Mating Disruption of a Flighted Spongy Moth, Lymantria Dispar Japonica (Motchulsky) in Japan.

Mating disruption of a flighted spongy moth, Lymantria dispar japonica (Motchulsky)(Lepidoptera: Lymantridae), with a synthetic version of its sex pheromone, (+)-disparlure ([7R,8S] -cis-7,8-epoxy-2- methyloctadecane), was tested in the forests in Japan. Pheromone trap catches and the percentage mating of tethered females were measured in the pheromone-treated and untreated control forests. The attraction of male moths to pheromone traps placed at a height of 1.5 m was significantly disrupted when the pheromone dispensers were placed at 1.5 m height, but many moths were captured in control plots. Mating of tethered females placed at 1.5 m was inhibited entirely, while 44% of females were mated in an untreated control forest. We report the first trial of mating disruption against a flighted spongy moth, and these results suggest that mating disruption with the synthetic sex pheromone appears promising for reducing damage caused by L. dispar japonica.

CRISPR/Cas9 mediated editing of pheromone biosynthesis activating neuropeptide (PBAN) gene disrupts mating in the Fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae).

The Fall armyworm, Spodoptera frugiperda, is a globally important invasive pest, primarily on corn, causing severe yield loss. Overuse of synthetic chemicals has caused significant ecological harm, and in many instances control has failed. Therefore, developing efficient, environmentally friendly substitutes for sustainable management of this pest is of high priority. CRISPR/Cas9-mediated gene editing causes site-specific mutations that typically result in loss-of-function of the target gene. In this regard, identifying key genes that govern the reproduction of S. frugiperda and finding ways to introduce mutations in the key genes is very important for successfully managing this pest. In this study, the pheromone biosynthesis activator neuropeptide (PBAN) gene of S. frugiperda was cloned and tested for its function via a loss-of-function approach using CRISPR/Cas9. Ribonucleoprotein (RNP) complex (single guide RNA (sgRNA) targeting the PBAN gene + Cas9 protein) was validated through in vitro restriction assay followed by embryonic microinjection into the G0 stage for in vivo editing of the target gene. Specific suppression of PBAN by CRISPR/Cas9 in females significantly affected mating. Mating studies between wild males and mutant females resulted in no fecundity. This was in contrast to when mutant males were crossed with wild females, which resulted in reduced fecundity. These results suggest that mating disruption is more robust where PBAN is edited in females. The behavioural bioassay using an olfactometer revealed that mutant females were less attractive to wild males compared to wild females. This study is the first of its kind, supporting CRISPR/Cas9 mediating editing of the PBAN gene disrupting mating in S. frugiperda. Understanding the potential use of these molecular techniques may help develop novel management strategies that target other key functional genes. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-023-03798-3.

Mating and post-copulation behavior in the tea leafhopper, Empoasca onukii (Hemiptera: Cicadellidae).

The tea leafhopper, Empoasca onukii, relies on substrate-borne vibrations for sexual communication and is mainly controlled with chemical pesticides, which poses risks to the environment and food safety. Based on previous studies, we conducted a series of behavioral assays by simultaneous observation of vibration signals and movement to investigate the mating and post-copulation behavior of tea leafhoppers. During mating, the activity of E. onukii was restricted to dawn and dusk and concentrated on the sixth or seventh mature leaf below the tea bud. By comparing the time spent in locating females among different males, the timely reply of females was the key factor affecting mating success. Empoasca onukii females mated only once in their lives, while males could mate multiple times. Male rivalry behavior involved two distinct strategies. The rivals could send disruptive pulses to overlap the male calling signals, locate the courting males, and drive them away after contact. Some rivals could emit mating disruption signals (MDSs) to interrupt the ongoing identification duet and establish their own mating communication. Both identification and location duets could be interrupted by playback of MDSs, which is essential to create effective synthetic signals to disrupt mating communication of E. onukii. Our study clarified the spatial and temporal distribution of E. onukii in mating and the function of MDSs, which will be essential to develop future vibrational mating disruption techniques for E. onukii and its energy-efficient application in the field.

CRISPR/Cas9 mediated mutagenesis of the major sex pheromone gene, acyl-CoA delta-9 desaturase (DES9) in Fall armyworm Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae).

The Fall armyworm, Spodoptera frugiperda is a significant global pest causing serious yield loss on several staple crops. In this regard, this pest defies several management approaches based on chemicals, Bt transgenics etc., requiring effective alternatives. Recently CRISPR/Cas9 mediated genome editing has opened up newer avenues to establish functions of various target genes before employing them for further application. The virgin female moths of S. frugiperda emit sex pheromones to draw conspecific males. Therefore, we have edited the key pheromone synthesis gene, fatty acyl-CoA Delta-9 desaturase (DES9) of the Indian population of S. frugiperda. In order to achieve a larger deletion of the DES9, we have designed two single guide RNA (sgRNA) in sense and antisense direction targeting the first exon instead of a single guide RNA. The sgRNA caused site-specific knockout with a larger deletion which impacted the mating. Crossing studies between wild male and mutant female resulted in no fecundity, while fecundity was normal when mutant male crossed with the wild female. This indicates that mating disruption is stronger in females where DES9 is mutated. The current work is the first of its kind to show that DES9 gene editing impacted the likelihood of mating in S. frugiperda.

Pheromone and Host Plant Odor Detection in Eastern Spruce Budworm, Choristoneura fumiferana Clemens (Lepidoptera: Tortricidae).

Spruce budworm, Choristoneura fumiferana Clemens, is an ecologically significant defoliator of spruce and balsam fir in North America. Optimization of semiochemical-mediated control is needed to improve the existing integrated pest management systems such as mating disruption and population estimation. This study used single sensillum recordings (SSR) to identify the responses of olfactory receptor neurons (ORNs) in the antennal sensilla of adult male and female C. fumiferana to host plant volatiles, and female sex pheromones. There have been few SSR studies done on spruce budworm, and to our knowledge, the present study represents the first attempt to examine the responses of ORNs from antennal sensilla in response to a range of host and conspecific stimuli. A total of 86 sensilla were characterized and sorted into 15 possible sensillum categories based on odor responses. We observed that specialist sensilla responding to few ligands were more abundant in both male and female than sensilla exhibiting more generalized odorant responses. (E/Z)-11-tetradecenal elicited responses from ORNs from any sensilla which were sensitive to pheromones in both males and females. Female C. fumiferana ORNs were able to detect and physiologically respond to female-produced sex pheromones with the same degree of sensitivity as their male counterparts. Together, these data improve our knowledge of mechanisms by which adult budworms respond to pheromone and host plant volatiles and provide insights that may be complementary to existing integrated pest management (IPM) strategies based on the chemical ecology of spruce budworm.

Dispensers for pheromonal pest control.

The detrimental effects of pesticides on the environment and human health have motivated the development of alternative pest control strategies. Pheromonal pest control is one alternative strategy that is attractive because most pheromones used commercially are non-toxic. Pheromones are also effective at low concentrations, and insects are slower to develop resistance to them compared to pesticides. Pheromones can be used to control pests by attracting them towards traps, repelling them from crops, or disrupting their mating behaviour. Viability of pheromonal control strategies must be evaluated on a case-by-case basis and depends on the target species, the pheromone being used, the specific control strategy, the method of dispensing pheromone, other pest control strategies pheromones being used alongside, and many other factors. The efficacy of pheromonal control has been demonstrated in commercial applications such as the control of palm weevils using traps releasing their male aggregation pheromone. Mating disruption using female sex pheromones has also been widely applied for control of both the codling moth Cydia Pomonella and the european grapevine moth Lobesia Botrana (Bangels and Beliën, 2012; Lucchi et al., 2018). Pheromones are volatiles that both degrade quickly in the environment and can be rapidly dispersed by wind. Consequently, administering pheromones to fields requires the use of dispensers that emits pheromone continuously or intermittently. Septum dispensers, membrane dispensers and solid matrix dispensers are best suited to treating smaller areas of cropland since they need to be installed by hand, a labor-intensive process. For treating a large area with pheromones, sprayable formulations and aerosol dispensers are alternative dispensing technologies that can be employed. The characteristics of these different dispenser designs are discussed as well as the kinetics governing pheromone release. Possible areas for future work in pheromone dispenser technology include examining new integrated strategies that employ pheromones alongside other pest control techniques in unique ways. The combination of pheromonal control with physical exclusion or predator release are examples of integrated strategies that are promising but have yet to be widely commercialized. Most commercial pheromonal dispensers are also noted to be impossible or impractical to reuse, apart from aerosol devices. Creating new types of rechargeable dispenser might have some cost saving benefits and would be an interesting area for future innovation in this field.

Use of a Sprayable Sex Pheromone Formulation in Landscape-Level Control of Choristoneura fumiferana Populations.

Choristoneura fumiferana (SBW) is a major defoliating pest of balsam fir and spruce in eastern North America. As part of an integrated management strategy for SBW, we evaluated the effectiveness of mating disruption as a landscape-level population control tactic. Using a sprayable formulation (CONFOUNDSBW) containing a synthetic sex pheromone blend, we treated five 300 ha blocks in Northern New Brunswick with an aerially applied microencapsulated mixture. There were significant reductions in adult trap catches in treated blocks compared to untreated control blocks. Branch sampling in treated blocks showed uniform distribution of CONFOUNDSBW deposition throughout the blocks. Population densities following treatment were not significantly affected when compared to densities in control blocks, or prior to treatment. Analysis of egg:adult ratios indicates that no immigration events occurred within treatment or control blocks. The lack of population reduction following treatment strongly suggests that widespread application of CONFOUNDSBW at a rate of 50 g of active ingredient per hectare is not an effective tool in controlling SBW populations.

Behavioral Response of Unmated Female Plodia interpunctella Hübner (Lepidoptera: Pyralidae) to Synthetic Sex Pheromone Lure.

Indian meal moth, Plodia interpunctella Hübner, is an important pest of stored products in food facilities like processing plants, warehouses, and retail stores. Mating disruption, which uses synthetic pheromone to delay or prevent mating, is a relatively new management tactic for this pest but is becoming widely adopted. However, little is known about the mechanisms behind its efficacy, including how artificial pheromone impacts female behavior. Here we assay behavioral responses of two strains of unmated female P. interpunctella exposed to pheromone. Results show one strain increased the duration of calling behavior while the other decreased calling when exposed to pheromone lures. Time walking decreased, and time cleaning increased for both strains when exposed to pheromone. Time of first walking behavior was also delayed for one strain when exposed to pheromone. Females of both strains were less mobile when exposed to pheromone. These results show autodetection of pheromone by females, but also indicate that strains may vary in behavioral responses. Differing patterns of calling behavior between strains could be driven by either strain-specific genetic differences or laboratory induced effects. Decreasing calling behavior and overall movement during exposure to pheromone could enhance the effectiveness of a mating disruption program. However, increased calling by females in the presence of pheromone may be a competitive response and could increase mating success under certain scenarios. These findings suggest that artificial pheromone associated with monitoring and mating disruption programs has impacts on female behavior and warrants further study to determine the overall impacts on program effectiveness.

Perception of Heterospecific Sex Pheromone Causes Less Effective Mating Disruption in the Beet Semilooper, Autographa nigrisigna (Lepidoptera: Noctuidae).

Confuser® V is a pheromone-based mating disruptant designed to reduce damage caused by seven species of moth pests, including the beet semilooper, Autographa nigrisigna (Lepidoptera: Noctuidae). Eggs and larvae of A. nigrisigna are often found in fields treated with Confuser® V, suggesting that some components in the Confuser® V blend may have adverse effects on the efficacy of mating disruption of this species. Therefore, we examined whether A. nigrisigna perceives heterospecific pheromone components in the Confuser® V blend and delineated the roles of these components with respect to attraction and communication disruption. We found that several heterospecific pheromone components in the Confuser® V blend were perceived by male A. nigrisigna, and the addition of these components to the pheromone blend of A. nigrisigna reduced the attraction of males in the field, and tended to reduce the efficacy of mating disruption in cage bioassays.

Bioproduction of (Z,E)-9,12-tetradecadienyl acetate (ZETA), the major pheromone component of Plodia, Ephestia, and Spodoptera species in yeast.

BACKGROUND: (Z,E)-9,12-tetradecadienyl acetate (ZETA, Z9,E12-14:OAc) is a major sex pheromone component for many stored-product moth species. This pheromone is used worldwide for mating disruption, detection, monitoring, and mass trapping in raw and processed food storage facilities. In this study, we demonstrate the biological production of ZETA pheromone by engineered yeast Saccharomyces cerevisiae. RESULTS: We mined the pheromone gland transcriptome data of the almond moth, Ephestia (Cadra) cautella (Walker), to trace a novel E12 fatty acyl desaturase and expressed candidates heterologously in yeast and Sf9 systems. Furthermore, we demonstrated a tailor-made ZETA pheromone bioproduction in yeast through metabolic engineering using this E12 desaturase, in combination with three genes from various sources coding for a Z9 desaturase, a fatty acyl reductase, and an acetyltransferase, respectively. Electrophysiological assays (gas chromatography coupled to an electroantennographic detector) proved that the transgenic yeast-produced ZETA pheromone component elicits distinct antennal responses. CONCLUSION: The reconstructed biosynthetic pathway in yeast efficiently produces ZETA pheromone, leaves an undetectable level of biosynthetic intermediates, and paves the way for the economically competitive high-demand ZETA pheromone's bioproduction technology for high-value storage pest control.

Pheromone antagonism in Plu tella xylostella (Linnaeus) by sex pheromones of two sympatric noctuid moths.

BACKGROUND: Responses to sex pheromones are commonly antagonized by pheromone components of closely related species. Pheromone antagonism has not been widely explored for phylogenetically distant species that have completely different pheromone components. Yet, pheromone components of sympatrically occurring species may also interfere with each other even if these species are distantly related. Here, the effects of heterospecific pheromones on electrophysiology (electroantennogram, EAG) and behavioral responses were tested on the diamondback moth Plutella xyloslella (Plutellidae) and two sympatric noctuid moth species, Spodoptera litura and Spodoptera exigua, whose larvae also feed on Brassica crops. RESULTS: The sex pheromone blend of P. xyloslella, and its components, did not elicit EAG responses in males of the two noctuid species, while sex pheromone components of the noctuid moths elicited significant EAG responses in P. xyloslella males. In wind tunnel bioassays, both (Z, E)-9, 12-tetradecadienyl acetate (ZE-9,12-14:OAc) and (Z, E)-9, 11-tetradecadienyl acetate (ZE-9,11-14:OAc), sex pheromone components from the noctuid moths, inhibited the upwind flight behavior of P. xyloslella males toward an intraspecific pheromone odor source. In Brassica fields, sex pheromone lures of P. xyloslella did not influence trap catches of the noctuid moths, while P. xyloslella pheromone lures baited with either ZE-9,11-14:OAc or ZE-9,12-14:OAc decreased trap catches of P. xyloslella males in a dose-dependent manner. Trap catches of P. xylostella males were also affected by the proximity of ZE-9,11-14:OAc or ZE-9,12-14:OAc to P. xylostella lures. CONCLUSION: The uni-directional pheromone antagonism by ZE-9,11-14:OAc and ZE-9,12-14:OAc suggests innovative semiochemical-based strategies for the management of P. xyloslella and other economically important pests in Brassica fields. © 2021 Society of Chemical Industry.

Mating Disruption of the California Red Scale, Aonidiella aurantii (Hemiptera: Diaspididae) in Central California Citrus.

A warmer climate and the development of pesticide resistance have led to an increase in the number of generations and higher population densities of California red scale, Aonidella aurantii (Maskell) in central California. Commercial citrus orchard studies were conducted to determine how effective mating disruption using CheckMate CRS was at reducing A. aurantii. In 2016-2017, two replicated trials were conducted in 15.0-15.5 ha orchards and in 2018 and 2019, one half of each of 10 orchards 8-16.2 ha in size were treated with CheckMate CRS. Mating disruption significantly suppressed male captures for up to 8 mo. Average reductions of 90% in cumulative male flight trap catches were recorded, twig and leaf infestations were reduced by 95%, and highly scale-infested fruit were reduced by 75% in the CheckMate CRS plots for the 2018 and 2019 trials. In seven of 12 sites the percentage of highly infested fruit was reduced below 0.5%. Leaf and twig infestations in August and reductions in male captures during the 4th flight were strongly related to the percentage of highly infested fruit at the end of the season and could be used as predictors of the success of mating disruption. The results of the study indicated mating disruption using CheckMate CRS can be an effective method to reduce California red scale populations throughout the 4+ generations that occur in central California. Mating disruption has the potential to reduce or eliminate pesticide applications, especially in low scale density situations.

Effects of Delayed Mating on Mating Performance and Reproductive Fitness of the Willow Leaf Beetle (Coleoptera: Chrysomelidae) under Laboratory Conditions.

Age at mating is one of the most important factors that affect mating selection, sexual performance, and fecundity. We studied the effects of mating age on the mating performance and reproductive fitness of Plagiodera versicolora Laicharting, a serious pest of poplar and willow, by measuring the time from pairing to successful mating, mating duration, fecundity, hatching probability, and female lifespan. Delayed mating of females and males significantly prolonged the time from pairing to successful mating and the mating duration, but had no effect on the duration of the egg-laying period. Delayed mating of females did not significantly affect fecundity or egg hatching, but significantly prolonged the female lifespan. Although delayed mating of males had a significant negative impact on egg hatching, it had no effect on the lifespan or fecundity of females. These results indicate that delayed mating affects the mating performance of P. versicolora, although it has a limited effect on reproductive fitness. This suggests that delayed mating is unlikely to contribute to the success of mating disruption, when applied to control P. versicolora.

Pinyon Engraver Beetle Acoustics: Stridulation Apparatus, Sound Production and Behavioral Response to Vibroacoustic Treatments in Logs.

Bark beetles are among the most influential biotic agents in conifer forests, and forest management often focuses on bark beetle chemical communication for tree protection. Although acoustic communication occurs in many bark beetle species, we have yet to utilize acoustic communication for bark beetle control. Here, we describe the stridulatory organs and 'stress' chirps of the pinyon engraver, Ips confusus, a significant pest and mortality agent of pinyon pine in western North America. Only females possessed stridulatory organs and their stress chirps varied significantly in duration, pulses per chirp, and dominant frequency. We tested an array of acoustic-vibrational treatments into logs but were unable to disrupt male entry into logs or alter female-male interactions, female tunneling, and female oviposition. We found acoustic-vibrational treatments had little effect on I. confusus behavior and suggest further studies if acoustic methods are to be utilized for bark beetle control.

Drones That Deliver: Pheromone-Based Mating Disruption Deployed via Uncrewed Aerial Vehicles in U.S. Cranberries.

Cranberry fruitworm (Acrobasis vaccinii Riley (Lepidoptera: Pyralidae)) and blackheaded fireworm (Rhopobota naevana Hubner (Lepidoptera: Tortricidae)) threaten cranberry production annually by causing significant fruit damage. Up to four pesticide applications are made each year to control these insects, which are costly to producers and elevate pesticide residues in fruit. Pheromone-based mating disruption technology can provide control of these pests in cranberry production, with the potential to minimize, or eliminate, pesticide applications. In 2016, an uncrewed aerial vehicle (UAV) was investigated to apply a thick paraffin emulsion containing insect sex pheromones. Traditional agricultural equipment is not capable of applying the paraffin emulsion to cranberry beds due to the product's viscous, paste-like consistency. The first objective of this study was to retrofit an UAV (octocopter) with a novel extrusion device that had been engineered to deliver the pheromone-loaded paraffin at regular intervals during flight. The second objective was to confirm adequate distribution of the pheromones by measuring the mating disruption efficacy by monitoring male moth trap catches. The UAV was able to fly autonomously along a prescribed itinerary, deploying the paraffin product uniformly; however, the increased mass of the retrofitted UAV limited flight times to ~12 min. The number of male cranberry fruitworm and blackheaded fireworm moths caught in lure-baited traps were reduced in the paraffin-treated beds compared with untreated beds, indicating adequate distribution of the pheromones. The UAV-applied pheromones concept could be developed into a production scale application method in the future, although issues of battery life and lifting capacity will need to be resolved.

Evaluating the success of treatments that slow spread of an invasive insect pest.

BACKGROUND: Treatments for the suppression and eradication of insect populations undergo substantial testing to ascertain their efficacy and safety, but the generally limited spatial and temporal scope of such studies limit knowledge of how contextual factors encountered in operational contexts shape the relative success of pest management treatments. These contextual factors potentially include ecological characteristics of the treated area, or the timing of treatments relative to pest phenology and weather events. We used an extensive database on over 1000 treatments of nascent populations of Lymantria dispar (L.) (gypsy moth) to examine how place-based and time-varying conditions shape the success of management treatments. RESULTS: We found treatment success to vary across states and years, and to be highest in small treatment blocks that are isolated from other populations. In addition, treatment success tended to be lower in treatment blocks with open forest canopies, possibly owing to challenges of effectively distributing treatments in these areas. CONCLUSIONS: Our findings emphasize the importance of monitoring for early detection of nascent gypsy moth colonies in order to successfully slow the spread of the invasion. Additionally, operations research should address best practices for effectively treating with patchy and open forest canopies. © 2021 Society of Chemical Industry.

Tephritid Fruit Fly Semiochemicals: Current Knowledge and Future Perspectives.

The Dipteran family Tephritidae (true fruit flies) comprises more than 5000 species classified in 500 genera distributed worldwide. Tephritidae include devastating agricultural pests and highly invasive species whose spread is currently facilitated by globalization, international trade and human mobility. The ability to identify and exploit a wide range of host plants for oviposition, as well as effective and diversified reproductive strategies, are among the key features supporting tephritid biological success. Intraspecific communication involves the exchange of a complex set of sensory cues that are species- and sex-specific. Chemical signals, which are standing out in tephritid communication, comprise long-distance pheromones emitted by one or both sexes, cuticular hydrocarbons with limited volatility deposited on the surrounding substrate or on the insect body regulating medium- to short-distance communication, and host-marking compounds deposited on the fruit after oviposition. In this review, the current knowledge on tephritid chemical communication was analysed with a special emphasis on fruit fly pest species belonging to the Anastrepha, Bactrocera, Ceratitis, and Rhagoletis genera. The multidisciplinary approaches adopted for characterising tephritid semiochemicals, and the real-world applications and challenges for Integrated Pest Management (IPM) and biological control strategies are critically discussed. Future perspectives for targeted research on fruit fly chemical communication are highlighted.

Parthenogenesis in UK field populations of the tomato leaf miner, Tuta absoluta, exposed to the mating disruptor Isonet T.

BACKGROUND: The tomato leafminer, Tuta absoluta is a damaging pest of tomato crops worldwide. In the UK T. absoluta is controlled using an integrated pest management (IPM) strategy that includes pheromone-based mating disruption. However, some growers have reported a loss of efficacy of this technology, and there are concerns that T. absoluta may evolve resistance via changes in its capacity to reproduce asexually. In this study we investigated the reproductive capacity of virgin populations of T. absoluta collected from a UK glasshouse before (EVH2016) and after (EVH2019) the introduction of the mating disrupter Isonet T. RESULTS: In line with earlier reports, we demonstrate that UK populations of T. absoluta can reproduce parthenogenetically, and observed a small but significant increase in the rate of parthenogenesis associated with the use of Isonet T. Marked differences in several other life history traits associated with reproduction were also observed between the two virgin populations, with the EVH2019 strain producing fewer eggs, a delayed onset of egg laying and increased lifespan. CONCLUSION: The low rate of parthenogenetic reproduction seen in this study is unlikely to result in loss of efficacy of mating disruption. However, the observed changes in longevity and egg laying may allow T. absoluta to persist for longer within the crop, and, together with the increased rate of parthenogenesis, may reflect selection from the use of Isonet T. Thus, regular monitoring of the reproductive capacity of UK populations should be conducted, and mating disruption used only as part of IPM to avoid the emergence of resistance. © 2021 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Individual and Additive Effects of Insecticide and Mating Disruption in Integrated Management of Navel Orangeworm in Almonds.

Damage from Amyelois transitella, a key pest of almonds in California, is managed by destruction of overwintering hosts, timely harvest, and insecticides. Mating disruption has been an increasingly frequent addition to these management tools. Efficacy of mating disruption for control of navel orangeworm damage has been demonstrated in experiments that included control plots not treated with either mating disruption or insecticide. However, the navel orangeworm flies much farther than many orchard pests, so large plots of an expensive crop are required for such research. A large almond orchard was subdivided into replicate blocks of 96 to 224 ha and used to compare harvest damage from navel orangeworm in almonds treated with both mating disruption and insecticide, or with either alone. Regression of navel orangeworm damage in researcher-collected harvest samples from the interior and center of management blocks on damage in huller samples found good correlation for both and supported previous assumptions that huller samples underreport navel orangeworm damage. Blocks treated with both mating disruption and insecticide had lower damage than those treated with either alone in 9 of the 10 years examined. Use of insecticide had a stronger impact than doubling the dispenser rate from 2.5 to 5 per ha, and long-term comparisons of relative navel orangeworm damage to earlier- and later-harvested varieties revealed greater variation than previously demonstrated. These findings are an economically important confirmation of trade-offs in economic management of this critical pest. Additional monitoring tools and research tactics will be necessary to fulfill the potential of mating disruption to reduce insecticide use for navel orangeworm.

Management of Navel Orangeworm (Lepidoptera: Pyralidae) Using Four Commercial Mating Disruption Systems in California Almonds.

The navel orangeworm, Amyelois transitella (Walker), is the most significant pest of California almonds. Direct feeding on the kernel by the larvae causes reductions in salable crop, crop quality, and exportability. Pheromone mating disruption (MD) targeting navel orangeworm is a relatively new technique with the potential to improve management. In 2017, we used replicated ~16-ha plots to compare the efficacy of four commercial MD systems (CheckMate, Cidetrak, Isomate, and Semios) for their relative impacts on the number of navel orangeworm in monitoring traps and crop quality. From 2017 to 2018, we conducted nine direct comparison studies in 16 to 40 ha almond orchards to compare conventional pest management programs to programs incorporating pheromone MD systems. Across all studies, MD reduced male moth captures in pheromone traps by >94%. In the efficacy study, use of mating disruption led to 35% and 53% reductions in kernel damage in Nonpareil and pollinizer cultivars, respectively, and an average increase in crop value of $370 ha-1. In the direct comparison, kernel damage to Nonpareil and pollinizer cultivars was reduced by 65% and 78%, respectively, resulting in an average increase in crop value of $357 ha-1. Economic analyses showed that increases in crop returns exceeded the costs of implementing MD systems with the break-even point ranging from 0.86 to 1.06% of kernel damage. These results suggest that adding MD to an existing navel orangeworm management program is a cost-effective way to reduce damage while promoting sustainable pest management practices.