT: Unlike European species, the potential of Nearctic syrphids as biological control agents is still poorly studied. However, the American hoverfly, Eupeodes americanus (Wiedemann), has recently demonstrated promising traits as a biocontrol agent, notably against the foxglove aphid, Aulacorthum solani Kaltenbach, on pepper. The present study aims to extend our knowledge of the American hoverfly by evaluating its potential as a biocontrol agent in a banker plant system against the melon aphid, Aphis gossypii Glover, in a greenhouse cucumber crop. The preimaginal development and voracity of E. americanus were compared when preying upon the focal prey/pest (A. gossypii) or the banker prey (bird cherry-oat aphid, Rhopalosiphum padi L.) by daily observations of larvae from egg to adult. Preimaginal development time, survival rate, and occurrence of deformation were similar on both prey species. The weight of third instar and pupae, however, was higher for larvae that fed on the banker prey. The ad libitum voracity of the syrphid larvae was generally very high and did not significantly differ between prey species, except for the third-instar larvae which consumed more focal prey. Results suggest that a banker plant system involving the bird cherry-oat aphid may be a promising tactic for utilizing E. americanus for melon aphid biocontrol.
- Influence of refuge availability on the oviposition strategy of anachoretic and non-anachoretic aphidophagous ladybirdsPublication . Costa Miranda Soares, António Onofre; Vale, Marta; Borges, Isabel; Lucas, Eric; Montserrat, MartaABSTRACT: Scymnus nubilus Mulsant and Coccinella undecimpunctata L. (Coleoptera: Coccinellidae) are two generalist aphidophagous predators abundant in herbaceous habitats. C. undecimpuctata, a larger species, lays its eggs in uncovered clusters, whereas S. nubilus, a tiny species, lays its eggs singly and, possibly, in concealed sites. Reproductive strategies in ladybirds seem to be adaptive, allowing the co-occurrence of both predators, apparently without interfering with each other. The aim of this study was to characterize the following oviposition strategies in S. nubilus and C. undecimpunctata: daily fecundity, effect of available sites on females’ fecundity, and circadian rhythmicity of oviposition. We hypothesize that the single-egg-laying strategist (1) is more dependent on the availability of concealed sites to oviposit and (2) lays eggs closer to aphid colonies. We found that different levels of site concealability allows S. nubilus to increase fecundity. Contrary to C. undecimpunctata, in the absence of a suitable substrate to conceal its eggs, S. nubilus females refrain ovipositing. S. nubilus prefers to hide their eggs beneath prey carcasses while C. undecimpunctata is less selective concerning the oviposition sites. S. nubilus dilutes its fecundity effort through more oviposition sites and events, while C. undecimpunctata requires one event to lay its clusters. Our results showed that the smaller ladybird is more dependent than the larger one on habitat structural complexity to maximize its fitness and that laying a single hidden egg mainly during the scotophase confers a potential adaptive advantage to increase fitness.