Journal of economic entomology最新文献

Management of sugarcane stem borers (Diatraea spp.) in Colombia's Cauca River Valley (CRV) relies mainly on biological control. Augmentative releases of biocontrol agents are guided by damage assessments (percentage of internodes bored) at harvest and then scheduled accordingly for the next crop cycle. A more proactive monitoring method conducted during the current crop cycle could improve correspondence between natural enemy releases and actual pest pressure. Between 2013 and 2015, 644 commercial fields were sampled for larvae using a standardized 2 person-hour effort per field less than 3 mo post-emergence. Injury data (% of internodes bored) were also collected at harvest from 535 of these fields between 2014 and 2015, 348 before, and 187 after, larval sampling. The relationship between early larval counts and at-harvest damage was analyzed using geostatistical tools and Median tests. Larval counts ranged from 0 to 48 per unit of sampling effort, whereas damage ranged from 0% to 22% of internodes. The highest larval counts and injury levels occurred in northern and central CRV. Larval counts at 3 mo post-emergence were correlated with at-harvest damage in the previous crop: fields with 4% of internodes bored at harvest had a high probability of exceeding ≥30 larvae per sample in the subsequent crop. These results suggest that early season counts of ≥30 larvae per 2 person-hour sampling effort might represent a useful threshold for initiation of biocontrol augmentation programs.

Spruce beetle, Dendroctonus rufipennis (Kirby) (Coleoptera: Curculionidae), is the most significant pest of spruce, Picea spp. (Pinales: Pinaceae), in western North America. Several doses of 3-methylcyclohex-2-en-1-one (MCH), the primary antiaggregation pheromone of D. rufipennis, alone and combined with non-host volatiles have been demonstrated effective for Picea protection. Herein, we evaluate the effects of MCH dose on D. rufipennis captures in baited trapping assays in Alaska and Colorado, United States. Twenty-five, 12-unit, multiple-funnel traps were baited with a D. rufipennis lure (frontalin + MCOL + spruce terpenes; Synergy Semiochemical Corp., Delta, British Columbia, Canada) and randomly assigned to one of 5 treatments in each assay: SBL (baited control); SBL + 1 g MCH; SBL + 3.5 g MCH; SBL + 7 g MCH; and SBL + 10 g MCH. SPLAT MCH (experimental formulation ISR: MCH-001R1, ISCA Inc., Riverside, California, United States), a flowable matrix containing 10.0% MCH by weight, was used in both assays with dose manipulated by the number and size of SPLAT MCH dollops (release points) attached to traps. In both Alaska and Colorado, all MCH doses (1, 3.5, 7, and 10 g) significantly reduced D. rufipennis captures compared to SBL. No significant differences were observed among MCH doses. Males and females responded similarly to MCH doses. The implications of these and other results to management of D. rufipennis are discussed.

Frankliniella occidentalis (Western flower thrips; WFT) is an important pest of vegetable and flower crops. The development and application of plant-induced resistance and RNA interference (RNAi) technology are environmentally sustainable and promising approaches in pest control research. This study verified the regulatory role of digestive enzyme genes in the adaptation of WFT to jasmonic acid (JA)-induced defense responses in Phaseolus vulgaris (kidney bean) plants. First, 4 digestive enzyme-encoding genes were cloned and identified. Subsequently, their expression patterns during different developmental stages were analyzed. Second, the mRNA levels of these genes were analyzed in the F0 and F1 generation female adult WFT that fed on leaves from JA-induced bean plants. The results showed that the expression of FoαAmy1 (α-amylase gene) and FoEG1 (endoglucanase gene) was significantly upregulated during the adaptation of WFT to the JA-induced defense response in kidney bean plants. RNAi and bioassay results indicated that silencing FoαAmy1 and FoEG1 significantly reduced the survival rate and feeding damage caused by adult WFT that fed on JA-induced kidney bean plants. Overall, FoαAmy1 and FoEG1 may be involved in regulating the adaptability of WFT to JA-induced defense responses in kidney bean plants.

The novel meta-diamide insecticide cyproflanilide is highly effective on the rice stem borer, Chilo suppressalis (Lepidoptera: Pyralidae). Nevertheless, the sublethal effects on key natural enemies, such as Cotesia chilonis (Hymenoptera: Braconidae), remain unexplored, which is critical for ecological compatibility within IPM programs. We investigated the direct and indirect effects of sublethal doses of cyproflanilide on C. chilonis. Our results revealed that the LC50 of cyproflanilide on female and male wasps of C. chilonis were 1.17 mg/L and 0.37 mg/L, respectively. After treatment of C. suppressalis with cyproflanilide, they were then parasitized by C. chilonis. Compared with control groups, the cyproflanilide treatment showed no significant differences in the number of cocoons, total number of emerged wasps (including males and females), or the parasitism rate of C. chilonis. In contrast, when C. chilonis was exposed to cyproflanilide at LC30 concentration, no significant alteration in developmental duration was observed compared to the control group. The number of cocoons by C. chilonis decreased from 47 to 34. Similarly, the number of emerged wasps decreased from 47 to 31, and the parasitism rate decreased by 9%. Our results show that the indirect effects of cyproflanilide on C. chilonis were not significant; direct contact with the insecticide poses significant risks to the C. chilonis reproductive output. Thus, it can be seen that when applying pesticides in the field, it is necessary to stagger the emergence peaks of C. chilonis and C. suppressalis, which is important for the prevention and control effect.

Tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), is one of the most consistent pests of cotton in the southeastern United States. Tarnished plant bug primarily feeds on reproductive structures, including pre-floral buds (squares), flowers, and small bolls, but can also feed on apical meristem tissue during pre-floral stages. Damage to cotton terminals can lead to loss of apical dominance and irregular cotton growth, potentially reducing lint yield. In 2022 and 2023, trials were conducted in 5 southeastern United States states (ie Virginia, North and South Carolina, Georgia, and Alabama) to determine the impact of simulated terminal injury at the 7-node stage and the fourth week of squaring on cotton growth and lint yield. Terminal injury at the fourth week of squaring led to a reduction in plant height or plant canopy width at the end of the season in several trials. Despite changes in plant architecture occurring in some trials, cotton lint yield was rarely affected by early terminal removal, except for the latest planted trial across the 2 study years. This provides limited evidence which further emphasizes the importance of timely planting for cotton in the southeastern region. The current study demonstrates the limited impact that terminal injury has on cotton lint yield and will help shape management recommendations for pre-floral cotton in the southeastern cotton production region.

The floriculture and nursery industry is a key contributor to Hawaii's economy, with ornamental crop exports, particularly cut flowers, accounting for a significant portion of sales. However, pest-related shipment rejections have increasingly threatened market access. As a first step to develop an effective systems approach for maintaining market access, we analyzed California interception records from 2012 to 2016, which revealed 582 cut flower shipment interceptions from 92 Hawaiian growers and shippers, with rejections primarily due to ants, aphids, mealybugs, and scale insects for non-orchid cut flowers (eg ginger and heliconia) and thrips for cut orchid flowers (eg Dendrobium). For targeted trials of ginger and heliconia, the effect of sequential pre-harvest (systemic insecticide spraying and ant baiting) and postharvest treatments (washing, hot water treatment, and second washing) were evaluated under commercial conditions. While individual treatments alone did not achieve complete disinfestation of ginger and heliconia, combining them as a systems approach led to zero detectable infestation across 8 harvests during the second year of the study, indicating this may be a feasible phytosanitary strategy for Hawaii-grown cut flowers. In contrast, for Dendrobium orchids with limited postharvest treatment options, pre-harvest insecticide programs were ineffective for managing thrips, with 30% of Dendrobium flowers and 70% of the flower sprays remaining infested post-insecticide treatment, highlighting the need for improved thrips management and the potential for integrating with postharvest fumigation. Overall, our results demonstrate the potential of systems approach in reducing pest interceptions and supporting continued access of Hawaii-grown cut flowers to US mainland and international markets.

For an insect transmitted pathogen to spread, an insect must feed on an infected plant to acquire the pathogen and subsequently disperse and feed on a healthy plant. Because juvenile insects are wingless and adults are typically winged, adult insects are assumed to disperse greater distances and, therefore, have a greater contribution to pathogen spread. The glassy-winged sharpshooter (Homalodisca vitripennis) transmits Xylella fastidiosa, a bacterial plant pathogen that causes several plant diseases including Pierce's disease of grapevines. For many insects, oviposition preference is directly related to offspring performance on that host. However, studies have documented that glassy-winged sharpshooter ovipositional preference is not linked to offspring performance. One hypothesis for the lack of an association between oviposition preference and offspring performance by the glassy-winged sharpshooter is that nymphs disperse from oviposition sites shortly after egg hatch. Because glassy-winged sharpshooter nymphs are capable of transmitting X. fastidiosa, routine nymphal dispersal could contribute to secondary (plant-to-plant) pathogen spread. Dispersal of glassy-winged sharpshooter nymphs from oviposition sites on preferred and unpreferred hosts was quantified vertically and horizontally. In vertical movement tests, majority of nymphs moved upward into the grapevine canopy shortly after egg hatch, with faster dispersal away from less preferred plants. In horizontal movement tests, hourly dispersal rates were greater on the less preferred host than on the preferred host, with nymphs dispersing from unpreferred plants and congregating on preferred plants. Results indicate that glassy-winged sharpshooter nymphs routinely disperse from oviposition sites shortly after egg hatch in search of higher quality hosts. Such routine nymphal dispersal may contribute to secondary (plant-to-plant) pathogen spread in managed and natural systems.

Deploying semiochemicals in pest management is challenging for pollinator-dependent crops because floral-based attractants can divert bees and other pollinators. Cucurbit crops, for example, are highly dependent on pollination and their primary pests, Acalymma vittatum (F.) (striped cucumber beetle, StCB) and Acalymma trivitatum (Mannerheim) (western striped cucumber beetle, WStCB), are strongly attracted to the scent of cucurbit blossoms. To identify a more pollinator-friendly semiochemical lure for StCBs, we conducted a 2-year field experiment across 4 US states (IN, MD, VA, CA) that evaluated pest responses to: (i) a cucurbit floral mimic (TIC), (ii) indole, a single component of TIC; and (iii) vittatalactone, an aggregation pheromone of StCB. These compounds were tested both individually and in combination to test for non-additivity. We also assessed responses from 2 other co-occurring pests-Diabrotica undecimpunctata howardi Barber (spotted cucumber beetle, SpCB), Diabrotica virgifera virgifera LeConte (western cornrootworm, WCR)-and pollinators (Apis mellifera L., honey bees; Eucera and Lasioglossum). We found that vittatalactone, but not TIC, was a strong and consistent attractant of Acalymma species (StCB, WStCB), whereas the reverse pattern was observed for Diabrotica species (SpCB, WCR). As expected, TIC-but not indole or vittatalactone-attracted pollinators. Pest trap catch was almost always highest when vittatalactone was combined with either indole or TIC, and this increase was synergistic in 33% of cases. These data suggest that combining indole with vittatalactone creates a potent pest attractant that does not attract bees, making it a pollinator-friendly lure.

Interactions between coexisting species can profoundly influence reproductive dynamics, particularly in systems involving heterospecific mating. Previously, we reported that Cheilomenes sexmaculata Fabricius affects the reproductive traits of Propylea dissecta Mulsant. Additionally, a prior study showed that heterospecific males of various ages exhibit varying behavior toward P. dissecta. In continuation of this line of research, we investigated how the mating status of C. sexmaculata males (unmated, once mated, or multiply mated [five times]) affects the reproductive outcomes in P. dissecta, a species commonly used in biological control. Earlier observations of heterospecific mating between C. sexmaculata males and P. dissecta females suggest that such interactions may influence reproductive success in conspecific pairings. Our finding indicate that multiply mated males exhibit increased mating disruption during conspecific interactions but show reduced responsiveness post mating. Conversely, unmated and once mated C. sexmaculata males exert greater reproductive interference, leading to increased heterospecific mating. This interference significantly impacted P. dissecta females, reducing fecundity, and egg viability, likely due to behavioral disruption and the consequences of heterospecific matings. These findings show that such interactions may drive selection for traits that minimize these costs. The interplay between conspecific and heterospecific interactions highlights a complex selective environment shaping reproductive strategies in coexisting species. As both species serve as important biocontrol agents, understanding these interactions is crucial for selecting compatible predator combinations and enhancing the efficiency of integrated pest management programs.

With global climate change, the intensity and frequency of thermal extreme events are increasing. It is crucial to study the effects of environmental fluctuations and stressful temperatures on insects, which are small ectotherms. However, the impact of the temporal proportion of extreme heat exposure within diel cycles on insects remains poorly understood. To define the effect of different temporal proportions of a permissively stressful temperature 34 °C, and an optimal temperature 24 °C, on the performance of Plutella xylostella L. (Lepidoptera: Plutellidae) in diel cycles, we used the 2 temperature phases to study the effect of heat phase duration (0 h, 6 h, 12 h, 18 h, 24 h) on P. xylostella. The results showed that the developmental durations of individual life cycles were significantly shorter with longer heat phases. The life span of the adult was significantly shorter, and pupa weight was significantly reduced with increasing duration of the heat phase. Eggs of all female adults were unable to hatch in the 18 h heat treatment. This study provides critical insights into the temporally scaled impacts of extreme heat on insects under rapid climate change.