Journal of economic entomology最新文献

Aphis gossypii Glover (Hemiptera: Aphididae) is a significant agricultural pest, and the growing issue of pesticide resistance, in this species, has underscored the urgent need to identify alternative, sustainable insecticides. Allium sativum Linnaeus (Asparagales: Amaryllidaceae) is renowned for its broad-spectrum biological activities, including antibacterial and detoxifying properties. Consequently, it has gained considerable attention in the field of plant protection. This study investigates the repellent effects of allicin on A. gossypii and its impact on the pest's growth and development under fumigation conditions, leveraging the volatile nature of allicin. The findings revealed that fumigation with allicin, diluted 50-fold, exhibited the most pronounced repellent effect on A. gossypii. The repellency rates reached 88% and 86% after 12 and 24 hours of treatment, respectively, while the mortality rates were 46% and 66% for the exact durations. Additionally, allicin significantly influenced the behavioral choices, growth and development, reproductive capacity, and population establishment of A. gossypii. The efficacy of allicin against A. gossypii demonstrated a concentration-dependent effect, with its fumigation activity diminishing as the concentration decreased. These results provide a scientific foundation for the application of allicin in controlling A. gossypii, offer valuable insights for further field trials, and establish a groundwork for utilizing allicin as a fumigant to manage and prevent aphid infestations in agricultural settings.

The diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae), is a major pest affecting Brassica crops worldwide. In North America, P. xylostella outbreaks have caused substantial economic losses in canola (Brassica napus L. and Brassica rapa L.) and brassicaceous vegetable (Brassica oleracea L.) crops. Natural enemies, including the parasitoid Diadegma insulare (Hymenoptera: Ichneumonidae), play a key role in controlling P. xylostella populations. To better understand the distribution and impact of Diadegma spp., we adopted Diadegma-specific primers, developed originally for haplotyping, and used a molecular screening approach to detect parasitism of P. xylostella larvae collected across Canada and the United States. The primer set was first tested on D. insulare adults and laboratory parasitized P. xylostella to confirm amplification and specificity and determine sensitivity. Screening was then conducted on 421 field-collected larvae from 45 localities to detect and estimate parasitism rates and assess geographic variability. The results revealed notable variation across collection sites in parasitism of P. xylostella larvae by Diadegma spp., with more parasitized larvae collected from field sites in Canada than from field sites in the United States. Variation in parasitism across collection sites could be the result of differences in climate, agricultural practices, and insecticide use between agricultural systems. This research demonstrates the utility of molecular screening to detect parasitism of P. xylostella larvae and highlights potential differences in the impact of Diadegma spp. on the population dynamics of P. xylostella in Canada and the United States.

Avocado lace bug, Pseudacysta perseae (Heidemann) (Hemiptera: Tingidae), is a sap-feeding insect that feeds on avocado leaves. Injury from P. perseae is indicated by areas of leaf chlorosis/necrosis. Large areas of injury can lead to premature leaf drop, and severe infestations can lead to large proportions of leaves dropping, adversely affecting fruit development and quality. Since its establishment in Hawai'i, P. perseae has become a ubiquitous pest across the islands and is correlated with yield decline. Due to the challenging topography of Hawai'i, lack of biocontrol agents, and mixed fruit tree orchards, effective management strategies are limited to pesticide use. Even so, routine foliar sprays of pesticides are not economically or logistically feasible for controlling P. perseae in Hawai'i. While synthetic systemic pesticides can be used as soil drenches, many show toxicity to nontarget animals and have limited application frequencies. However, research shows azadirachtin, an active component in the organic pesticide neem oil, has some systemic properties. This study investigated soil drenches of varying concentrations of azadirachtin in avocado seedlings on P. perseae nymphal mortality over eight weeks. Results showed mortality had an 85% to 98% probability of occurrence in the first week following drenching for nymphs feeding on azadirachtin-treated trees compared to 14% for untreated trees. Mortality for treated trees decreased through time but remained significantly higher than untreated trees 3 to 6 weeks following drenching. The findings from this study will aid in developing a more practical and economically reasonable management strategy for P. perseae in Hawai'i.

The weevil Aegorhinus nodipennis (Coleoptera: Curculionidae) (Hope, 1834) is a polyphagous woodboring beetle of economic concern in Chile and southern Argentina, mainly affecting berries and hazelnut. Although insecticides may be applied in hazelnut orchards, their effectiveness is limited and can be environmentally impactful, underscoring the need for alternative, sustainable control strategies. Attempts to exploit semiochemicals for attraction or repellence have yielded only modest results, failing to support effective trapping or deterrence. This study investigates substrate-borne vibrations as a complementary behavioral management tool by examining their potential to induce defensive responses in A. nodipennis. We demonstrate that walking individuals exhibit a stereotyped freezing response to vibrational stimuli, with peak sensitivity at 50 to 150 Hz (median threshold at 0.71 m/s2) and a secondary sensitivity increase at 1-2 kHz. The duration of the immobile phase increases strongly with stimulus duration, with a median around 200 s following a 5 s stimulus, but is much less affected by amplitude once the threshold is exceeded. In addition, weevils exhibit a marked postfreeze locomotor suppression, with walking speed reduced to 25% to 30% of prestimulus levels. These findings suggest that extended low-amplitude vibrational stimuli could effectively suppress activity and feeding. This offers a novel, nonchemical, and potentially economically viable approach in managing this pest. Deterrent vibrations could be deployed directly on host plants or on structural barriers in orchards. This study provides a foundation for integrating vibrational cues into pest management frameworks for A. nodipennis and related weevils, though results are currently limited to females.

Short-stature corn is approximately 60 cm shorter than conventional corn at maturity and is expected to soon be commercially available in the United States. One advantage of short-stature corn is lodging resistance, which should help facilitate its adoption by producers. However, knowledge gaps exist concerning how insect pests interact with short-stature corn. Western corn rootworm, Diabrotica virgifera virgifera LeConte, and European corn borer, Ostrinia nubilalis Hübner, are important pests of corn in the United States. To manage these pests, transgenic corn producing insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt) is commonly planted. Blended refuges, where non-Bt and Bt plants are interspersed within a field, are a method of insect resistance management for Bt corn. However, past research has found that larval movement between Bt and non-Bt plants can reduce the effectiveness of non-Bt refuges in delaying Bt resistance. The primary goal of this work was to understand whether the effectiveness of a non-Bt blended refuge to delay resistance would be similar between tall corn and short-stature corn. We conducted a field study to evaluate larval survival and movement patterns between Bt and non-Bt corn. The experimental design simulated a blended refuge in order to understand whether patterns of pest movement and survival were similar between tall- and short-stature corn. We found larval movement and survival for both pests on short-stature corn largely resembled the effects on tall corn, and therefore, current resistance management strategies should be applicable for short-stature corn.

Drosophila suzukii (Matsumura), spotted-wing drosophila, is an invasive pest native to East Asia that causes significant economic losses in soft-skinned high-value fruit like blueberries. Current management strategies heavily rely on insecticide applications, raising concerns about resistance and sustainability. This study evaluated the efficacy of plant-derived volatile blends, including Decoy Attract and Kill (A&K) (Batch no. 24026021), Combi-protec (Batch no. SP2211XXUS), Decoy (Batch no. 42022121, 10% citric acid), and fermentation-based volatiles of Scentry experimental blend (SEB) (Batch no. SBI2024200-005), and Droski drink (acetic acid) as potential behavioral disruptors that reduce D. suzukii oviposition without insecticide use. These five volatile blends, except Decoy and Droski drink have undisclosed active ingredients. Three concentrations of Decoy A&K (0.5, 2, and 5 mM) and four other blends were tested using Drosophila activity monitor (DAM), electroantennography (EAG), laboratory behavioral trials, and exclusion cage semi-field oviposition trials. DAM quantified positional preference and dwell time to blends, while EAG measured antennal responses to Decoy A&K. Laboratory behavioral trials assessed oviposition and dwelling behaviors, while exclusion caged semifield trials evaluated oviposition behavior alone. Decoy A&K, Combi-protec, and Decoy significantly increased dwell time and reduced oviposition on blueberries, both in controlled and semi-field conditions. EAG responses showed that D. suzukii can detect Decoy A&K volatiles through olfaction, likely mediating the observed behavioral results. These findings highlight the potential of selected volatile blends as tools for behavioral disruption, supporting their application in integrated pest management strategies, including push-pull or attract-and-kill systems for D. suzukii.

Semifield trials were conducted to evaluate the efficiency of inoculative releases of the larval endoparasitoid Pseudapanteles dignus (Muesebeck), to control the South American tomato pinworm Phthorimaea (=Tuta) absoluta (Meyrick). The trials took place in experimental tomato greenhouses located in a major horticultural region of Argentina during 2018 and 2024. In 2018, three treatments were established: (i) Biocontrol 1, one mated adult female P. dignus + two P. absoluta larvae per plant; (ii) positive control, two P. absoluta larvae per plant, and (iii) negative control, uninfected plants. In 2024, the biocontrol treatment consisted of two releases of P. dignus, called Biocontrol 2, in which the initial release was carried out under the same conditions as in 2018, that is, Biocontrol 1, and the second release was carried out 30 d later, and consisted of one female P. dignus per plant. Each treatment was replicated three times. Weekly monitoring (March to April, 10 wk) was performed to record densities of P. absoluta and P. dignus (immature stages and adults) on five randomly selected plants per replicate. Besides, crop yield (number and weight of healthy fruits) and the cosmetic damage of fruits were assessed. Biocontrol 1 reduced larval and adult P. absoluta densities; in 2024, greater reductions were observed under Biocontrol 2. Although yield did not show differences across the whole experiment, cosmetic fruit damage was significantly reduced in both biocontrol treatments. These results support the potential of P. dignus as a biological control agent against P. absoluta in protected tomato production systems.

The cigarette beetle, Lasioderma serricorne (Fabricious) (Coleoptera: Anobiidae), is a serious insect pest species in tobacco storage. In this paper, we initially tested the behavioral responses of cigarette beetle adults to 32 plant essential oils in a dual-choice bioassay. Then we selected twelve essential oils showing significant behavioral activity on the cigarette beetle adults and validated their activity on a second bioassay apparatus using a locomotion compensator. Among the essential oils tested, 8 exhibited a significant attractive effect (Litsea cubeba; Nardostachys jatamansi; Cymbopogon citratus; Capsicum annuum; Morus alba; Citrus limon; Matricaria chamomilla; Coffea arabica), while 4 essential oils exhibited significant repellent effect (Syringa oblate; Perillae folium; Carthamus tinctorius; Valeriana officinalis). The result of locomotion compensator bioassay was fully consistent with those of the dual-choice bioassay. Principle component analysis of the walking parameters recorded by locomotion compensator shows that the 7 parameters could be integrated as "activity factor" and "attractivity factor."

Bed bugs (Cimex lectularius L.) are blood feeders whose survival is significantly influenced by environmental factors such as temperature and relative humidity (RH). Despite their adaptations to survive in harsh environments such as a low net transpiration rate and high critical thermal maximum, their physiological limits to heat and humidity remain underexplored. This study aims to determine the lethal temperature and RH combinations for bed bugs to improve non-chemical pest management strategies. Adult male bed bugs were exposed to 5 temperatures (25, 37, 38, 39, and 40 °C) and 3 RH levels (10%, 45%, and 90%) in controlled incubators for 14 d. Median survival times (MSTs) and hazard ratios were determined using Kaplan-Meier survival analysis. The results revealed that at 37 °C, bed bugs exhibited relatively higher survival (MST > 14 d), particularly at 45% and 90% RH suggesting that physiological mechanisms may mitigate heat stress. However, survival declined to 12 d at 37 °C with 10% RH, and this reduction at low RH was amplified at higher temperatures, where MST fell to 4-6 d at 39 °C and only 3 d at 40 °C. These results demonstrate that dry environments exacerbate thermal stress. At 40 °C, mortality was highest across all RH levels, with the shortest survival time (1 d) observed at 90% RH, which indicates that heat in combination with high humidity is most effective at inducing heat-related mortality in C. lectularius. These findings highlight bed bugs' vulnerability to environmental stressors outside their temperate origins.

"Candidatus" Liberibacter spp. infect crop plants and the psyllid vector, and at least 2 species have been shown to be susceptible to RNAi. Here, the knockdown efficacy was analyzed of 4 genes essential for insect physiological processes, vacuolar ATPase (V-ATPase) subunit genes A, B, D, and E, for potential biopesticide activity against the potato psyllid, Bactericera cockerelli Šulc (Hemiptera: Triozidae). Adults and third instar psyllids were given a 48-h ingestion-access period (IAP) on either single or stacked dsRNAs to compare knockdown effects. While adults showed no significant mortality, 10-d post IAP on the individual dsRNAs, mortality was significantly greater post-IAP on the stacked dsRNAs compared to negative controls. Oviposition of dsRNA-treated females was reduced by 50% to 70%, however, there was no significant difference between the single and stacked dsRNA treatments. Adult and third instar psyllids exhibited 58% and 45% mortality, respectively, post-IAP on the 4 stacked dsRNAs. In contrast, only third instar nymphs showed significant mortality after individual dsRNAs targeting V-ATPase subunits, at 42% for subunit A and 35% for subunits D and E. In general, gene silencing was more robust in potato psyllid nymphs compared to the adults. Although gene knockdown was moderately lower following an IAP on dsRNAs delivered singly, IAP on stacked dsRNAs resulted in equal or greater mortality in both psyllid life stages. These findings highlight the potential for delivering multiple dsRNAs to suppress genes involved in essential cellular processes and enhance RNAi efficacy in insects.