Monitoring codling moth (Lepidoptera: Tortricidae) in sex pheromone-treated orchards with (E)-4,8-dimethyl-1,3,7-nonatriene or pear ester in combination with codlemone and acetic acid

Biodegradable electrospun fibers as sustained-release carriers of insect pheromones for field trapping of Spodoptera litura (Lepidoptera: Noctuidae)

BACKGROUND

Insect pheromones are highly effective and environmentally friendly, and are widely used in the monitoring and trapping of pests. However, many researchers have found that various factors such as ultraviolet light and temperature in the field environment can accelerate the volatilization of pheromones, thus affecting the actual control effect. In recent years, electrospinning technology has demonstrated remarkable potential in the preparation of sustained carriers. Moreover, the utilization of biodegradable materials in electrospinning presents a promising avenue for the advancement of eco-friendly carriers.

RESULTS

In this study, homogeneous and defect-free pheromone carriers were obtained by electrospinning using fully biodegradable polyhydroxybutyrate materials and pheromones of Spodoptera litura. The electrospun fibers with porous structure could continuously release pheromone (the longest can be ≤80 days). They also had low light transmission, hydrophobic protection. More importantly, the pheromone-loaded electrospun fiber carriers showed stable release and good trapping effect in the field. They could trap pests for at least 7 weeks in the field environment without other light stabilizers added.

CONCLUSION

Sustained-release carriers constructed by electrospinning and green materials could improve the efficacy of pheromones and ensure environmental friendliness, and provided a tool for the management of S. litura and other pests and sustainable development of agricultural. © 2023 Society of Chemical Industry.

Remote monitoring of Cydia pomonella adults among an assemblage of nontargets in sex pheromone-kairomone-baited smart traps

BACKGROUND

Captures of codling moth, Cydia pomonella (L.), in traps are used to establish action thresholds and time insecticide sprays. The need for frequent trap inspections in often remote orchards has created a niche for remote sensing smart traps. A smart trap baited with a five-component pheromone-kairomone blend was evaluated for codling moth monitoring among an assemblage of other nontargets in apple and pear orchards.

RESULTS

Codling moth captures did not differ between the smart trap and a standard trap when both were checked manually. However, the correlation between automatic and manual counts of codling moth in the smart traps was low, R²  = 0.66 ÷ 0.87. False-negative identifications by the smart trap were infrequent <5%, but false-positive identifications accounted for up to 67% of the count. These errors were primarily due to the misidentification of three moth species of fairly similar-size to codling moth: apple clearwing moth Synanthedon myopaeformis (Borkhausen), oriental fruit moth Grapholita molesta (Busck), and carnation tortrix Cacoecimorpha pronubana (Hübner). Other false-positive counts were less frequent and included the misidentifications of dipterans, other arthropods, patches of moth scales, and the double counting of some moths.

CONCLUSION

Codling moth was successfully monitored remotely with a smart trap baited with a nonselective sex pheromone-kairomone lure, but automatic counts were inflated in some orchards due to mischaracterizations of primarily similar-sized nontarget moths. Improved image-identification algorithms are needed for smart traps baited with less-selective lures and with lure sets targeting multiple species.

Comparison of New Kairomone-Based Lures for Cydia pomonella (Lepidoptera: Tortricidae) in Italy and USA

Simple Summary

Adult codling moth (Cydia pomonella L.) monitoring with lure-baited traps is a prerequisite to effectively manage this key pest in apple and pear crops without over-spraying insecticides. We evaluated new multi-component lures comprised of blends of sex pheromone and volatile organic compounds (pear ester, dimethyl nonatriene and linalool oxide) loaded into different substrates (septa and PVC lures). Acetic acid in a second membrane lure was used as a co-lure with all blends. Lure comparisons were performed during the period 2019/2020 in Italy and Washington State (USA) in orchards treated with or without sex pheromone dispensers for mating disruption. The highest total moth counts occurred with the sex pheromone/pear ester PVC lure in both countries. The new multi-component PVC lure without sex pheromone captured the greatest number of female moths only in the USA. This geographical disparity may limit the effectiveness of using a ‘female removal’ strategy to manage this pest without insecticides across major production areas.

Abstract

Studies were conducted during the period 2019/2020 to evaluate the effectiveness of four lures for codling moth (Cydia pomonella L.) in pome fruits in Italy and the USA. Multi-component blends of sex pheromone ((E,E)-8,10-dodecadien-1-ol, PH), pear ester ((E,Z)-2,4-ethyl decadienoate, PE), (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT), and pyranoid linalool oxide (6-ethenyl-2,2,6-trimethyloxan-3-ol, LOX) were loaded in either a halobutyl elastomer septum or a PVC matrix and always used in combination with acetic acid (AA) loaded in a closed membrane co-lure. Total moth capture was significantly greater with the PVC than the septum lure loaded with PH/PE + AA in both countries. Female capture in the USA study was significantly greater for 8 weeks in traps baited with the PE/DMNT/LOX blend + AA co-lure than with other lures and adding PH to this blend in a PVC lure significantly reduced female capture. In contrast, female capture in Italy did not differ among lures and counts were similar in both apple and pear crops treated with or without mating disruption. These results suggest that the effectiveness of ‘female removal’ strategies to manage codling moth may be geographically limited and further comparisons are needed in other production regions and in walnut.

CRISPR/Cas9 Editing of the Codling Moth (Lepidoptera: Tortricidae) CpomOR1 Gene Affects Egg Production and Viability

The codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), is a major pest of pome fruit worldwide. Incorporation of semiochemicals, including the main sex pheromone (codlemone), into codling moth IPM programs has drastically reduced the amount of chemical insecticides needed to control this orchard pest. Odorant receptors located in sensory neuron membranes in the antennae are key sensors in the detection of semiochemicals and trigger downstream signaling events leading to a behavioral response. CpomOR1 is an odorant receptor belonging to the pheromone receptor subfamily in codling moth, and is a prime candidate for being a codlemone receptor based on its high expression levels in male antennae. In this study, the CpomOR1 gene was targeted using CRISPR/Cas9 genome editing to knockdown functional OR1 protein production to determine physiological function(s). By injecting early stage eggs, mutations were successfully introduced, including both deletions and insertions. When attempting to create stable populations of codling moth through mating of males with females containing mutations of the CpomOR1 gene, it was found that fecundity and fertility were affected, with edited females producing nonviable eggs. The role of CpomOR1 in fecundity and fertility in codling moth is unknown and will be the focus of future studies.

Flowering mechanisms, pollination strategies and floral scent analyses of syntopically co-flowering Homalomena spp. (Araceae) on Borneo

In this study, the flowering mechanisms and pollination strategies of seven species of the highly diverse genus Homalomena (Araceae) were investigated in native populations of West Sarawak, Borneo. The floral scent compositions were also recorded for six of these species. The selected taxa belong to three out of four complexes of the section Cyrtocladon (Hanneae, Giamensis and Borneensis). The species belonging to the Hanneae complex exhibited longer anthesis (53-62 h) than those of the Giamensis and Borneensis complexes (ca. 30 h). Species belonging to the Hanneae complex underwent two floral scent emission events in consecutive days, during the pistillate and staminate phases of anthesis. In species belonging to the Giamensis and Borneensis complexes, floral scent emission was only evident to the human nose during the pistillate phase. A total of 33 volatile organic compounds (VOCs) were detected in floral scent analyses of species belonging to the Hanneae complex, whereas 26 VOCs were found in samples of those belonging to the Giamensis complex. The floral scent blends contained uncommon compounds in high concentration, which could ensure pollinator discrimination. Our observations indicate that scarab beetles (Parastasia gestroi and P. nigripennis; Scarabaeidae, Rutelinae) are the pollinators of the investigated species of Homalomena, with Chaloenus schawalleri (Chrysomelidae, Galeuricinae) acting as a secondary pollinator. The pollinators utilise the inflorescence for food, mating opportunities and safe mating arena as rewards. Flower-breeding flies (Colocasiomyia nigricauda and C. aff. heterodonta; Diptera, Drosophilidae) and terrestrial hydrophilid beetles (Cycreon sp.; Coleoptera, Hydrophilidae) were also frequently recovered from inflorescences belonging to all studied species (except H. velutipedunculata), but they probably do not act as efficient pollinators. Future studies should investigate the post-mating isolating barriers among syntopically co-flowering Homalomena sharing the same visiting insects.

Control and Monitoring of Codling Moth (Lepidoptera: Tortricidae) in Walnut Orchards Treated With Novel High-Load, Low-Density "Meso" Dispensers of Sex Pheromone and Pear Ester

Low-density per ha "meso" dispensers loaded with pear ester, ethyl (E,Z)-2,4-decadienoate, kairomone and codlemone, (E,E)-8,10-dodecadien-1-ol, pheromone of codling moth, Cydia pomonella (L)., were evaluated versus meso dispensers loaded with pheromone alone for mating disruption control in walnut orchards receiving no insecticide sprays. Meso dispensers loaded with codlemone alone (Ph meso) were applied at 50 ha-1 and compared with mesos combining codlemone and pear ester (Ph + PE meso) at 25 and 50 ha-1. Various lures containing pear ester (PE), Ph-PE combo, and an experimental codlemone plus (E)-4,8-dimethyl-1,3,7-nonatriene lure were tested alone and with acetic acid (AA) lures for moth capture efficacy. Male moth capture in pheromone traps was significantly reduced by 88% in Ph meso plots and 96% in Ph + PE meso plots versus control plots. Moth capture in Ph-PE combo traps was significantly reduced for both sexes in all meso plots. Harvest damage by both the codling moth and the secondary pest, navel orangeworm, Amyelois transitella (Walker), was significantly lower in all meso treatment plots compared with damage in control plots. Nut injury level with the Ph + PE meso treatment (50 ha-1) was significantly lower than in Ph meso plots for both codling moth and combined pest injury. Regression analysis suggested that nut infestation levels by navel orangeworm were influenced by codling moth levels. In all meso plots, the most effective lures attracting both codling moth sexes were PE & AA or Ph-PE combo & AA. Demonstrated disruption and control efficacy of these pheromone plus PE-meso dispensers applied at low densities supports development of the meso dispenser tactic for practical pest management use in walnut orchards with inherent low planting densities.

A Binary Host Plant Volatile Lure Combined With Acetic Acid to Monitor Codling Moth (Lepidoptera: Tortricidae)

Field studies were conducted in the United States, Hungary, and New Zealand to evaluate the effectiveness of septa lures loaded with ethyl (E,Z)-2,4-decadienoate (pear ester) and (E)-4,8-dimethyl-1,3,7-nonatriene (nonatriene) alone and in combination with an acetic acid co-lure for both sexes of codling moth, Cydia pomonella (L.). Additional studies were conducted to evaluate these host plant volatiles and acetic acid in combination with the sex pheromone, (E,E)-8,10-dodecadien-1-ol (codlemone). Traps baited with pear ester/nonatriene + acetic acid placed within orchards treated either with codlemone dispensers or left untreated caught significantly more males, females, and total moths than similar traps baited with pear ester + acetic acid in some assays. Similarly, traps baited with codlemone/pear ester/nonatriene + acetic acid caught significantly greater numbers of moths than traps with codlemone/pear ester + acetic acid lures in some assays in orchards treated with combinational dispensers (dispensers loaded with codlemone/pear ester). These data suggest that monitoring of codling moth can be marginally improved in orchards under variable management plans using a binary host plant volatile lure in combination with codlemone and acetic acid. These results are likely to be most significant in orchards treated with combinational dispensers. Significant increases in the catch of female codling moths in traps with the binary host plant volatile blend plus acetic acid should be useful in developing more effective mass trapping strategies.

Field Evaluation of Agrotis ipsilon (Lepidoptera: Noctuidae) Pheromone Blends and Their Application to Monitoring Moth Populations in China

The attractiveness of a series of mixtures of (Z)-7-dodecenyl acetate (Z7-12:Ac), (Z)-9-tetradecenyl acetate (Z9-14:Ac), and (Z)-11-hexadecenyl acetate (Z11-16:Ac), the Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae) pheromone, were evaluated in four locations in China. The ternary blend of Z7-12:Ac, Z9-14:Ac, and Z11-16:Ac was the complete pheromone blend for A. ipsilon and the ratio of Z7-12:Ac and Z9-14:Ac was optimal at 3:1. The most attractive ratio of Z11-16:Ac to the other components depended on geographic location. The optimal ratio was 3:1:6 in Yunnan and Shanxi, 3:1:2 in Sichuan and ranged from 3:1:2 to 3:1:12 in Shanghai, which differs significantly from the ratio of 3:1:16 in Japan. The dose of the blend in the pheromone lure influenced attractiveness to male moths and was related to the temperature in the test locations. Attractiveness of sugar-acetic acid-baited and pheromone-baited traps to male and female moths was different before and after the start of flowering of the oilseed rape crop; large numbers of female moths were attracted to sugar-acetic acid traps before flowering but none after flowering had started. This was similar for male moths and there was no synergistic effect when sugar-acetic acid solutions and pheromone were used together. These studies suggest that pheromone trapping based on the blends of three components can be an effective tool to improve the efficiency of monitoring of this pest in China.