Selection of insectary plants for the conservation of biological control agents of aphids and thrips in fruit orchards–CORRIGENDUM

Few management strategies exist for silver scurf, an important postharvest disease of potatoes. In this study, the microbiota of 47 agricultural soils and 7 tuber samples was screened for biological control agents of silver scurf. Soil or periderm samples were transferred to separate samples of γ irradiation-sterilized field soil enriched with potato periderm. After incubation, the samples were assayed for biological suppressiveness to silver scurf using a whole-tuber/infested soil assay. Over 430 isolates of bacteria, yeasts, and actinomycetes were recovered from tubers and soil associated with the 12 most suppressive soil samples. Thirteen strains were selected for further study on three different strains of Helminthosporium solani, including one that was resistant to thiabendazole. Microbial strains that significantly inhibited H. solani (P ≤ 0.05) in at least one experiment were identified as Pseudomonas putida (PM1), Nocardia globerula (S244), and Xanthomonas campestris (P76). Colonization studies with rifampicin-resistant strains of putative biological control agents revealed that long-term colonization of the tuber surface was not necessary to reduce disease symptoms. Highly variable levels of conidiophore production prevented selection of the single most suppressive strain. Possible sources of variability in biological control are discussed, including physiological age of the tuber, tuber infection in the field, and uneven free moisture in the storage.

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Selection of insectary plants for the conservation of biological control agents of aphids and thrips in fruit orchards

Bulletin of Entomological Research ◽

10.1017/s0007485321000183 ◽

2021 ◽

pp. 1-11

Author(s):

Carmen Denis ◽

Jordi Riudavets ◽

Rosa Gabarra ◽

Paula Molina ◽

Judit Arnó

Keyword(s):

Biological Control ◽

Plant Species ◽

Natural Enemies ◽

Fruit Production ◽

Flowering Plant ◽

Biological Control Agents ◽

North East ◽

The North ◽

Flowering Plant Species ◽

Fruit Orchards

Abstract This study evaluated the potential of flowering plant species naturally occurring to promote the conservation and early establishment of key natural enemies of aphids and thrips in apple and peach orchards. Flowering plants present in the North East of Spain, a main fruit production area in Europe, were sampled to determine their flowering period and to identify potential natural enemies present on each plant species. Thirty-six plant species were found blooming from early March to late May and provided an array of flowers that might ensure food resources for natural enemies. Among them, six species – Eruca vesicaria (L.) Cav., Cardaria draba (L.) Desv., Euphorbia serrata (L.) S.G. Gmel., Malva sylvestris L., Anacyclus clavatus (Desf.) Pers. and Diplotaxis erucoides (L.) DC. – hosted a high diversity of potential natural enemies of aphids and thrips. Their blooming started early in the season and lasted for several sampling weeks and they were widely distributed. Moreover, they had available nectar even in those species with protected nectaries. Therefore, these plant species can be considered as promising candidates for inclusion in the ecological infrastructure designed for fruit orchards in the study area to promote the conservation of the biological control agents of aphids and thrips.

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