(1) Habitat management can enhance beneficial arthropod populations and provide ecosystem services such as biological control. However, the implementation of ecological infrastructures inside orchards has a number of practical limitations. Therefore, planting/growing insectary plants in the margins of orchards should be considered as an alternative approach. (2) Here, we assessed the efficacy of a flower margin composed by four insectary plant species (Achillea millefolium, Lobularia maritima, Moricandia arvensis and Sinapis alba), which was placed on an edge of four Mediterranean apple orchards to attract natural enemies of two apple tree aphids (Dysaphis plantaginea and Eriosoma lanigerum). We also characterized the natural enemies present in the aphid colonies. (3) Our results show that the implementation of a flower margin at the edge of apple orchards attracts predators (Syrphidae, Thysanoptera, Araneae, Heteroptera, Coleoptera) and parasitoids. Parasitoids are the main natural enemies present in aphid colonies in our area. (4) The implementation of the flower margins successfully recruited natural enemy populations, and the presence of parasitoids in the surroundings of the orchards increased the parasitism of D. plantaginea colonies.

Nature-based solutions, such as biological control, can strongly contribute to reducing the use of plant protection products. In our study, we assessed the effect of augmentative releases of the European earwig (Forficula auricularia) to control the woolly apple aphid (Eriosoma lanigerum), a worldwide pest that causes serious damage to apple trees. The trials were carried out in two organic apple orchards located in Catalonia (NE Spain) from 2017 to 2020. Two treatments were compared: with vs. without earwig release. For the treatment, 30 earwigs per tree were released by means of a corrugated cardboard shelter. These releases were performed once per season and were repeated every year. We periodically assessed the length of the woolly apple aphid colonies, the number of colonies per tree, the percentage of aphids parasitized by Aphelinus mali, and the number of earwigs per shelter. Our results showed that earwig releases reduced the length of the colonies, but this effect was noticeable only for the second year onwards. Moreover, we found that those releases were compatible with A. mali. Overall, we demonstrated the positive impact of earwig releases on the woolly apple aphid control and the importance of considering time on augmentative biological control strategies.

Hoverflies can play an important role in aphid biological control. Adult hoverflies depend on pollen and nectar to survive. Therefore the placement of flower resources in agroecosystems is a common method to enhance the populations of these insects. When foraging, hoverflies rely on visual cues to select flowers. We studied the preference of Sphaerophoria rueppelli (Wiedemann) (Diptera: Syrphidae) adults for several flower traits and examined whether mating influenced foraging behavior. We observed that these insects were greatly attracted to bouquets of 12 flat circle-shaped flowers (half white and half yellow). Furthermore, yellow flowers elicited landing more than other colors, regardless of the type of bouquet. With respect to the effect of mating on posterior foraging behavior, virgin individuals showed more movement than gravid ones. Our results shed light on the behavior of adult hoverflies and can be used to improve habitat management practices that seek to promote biological control.

The rosy apple aphid, Dysaphis plantaginea Passerini (Hemiptera: Aphidae), is a major pest of apple trees. In organic apple production, this aphid is commonly controlled by spraying azadirachtin, targeted against fundatrices in spring. However, this is the only active ingredient that has proved effective for the management of this pest in organic production, and therefore it would be desirable to provide other alternatives. In this study, several treatments (pyrethrins, garlic extract, kaolin, potassium salts of fatty acids, and defoliation) applied in autumn to prevent or reduce the presence of winged forms and oviparae in the trees were compared. In addition, applications of paraffin oil and lime sulphur in winter against rosy apple aphid eggs were tested. The trials were carried out in Catalonia (NE of Spain) from 2005 to 2010. The results showed that pyrethrins reduced the presence of rosy apple aphid oviparae but they did not have a knockdown effect. The time of application was crucial since the spring infestation was kept under control only when pyrethrins were sprayed throughout the period when oviparae were in the apple trees. It was demonstrated for the first time that pyrethrins sprayed in autumn can prevent outbreaks of rosy apple aphid and can therefore provide an alternative to azadirachtin. As a result, the rosy apple aphid can be successfully managed in countries where azadirachtin is not approved and the likelihood of development of resistance will be reduced since more than one active ingredient will be available for the control of this pest.

Fungicides may interact synergistically with insecticides. However, our understanding of the impacts of sublethal insecticide-fungicide combinations on solitary bees is mostly restricted to laboratory studies, providing no information about potential consequences on behavior and reproductive success. We analyzed the effects of a fungicide application, alone and in combination with sublethal levels of an insecticide, on the nesting behavior and reproductive output of the solitary bee Osmia cornuta. We released individually-marked females into oilseed rape field cages, and subsequently sprayed the plants with four treatments: control (water), fungicide (tebuconazole), insecticide (acetamiprid at a sublethal concentration), and mixture (fungicide + insecticide). We recorded nesting activity before and after the sprays and assessed post-spray individual reproductive success. Bees of the single pesticide treatments were unaffected by the sprays and did not differ from control bees in any of the parameters measured. The longevity of bees of the mixture treatment was unaffected. However, these bees showed reduced foraging activity, shorter in-nest pollen-nectar deposition times, and increased difficulty recognizing their nesting cavity, leading to a decrease in provisioning rate, parental investment, and offspring production. Our study demonstrates that co-exposure to a fungicide with otherwise harmless levels of an insecticide caused behavioral effects with consequences on reproductive success. Because longevity was unaffected, these effects would not have been easily detected in a chronic laboratory test. Our results have important implications for bee risk assessment, which should account for exposure to multiple compounds and address behavioral effects and reproductive output under semi-field and/or field conditions.

Enhancing natural enemy populations in agricultural systems by combining habitat manipulation and herbivore-induced plant volatiles (HIPVs) offers a promising approach to conservation biological control. The aphidophagous midge Aphidoletes aphidimyza is widely used in biological control programs in many crops, and the development of novel attract and reward (A&R) strategy may promote the establishment and survival of A. aphidimyza in crops. Here, we focus on (i) the attractiveness (under laboratory conditions) to A. aphidimyza of the HIPVs phenylacetaldehyde (Pal) and methyl salicylate (MeSA) and plants in the families Brassicaceae, Euphorbiaceae, Asteraceae and Fabaceae, all evaluated separately, and (ii) the effect of consuming nectar from Eruca vesicaria , Euphorbia segetalis , Moricandia arvensis , Calendula officinalis , Vicia faba , V. sativa , Medicago sativa , and Centaurea cyanus on A. aphidimyza survival, as well as the impact of the first five species on egg load. Neither of the tested HIPVs (Pal and MeSA) induced a positive chemotactic response in double-choice bioassays, nor did any of the tested plants. Survival curves varied according to the food provided; A. aphidimyza females fed V. faba , V. sativa (Fabaceae), or E. vesicaria (Brassicaceae) had the highest survival rates, significantly higher than those of A. aphidimyza fed only water. Plant food sources also impacted egg load, which was significantly higher in females fed C. officinalis than in those fed V. faba ; egg numbers in females fed E. vesicaria did not differ significantly from either. Together, these findings represent a first step toward determining the potential of insectary plants for improving A. aphidimyza performance.