MATING DISRUPTION OF GRAPHOLITA MOLESTA BUSCK. TO IMPROVE QUALITY AND HEALTHY OF PEACH FRUITS

In Bulgarian fruit growing agriculture mainly chemical plant protection is applied. Applications with organophosphates and pyrethroids are carried out to control the economically most important peach pest - the oriental fruit moth (Grapholita molesta Busck.). Annually during the vegetation season 7-8 insecticide treatments are applied. This leads to contamination of fruit products and the environment, which is a prerequisite for seeking other approaches. Regarding to fruit moth, sex pheromones are one of the most widely used environmental control methods, but they are most commonly used in apples. Their introduction in the monitoring of the main peach pest can lead to a reduction of chemical treatments and production with less pesticide residues. A promising direction is the use of pheromones to control the pests through sexual disorientation of males. The trial of mating disruption in the present study were carried out with ISOMATE® OFM TT dispensers in 0.9 ha peach orchard in 2020 and 2021. Pheromone traps type "Delta" of the Hungarian company CSALOMON® were used. The ISOMATE OFM TT dispensers, installed before the first flight of OFM at the rate of 250 units per ha, efficiently reduced fruit damages - down to 0.1-0.2% at harvest. In the reference orchard with 6 insecticide treatment against OFM, the damages reached 3.0-3.6%. The results indicate that mating disruption for control of Grapholita molesta Busck. can be used in production of quality and healthy peach fruits.

Oviposition Preferences of Oriental Fruit Moth Grapholita Molesta (Lepidoptera: Tortricidae) To Pear HIPVs

Herbivore-induced plant volatiles (HIPVs) are regarded as an indirect plant defense against herbivores, since they attract natural enemies to the infested plant. On the other hand, HIPVs also affect behavioral responses of herbivores. In a previous study, Lytopylus rufipes, a parasitoid of the oriental fruit moth (Grapholita molesta), showed positive responses to pear HIPVs, but the influence of pear HIPVs on G. molesta is still unclear. To better understand these responses, we first tested oviposition preferences of G. molesta to uninfested and infested pear shoots (US and IS, respectively) and uninfested mature leaves (ML) in dual-choice bioassays with a cylindrical tube. Then, preferences to volatile components were also assessed. Results show that G. molesta females preferred US-, IS-, and ML-treated areas compared to the control area (no leaves), respectively. Subsequently, G. molesta females preferred IS over US, and US more than ML when comparing pear tissues. Furthermore, G. molesta females didn’t show any significant preference to individual volatile components, but more eggs were laid in the area treated with a synthetic pear HIPV blend, compared to the hexane-treated area (control). These results indicate that G. molesta females do not avoid infested pear shoots nor HIPVs. Moreover, HIPVs may recruit not only natural enemies, but herbivores to the release point of HIPVs. Thus, it is important to examine the responses of G. molesta females to HIPVs in the field before employing them for pest management.

Molecular Advances in Larval Fruit Moth Identification to Facilitate Fruit Export From Western United States Under Systems Approaches

Molecular advances facilitate fruit export by improving rapid pest diagnosis by polymerase chain reaction (PCR) and advanced sequencing technology. Improved pest detection provides timely certification of the quarantine pest-free status in the commodity being exported, avoiding unnecessary commodity treatment. The U.S.–Japan Systems Approach to export fresh cherries from the Western United States that targets the codling moth, Cydia pomonella (Linnaeus) (Lepidoptera: Tortricidae), is used as an example. Suspect codling moth larvae interdicted at cherry packing houses are distinguished by PCR from other internal fruit moth larvae such as the oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae); lesser appleworm, G. prunivora (Walsh) (Lepidoptera: Tortricidae); cherry fruitworm, G. packardi (Zeller) (Lepidoptera: Tortricidae); and filbertworm, Cydia latiferreana (Walsingham) (Lepidoptera: Tortricidae). Identification is confirmed by sequencing the amplicon of a 301 bp region of the COI gene produced by PCR of the DNA from a suspect moth and comparing this sequence of COI gene sequences of other internal fruit feeders of pome fruit. This sequence comparison results in unambiguous pest identification. These findings are discussed in the context of systems approach research to meet evolving needs of phytosanitary requirements for global export of fruits.

Comparison of Gut Bacterial Communities of Grapholita molesta (Lepidoptera: Tortricidae) Reared on Different Host Plants

Intestinal symbiotic bacteria have played an important role in the digestion, immunity detoxification, mating, and reproduction of insects during long-term coevolution. The oriental fruit moth, Grapholita molesta, is an important fruit tree pest worldwide. However, the composition of the G. molesta microbial community, especially of the gut microbiome, remains unclear. To explore the differences of gut microbiota of G. molesta when reared on different host plants, we determined the gut bacterial structure when G. molesta was transferred from an artificial diet to different host plants (apples, peaches, nectarines, crisp pears, plums, peach shoots) by amplicon sequencing technology. The results showed that Proteobacteria and Firmicutes are dominant in the gut microbiota of G. molesta. Plum-feeding G. molesta had the highest richness and diversity of gut microbiota, while apple-feeding G. molesta had the lowest. PCoA and PERMANOVA analysis revealed that there were significant differences in the gut microbiota structure of G. molesta on different diets. PICRUSt2 analysis indicated that most of the functional prediction pathways were concentrated in metabolic and cellular processes. Our results confirmed that gut bacterial communities of G. molesta can be influenced by host diets and may play an important role in host adaptation.

Development of DNA Melt Curve Analysis for the Identification of Lepidopteran Pests in Almonds and Pistachios

Almonds and pistachios are fed upon by a diverse assemblage of lepidopteran insects, several of which are economically important pests. Unfortunately, identification of these pests can be difficult, as specimens are frequently damaged during collection, occur in traps with non-target species, and are morphologically similar up to their third instar. Here, we present a quantitative PCR based melt curve analysis for simple, rapid, and accurate identification of six lepidopteran pests of almonds and pistachios: navel orangeworm (Amyelois transitella), peach twig borer (Anarsia lineatella), oriental fruit moth (Grapholita molesta), obliquebanded leafroller (Choristoneura rosaceana), raisin moth (Cadra figulilella), and Indian meal moth (Plodia interpunctella). In this approach, the dissociation (melt) temperature(s) of a 658 bp section of cytochrome c oxidase subunit 1 was determined using quantitative PCR (qPCR). Within these six species, the distribution and the number of melt peak temperatures provide an unambiguous species level identification that is reproducible when unsheared DNA can be extracted. The test is robust across a variety of sampling approaches including insects removed from sticky card traps, museum specimens, and samples that were left in the field for up to 7 days. The melt curve’s simplicity allows it to be performed in any basic molecular biology laboratory with a quantitative PCR.

Grapholita molesta (Oriental fruit moth).

G. molesta is a serious pest of economic importance of commercial stone and pome fruits around the world. G. molesta damages peaches, nectarines, plums, cherries, apricots, apples, pears, quinces and nashi (Asian pears) and can also attack and cause economic damage on other commercial fruits. In severe attacks, young trees can suffer distortion of growing shoots and stems, which makes pruning, training and shaping the tree canopy difficult, particularly for close-planting industrial systems such as Tatura trellis. One larva can damage many shoots by tunnelling deep into young shoot tips. Larvae move to feed on the green fruits usually after shoots mature and harden. One larva can damage many fruits, particularly when fruits are located close to each other.

Population and harmfulness of phytophages in peach orchards in the conditions of the Southern Steppe of Ukraine

Goal. To determine the number and harmfulness of the main phytophages on peach cultivars of different ripening terms in order to plan measures to protect the crop from pest damage. Methods. Laboratory-field. The research was carried out in peach orchards of the Scientific and Production Site «Naukova» of Melitopol Fruit Growing Research Station named after M.F. Sydorenka of Institute of Horticulture of NAAS according to generally accepted methods. Monitoring of the number of phytophages was performed on peach cultivars of different ripening terms: Iiun`s`kyi rannii, Melіtopol’s’kyi iasnyi, Charivnyk, Zlatodar, Vireneia, Redhaven, Spokusa, Zolotystii, Mriia and Yuvileinyi Sydorenka during bud swelling, inflorescence opening (pink tip), flowering, growth and maturations of the fruits. Results. Entomoacarocenosis of peach plantations has 15 species of insects pests and 2 species of mites. During the flowering period, the main harmful species was Epicometis hirta Poda., the number of imagoes in different cultivars was 0.3—5.8 specimens/100 flowers. Population intensity of peach trees with green peach aphids (Myzodes persicae Sulz.) for certain cultivars reached the level of 1.9 points, mealy plum aphid (Hyalopterus pruni Geoffr.) — did not exceed 0.8 points. Density of mites, Thrips fuscipennis Haliche and Typhlocyba rosae L. varied in the range of 0.4—2.5; 0.8—2.4; 0.5—1.6 specimen/leaf, respectively. The main fruit-damaging pests in peach orchards were oriental fruit moth (Grapholitha molesta Busck.) and peach twig borer (Anarsia lineatella Zell.). The degree of fruit damage by Lepidoptera pest oriental fruit moth on early-ripening peach cultivars was 3.0—4.0%, increased on medium- and late-ripening cultivars to 6.8% and 11.7%, respectively. The level of fruit damage by peach twig borer compared to the eastern fruit moth was 2.8—10.7 times lower, depending on the cultivar. Conclusions. In the conditions of the South of Ukraine, 15 insect pests and 2 species of mites were recorded in peach orchards. During the growing season, the number of most species of phytophagous, including weevils, leafroller moths, mites, thrips, Typhlocyba rosae on different peach cultivars did not exceed the economic threshold of harmfulness. During the flowering period, Epicometis hirta was the threat to peach orchards. In the summer of 2019, the harmful effects of sucking phytophages, in particular aphids, led to delayed growth and development of shoots, deformation of leaves. The main species of pests that reduced the yield and fruit quality were oriental fruit moth and peach twig borer.

Similar Gut Bacterial Microbiota in Two Fruit-Feeding Moth Pests Collected from Different Host Species and Locations

Numerous gut microbes are associated with insects, but their composition remains largely unknown for many insect groups, along with factors influencing their composition. Here, we compared gut bacterial microbiota of two co-occurring agricultural pests, the peach fruit moth (PFM), Carposina sasakii, and the oriental fruit moth (OFM), Grapholita molesta, collected from different orchards and host plant species. Gut microbiota of both species was mainly composed of bacteria from Proteobacteria, followed by Firmicutes. The two species shared bacteria from the genera Pseudomonas, Gluconobacter, Acetobacter, and Pantoea. When we compared two pairs of PFM and OFM populations collected from the same host species and the same orchard, there is no difference in alpha and beta diversity in gut microbiota. When we compared gut microbiota of the same species and host plant from different orchards, alpha and beta diversity was different in populations of PFM collected from two pear orchards but not in other comparisons. Our study suggests that the two pests share many features of gut microbiota and environment in orchards is a main factor influencing their gut microbiota.