Control of Woolly Apple Aphid ( Eriosoma lanigerum ) by Augmenting Earwigs ( Forficula auricularis ) in the Canopy of Apple Trees

Goal. To investigate the effectiveness of the insecticide Jalentra, CS (chlorantraniliprole, 106 g/l + bifenthrin, 159 g/l) in reducing the population and harmfulness of phytophagous arthropods and its impact on the productivity indicators of apple trees in commercial orchards. Methods. Route surveys were conducted from 2015 to 2024 in horticultural farms in the Forest-Steppe zone of Ukraine (Chernivtsi, Vinnytsia, Cherkasy, Poltava, and Kyiv regions) to determine the species composition and population density of major pests, the areas of orchards they infest, including the codling moth and various leafrollers, sucking pests (scale insects, false scale insects, aphids, and fruit mites). Research was carried out in 2023—2024 in commercial apple orchards under the conditions of the university’s educational and production department. The technical efficiency of Jalentra, CS (chlorantraniliprole, 106 g/l + bifenthrin, 159 g/l) was evaluated at different application rates against plant-feeding mites and insects damaging leaves, shoots, and generative organs of trees and its impact on apple productivity in commercial orchards. The accounting was carried out according to standard methods in fruit growing and plant protection. Results. According to route surveys in apple orchards of the Forest-Steppe of Ukraine, the most numerous and harmful arthropod species during the summer growing season included 21 phytophagous species, specifically: Three mite species (family Tetranychidae); Three aphid species (suborder Aphidinea); Four scale insect and false scale insect species (suborder Coccidae); Five leafroller species (family Tortricidae); Six moth species (family Gracillariidae). During 2023—2024, the most harmful species in the university’s commercial apple orchards were: Mites: red fruit mite, common spider mite; Aphids: green apple aphid, red-gall or gray apple aphid, woolly apple aphid; Scale insects: California red scale, oyster shell scale (or false California scale), acacia false scale; Moths: rose leafroller, netted leafroller, timid leafroller, codling moth; Leaf-mining moths: hawthorn blotch miner, apple lower-side leaf miner, apple upper-side fruit miner. The application of Jalentra, CS resulted in a population reduction of: Mites by 87.9—90.5%; Aphids by 90.9—94.8%; Scale insects and false scale insects by 83.8—90.7%; Moths by 90.8—96.1%. This contributed to obtaining high-quality apple production, with yields 1.39—1.43 times higher than the control (water treatment). The percentage of non-standard products did not exceed 13.1%, compared to 24.8% in the control. The study also confirmed an increase in the biometric indicators of trees, namely: Annual shoot length: +2.0—14.5%; Internode length: +8.8—9.5%; Shoot thickness: 1.05 times thicker; Leaf surface area: +19.6—30.8%. These factors are crucial for forming fruit buds and future yields in apple orchards. No phytotoxic effects of the insecticide on plants were observed during the study. Conclusions. The application of Jalentra, CS (0.25—0.4 l/ha) effectively reduces the harmfulness of major arthropods in commercial apple orchards, providing long-term pest control during the growing season. It improves tree biometric parameters, increases yields, and enhances the commercial quality of apple production. For mites, woolly apple aphids, and California red scale, the recommended application rate is 0.35—0.4 l/ha. The technical efficiency results of Jalentra, CS against major arthropods in apple orchards suggest that it should be recommended to the Ministry of Environmental Protection and Natural Resources of Ukraine for further registration for apple orchards at the specified application rates and inclusion in the national list of approved pesticides and agrochemicals for use in Ukraine.

Abstract1. European apple (Malus domestica) orchards face persistent threats from aphid infestations, which can severely compromise fruit yields.2. In this study, we compared aphid communities in two microhabitats (tree canopy and orchard alley) in commercial apple orchards under organic and integrated pest management (IPM), in relation to aphidophagous predator abundance at three stages of the growing season: early fruit development, fruit maturity and post‐harvest.3. We sampled eight organic and eight IPM apple orchards in eastern Germany using standardised canopy beating of apple trees and suction sampling in the orchard alleys.4. Our results indicate no significant differences in aphid infestation between organic and IPM orchards, regardless of the sampled microhabitat. However, aphid communities in the tree canopy of organic orchards exhibited greater evenness across species than those of IPM orchards. Eriosoma lanigerum consistently dominated canopy aphid communities across both management systems, highlighting the need for targeted management practices for this pest. Additionally, aphidophagous predator abundance in the tree canopy increased over time and showed a positive association with aphid abundance. Aphid community structure varied significantly across sampling periods and microhabitats. Differences between organic and IPM orchards were observed during the early fruit development phase in orchard alleys, with higher levels of infestation in organic orchards. Aphid taxa such as Macrosiphum euphorbiae, Dysaphis spp., Aphis spiraecola and Rhopalosiphum insertum contributed to these differences.5. Our findings provide a better understanding of the temporal dynamics of aphid communities in apple orchards in eastern Germany, highlighting the importance of microhabitats and host plant phenology.

Field evidence and grower perceptions on the roles of an omnivore, European earwig, in apple orchards

Earwigs and woolly apple aphids in integrated and organic apple orchards: responses of a generalist predator and a pest prey to local and landscape factors

This study explored the combined influences of land use diversity, chemical pest management and grass alley management on the abundance of two key predatory taxa which act as natural enemies of pests in UK commercial dessert apple orchards, namely ground beetles (Coleoptera: Carabidae) and the European Earwig Forficula auricularia (Dermaptera: Forficulidae). Carabid and earwig numbers were positively related to higher predation levels; however, each was affected differently by land use diversity. Land use factors were not related to carabid activity-density but were related to community composition and the representation of traits in the community. Higher proportions of larger, polyphagous species and fewer spring breeders were observed in more diverse land use settings, while adjacent land use was found to influence diurnal activity and habitat associations. The proportion of polyphagous carabids in the assemblage was in turn found to be related to increased predation. Earwigs were not affected by land use diversity in isolation at either scale, though an interaction between adjacent land use and distance into the orchard was observed, indicating a distance mediated effect of non-crop habitats on earwig numbers. Earwig abundance was positively related to increased predation. Use of the neonicotinoids flonicamid and thiacloprid was associated with declines in the numbers of carabids and earwigs, with thiacloprid use also associated with a number of other carabid community metrics. Chlorpyrifos was associated with greater activity-density of carabids, but lower functional diversity. Earwig numbers did not appear to be affected by chlorpyrifos use under the field conditions employed here. Both a reduction in the frequency of mowing and raising the height of mower blades led to increases in the abundance of epigeal predators in a study orchard. In contrast, arboreal predator communities were not affected by the mowing treatments applied. The work presented here clearly demonstrates that generalist natural enemies found within commercial dessert apple orchards are influenced by both the adjacent land use and the diversity of the surrounding land use at a landscape scale. Farm management and chemical pest control have also been shown to affect orchard natural enemy communities. These findings show that both carabids and the European earwig have the potential to contribute to natural pest control in orchards. Further, this work may explain some of the variation observed in earwig populations between orchards. The provision of non-crop habitat, reductions in chemical use and vegetation management could be employed to enhance these natural enemy communities in commercial dessert apple orchards.

Environmental complexity and predator density mediate a stable earwig-woolly apple aphid interaction

The plum curculio, Conotrachelus nenuphar (Herbst), is a key pest of pome and stone fruit in eastern and central North America. For effective management of this insect pest in commercial apple (Malus spp.) orchards in the northeastern United States and Canada, one of the greatest challenges has been to determine the need for and timing of insecticide applications that will protect apple fruit from injury by adults. In a 2004-2005 study, we assessed the efficacy and economic viability of a reduced-risk integrated pest management strategy involving an odor-baited trap tree approach to determine need for and timing of insecticide use against plum curculio based on appearance of fresh egg-laying scars. Evaluations took place in commercial apple orchards in seven northeastern U.S. states. More specifically, we compared the trap-tree approach with three calendar-driven whole-block sprays and with heat-unit accumulation models that predict how long insecticide should be applied to orchard trees to prevent injury by plum curculio late in the season. Trap tree plots received a whole-plot insecticide spray by the time of petal fall, and succeeding sprays (if needed) were applied to peripheral-row trees only, depending on a threshold of one fresh plum curculio egg-laying scar out of 25 fruit sampled from a single trap tree. In both years, level of plum curculio injury to fruit sampled from perimeter-row, the most interior-row trees and whole-plot injury in trap tree plots did not differ significantly from that recorded in plots subject to conventional management or in plots managed using the heat-unit accumulation approach. The amount of insecticide used in trap tree plots was reduced at least by 43% compared with plots managed with the conventional approach. Advantages and potential pitfalls of the bio-based trap tree approach to plum curculio monitoring in apple orchards are discussed.

Movement of insect pests between spatially subdivided populations can allow them to recolonize areas where local extinction has occurred, increasing pest persistence. Populations of woolly apple aphid (Eriosoma lanigerum [Hausmann]; Hemiptera: Aphididae), a worldwide pest of apple (Malus domestica [Borkhausen]), occur both below- and aboveground. These spatially subdivided subpopulations encounter different abiotic conditions, natural enemies, and control tactics. Restricting movement between them might be an effective management tactic to decrease woolly apple aphid persistence and abundance. We examined this possibility in the field, using sticky barriers to restrict upward woolly apple aphid movement to tree canopies, and in the greenhouse, using mulches and sand amendments to restrict downward movement to roots. In the field, blocking aphid movement up tree trunks did not decrease the number of colonies in tree canopies. Instead, sticky-banded apple trees had higher aphid colony counts late in the study. Earwigs, which are woolly apple aphid predators, were excluded from tree canopies by sticky bands. In the greenhouse, fewer root galls (indicative of aphid feeding) occurred on trees in sandy potting media and on those with mulch (wood chips or paper slurry). Our results suggest that upward movement is less important than other factors that affect aboveground aerial woolly apple aphid population dynamics. In addition, apple orchards planted in sandier soils or with mulches may be partially protected from woolly apple aphid root feeding.

The spatial variability of yield in an apple orchard is high due to the inherent soil variability and the impact of the environment on the trees. One practice of precision agriculture is the variable rate application (VRA) of inputs, which gives farmers the opportunity to manage field variability. The objective of the present study was to demonstrate how the use of variable rate fertilization in an apple orchard can change the farmer’s profit. For every other row, in a commercial apple orchard in central Greece, VRA was applied while the remaining rows were used as reference and received a uniform rate similar to the rate typically used by the farmer. The VRA rates of nitrogen were based on the literature which suggests that for every t/ha of apple yield, 2.45 kg/ha of N are removed from the soil in one growing season. The comparison of the results between VRA and reference treatments showed that the amount of fertilizer used in VRA treatments was reduced by 32.4% while the farmer’s profit increased by 21%. More years of research are required to give more reliable results.

Simple SummaryBiological control, which is the use of natural enemies to regulate crop pests, is considered a key aspect of integrated pest management. In pome fruit (apple and pear) crops of the northwestern United States, the European earwig Forficula auricularia (L.) sensu lato may provide a unique opportunity for augmentative biological control. While this generalist omnivore is a direct pest in stone fruit crops like cherries and peaches, it is a beneficial predator in apple and pear crops. In these crops, it feeds on two key pests, the woolly apple aphid and pear psylla, respectively, and rarely damages fruit. Here, we tested a two-way strategy to reduce fruit damage by removing earwigs from crops where they are pests and releasing earwigs into orchards where they can help control pest populations. We found that mass-trapping earwigs in stone fruit orchards did not significantly reduce earwig numbers or fruit injury; however, this was a relatively easy and practical method for collecting thousands of individuals for augmentative release in pome fruit orchards. Two mass releases (once annually) of earwigs helped control key pests in pears and apples, such as pear psylla and woolly apple aphids, by the second year. We did not find evidence of a reduction in other pests, such as mites and other aphid species. Finally, we found that earwig releases can be useful in establishing their populations in orchards where they are absent or rarely found, potentially providing increased pest control over multiple seasons.The European earwig Forficula auricularia (L.) (Dermaptera: Forficulidae) is an omnivorous insect that is considered a minor pest of stone fruit and a key predator of pests in pome fruit orchards. In many pome fruit orchards, earwigs are absent or in low abundance due to broad-spectrum spray programs and the slow recolonization rate of earwigs. Orchards in transition to organic or “selective” conventional programs often struggle to achieve effective levels of biological control, and thus, may benefit from inoculating earwigs to expedite their re-establishment. In a two-year study, we evaluated the potential for mass trapping earwigs from stone fruit using rolled cardboard traps to reduce fruit damage and provide earwigs for augmentation in pome fruit. We also tested whether a single mass release or five releases (on alternating weeks) of the same total number of earwigs in apples and pears reduced pests relative to plots where no releases occurred. Mass trapping did not decrease earwig abundance or substantially reduce fruit damage in stone fruit orchards. However, trapping was an efficient method for providing earwigs for augmentation. Earwig abundances were only increased in orchards where earwigs were previously low or absent; however, multiple orchards with varying prior levels of earwigs exhibited reductions in key pests (woolly apple aphid and pear psylla). For some other pests evaluated, plots with mass releases of earwigs had a slight trend in overall lower pest density when compared with control plots. A strategy for moving earwigs out of stone fruit orchards and into pome fruit orchards could be an effective method for augmenting orchard predator populations.

The woolly apple aphid (WAA), Eriosoma lanigerum (Hausmann) (Hemiptera: Aphididae) is a well-known pest of apple orchards world-wide. Several studies have demonstrated variable control of WAA populations by the European earwig, Forficula auricularia (L.) (Dermaptera: Forficulidae) and the WAA parasitoid Aphelinus mali (Halderman) (Hymenoptera: Aphelinidae). We examine whether a beneficial interaction between F. auricularia and A. mali exists and calculate optimal numbers for each species to maintain WAA infestations below acceptable levels. We demonstrate that trees possessing >14 earwigs per trunk trap per week within the first seven weeks post-blossom contained WAA infestations well below acceptable levels. Where these earwig thresholds were not met, a first generation of A.mali greater than 0.5 wasps per tree was required. If these beneficial insect targets were not met, severe WAA infestations occurred. Our findings suggest that if F. auricularia and A. mali numbers exceed these thresholds chemical intervention may not be required.

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.

We evaluated responses of adult plum curculios, Conotrachelus nenuphar (Herbst), to black unbaited pyramids (111 cm tall) capped by conical boll weevil trap tops and placed at various locations on the ground in a small commercial apple orchard or in patches of unsprayed apple trees in Massachusetts. Pyramid traps adjacent to apple tree trunks captured significantly more adults than those between apple trees, those between apple trees and an adjacent woods, and those between apple trees and an adjacent open field. Also, they captured significantly more adults than unbaited conical boll weevil trap tops placed on cut ends of vertical twigs or in other positions in apple tree canopies. Further tests revealed that the nature of the ground cover (bare soil or short grass) beneath or between tree canopies had no detectable effect on captures by pyramid traps, whereas captures decreased significantly as traps were placed further from the tree trunk. Indirect evidence from additional tests with pyramids and direct evidence from observations of released adults permitted classification of responses to pyramids according to curculio arrival by flight or by crawling and according to arrival during light or darkness. Together, these provided a possible explanation for lack of effect of ground cover but significant effect of trap location on captures. Even at the most favored location (next to tree trunks), daily captures on pyramid traps failed to correlate positively with daily incidence of injury to fruit caused by plum curculio feeding or egglaying, suggesting that further research is necessary before unbaited pyramid traps can be recommended for use in monitoring plum curculio populations in commercial apple orchards in Massachusetts.

We evaluated responses of plum curculio, Conotrachelus nenuphar (Herbst), to four trap types in commercial and unsprayed apple and peach orchards. Trap types included black pyramid and clear Plexiglas panel traps deployed outside the orchard 2 m from the border row, and branch-mimicking cylinder and trunk-mounted screen traps attached to trees in the border row. Bait treatments evaluated in conjunction with each trap type included the synthetic fruit volatile benzaldehyde, the aggregation pheromone grandisoic acid (GA), benzaldehyde in combination with GA, and an unbaited control treatment. In commercial apple orchards, significantly more plum curculio were captured in traps baited with benzaldehyde + GA compared with traps baited with other treatments. Furthermore, significantly more plum curculio were captured by screen traps baited with benzaldehyde + GA compared with unbaited control traps. Significantly more plum curculio were captured by screen traps compared with other trap types in an unsprayed apple orchard. Very few captures were recorded in commercial peach orchards. Dissections of trapped females indicate that bivoltine populations are present in the mid-Atlantic. In general, correlations between timing and amount of trap captures and timing and amount of fruit injury inflicted concurrently or 1 wk after trap captures were very weak for all trap types and bait combinations. Our results agree with previous studies in the northeastern United States in which trap captures are increased by presence of semiochemical baits but fail to serve as reliable tools to determine need for and timing of insecticide application against plum curculio.

We evaluated responses of plum curculio, Conotrachelus nenuphar (Herbst), to four trap types in commercial and unsprayed apple and peach orchards. Trap types included black pyramid and clear Plexiglas panel traps deployed outside the orchard 2 m from the border row, and branch-mimicking cylinder and trunk-mounted screen traps attached to trees in the border row. Bait treatments evaluated in conjunction with each trap type included the synthetic fruit volatile benzaldehyde, the aggregation pheromone grandisoic acid (GA), benzaldehyde in combination with GA, and an unbaited control treatment. In commercial apple orchards, significantly more plum curculio were captured in traps baited with benzaldehyde + GA compared with traps baited with other treatments. Furthermore, significantly more plum curculio were captured by screen traps baited with benzaldehyde + GA compared with unbaited control traps. Significantly more plum curculio were captured by screen traps compared with other trap types in an unsprayed apple orchard. Very few captures were recorded in commercial peach orchards. Dissections of trapped females indicate that bivoltine populations are present in the mid-Atlantic. In general, correlations between timing and amount of trap captures and timing and amount of fruit injury inflicted concurrently or 1 wk after trap captures were very weak for all trap types and bait combinations. Our results agree with previous studies in the northeastern United States in which trap captures are increased by presence of semiochemical baits but fail to serve as reliable tools to determine need for and timing of insecticide application against plum curculio.