Apple Aphid Research Articles

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.

Flower diet enhances Adalia bipunctata larval development significantly when prey is limited

AbstractPredaceous coccinellids can feed on non‐prey food, but the ecological value of this feeding to maintain a coccinellid population is not well understood. Prey density can vary greatly in the field, whereas non‐prey food sources such as pollen and nectar are more predictable. In the present study, Adalia bipunctata L. (Coleoptera: Coccinellidae) larval performance on pure and mixed diets of a high‐quality non‐prey food with varying amounts of prey was investigated. Rosy apple aphid, Dysaphis plantaginea Passerini (Hemiptera: Aphididae), served as prey in the experiment and was given to A. bipunctata larvae either ad libitum as a surplus diet or as a limited diet, the amount of which was selected so that it would limit larval development, according to a pilot study. Flowers of buckwheat, Fagopyrum esculentum L. (Polygonaceae), a high‐value floral diet, served as the non‐prey food. Newly hatched A. bipunctata larvae were reared on each of five diets: (1) flowers only, (2) limited prey only, (3) limited prey plus flowers, (4) surplus prey only, (5) surplus prey plus flowers. Larval survival, developmental time, and adult dry weight were measured. The addition of floral diet had a significant positive impact on A. bipunctata larval survival and development when prey diet was limited, survival ratio was 6× higher and developmental time was 25% shorter. In conclusion, A. bipunctata immature development can benefit from a floral diet supplemented to a prey diet, which indicates that the use of flowers in cropping systems can help to enhance biocontrol services by A. bipunctata.

Efficacy and Nontarget Effects of Net Exclusion Enclosures on Apple Pest Management.

Management of direct apple pests, such as codling moth, continues to be problematic despite the widespread implementation of behavioral and chemical controls. Apple growers have increased their use of netting to protect fruit from environmental injury, with some structures enclosing the entire orchard. These enclosures represent a new pest management tactic through physical exclusion. We conducted a two-year trial to examine the effects of full exclusion netting on pests and natural enemies of apples. Insect densities and damage in trees under fully enclosed (net) cages were compared with conventionally (insecticide only) treated and untreated plots. Caged plots had 18.1- and 11.4-fold less codling moth damage than the check, and 4.9- and 4.2-fold less damage than the insecticide-only plots in 2016 and 2017, respectively. However, densities of woolly apple aphid and its parasitoid Aphelinus mali (Haldeman) (Hymenoptera: Aphelinidae) were significantly greater in the caged plots. Densities of earwigs, a typically flightless generalist predator, were not different among treatments, while adults of more mobile flying generalist predators, lacewings and syrphids, were significantly lower in cages compared with uncaged plots. These results demonstrate that although biological control may be partially disrupted, net enclosures have significant potential as a holistic apple management technique.

Towards a Knowledge-Based Decision Support System for Integrated Control of Woolly Apple Aphid, Eriosoma lanigerum, with Maximal Biological Suppression by the Parasitoid Aphelinus mali.

Simple SummaryThe woolly apple aphid Eriosoma lanigerum is an important pest in apple orchards worldwide. At present, effective limitation of woolly aphid populations relies on a good synergy between chemical control treatments and biological suppression by beneficial insects, especially by its main specific natural enemy, the parasitic wasp (parasitoid) Aphelinus mali. In order to reach maximum control levels on woolly apple aphids and avoid negative side effects on A. mali, decision support for the optimal timing and positioning of control treatments is needed. In this study, we developed prediction models that based on the weather conditions (temperature data) can reasonably accurately predict crucial development/activity phases of both insects in the orchard. These prediction models can be utilized to target insecticide sprayings at the most sensitive stage of the pest (woolly apple aphids) and/or to avoid insecticide sprayings with detrimental side effects at the vulnerable stage of the beneficial insect (parasitoid A. mali), as was demonstrated by the outcomes of a field trial in this study.The woolly apple aphid Eriosoma lanigerum (Homoptera: Aphidiae) is an important pest in apple orchards worldwide. Since the withdrawal or restricted use of certain broad-spectrum insecticides, E. lanigerum has become one of the most severe pests in apple growing areas across Western Europe. At present, effective limitation of woolly aphid populations relies on a good synergy between chemical control treatments and biological suppression by beneficial arthropods, especially by its main specific natural enemy, the parasitoid Aphelinus mali (Hymenoptera: Aphelinidae). To develop a knowledge-based decision support system, detailed monitoring data of both species were collected in the field (region of Sint-Truiden, Belgium) for a period of ten years (2010–2020). Aphelinus mali flights were monitored in the field, starting before flowering until the end of the second-generation flight at minimum. The seasonal occurrence of the most important management stages of E. lanigerum, e.g., start of wool production or activity on aerial parts in spring and migration of crawlers from colonies towards flower clusters or shoots, were thoroughly monitored. All obtained data were compared with historical and literature data and analysed in a population dynamics phenological model. Our outcomes showed that the emergence of first-generation A. mali adults (critical for the first parasitation activity and the basis for following A. mali generations in the continuation of the season) can be accurately predicted by the developed model. Hence, this information can be utilized to avoid insecticide sprayings with detrimental side effects at this particular moment as demonstrated by the outcomes of a field trial. In addition, the start of migration of E. lanigerum crawlers towards flower clusters or shoots is accurately predicted by the model. In conclusion, our results demonstrate that the model can be used as decision support system for the optimal timing of control treatments in order to achieve effective control of E. lanigerum with maximal biological suppression by its main natural enemy.

Resistance Evaluation of G, CG, or M Series Apple Rootstocks to Soil-borne Diseases (Phytophthora Root Rot, White Root Rot, and Southern Blight) and Woolly Apple Aphid

Resistance Evaluation of G, CG, or M Series Apple Rootstocks to Soil-borne Diseases (Phytophthora Root Rot, White Root Rot, and Southern Blight) and Woolly Apple Aphid

Genetic structure of Malus sylvestris and potential link with preference/performance by the rosy apple aphid pest Dysaphis plantaginea

The European crabapple Malus sylvestris, a crop wild relative of Malus domestica, is a major contributor to the cultivated apple genome and represents a potential source of interesting alleles or genes, particularly pest resistance traits. An original approach was used to explore the trophic interaction between M. sylvestris populations and its pest, the rosy apple aphid (Dysaphis plantaginea). Using 13 microsatellite markers, population genetic structure and level of crop-to-wild introgressions were inferred between M. sylvestris seedlings from three sites in Europe (Denmark, France, Romania), and M. domestica seedlings. Genetically characterized plants were also used to analyze aphid feeding behavior and fitness parameters. First, aphids submitted to two genetically close M. sylvestris populations (the Danish and French) exhibited similar behavioral parameters, suggesting similar patterns of resistance in these host plants. Second, the Romanian M. sylvestris population was most closely genetically related to M. domestica. Although the two plant genetic backgrounds were significantly differentiated, they showed comparable levels of sensitivity to D. plantaginea infestation. Third, aphid fitness parameters were not significantly impacted by the host plant’s genetic background. Finally, crop-to-wild introgression seemed to significantly drive resistance to D. plantaginea independent of host plant population genetic structure, with hybrids being less suitable hosts.

Seasonal Incidence of Major Insect Pests of Apple in Mid Hills of Meghalaya

Seasonal incidence of major insect pests of apple in mid hills of Meghalaya was evaluated during 2018 at the Experimental farm of CPGSAS, Umiam, Meghalaya. A total of 43 insect species were observed. The major ones include- green apple aphid Aphis pomi De Geer, pale tussock moth Calliteara pudibunda L., tussock moth Euproctis guttata Collenette, giant looper Ascotis selenaria Denis and Schiffermuller and cocoa tussock moth Orgyia postica Walker. Also, 21 species were observed as minor pests, ten species as natural enemies, two species as pollinators and five species as occasional visitors. Results revealed that the aphid incidence is at its peak (34.75 aphids/ 10cm apical length of twig/shoot/ plant) on the 25th SMW (standard meteorological week) (3rd week of June 2018). Such a peak of pale tussock moth larval incidence (3.82 larva/ plant) was during 28th SMW (2nd week of July). Likewise, the tussock moth larval incidence (4.15 larvae/ plant) was its peak on the 35th SMW (last week of August). The giant looper was at its peak (3.46 larvae/ plant) in the 28th SMW (2nd week of July). The cocoa tussock moth incidence was at the maximum of 4.75 larvae/ plant on the 26th SMW (27th June). Correlation coefficients (r) indicated significant correlation between the incidence of green apple aphid with maximum temperature; and larval incidence of tussock moth and cocoa tussock moth exhibiting a significant correlation with minimum temperature. Regression analysis done herein will provide the impact of independent variables on the dependent variables.

Effect of Insecticides on Woolly Apple Aphid, 2020

Effect of Insecticides on Woolly Apple Aphid, 2020

Biological properties and influencing factors of woolly apple aphid (Eriosoma lanigerum Hausm) in the condition of orchard agrobiocenosis

This article provides information on the influence of biotic and abiotic factors on the development of the population of orchard agrobiocenosis of woolly apple aphid (Eriosoma lanigerum Hausm), the main sucking pest of seed orchards.

Species composition of aphids (order Homoptera, family Aphididae) in fruit agrocenoses of the Crimea

Nine species of aphids have been identified in fruit plantations in the Crimea. The species composition and percentage varies depending on the zoning of the plantings. The correlation coefficient between the hydrothermal conditions of April-June and the number of green apple aphids r=0,55, and gray apple (rosy leaf-curling) aphids - r=0,46. Mass reproduction of apple aphids was recorded in May, which was facilitated by dry and warm weather. Low temperatures in April during the beginning of hatching of larvae restrained the growth of the number of phytophages and provoked the almost complete death of the woolly aphid population.

Effectiveness of modern insecticides in protection of apple planting from red-headed aphides

Goal. To investigate an efficacy of the insecticides Movento 100 SC (spirotetramate, 100 g/l), Sivanto Prime 200 SL (flupiradifuran, 200 g/l) and Transform WG (sulfoxaflor, 500 g/kg) on a reduction of a number and a harmfulness of red-headed or gray apple aphid (Disaphis devecta Walk.) in commercial apple orchards.
 Methods. A field method, in the commercial apple orchards under the conditions of educational production department of university. A type of apple trees was Golden Delicious. Planting scheme — 4.0 × 3.0 m. Year of planting — 1992. Crown shape — sparsely (improved) — tiered. Rootstock — MM-106. Phases of plant development at application timing — «after blooming, fruit size — up to 20 mm» (BBCH 72). Soil — shallow, low — humus dusty — loamy podzolic leached black soils: humus content — 1.3—2.5%; pH 4.8—5.2; mobile compounds Р2О5 — 130—180 mg/ kg and К2О — 8,9—9,2 mg/kg (by Chirikov method). The measures for care of the experimental site — loosening a soil in the stem strips during the growing period, an application of organic and mineral fertilizers, a pruning, a splaying of grass between the rows (row spacing),a protection from pests and diseases. The technical effectiveness of applications was determined in different rates against red-headed aphids in the apple orchards. Calculations were made according to generally accepted methods in plant protection and entomology.
 Results. The use of insecticides Movento 100 SC, Sivanto Prime 200 SL and Transform WG against red-headed aphids provided a reduction of this species in the number of 92.8—97.2%. It allowed to obtain a high — grade apple product with a yield of 1.7—1.9 times higher comparing to control. The outcome of non-standard products did not exceed 4.9% compare to 24.9% in the control (water treatment).
 Conclusions. The use of insecticides Movento 100 SC, Sivanto Prime 200 SL, Transform WG can reduce effectively the harmfulness of red-headed aphids in apple orchards and control its number during the growing period. A limiting the number of a current sucking species in the apple orchard by using the studied applications provided a yield increase and a marketable quality of the obtained fruit products.

Wolbachia, Spiroplasma, and Rickettsia symbiotic bacteria in aphids (Aphidoidea).

Aphids are a diverse family of crop pests. Aphids formed a complex relationship with intracellular bacteria. Depending on the region of study, the species composition of both aphids and their facultative endosymbionts varies. The aim of the work was to determine the occurrence and genetic diversity of Wolbachia, Spiroplasma and Rickettsia symbionts in aphids collected in 2018–2019 in Moscow. For these purposes, 578 aphids from 32 collection sites were tested by PCR using specific primers. At least 21 species of aphids from 14 genera and four families were identified by barcoding method, of which 11 species were infected with endosymbionts. Rickettsia was found in six species, Wolbachia in two species, Spiroplasma in one species. The presence of Rickettsia in Impatientinum asiaticum, Myzus cerasi, Hyalopterus pruni, Eucallipterus tiliae, Chaitophorus tremulae and Wolbachia in Aphis pomi and C. tremulae has been described for the first time. A double infection with Rickettsia and Spiroplasma was detected in a half of pea aphid (Acyrthosiphon pisum) individuals. For the first time was found that six species of aphids are infected with Rickettsia that are genetically different from previously known. It was first discovered that A. pomi is infected with two Wolbachia strains, one of which belongs to supergroup B and is genetically close to Wolbachia from C. tremulae. The second Wolbachia strain from A. pomi belongs to the supergroup M, recently described in aphid species. Spiroplasma, which we observed in A. pisum, is genetically close to male killing Spiroplasma from aphids, ladybirds and moths. Both maternal inheritance and horizontal transmission are the pathways for the distribution of facultative endosymbiotic bacteria in aphids.

Comparison between sustained effects of spray and injection thiamethoxam on apple aphids and non-target insects in apple orchard

Spray application is considered to be the most common method of insecticide use in apple orchard, while trunk injection has often be used in labor-intensive areas. Here, a comparison of both methods in aphid control efficiency and non-target effects was conducted. We evaluated the effects of thiamethoxam by either spray or injection on apple aphid Aphis citricola, and examined the temporal dynamic of thiamethoxam in leaves by using residue analysis. Results showed that thiamethoxam had a remarkable suppression effect on Aphis citricola, and both application methods had obvious control efficiency with the highest value above 90%. The control effect of spray method on Aphis citricola reached the maximum at 7 days after application, while that of injection method reached the maximum at 14 days after application. Moreover, the control effect of injection after 14 days and that of spray after 7 days were not significant, suggesting the spray method had a higher quick-acting effect than the injection method, and the two methods had a similar persistence effect. The population dynamics of non-target insects (ladybugs, parasitoid wasps and predatory bugs) showed basically the same as that of blank controlled. The control effect evaluation of thiamethoxam on Aphis citricola suggest that injection treatment was more effective in protecting natural enemies than spray treatment, and thiamethoxam didn't interfere with natural enemies to control Aphis citricola with both two application methods.

Does combining Forficula auricularia L. (Dermaptera: Forficulidae) with Harmonia axyridis Pallas (Coleoptera: Coccinellidae) enhance predation of rosy apple aphid, Dysaphis plantaginea Passerini (Hemiptera: Aphididae)?

A good knowledge of interactions between natural enemy species is necessary for effective implementation of biological control programmes. This laboratory study aimed at assessing the outcome of intraguild interactions between two generalist predators frequently observed in the colonies of the rosy apple aphid (RAA), Dysaphis plantaginea Passerini (Hemiptera: Aphididae). The level of complementarity between these two species was estimated by the comparison of their individual and combined predation on RAA. Predation by 1st (H1) to 4th (H4) instar larvae of Harmonia axyridis Pallas (Coleoptera: Coccinellidae) and 3rd (F3) and 4th (F4) instar nymphs of Forficula auricularia L. (Dermaptera: Forficulidae) was evaluated for 24 h in Petri dishes using seven different densities (5, 10, 25, 50, 75, 100 and 200) of 3rd instar nymphs of RAA. Both predator species were more voracious as their age increased. The satiation level, i.e. the highest number of consumed RAA, reached on average of 17.8, 36.3, 49.4, 79.6, 62.9 and 84.3 aphids per day for H1, H2, H3, H4, F3 and F4, respectively. In the combined treatments, there was little evidence of intraguild predation. Only 2.9% of H1 and H2 died or disappeared at low RAA densities (≤25 aphids). At the non-limiting RAA density of 200, we observed a slight agonistic interaction with 7.9% less RAA consumption when the two predators were in the same arena than the sum of their individual consumptions. However, this effect was very small and was largely outweighed by the benefits of using these two predators in combination to increase prey consumption. For the other six RAA densities, predators in combination consumed a high proportion (>90%) of RAA. Our results point to the use of combinations of these two predator species, especially of their oldest instars, as promising aphidophagous candidates in early spring against RAA.

Enzymatic Defense Response of Apple Aphid Aphis pomi to Increased Temperature.

Climate change, and in particular the increase in temperature we are currently observing, can affect herbivorous insects. Aphids, as poikilothermic organisms, are directly exposed to temperature increases that influence their metabolism. Heat stress causes disturbances between the generations and the neutralization of reactive oxygen species (ROS). The aim of this work is focused on explaining how the aphid, using the example of Aphis pomi, responds to abiotic stress caused by temperature increase. The experiment was carried out under controlled conditions at three temperatures: 20, 25, and 28 °C. In the first stage, changes in the activity of enzymatic markers (superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), β-glucosidase, polyphenol oxidase (PPO), and peroxidase (POD)) were determined in aphid tissues, at each temperature. In the second stage, microcalorimetry monitored changes in heat emitted by aphids, at each temperature. Our results showed that A. pomi defense responses varied depending on temperature and were highest at 28 °C. The flexible activity of enzymes and increase in the metabolic rate played the role of adaptive mechanisms and ran more effectively at higher temperatures. The A. pomi thus protected itself against ROS excessive induction and the aphids were able to respond quickly to environmental stress.

Biology and feeding potential Episyrphus balteatus De Geer (Diptera: Syrphidae) on green apple aphid Aphis pomi De Geer (order Hemiptera: Aphididae) in Hills of Shimla, (H.P.), India

In the present study three species of syrphid predators were found feeding on green apple aphid on the apple nursery plants. These species are Betasyrphus serarius (Wiedemann), Episyrphus balteatus De Geer, and Metasyrphus confrater (Wiedemann). These syrphid species belonging to Family Syrphidae of order Diptera. Observations were made on Episyrphus balteatus De Geer a syrphid predator of green apple aphid, Aphis pomi De Geer in Shimla Hills of Himachal Pradesh, India. The larval stages of Episyrphus balteatus De Geer, was found to predate upon the green apple aphid, Aphis pomi De Geer which is a serious pest of apple nursery plants in Himachal Pradesh which is the main apple growing state of India. Feeding potential of larval stages of Episyrphus balteatus De Geer was recorded during summer and autumn season. Present studies show that the larvae of this species can effectively control the populations of green apple aphid, Aphis pomi De Geer in the apple orchards and nurseries.

Aphid-infested beans divert ant attendance from the rosy apple aphid in apple-bean intercropping

Ecological intensification of cropping systems aims at restoring multi-functionality while supporting current productivity levels. Intercropping is a form of ecological intensification involving ecological processes beneficial to farmers that do not take place in monocultures. Thus, it represents a practical approach to decrease the use of synthetic inputs such as insecticides in cultivated systems. Whereas insecticide reduction via intercropping-facilitated suppression of aphids is reported in literature, the majority of published studies focussed on herbaceous crops. Thus, the effect of intercropping on aphid populations of cultivated trees remains largely unaddressed. In this study we hypothesized that intercropping a specific companion plant within perennial crops would divert ant attendance from an aphid attacking the crop to another aphid feeding on the newly introduced plant, reducing aphid damage on the crop. We tested our hypothesis in the system of apple (Malus domestica Borkhausen), the rosy apple aphid (Dysaphis plantaginea Passerini) and the black garden ant (Lasius niger L.). Bean plants (Vicia faba) with the black bean aphid (Aphis fabae Scopoli) were intercropped within apple trees inoculated with D. plantaginea. We measured ant attendance, aphid development and survival as well as honeydew composition on both plant species through semi-field and field experiments. The majority of ants chose to attend A. fabae over D. plantaginea in the semi-field experiment with potted plants. In the orchard, a larger majority of scouts were scored on A. fabae over D. plantaginea. A higher number of D. plantaginea colonies remained active in the apple control, whilst they were almost eradicated by intercropping. Although chemical analyses of honeydew disclosed differences in the carbohydrate and amino acid profiles between aphid species, the difference in honeydew composition did not explain the preference for A. fabae. Ants did not discriminate between the two honeydew mimics both in laboratory and field bioassays. Our results showed the potential of intercropping apple trees with beans as a method to reduce ant attendance and thus colony survival. We propose that intercropping represents a bottom-up approach towards ecological intensification of perennial crops. Together with other ecosystem-based measures such as habitat management, intercropping should be considered when planning ecosystem redesign to increase biological control of pests.

Comparative Analysis of Stylet Penetration Behaviors of Eriosoma lanigerum (Hemiptera: Aphididae) on Main Apple Cultivars in China

The preference and behavioral mechanism of the feeding behavior of the woolly apple aphid, Eriosoma lanigerum (Hausmann), on Chinese apple cultivars was investigated using the electrical penetration graph (EPG) technique. Feeding of adult aphids was assessed for the four main cultivars of apple in China (Red Fuji, Ralls Genet, Starkrimson, and Jonagold) over an 8-h monitoring period, what that of fourth-instar nymphs was assessed for 8 h on Jonagold only. EPG waveforms representing the details of probing behaviors, parameters were measured for analysis. We found that at the nonphloem phase, the total duration of the nonpenetration (np) waveform and the total duration of the stylet pathway phase (the 'C wave') on Ralls Genet and Starkrimson were significantly longer than on Red Fuji. In addition, the phloem-feeding phase, the total duration of 'release of saliva into the phloem', (the E1 waveform) was significantly longer on Ralls Genet and Jonagold than on Red Fuji. The total duration of the 'ingestion from sieve cells' phase (the E2 waveform) on Red Fuji, meanwhile, was significantly longer than on Ralls Genet or Starkrimson. At the same time, when combined with EPG parameters, Red Fuji was found to have no obvious resistance to woolly apple aphid and to be a susceptible cultivar. This experiment also recorded the feeding waveform of fourth-instar aphid nymphs. Based on the phloem and nonphloem parameters recorded in this study, it was inferred that adult aphids are more likely than nymphs to feed on apple trees.

Role of temperature on the interaction between Japanese quince Chaenomeles japonica and herbivorous insect Aphis pomi (Hemiptera: Aphidoidea)

Observations in recent years have shown that climate change can affect plants and herbivorous insects. An increase in temperature can indirectly affect insects by changing quality of host plant tissues or directly affecting their biology. So far, little research has addressed the problem of the interactive impact of abiotic and biotic stress on defence mechanisms, and effectivity of plant defence mechanisms. The work is aimed at explaining how the plant reacts to abiotic stress caused by elevated temperature and additional biotic stress caused by feeding Aphis pomi aphids. Experiments in a climatic chamber at three temperatures: 20, 25 and 28 °C were carried out to detect changes in developmental stages, demographic parameters and insect fecundity. The activity of enzymatic markers (superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), β-glucosidase, polyphenol oxidase (PPO), peroxidase (POD)) in the tissues of the host plant was determined. An increase in temperature to 28 °C had significant negative effects on the biology of A. pomi, with a shortening of the reproduction period, total lifespan, a reduction in population demographic parameters and fecundity, by half. The temperature and foraging of sucking insects, act additively, causing a synergistic defence effect in the plant. The plant defence responses differed significantly depending on the temperature and were highest at 20 °C. Due to the flexible activity of enzymes, which played a role as adaptive mechanisms and ran more effectively at lower temperatures, the Ch. japonica protected itself against ROS excessive induction and the plants were able to respond quickly to the combined effect of both stress factors.

Comparison of the toxicity and repellency of two conventional neonicotinoids and a coconut-derived insecticide soap toward the parasitoid wasp Aphelinus mali Haldeman, 1851

The parasitoid wasp Aphelinus mali,Haldeman, 1851 (Hymenoptera: Aphelinidae) is the most important biological control agent against the woolly apple aphid, Eriosoma lanigerum (Hausemann, 1802) (Hemiptera: Aphididae), which is an important apple orchards pest throughout the world. Based on the importance of using low-risk compounds to protect beneficial agents, the present study was carried out to evaluate the toxic and repellent effects of two conventional chemicals (imidacloprid and thiacloprid) and coconut-derived biopesticide soap (PalizinÒ) toward A. mali. The results of residual bioassays on apple leaf discs indicated that imidacloprid after 24 h and insecticide soap after 72 h exposure time categorized at the highest and no/little toxicity rates, respectively. Ingestion bioassays on filter papers revealed that imidacloprid and thiacloprid had moderate toxicity rate, while insecticide soap had a low-level toxicity rate. Repellency test at Y-tube olfactometer showed that the repellent effects of both chemicals were more than that of insecticide soap. It is concluded that coconut-derived soap was compatible with the parasitoid activity, and the caution should be paid when including the two neonicotinoid insecticides imidacloprid and thiacloprid for E. lanigerum management.