Pest Of Almonds Research Articles

Visual ID guide from UC aids in managing new almond pests

Visual ID guide from UC aids in managing new almond pests

Diet quality influences nutrient retention and reproductive fitness of the biocontrol agent Hadronotus pennsylvanicus (Hymenoptera: Scelionidae)

Diet can have a direct influence on the reproductive success of parasitoid wasps. For synovigenic parasitoids, the nutrients obtained from floral resources, such as nectar and pollen, play a vital role in fueling bodily functions and physiological energy expenditure incurred from reproduction. Insufficient access to nutrient-rich diets can lead to lower rates of reproductive fitness, therefore reducing the efficacy of biocontrol. Here, a study was conducted to evaluate the influence of diet quality on nutrient retention and reproductive fitness of the egg parasitoid Hadronotus pennsylvanicus (Hymenoptera: Scelionidae), a prospective biocontrol agent for the leaffooted bug Leptoglossus zonatus (Heteroptera: Coreidae), a primary pest of almonds and pistachios. Newly emerged parasitoid females were provided host eggs every other day accompanied by diets of varying sucrose concentrations (source of carbohydrates) and pollen (source of lipid and proteins). The sucrose concentration in the diet, regardless of pollen content, significantly increased the survival and lifetime fecundity of female H. pennsylvanicus. While wasps fed high sucrose diets depleted bodily sugars, glycogen, and lipids at a slower rate than wasps fed low sucrose diets, there was no effect on bodily protein levels. Given these findings, further research is now needed to identify floral resources that are compatible, attractive, and nutritionally-sufficient for optimal H. pennsylvanicus reproductive fitness, which could lead to enhanced parasitism of L. zonatus in crop systems.

Adoption of Amyelois transitella (navel orangeworm) monitoring and management practices across California tree nut crops

Abstract In California, the most significant insect pest of almonds and pistachios is the navel orangeworm, Amyelois transitella (Walker) and is a pest of walnuts. This pest attacks the nuts and infestation is associated with aflatoxin contamination. While there are multiple integrated pest management (IPM) practices available, anecdotal evidence suggests that not all tools are equally utilized. To understand current industry practices and barriers to adoption, the authors surveyed tree nut growers and industry professionals across 7 University of California Cooperative Extension meetings in California’s Central Valley. Findings indicate that as managed acres decreased, participants were less likely to report using as many IPM tools, and pest control advisers reported higher use of multiple practices compared to orchard owners and managers. Key barriers to adoption varied by practice and included high economic costs, low labor availability, environmental conditions, and/or timing constraints. Many respondents were skeptical of the efficacy of mating disruption, a relatively new strategy compared to other IPM tools. Finally, a cluster analysis identified thirteen aggregate grower profiles. Groups primarily differed in their use of monitoring practices, although some groups were also less likely to use sanitation or pesticides. Two groups were distinguished as “early adopters” through their use of mating disruption and/or ovibait traps. These findings document variability in adoption of IPM practices for A. transitella in tree nuts. Identification of the primary barriers and constraints for specific grower groups will inform research and extension efforts to further promote adoption of key IPM strategies.

Updated spider mite management guidelines for California almonds as sixspotted thrips replace phytoseiids as predominant predator

Spider mites (Tetranychus sp.) are a universal pest of almonds in California that are naturally regulated by a variety of biological control organisms. Historically, phytoseiids have served as the predominant predator whereas recent changes in pesticide spray programs have caused a higher-level predator, the sixspotted thrips, Scolothrips sexmaculatus, to gain importance. Given the changing dynamics, we conducted research to re-evaluate treatment thresholds for spider mites and compare those to previous thresholds established in the 1980s. Efforts were made to develop a sticky card trap system to monitor for sixspotted thrips (Haviland et al., 2021a) that was used to generate key information on its biology, phenology, and role in predator-prey relationships (Haviland et al., 2021b). Finally, capture data for sixspotted thrips were used to develop thresholds based on sixspotted thrips sampling that could be used to predict whether mite populations would increase, decrease, or stay the same (Haviland et al., 2021c).

Pest risk assessment of Amyelois transitella for the European Union.

Following a request from the European Commission, the EFSA Panelon Plant Health performed a pest risk assessment of Amyelois transitella (Lepidoptera: Pyralidae), the navel orangeworm, for the EU. The quantitative assessment considered two scenarios: (i) current practices and (ii) a requirement for chilled transport. The assessment focused on pathways of introduction, climatic conditions and cultivation of hosts allowing establishment, spread and impact. A. transitella is a common pest of almonds, pistachios and walnuts in California, which is the main source for these nuts imported into the EU. Based on size of the trade and infestation at origin, importation of walnuts and almonds from the USA was identified as the most important pathways for entry of A. transitella. Using expert knowledge elicitation (EKE) and pathway modelling, a median estimate of 2,630 infested nuts is expected to enter the EU each year over the next 5 years (90% certainty range (CR) from 338 to 26,000 infested nuts per year). However, due to estimated small likelihoods of transfer to a host, mating upon transfer and survival of founder populations, the number of populations that establish was estimated to be 0.000698 year-1 (median, 90% CR: 0.0000126-0.0364 year-1). Accordingly, the expected period between founding events is 1,430 years (median, 90% CR: 27.5-79,400 year). The likelihood of entry resulting in establishment is therefore considered very small. However, this estimate has high uncertainty, mainly concerning the processes of transfer of the insect to hosts and the establishment of founder populations by those that successfully transfer. Climate matching and CLIMEX modelling indicate that conditions are most suitable for establishment in the southern EU, especially around the Mediterranean basin. The median rate of natural spread was estimated to be 5.6 km/year (median, 90% CR 0.8-19.3 km/year), after an initial lag period of 3.1 year (mean, 90% CR 1.7-6.2 year) following the establishment of a founder population. If A. transitella did establish, estimated median yield losses in nuts were estimated to be in the order of 1-2% depending on the nut species and production system. A scenario requiring imports of nuts to be transported under chilled conditions was shown to provide potential to further reduce the likelihood of entry.

Winter Cover Crops Reduce Spring Emergence and Egg Deposition of Overwintering Navel Orangeworm (Lepidoptera: Pyralidae) in Almonds.

Habitat diversification has been shown to positively influence a variety of ecosystem services to agriculture, including biological control of arthropod pests. The impact of increased biodiversity tends to be species specific though, and practices therefore need to be developed on a case-by-case basis for each cropping system. In perennial systems, numerous studies have demonstrated that cover crops can have positive impacts on soil quality and other ecosystem services, such as pollination and pest management. However, few studies have focused on the use of cover crops to enhance pest control in almond orchards, especially winter cover crops. The primary pest of almonds in North America is navel orangeworm, Amyelois transitella Walker, which overwinter as larva or pupa on remnant nuts, many of which remain on the orchard soil surface. In the spring, first flight adults subsequently use these remnant nuts as reproductive substrate. An experiment was conducted to evaluate the influence of two distinct winter cover crop mixtures on overwintering mortality and spring egg deposition of A. transitella. Remnant nuts placed into cover crop plots produced fewer adult A. transitella in the spring, suggesting increased overwintering mortality. Additionally, spring egg deposition was reduced on remnant nuts in the cover crops, possibly due to the ground covers interfering with host location and access. In this way, winter cover crops appear to contribute to the reduction of A. transitella populations in the orchard by altering abiotic and physical conditions, although studies to document specific mechanisms are still needed.

Evaluation of egg parasitoid Hadronotus pennsylvanicus as a prospective biocontrol agent of the leaffooted bug Leptoglossus zonatus

The western leaffooted bug, Leptoglossus zonatus (Dallas) (Heteroptera: Coreidae), is a key pest of almonds and pistachios in the USA. With limited monitoring strategies and no economic threshold developed, the use of broad-spectrum insecticides remains the primary control tactic for L. zonatus. In pursuit of more sustainable management options, experiments were carried out to assess the biocontrol potential of the egg parasitoid Hadronotus pennsylvanicus (Ashmead) (Hymenoptera: Scelionidae) against L. zonatus. Biological and demographical attributes of H. pennsylvanicus were evaluated under controlled laboratory conditions. Mated females lived on average 116 days. However, female longevity declined by 74% when provided with host eggs, and by 97% when deprived of a suitable diet. Females produced an average 39.70 offspring, with peak fecundity observed within the first week of their lifespan. The total progeny was on average 92.75% female. Non-reproductive host mortality accounted for > 52% of the total egg mortality observed within the first two weeks, and represented the majority of total host egg mortality thereafter. Age of host eggs did not influence parasitism rates. Under laboratory conditions, H. pennsylvanicus exhibits suitable demographic and reproductive traits as a candidate biocontrol agent of L. zonatus. Further research is needed to determine how to best manipulate and enhance H. pennsylvanicus populations to promote biocontrol of L. zonatus under field conditions.

Evaluating Flight Performance of Mass-Reared and Irradiated Navel Orangeworm (Lepidoptera: Pyralidae) for Sterile Insect Technique.

Navel orangeworm (Pyralidae: Amyelois transitella) is a key pest of almonds and pistachios in California. Moths directly infest nuts which leads to reduced crop yield and quality, and infestation can predispose nuts to fungal pathogens that produce aflatoxins. While several integrated pest management strategies have been developed for A. transitella, studies have recently been initiated to explore the use of sterile insect technique (SIT) as an additional control tool. Mass-rearing, sterilization, and transportation methods originally developed for Pectinophora gossypiella (Lepidoptera: Gelechiidae) are currently being used for production of A. transitella in a mass-rearing facility, but the impacts of these processes on performance of A. transitella remain unclear. In this study, computerized flight mills were used to evaluate multiple flight parameters of mass-reared and irradiated A. transitella males and females relative to non-irradiated mass-reared moths and two strains of locally reared moths which were neither mass-reared nor irradiated. Mass-reared non-irradiated females performed similarly to both strains of locally reared females, flying a mean 9.4-11.8 km per night, whereas mass-reared and irradiated males and mass-reared non-irradiated males all flew shorter distances, in the range of 3.0-6.7 km per night. All of the mass-reared moths compared to locally reared moths had significantly more non-fliers that did not engage in more than two minutes of continuous flight. Findings from this study suggest that mass-rearing conditions reduce A. transitella flight capacity, while irradiation interacts with moths in a sex-specific manner.

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

Simple SummaryMating disruption is an increasingly important part of pest management for the navel orangeworm Amyelois transitella. Industry groups have long supported mating disruption research and development with the divergent objectives of both minimizing damage from this key pest and reducing insecticide used on these crops. It is therefore important to know whether the benefits of mating disruption and insecticide are additive or, alternatively, if using both together provides no additional benefit over either alone. Ten years of data from research trials in a large commercial almond orchard found that the benefits of mating disruption are generally additive with lower damage if both are used together than either alone. Substantial year-to-year variability in navel orangeworm damage was also evident, even with stringent management. These findings indicate that the combination of mating disruption and insecticide can reduce the impact of navel orangeworm damage on the almond industry. Further improvements in monitoring and predictions of navel orangeworm abundance and damage are necessary for mating disruption to effectively contribute to the industry goal of reduction of insecticide use by 25%.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.

Almond pest in forest agrobiocenosis and measures against them

In this research, almond pets in forests and identified measures were studied. According to the results of the research, the main pests of the genus Lepidoptera in forestry were almonds (Erschoviella musculana Ersch.), Oriental fruit on the branches, unequal silkworm on the leaves (Lymantria dispar L.) and fragrant wood on the body). It was noted that walnut pest was the dominant among the observed pests. The results of the experiment on almond pests represented that 12 species of entomophagous almonds were recorded, including Braconidae, Trichogrammatidae, Ichneumonidae, Chalcidoidae, Pteromalidae, Encyrtidae, Tachinidae, Coccinellidae, Chrysopidae. Furthermore, representatives of the families of Miridae, including Microgaster nemorum Hrtg., Microdus rufipes Nees., Macrocentrus delicatus Cress., Ascogaster quadridentatus Trichogramma embryophagum Htg., Trichogramma evanescens Gir., Diadegma armillatus Grav., Pimpla inquisitor Scop., Liotrifon punctulatus were identified. Avaunt with 15% (0.5 l/ha) and Mospilan with 20% (0.4 kg/ha) were used against the main almond pests, and biological efficiency was achieved by 88.8% and 94.8%, correspondingly.

Evaluating Response of Mass-Reared and Irradiated Navel Orangeworm, Amyelois transitella (Lepidoptera: Pyralidae), to Crude Female Pheromone Extract.

Simple SummaryThe navel orangeworm is an important pest of almonds and pistachios in California. Sterile insect technique (SIT) is being explored as an additional component of management of this pest. Preliminary field releases of sterile navel orangeworm shipped from a facility in Phoenix, AZ resulted in poor recovery of males in pheromone traps, raising concerns about the mass-reared male moths’ quality. In this study, a wind tunnel was used to evaluate the response of irradiated and non-irradiated mass-reared navel orangeworm males to pheromone extract from females, and their performance was compared to two strains of locally reared non-irradiated navel orangeworm. Initial responses were similar for all moths tested. A lower proportion of mass-reared moths contacted the pheromone source. The underlying mechanism for this reduction remains unclear, but is likely related to damage incurred during the mass-rearing and shipping process. Our findings indicate navel orangeworm in the current program is generally competent to locate a sex pheromone source, but the rearing and transportation protocols may need refining.The navel orangeworm, Amyleois transitella (Lepidoptera: Pyralidae), is a key pest of almonds and pistachios in California. Larvae directly feed on nuts, reducing quality and yield, and adults can introduce fungi that produce aflatoxins. The development of sterile insect technique (SIT) is currently being explored as a management tool for this pest. Large quantities of A. transitella are mass-reared, irradiated, and shipped to California from a USDA APHIS facility in Phoenix, AZ. Preliminary field releases of sterile A. transitella from this facility resulted in poor recovery of males in pheromone traps, raising concerns that mass-reared male A. transitella may not be responding to pheromone from virgin females. In this study, a wind tunnel was used to evaluate the response of both irradiated and non-irradiated mass-reared A. transitella males to crude pheromone extract from females, and their performance was compared to two strains of locally reared non-irradiated A. transitella. While initial responses associated with pheromone detection where similar between mass-reared and locally reared moths, a lower proportion of the mass-reared moths ultimately made contact with the pheromone source. Surprisingly, the addition of irradiation did not further decrease their performance. While mass-reared moths respond to pheromone, their ability to locate and make contact with the pheromone source appears to be impeded. The underlying mechanism remains unclear, but is likely related to damage incurred during the mass-rearing and shipping process.

Evaluation of an unmanned aerial vehicle as a new method of pesticide application for almond crop protection

Unmanned Aerial Vehicles (UAVs), a new method of application to deliver pesticides, is rapidly being adopted for commercial use in crop protection in East Asia with increasing worldwide interest. Pest control in mature almond orchards with dense foliar canopies presents greater coverage challenges than field crops and smaller orchard or vineyard crops. We investigated the use of an electric hexacopter to provide acceptable spray deposition and canopy penetration to be considered credible for use in an almond pest control program. The performance of the aerial and ground methods at different spray volumes were compared by analyzing spray deposition on water sensitive papers, insecticide residues on filter papers and residues on whole unhulled almonds at three canopy elevations. Overall residue levels of chlorantraniliprole insecticide on whole unhulled almonds across all pooled canopy strata were similar between UAV applied at 46.8 L/ha and 93.5 L/ha and the comparative air blast sprayer treatments applied at 935 L/ha. However, significant interactions between canopy elevation and spray method showed distinct residue patterns between the two application methods. Penetration and spray deposition at the lower canopy were observed and validated for the UAV application. Pest efficacy was evaluated by measuring nut damage at harvest. This study presents promising data that support the potential innovative integration of UAV's into crop protection programs for large canopy crops such as almonds and may guide future research for developing relevant label recommendations.

Optimizing Trap Characteristics to Monitor the Leaffooted Bug Leptoglossus zonatus (Heteroptera: Coreidae) in Orchards.

The leaffooted bug, Leptoglossus zonatus (Heteroptera: Coreidae), has become a key pest of almonds, pistachios, and pomegranates in California. Adults and nymphs directly feed on nuts and fruits, which reduces crop yield and quality and can facilitate pathogen infections. Current monitoring strategies require growers to actively sample the tree canopy, with no economic thresholds being developed for this pest. To improve monitoring of L. zonatus, a three-year study was conducted to identify an optimal trap. A hanging cross-vane panel trap was identified as the best trap type in Year 1, and subsequent work in Years 1–3 focused on refining its use by modifying surface texture and color. Results indicated that coating trap surfaces with the lubricant fluon improved trap catching ability, and adults were most frequently recovered in yellow traps. A hanging cross-vane panel trap with these features could serve as the basis for the development of a new monitoring system for this pest in orchards, which could be improved further if semiochemical lures will be developed.

Biology and Management of Navel Orangeworm (Lepidoptera: Pyralidae) in California

AbstractNavel orangeworm, Amyelois transitella (Walker), is a primary pest of almonds, pistachios, and walnuts in California. These specialty tree nut crops are widely planted across the state and account for a significant share of total agricultural revenue, with 1.7 million combined acres generating a total farm-gate value of $8.9 billion. Larvae of A. transitella cause direct damage to the nut, burrowing into the kernel and contaminating it with frass and webbing, while adults are able to introduce fungi during oviposition that produce aflatoxin, a known human carcinogen that is heavily regulated both domestically and in key foreign markets. As such, there is little tolerance for A. transitella infestation, and most operations aim for <2% crop damage from this pest. Currently, integrated management of A. transitella involves a combination of orchard sanitation, well-timed insecticide sprays, timely harvest, and, most recently, mating disruption. Additional novel tools, such as sterile insect technique, are currently being explored. This species has a strong dispersal capacity, and given the extensive, and many times contiguous, acreage of tree nuts in California, long-term management will require the development of an effective area-wide management strategy. Tools, tactics, and conditions are in an ongoing state of change, and therefore pest management for this economically important species is a work in progress. Here, we discuss the biology, seasonal phenology, monitoring, and management of A. transitella across almonds, pistachios, and walnuts.

Evaluation of spray application methods for navel orangeworm control in almonds.

Gear Up/Throttle Down (GUTD) and Inward Only strategies represent potential alternatives to conventional airblast applications to reduce spray drift. This study evaluates Inward Only and a modified version of GUTD in almonds, the largest US tree crop, at the recommended hull split treatment timing for control of navel orangeworm (NOW), the key almond insect pest. Conventional treatment produced the most drift (15.6% of total bifenthrin load), while the GUTD and Inward Only treatments produced only 7.6 and 9.7% respectively. For all methods, 92-94% of the drift was found in the first 15.2 m downwind of the orchard. NOW control was lower for the Inward Only treatment compared with the GUTD and conventional treatments. NOW control was consistently lower at 4.88 m height relative to 2.44 m in all treatments, reflecting the reduced deposition higher in the tree canopy recorded in deposition samples. While Inward Only treatments reduced spray drift relative to the conventional application method, poorer control of NOW, the key insect pest of almonds, in the Inward Only treatment would likely limit its voluntary use by growers. However, GUTD holds promise for use at the hull split treatment timing to address spray drift. © 2016 Society of Chemical Industry.

Electrophysiological responses of male and female Amyelois transitella antennae to pistachio and almond host plant volatiles

AbstractThe polyphagous navel orangeworm, Amyelois transitella Walker (Lepidoptera: Pyralidae), is a major insect pest of almonds and pistachios in California (USA). Amyelois transitella moths have proven difficult to monitor and control for over 5 decades; however, recent reports indicate progress towards attractants using pheromone or semiochemical blends. Despite advances of a host plant volatile attractant blend that is effective for monitoring moth populations in almond orchards, the blend's attractancy and capture efficacy of A. transitella has not translated to pistachio orchards. The apparent orchard specificity of A. transitella to the blend suggests a different composition of host plant volatiles is needed to either improve the current blend or a new blend formulation is required for monitoring in pistachio orchards. One objective of this study was to evaluate available individual host volatiles via a standardised puff method in combination with electroantennographic analysis. In total 105 volatiles were evaluated individually for their ability to elicit an electrophysiological chemoreception response from excised male and female A. transitella antennae. Male antennae responded significantly higher to alcohols, aldehydes, alkyls, aromatics, and ketones. Female antennae responded significantly higher to benzenoids, monoterpenes, sesquiterpenes, and short‐chain alcohols.

Quasi-Double-Blind Screening of Semiochemicals for Reducing Navel Orangeworm Oviposition on Almonds

A three-step, quasi-double-bind approach was used as a proof-of-concept study to screen twenty compounds for their ability to reduce oviposition of gravid female navel orangeworm(NOW), Ameylois transitella (Lepidoptera: Pyralidae). First, the panel of compounds, whose identity was unknown to the experimenters, was tested by electroantennogram (EAG) using antennae of two-day old gravid females as the sensing element. Of the twenty compounds tested three showed significant EAG responses. These three EAG-active compounds and a negative control were then analyzed for their ability to reduce oviposition via small-cage, two-choice laboratory assays. Two of the three compounds significantly reduced oviposition under laboratory conditions. Lastly, these two compounds were deployed in a field setting in an organic almond orchard in Arbuckle, CA using black egg traps to monitor NOW oviposition. One of these two compounds significantly reduced oviposition on black egg traps under these field conditions. Compound 9 (later identified as isophorone) showed a significant reduction in oviposition in field assays and thus has a potential as a tool to control the navel orangeworm as a pest of almonds.

Effects of a Naturally Occurring and a Synthetic Synergist on Toxicity of Three Insecticides and a Phytochemical to Navel Orangeworm (Lepidoptera: Pyralidae)

The navel orangeworm, Amyelois transitella (Walker) (Lepidoptera: Pyralidae), is the most destructive lepidopteran pest of almonds [Prunus dulcis (Mill.) D.A.Webb] and pistachios (Pistacia vera L.) in California and is a serious problem in figs (Ficus carica L.) and walnuts (Juglans spp.). In addition to direct damage, larval feeding leaves nuts vulnerable to infection by Aspergillus spp., fungi that produce toxic aflatoxins. A potentially safe and sustainable approach for managing navel orangeworm in orchards may be to use natural essential oil synergists to interfere with this insect's ability to detoxify insecticides and phytochemicals. We tested the effects of a naturally occurring plant-derived chemical, myristicin, and a synthetic inhibitor of cytochrome P450 monooxygenases (P450s), piperonyl butoxide, on the toxicity of three insecticides (alpha-cypermethrin, tau-fluvalinate, and methoxyfenozide [Intrepid]) and a phytochemical (xanthotoxin) to A. transitella. Piperonyl butoxide significantly synergized alpha-cypermethrin and tau-fluvalinate, whereas myristicin synergized only alpha-cypermethrin. Piperonyl butoxide synergized the toxicity of xanthotoxin as early as 72 h after exposure, whereas myristicin synergized xanthotoxin after 120 h. In view of these findings and the limited availability of environmentally safe synthetic insecticides for sustainable management, particularly in organic orchards, myristicin is a potential field treatment in combination with insecticides to reduce both navel orangeworm survival and aflatoxin contamination of nuts. In addition, this study demonstrates that in A. transitella the insect growth regulator methoxyfenozide is not detoxified by P450s.

Comparison of Trapping for Eggs, Females, and Males of the Naval Orangeworm (Lepidoptera: Pyralidae) in Almonds

The navel orangeworm is the primary insect pest of almonds in California, and egg traps are the primary means of monitoring this pest. A previous study found that the current use of 2-4 traps per 64 ha block usually is not sufficient to provide management information specifically for that block. In this study, we compare data from large grids of egg traps in varied commercial almond orchards with trapping data for females and males, with the objective of finding a more cost-effective monitoring program using currently available attractants. The proportion of egg traps with eggs was highly correlated with mean eggs per egg trap, and with females and males trapped simultaneously at the same location. Almond variety and the type of bait used had little impact on the relationship between the proportion of egg traps with eggs and the number of eggs per traps. Traps in orchards with more unharvested (mummy) almonds had more eggs, suggesting that navel orangeworm abundance affected traps more than competition from mummies. Laboratory experiments comparing age-specific oviposition in two-choice and no-choice situations found that younger, more fecund females laid a greater proportion of eggs on the preferred substrate in a two-choice situation, but that age-specific fecundity was not different between substrates in no-choice tests. These findings indicate that the proportion of egg traps with eggs provides a more stable indication of navel orangeworm phenology than mean eggs per trap. We suggest that similar information could be obtained in a more cost-effective manner with female trapping.

Ambient orchard volatiles from California almonds

The volatile emissions of various plant parts of almonds have been studied via various techniques in the past. These analyses have typically been performed on single cultivars and hence may not be representative of the volatiles found in an entire almond orchard. Recent reports suggest some almond volatiles exhibit semiochemical activities for the navel orangeworm (NOW), a major insect pest of almonds; thus, the volatile composition of the comprehensive almond orchard would be helpful to research concerning NOW. The ambient volatile emissions of an almond orchard containing the cultivar Nonpareil and associated pollenizers were collected at four intervals during the 2009 growing season from orchards in the south Central Valley of California. The volatiles hexanal, octanal, nonanal, benzaldehyde, acetophenone, ethyl benzoate, methyl salicylate, and phenol were consistent in their presence and in relatively high amounts. The orchard volatile composition was analyzed via electroantennogram (EAG) analysis, which produced strong responses from NOW antennae.