Flower strips increase the control of rosy apple aphids after parasitoid releases in an apple orchard

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 early parasitoid releases—and of other naturally present aphid enemies—on the control of aphid colonies and number of aphids per tree. Apple trees located at different distances from parasitoid release points were monitored in plots with and without flower strips in an organic apple orchard over two years, along the season of aphid infestation (March to July). Our case study demonstrated that the presence of flowering plant mixes in the alleyways of an apple orchard improved the biological control of D. plantaginea, with an effect size of 33.4% less aphids in plots with flower strips, compared to plots without flower strips, at the infestation peak date. We also showed a negative effect of higher distance to parasitoid release points on aphid control, but our results at the infestation peak date suggest that the presence of flowers could marginally compensate for the detrimental effect of distance, probably by improving the persistence and dispersal capacities of natural enemies. Despite high variations in aphid population dynamics between years, we conclude that combining flower strips with early parasitoid releases in apple orchards is promising for biological control of the rosy apple aphid, although the method merits to be further refined and repeated in more orchards.

Assessing the optimal frequency of early parasitoid releases in an apple orchard to control Dysaphis plantaginea: a proof of concept study

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 parasitoid species, Aphidius matricariae and Ephedrus cerasicola, early in the season to match the presence of aphid fundatrix (sensitive stages). In this trial focusing on an organic apple orchard, three releases were done either every week or every two weeks to test the effect of the release frequency, during two consecutive years. The number of aphid colonies and aphid number per tree were monitored from late March to late May. Degree-days necessary for parasitoid emergence in the field after release were calculated. We show that a sufficient level of aphid control by parasitoids is reached during the first month of the survey, but control mostly fails during the second part of the monitoring session, for both release treatments, and compared to the neem oil control treatment. The relative effects of release frequencies were different between years probably because of interannual differences in aphid population dynamics and initial infestation in orchards. The field survey and the degree-day model suggest that parasitoid releases, at either frequency, are promising candidates for biological control of the rosy aphid, although the method still needs proper calibration. This conclusion needs to be reinforced by repeating the study in more orchards, but our case study lays the first empirical basis that will help to develop future control methods of aphids by parasitoid releases in apple orchards. We argue that releases should be done one to two weeks before first aphid detection to account for long development times of parasitoids at relatively low temperatures.

Additional data on Aphidiinae (Hymenoptera, Braconidae) fauna of Kyrgyzstan, with description of a new species

Here we present additional data on the Aphidiinae fauna of Kyrgyzstan. We identified 18 Aphidiinae species. One species new to science (Trioxys depressussp. nov.) is described, while 11 species are reported for the first time: Aphidius avenae Haliday, A. ervi Haliday, A. matricariae Haliday, A. salicis Haliday, A. urticae Haliday, Ephedrus cerasicola Starý, E. niger Gautier, Bonnamour & Gaumont, Lysiphlebus cardui (Marshall), L. confusus Tremblay & Eady, Monoctonus crepidis (Haliday), and Praon yomenae Takada. Current knowledge of Kyrgyz Aphidiinae is summarized and discussed.

Aphid parasitoids (Hymenoptera, Braconidae, Aphidiinae) of the Forest Zones of Ukraine: species composition and habitat associations

The article presents data on species composition and habitat associations of the species of a practically important group of parasitic hymenopterous insects from the subfamily Aphidiinae (Hymenoptera, Braconidae) within the Forest zones of Ukraine. Species composition of aphidiines of the territory of research includes 45 species from 16 genera. Among them, 32 species were recorded only in the Zone of Mixed Forest: Adialytus salicaphis, Aphidius matricariae, A. megourae, A. rhopalosiphi, A. ribis, A. urticae, Areopraon silvestre, Binodoxys angelicae, Diaeretellus ephippium, Diaeretiella rapae, Diaeretus leucopterus, Ephedrus cerasicola, E. lacertosus, E. niger, E. plagiator, E. validus, Lysiphlebus cardui, L. dissolutus, L. hirticornis, Pauesia abietis, P. laricis, P. longicauda, P. pini, P. pinicollis, Praon bicolor, P. longicorne, P. megourae, P. pubescens, Protaphidius wissmannii, Trioxys cirsii, T. curvicaudus, T. pallidus; 3 species were recorded only in the Zone of Deciduous Forests: Lipolexis gracilis, Praon abjectum, Toxares deltiger; 10 species were registered in both zones: Adialytus ambiguus, Aphidius asteris, A. ervi, A. rosae, Binodoxys acalephae, Ephedrus persicae, Lysiphlebus confusus, L. fabarum, Paralipsis evervis, Praon volucre. Eight species are associated only with aphids on coniferous trees: Diaeretus leucopterus, Pauesia abietis, P. laricis, P. longicauda, P. pini, P. pinicollis, P. unilachni, Praon bicolor. Four species are euribiotic: Aphidius ervi, Ephedrus plagiator, Lysiphlebus fabarum, Praon volucre. At the same time, we consider ten species as rare on the time of research: Diaeretus leucopterus, Diaeretellus ephippium, Pauesia abietis, P. longicauda, Р. pini, P. pinicollis, Praon bicolor, P. megourae, P. pubescens, Protaphidius wissmannii. Factors that may affect the low abundance of some species in Forest zones in Ukraine: trophic specialization of species, features of biology, patterns of geographical and habitat associations of species in the area of research, patterns of material collection.

The fate of released parasitoids (Hymenoptera: Braconidae, Aphidiinae) for biological control of aphids in Chile

Research on aphid-parasitoid associations was carried out in Chile in 1979–80 and 1991–92 on the biological control of the cereal aphid pests Metopolophium dirhodum (Walker), Sitobion avenae (Fabricius), and Diuraphis noxia (Mordvilko). The introduced parasitoid species, Aphidius ervi Haliday, A. rhopalosiphi De Stefani Perez, A. smithi Sharma & Subba Rao, A. uzbekistanicus Luzhetski, Ephedrus cerasicola Starý, E. nacheri QuilisPerez, E. plagiator (Nees), Monoctonus nervosus (Haliday), Prnon gallicum Starý, P. volucre (Haliday) were all recovered in cereal and other ecosystems. Most of the parasitoids had adapted well and some of them had even extended their host range; ecological relationships were all found to extend beyond those of the target pests. The parasitoid complex, which had developed from the indigenous and introduced species, was found to be successful in preventive biocontrol and the endemic fauna of Chile was not affected.