Rosy Apple Aphid Dysaphis Plantaginea Research Articles

Effects of winter pruning intensity on the interactions between the apple tree and rosy apple aphid Dysaphis plantaginea (Hemiptera: Aphididae)

Effects of winter pruning intensity on the interactions between the apple tree and rosy apple aphid Dysaphis plantaginea (Hemiptera: Aphididae)

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

AbstractMass 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 an exploratory 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 the number of aphids per tree. Apple trees located at various 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 the apple orchard reduced the presence of D. plantaginea by 33.4%, compared to plots without flower strips, at the infestation peak date. We also showed a negative effect of increasing the distance to parasitoid release points on aphid control. However, our results at the infestation peak date suggest that the presence of flower strips could marginally compensate for the detrimental effect of increasing distance to the release point, 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.

Thermal tolerance of the rosy apple aphid Dysaphis plantaginea and its parasitoids: Effect of low temperatures on some fitness activities of Aphidius matricariae

Understanding the thermal tolerance of insect herbivores and their natural enemies is crucial for biological control programs. The rosy apple aphid Dysaphis plantaginea is one of the most problematic pests of apple orchards, causing economic losses of up to 30% due to damage to fruits. Dysaphis plantaginea is highly adapted to low temperature, enabling it to appear early in the season. This study aimed at evaluating the critical thermal minimum of D. plantaginea and of two parasitoid species: Aphidius matricariae and Ephedrus cerasicola. For the generalist parasitoid A. matricariae we also evaluated the fitness traits of flight, walking, and oviposition, at four temperatures: 20, 15, 10 and 8 °C. We found that both males and females did not fly at the two lowest temperatures. Walking, parasitism rate and sex ratio (proportion of female progeny) were reduced at 8 °C. In addition, the parasitism rate was significantly lower at 8 and 10 °C compared to 15 and 20 °C. The progeny emerging from the oviposition experiment at 8 °C were significantly larger compared with other temperatures, possibly attributed to longer development time. The fact that the parasitoids were unable to fly at 8 and 10 °C, in combination with a more male-biased sex ratio, could reduce their efficiency at low temperature, even though they may still be able to walk and parasitize aphids.

Effects of Bacillus lipopeptides on the survival and behavior of the rosy apple aphid Dysaphis plantaginea

Within the framework of biocontrol development, several natural lipopeptides produced by Bacillus subtilis show well-documented anti-microbial properties, especially in orchards. However, the number of studies on their putative insecticidal effects remain low despite the growing interest to develop new strategies of orchards pests’ control. The rosy apple aphid Dysaphis plantaginea is the major aphid pest causing great leaf damage to apple trees. In this study, we submitted young adult aphids to topical application of three different families of lipopeptides, Plipastatin (Fengycin), Mycosubtilin (Iturin), and Surfactin, either separately or as a ternary mixture. Their aphicidal effects were investigated at 1, 2.5 and 5 g/L, both at 1 h and 24 h after exposure, and their effects on aphid behavior were studied at the 2.5 g/L concentration at 24 h after exposure. When delivered alone, lipopeptides displayed contrasted effects varying from no aphicidal activity for Mycosubtilin to a mortality induced even at low concentrations by Surfactin. Surprisingly, locomotor activity of the surviving aphids was only affected by the two least lethal treatments, Mycosubtilin and the ternary mix. Their feeding behavior was only impacted by Surfactin, the most lethal treatment, that unexpectedly increased phloem sap ingestion. The results are discussed in the context of lipopeptides applicability for integrated pest management.

Effects of Constant versus Fluctuating Temperatures on Fitness Indicators of the Aphid Dysaphis plantaginea and the Parasitoid Aphidius matricariae.

Simple SummaryLike all organisms, insects encounter temperatures that fluctuate on different time scales: within a day, between days, or throughout the seasons. However, most studies on the impact of temperature on insect physiology, behavior, morphology, or ecology have focused on constant temperatures tested in the laboratory. In our study, we wanted to know if fluctuating temperatures during the day (7–17 °C, average 12 °C) can affect insects differently compared to a constant temperature of 12 °C. We used, as a model, the apple aphid Dysaphis plantaginea, a major threat to apple orchards worldwide, and its parasitoid Aphidius matricariae, which is used in biological control. We found that many traits—but not all—were affected. In particular, the fluctuating thermal regime reduced the development time of aphids and parasitoids, improved the rate of parasitism, and tended (albeit slightly) to increase the longevity of both species. In contrast, we did not find strong effects on morphological traits. Our results can be used to better predict how these agronomically important insects behave in orchards, how ecologically-relevant fluctuating temperatures affect host–parasitoid relationships, and ultimately what the implications are in the context of climate change and biological control.Testing fluctuating rather than constant temperatures is likely to produce more realistic datasets, as they are ecologically more similar to what arthropods experience in nature. In this study, we evaluated the impact of three constant thermal regimes (7, 12, and 17 °C) and one fluctuating thermal regime (7–17 °C with a mean of 12 °C) on fitness indicators in the rosy apple aphid Dysaphis plantaginea, a major pest of apple orchards, and the parasitoid Aphidius matricariae, one of its natural enemies used in mass release biological control strategies. For some—but not all—traits, the fluctuating 7–17 °C regime was beneficial to insects compared to the constant 12 °C regime. Both aphid and parasitoid development times were shortened under the fluctuating regime, and there was a clear trend towards an increased longevity under the fluctuating regime. The fecundity, mass, and size were affected by the mean temperature, but only the mass of aphids was higher at 7–17 °C than at a constant 12 °C. Parasitism rates, but not emergence rates, were higher under the fluctuating regime than under the constant 12 °C regime. Results are discussed within the framework of insect thermal ecology and Jensen’s inequality. We conclude that incorporating thermal fluctuations in ecological studies could allow for the more accurate consideration of how temperature affects host–parasitoid interactions and insect responses to temperature change over time.

Species-Specific Induction of Plant Volatiles by Two Aphid Species in Apple: Real Time Measurement of Plant Emission and Attraction of Lacewings in the Wind Tunnel

Upon damage by herbivores, plants release herbivory-induced plant volatiles (HIPVs). To find their prey, the pest’s natural enemies need to be fine-tuned to the composition of these volatiles. Whereas standard methods can be used in the identification and quantitation of HIPVs, more recently introduced techniques such as PTR-ToF–MS provide temporal patterns of the volatile release and detect additional compounds. In this study, we compared the volatile profile of apple trees infested with two aphid species, the green apple aphid Aphis pomi, and the rosy apple aphid Dysaphis plantaginea, by CLSA-GC–MS complemented by PTR-ToF–MS. Compounds commonly released in conjunction with both species include nonanal, decanal, methyl salicylate, geranyl acetone, (Z)-3-hexenyl acetate, (Z)-3-hexenyl butanoate, (Z)-3-hexenyl 2-methyl-butanoate, (E)-β-caryophyllene, β-bourbonene and (Z)-3-hexenyl benzoate. In addition, benzaldehyde and (E)-β-farnesene were exclusively associated with A. pomi, whereas linalool, (E)-4,8-dimethyl-1,3,7-nonatriene were exclusively associated with D. plantaginea. PTR-ToF–MS additionally detected acetic acid (AA) and 2-phenylethanol (PET) in the blends of both trees attacked by aphid species. In the wind tunnel, the aphid predator, Chrysoperla carnea (Stephens), responded strongly to a blend of AA and PET, much stronger than to AA or PET alone. The addition of common and species-specific HIPVs did not increase the response to the binary blend of AA and PET. In our setup, two host-associated volatiles AA + PET appeared sufficient in the attraction of C. carnea. Our results also show the importance of combining complementary methods to decipher the odor profile associated with plants under pest attack and identify behaviourally active components for predators.

Identification of candidate genes at the Dp-fl locus conferring resistance against the rosy apple aphid Dysaphis plantaginea

The cultivated apple is susceptible to several pests including the rosy apple aphid (RAA; Dysaphis plantaginea Passerini), control of which is mainly based on chemical treatments. A few cases of resistance to aphids have been described in apple germplasm resources, laying the basis for the development of new resistant cultivars by breeding. The cultivar ‘Florina’ is resistant to RAA, and recently, the Dp-fl locus responsible for its resistance was mapped on linkage group 8 of the apple genome. In this paper, a chromosome walking approach was performed by using a ‘Florina’ bacterial artificial chromosome (BAC) library. The walking started from the available tightly linked molecular markers flanking the resistance region. Various walking steps were performed in order to identify the minimum tiling path of BAC clones covering the Dp-fl region from both the “resistant” and “susceptible” chromosomes of ‘Florina’. A genomic region of about 279 Kb encompassing the Dp-fl resistance locus was fully sequenced by the PacBio technology. Through the development of new polymorphic markers, the mapping interval around the resistance locus was narrowed down to a physical region of 95 Kb. The annotation of this sequence resulted in the identification of four candidate genes putatively involved in the RAA resistance response.

Towards a physical map of the locus conferring resistance against the rosy apple aphid Dysaphis plantaginea from the cultivar ‘Florina’

Towards a physical map of the locus conferring resistance against the rosy apple aphid <i>Dysaphis plantaginea</i> from the cultivar ‘Florina’

Warming affects different components of plant–herbivore interaction in a simplified community but not net interaction strength

Global warming impacts natural communities through effects on performance of individual species and through changes in the strength of interactions between them. While there is a body of evidence of the former, we lack experimental evidence on potential changes in interaction strengths. Knowledge about multispecies interactions is fundamental to understand the regulation of biodiversity and the impact of climate change on communities. This study investigated the effect of warming on a simplified community consisting of three species: rosy apple aphid Dysaphis plantaginea feeding on plantain, Plantago lanceolata, and a heterospecific neighbouring plant species, perennial ryegrass, Lolium perenne. The aphid does not feed on L. perenne. The experimental design consisted of monocultures and mixtures of L. perenne and P. lanceolata at three temperature levels. We did not find indication for indirect temperature effects on D. plantaginea through changes in leaf nitrogen or relative water content. However, experimental warming affected the life history traits of the aphid directly, in a non‐linear manner. Aphids performed best at moderate warming, where they grew faster and had a shorter generation time. In spite of the increased population growth of the aphids under warming, the herbivory rates were not changed and consequently the plant–herbivore interaction was not altered under warming. This suggests reduced consumption rates at higher temperature. Also plant competition affected the aphids but through an interaction with temperature. We provide proof‐of‐concept that net interactions between plants and herbivores should not change under warming despite direct effects of warming on herbivores when plant–plant interaction are considered. Our study stresses the importance of indirect non–trophic interactions as an additional layer of complexity to improve our understanding of how trophic interactions will alter under climate change.

DEVELOPMENT OF THE ROSY APPLE APHID WITHIN ITS HABITAT: SOME STRUCTURAL AND PHYSIOLOGICAL ASPECTS IN APPLE TREES

Plant architecture governs living conditions of herbivores. In fruit trees, the perennial structure is modulated by training and pruning which may affect pests. The effect of tree architecture manipulation on the development of the rosy apple aphid Dysaphis plantaginea (RAA) was investigated from 2002 to 2009 in apple orchards. The first step (2002-2005) consisted in comparing the Centrifugal Training system (CT) with extinction pruning (i.e., selective removal of spurs at bud-burst to favour light penetration and spur fruiting) to the Solaxe system (OS) with no extinction pruning. RAA infestation was significantly lower in CT trees 2 years out of 4. The hypothesis of a within-tree structural effect on RAA development was proposed beside possible microclimatic and mechanical (i.e., infested shoot removal) effects. In a second step (2007-2008) we investigated the relationships between the branch structure and RAA development in both training systems. In CT trees, branches displayed higher shoot orders compared to OS. Infestation dynamics presented similar patterns in both systems, but RAA spreading rate was lower in CT trees. These results suggested that the complexity of the aerial system due to higher branching orders affected insect movement within its habitat. In 2009 a glasshouse experiment with oneyear- old potted apple trees was carried out to test the combined effect of simplified architectures (1 vs. 2 extension shoots per tree) and of three nitrogen regimes on the development of RAA artificially set on the trees. There was no significant difference in aphid numbers at peak infestation between architectural treatments although RAA migration was earlier with 1 extension shoot. Moreover, a higher aphid population was shown for intermediate nitrogen regimes highlighting the pest response to trophic parameters. These experiments confirm the importance of tree training strategies in the management of orchard pests. They provide avenues to design sustainable orchard systems based on cultural methods giving partial control of pests.

Temporal and spatial variability of rosy apple aphid Dysaphis plantaginea populations: is there a role of the alternate host plant Plantago major?

1 The rosy apple aphid Dysaphis plantaginea (Passerini) (Homoptera: Aphididae) is a pest of economic importance to the apple industry worldwide, particularly in organic apple orchards where no acceptable controls are available. In the Similkameen Valley of British Columbia, Canada, the rosy apple aphid population size varies widely between orchards and between years. To explain this variation, potential environmental correlates of aphid density were evaluated. The architecture of the alternate host was also evaluated for its effect on rosy apple aphid summer survival and reproduction. 2 The percentage of trees infested by rosy apple aphids among orchards was in the range 8–94% for trees having at least one cluster with more than ten aphids in 2007 and in the range 0–39% in 2008. 3 A general linear model correlating aphid densities to the environmental variables of abundance of the alternate host (plantain Plantago spp.), foliar nitrogen, tree age and planting density, and reduced by stepwise regression, indicated that foliar nitrogen and tree age explained 33% of the variation. Abundance of the summer, alternate food plant, plantain, was not related to later aphid densities on apple trees. 4 Plantain architecture, however, influenced aphid numbers and 25-fold more aphids were found on low-lying plantain leaves than on more upright leaves. Experimental manipulation of leaf angle and leaf size showed that significantly more aphids occurred on low angle, large leaves. Finally, mowing that encouraged low lying plants prior to spring aphid migration was associated with a four-fold greater number of both winged and wingless aphids on the plantain.

In-field production of parasitoids of Dysaphis plantaginea by using the rowan aphid Dysaphis sorbi as substitute host

A system was developed to provide the parasitic wasp Ephedrus persicae Froggatt (Hymenoptera: Braconidae: Aphidiinae), which attacks the rosy apple aphid Dysaphis plantaginea (Passerini) (Homoptera: Aphididae), with the alternative host Dysaphis sorbi Kaltenbach (Homoptera: Aphididae) in apple orchards. Rowan trees (Sorbus aucuparia L.) arranged along the side of an unsprayed orchard were artificially infested in late February 2002 with eggs of D. sorbi. Colonies of D. sorbi successfully developed from the introduced eggs and persisted on several trees until the end of June. The only primary parasitoid species emerging from a sample of mummified aphids collected in spring from the infested rowan trees was the braconid wasp species E. persicae. In a host-switching experiment, nymphs of D. plantaginea proved suitable for female parasitoids originating from mummified D. sorbi. A series of mummies collected from the rowan trees in early summer contained diapausing parasitoids and hyperparasitoids that only hatched in April of the following spring. These observations suggest the possibility of establishing a local population of E. persicae in apple orchards, so that D. plantaginea can be readily attacked by diapause-emerging parasitoids in early spring.

The Common Black Ant, Lasius niger (Hymenoptera: Formicidae), as a Vector of the Entomopathogen Lecanicillium longisporum to Rosy Apple Aphid, Dysaphis plantaginea (Homoptera: Aphididae)

The potential for common black ant Lasius niger workers to vector conidia of the entomopathogenic fungus Lecanicillium longisporum to colonies of the rosy apple aphid Dysaphis plantaginea was assessed in laboratory and field experiments. Scanning electron microscope studies showed that L. niger workers which were artificially contaminated with L. longisporum conidia, carried conidia primarily on their tarsae but also on antennae and mandibles. Neither L. niger workers nor larvae were susceptible to infection with L. longisporum. Workers which were artificially contaminated with conidia of L. longisporum initiated infection in colonies of healthy D. plantaginea on apple. Mortality due to L. longisporum was recorded as 68.3, 30.8 and 3.7% of aphids under laboratory, semi-field and field conditions, respectively.

Life history data of the rosy apple aphid Dysaphis plantaginea (Pass.) (Homopt., Aphididae) on plantain and as migrant to apple

The rosy apple aphid Dysaphis plantaginea (Passerini) is a key pest in western European apple orchards; the economic damage threshold is so low that outbreaks cannot be forecasted. A mass rearing of the species on plantain (Plantago lanceolata L.) was initiated, with the aim to infest apple trees with either the autumn migrants, gynoparae and males, or the egg-laying females (oviparae). Here, data are presented about the propagation of the species on plantain, on the production of autumn migrants under laboratory conditions, and on the duration of juvenile development and reproductive capacities of both gynoparae and oviparae. Under long-day conditions (18 h light/day) on plantain, the thermal constant for the duration of juvenile development was 166 dd (day-degrees) above the lower development threshold of 5.1 °C, and daily larviposition amounted to 1.87 times the temperature (°C)minus 0.8, above a lower threshold of 4.3 °C. Between 32 and 36 larvae were produced by the young female before the first larvae become adult and their reproduction started to overshadow their mother’s. A plant freshly infested with 12 reproducing females and transferred to short-day conditions (12 h light/day) yielded up to 5,000 autumn migrants, with males in the majority. The first gynoparae appeared after about 25 days at both 16 and 20 °C, and males appeared after 40 and 33 days, respectively. Young adult gynoparae produced most of their about ten offspring right after landing on apples, unless temperature was well below 15 °C. The duration of juvenile development of these oviparae appeared to be rather variable and their egg-laying so protracted that each of these females needs to survive several weeks to produce a handful of winter eggs. With reproductive capacities of up to 14 progeny/female for gynoparae and 7.4 for oviparae, release of one gynopara in the field could theoretically lead to the deposition of 100 winter eggs.

Effects of augmentative releases of eggs and larvae of the ladybird beetle, Adalia bipunctata, on the abundance of the rosy apple aphid, Dysaphis plantaginea, in organic apple orchards

AbstractThe impact of augmentative releases of larvae and eggs of the indigenous ladybird beetle Adalia bipunctata (L.) (Coleoptera: Coccinellidae) against the rosy apple aphid Dysaphis plantaginea Pass. (Homoptera: Aphididae), a major pest insect on apple trees, was assessed in field experiments in Switzerland, during 1997. In a first experiment, eggs and larvae were released on 3‐year old apple trees infested with five aphids at four different predator‐prey ratios (0:5, 1:5, 1:1, 5:1). In a second experiment, eggs and larvae were released at a predator‐prey ratio of 5:1 on branches of apple trees naturally infested with aphids. In both experiments, the interaction with ants was taken into account and the releases were done at two different times in spring. The results showed that an augmentative release of larvae significantly prevented the build‐up of colonies of D. plantaginea. Significant reductions in aphid numbers were recorded at the two highest predator‐prey ratios, 1:1 and 5:1. Larvae were efficient just before flowering of apple trees at a time when growers normally have to spray their trees. On trees where ants were present the larvae of A. bipunctata were significantly less efficient. Effects of eggs of A. bipunctata, however, were less reliable. At the first date of release (5 April), they did not hatch, probably as a consequence of bad weather conditions.