Environmental Entomology最新文献

Bactericera maculipennis (Crawford) and Bactericera cockerelli (Šulc) (Hemiptera: Triozidae) share hosts within the Solanaceae and Convolvulaceae (Solanales), and both are associated with "Candidatus Liberibacter solanacearum" (Lso). Lso, transmitted by B. cockerelli, causes diseases in solanaceous crops including zebra chip disease of potato. Up to 50% of B. maculipennis adults also harbor Lso, but transmission of Lso to plants by this psyllid has not been confirmed yet. The only documented field host of B. maculipennis in the Pacific Northwest is Convolvulus arvensis L. (Convolvulaceae) but diagnostic methods fail to detect Lso in leaves of this plant. It is therefore unclear how Lso persists within B. maculipennis populations. We surveyed species of Convolvulaceae and Solanaceae for B. maculipennis and report a widespread association between B. maculipennis and Lso throughout the western United States. Diagnostic polymerase chain reaction failed to detect Lso from leaves of C. arvensis yet readily detected Lso from stems where B. maculipennis nymphs tend to feed. Bactericera maculipennis transmitted Lso to species of Convolvulaceae in greenhouse experiments, confirming vector competency. We report high rates of Lso infection in populations of both B. maculipennis and B. cockerelli occurring on C. arvensis, but occurrence of B. cockerelli on C. arvensis was limited to autumn months only and with very low populations. Results suggest C. arvensis is a non-crop reservoir of Lso but do not suggest that B. maculipennis is a direct threat to solanaceous crops or that C. arvensis is a major source of Lso-infected B. cockerelli colonizing potato fields.

Elongate hemlock scale, Fiorinia externa Ferris (Hemiptera: Diaspididae), is an invasive pest of eastern hemlock, Tsuga canadensis, and other Pinaceae such as Fraser fir, Abies fraseri. Cut Fraser firs (ie for Christmas trees and other holiday greenery) with F. externa have been intercepted in US states beyond where the insect is known to be established and, in some cases, where exposure to freezing temperatures might be prolonged. This study measures the effect of constant low temperatures (3, -10, or -20 °C) on survival of overwintering F. externa females from eastern hemlock in Michigan and from eastern hemlock and Fraser fir in North Carolina. Survival was determined with biochemical viability testing, which assesses the presence of metabolically active cells, and changes in survivorship through time were quantified with Kaplan-Meier methods and beta regression. Collection date and host occasionally affected survival rate but not in a consistent pattern. Survival rates generally decreased as temperature decreased. At 3 °C, F. externa maintained high survival (>75%). At -10 °C, survival was projected to fall to 50% within 22 to 92 d and 10% by 45 to 195 d. At -20 °C, survival typically declined to 50% by 1 to 27 d and 10% by 6 to 52 d. We used survival durations at -20 °C to map how often F. externa might experience 50 or 90% mortality from prolonged cold exposure. Temperatures in recent winters have not been below -20 °C for long enough to stop F. externa from spreading throughout the ranges of eastern hemlock or other hosts in Canada and the continental United States.

When sap-feeding insects invade ecosystems, they create novel resource subsidies by exposing previously unavailable resources to resident consumers. Spotted lanternfly, Lycorma delicatula (White), is an invasive phloem-feeding planthopper native to Asia that has spread across multiple US states since its 2014 detection in Pennsylvania. It heavily feeds on tree-of-heaven, Ailanthus altissima (Mill.) Swingle, an invasive tree naturalized across the United States that previously lacked sap-feeders. During feeding, L. delicatula excretes honeydew and creates sap-exuding wounds, providing carbohydrate resources. Here, we document invertebrates consuming these subsidies in southeastern Pennsylvania from June to October 2021. At 43 sites sampled 3 times, we measured L. delicatula biomass via circle trunk traps and recorded 1,576 feeding observations through visual surveys. These observations were made up predominantly of Hymenoptera (78.0%) and Diptera (19.5%), with smaller proportions of Coleoptera (0.76%), Lepidoptera (0.44%), Hemiptera (0.44%), Orthoptera (0.38%), Opiliones (0.38%), and Stylommatophora (0.06%). Among Hymenoptera, we identified 33 species (29 native, 4 introduced) from 13 families, including key pollinators and parasitoids. The invasive wasp, Vespa crabro, was abundant and exhibited aggressive behaviors toward native consumers, including pollinators. Using redundancy analysis, we tested whether spatiotemporal variation in L. delicatula biomass explained the composition of honeydew-feeding Hymenoptera compared to other environmental factors. Lycorma delicatula biomass was the strongest predictor of Hymenoptera community composition, with temperature, landscape-scale impervious surface, and site-scale vegetation structure also contributing. The L. delicatula invasion has created novel resource subsidies for many invertebrates and altered temporal dynamics of Hymenoptera, with potential cascading effects on pollination and biocontrol ecosystem services.

The planthopper Lycorma delicatula (White) (spotted lanternfly; SLF) was introduced to North America from Asia. It was first found in southeastern Pennsylvania in 2014 and now, a decade later, has increased in abundance and spread into 18 eastern US states. To study naturally occurring fungal pathogens infecting SLF, eastern Pennsylvania sites were sampled every 1 to 2 wk in 2020 and 2021 during the adult life stage of L. delicatula to detect prevalence of infections by the fungi Batkoa major (Thaxt.) Humber (Entomophthorales: Batkoaceae) and Beauveria bassiana (Bals.-Criv.) Vuill. (Hypocreales: Cordycipitaceae). To sample, living adult SLF were collected and reared and cause of death was diagnosed. In 2020, at the site hosting a co-epizootic of these 2 generalist pathogens in 2018, an epizootic caused by B. major was documented from 30 September to 21 October. Low levels of infection by both pathogens were detected at an additional 2020 site and both 2021 sites. Overall, there was a negative association of B. major infection with SLF density and no association with density for B. bassiana. Co-infections in individual SLF by both fungi were never documented, and there was an inverse relationship between prevalence of B. major and B. bassiana infections in the sampled populations. At the time that SLF for rearing were sampled, adult cadavers were also sampled. For B. major, infection rates of sampled cadavers and reared individuals were positively correlated, but higher infection rates were observed in cadavers than among reared SLF. For B. bassiana, no such pattern occurred.

Multivoltine insects, those having more than one generation per year, often use daylength as a cue for terminating reproduction and entering diapause prior to the onset of winter. In a common garden experiment in Corvallis, Oregon, USA (44.6°), we compared voltinism and impacts of the loosestrife leaf beetle Galerucella calmariensis, a classical biological control agent for the wetland weed purple loosestrife (Lythrum salicaria), sourced from 6 locations in their introduced range (39.4 to 48.8° N). The populations were known to have diverged in their critical daylength for diapause since introduction in 1992. After rearing the populations in similar conditions for a generation, and overwintering the adult beetles outdoors, we followed cohorts of eggs on size-matched potted plants as they developed with natural timing through 2 generations in a randomized complete block design. Adult beetles from both the first and second generations were sampled to determine their reproductive status and voltinism. We harvested, dried, and weighed inflorescences and roots of the plants to measure agent impact. The 6 beetle populations were found to differ significantly in both voltinism and impacts, with a higher voltinism corresponding with greater impact. We also showed that voltinism in the introduced location was, to some extent, predictable based on laboratory determined photoperiod response curves, but other factors including plant quality also appeared to be influential. These results show that the efficacy of a biological control agent varies by geographic source and that this can be at least partially predicted by the population's diapause response to photoperiod.

Little is known about the interaction between different egg parasitoid species parasitizing a single host species, under field conditions. In a 2-yr study, we investigated the efficiency of finding and parasitism of eggs of Dalbulus maidis (DeLong) (Hemiptera: Cicadellidae) by the egg parasitoids Anagrus virlai Triapitsyn (Hymenoptera: Mymaridae) and Paracentrobia subflava (Girault) (Hymenoptera: Trichogrammatidae) in maize fields. Host-finding efficiency was compared in fields of plants that differed in age, and on maize edges versus within the maize fields. Then, host-finding and parasitism during short (1 d) versus long (5 d) exposure periods were compared. Anagrus virlai and P. subflava showed similar, highly efficient host searching of maize leaves baited with D. maidis eggs, with similar efficiency in maize crops of different ages. Host-finding was higher, however, in the maize edges than within the maize field. With regard to speed of finding, whereas both parasitoid species were able to search and parasitize D. maidis eggs (at similar levels) when given 5 d of exposure, only P. subflava was able to find and parasitize D. maidis eggs within 24 h. Host-finding of D. maidis eggs was independent between A. virlai and P. subflava when both species parasitized on a single maize leaf. These results suggest that co-occurrence of both parasitoid species is facilitated because each species finds host eggs at different times, parasitoids adults emerge at different times, and a high quantity of host eggs is available.

Pepper weevil, Anthonomus eugenii Cano, is a devastating pest of pepper that is typically controlled, to varying degrees, with chemical insecticides. Additional tools are needed to manage this pest, including host plant resistance. Field and laboratory studies were conducted over 4 yr to determine pepper weevil preferences for pepper hosts with different Scoville heat units (SHU): bell (0 SHU), jalapeño (2,500 to 8,000 SHU), habanero (100,000 to 350,000 SHU), ghost (855,000 to 1,041,427 SHU), and scorpion (1,200,000 to 2,000,000 SHU) peppers. In field trials, jalapeño had the highest number of weevil-infested fruit, and ghost pepper had the lowest. The number of adult weevils on the foliage was highest in jalapeño (0.94 ± 0.23) and lowest in ghost pepper (0.11 ± 0.05). The density of the weevils inside infested fruit was highest on jalapeño and lowest in scorpion pepper. Laboratory olfactometer tests documented a higher preference of adult weevils for bell and jalapeño followed by habanero, ghost, and scorpion peppers. Differences in plant height and width among hosts were not correlated with weevil infestation level. Pepper weevil host preference appears inversely related to pepper hotness (SHU), as bell and jalapeño peppers, the hosts with the lowest SHUs, were the most susceptible to weevil infestation. The greater weevil susceptibility of jalapeño and bell pepper than other species/cultivars may be related to the fact that jalapeño and bell pepper and the weevil co-evolved in Mexico. This study could help in the selection of resistant pepper species for managing pepper weevil.

One of the main challenges in improving agricultural productivity is the prevalence of pests and diseases, which are highly sensitive to extreme weather conditions. The interaction between weather patterns and pest infestations significantly affects crop yield. Traditional statistical methods often struggle to capture the complex temporal and geographical dynamics of these interactions. However, employing multivariate cointegration has proven valuable for estimating such interactions and quantifying the extent to which various environmental conditions influence pest populations. The study further investigated impulse response functions, which revealed substantial impacts of temperature and relative humidity on pest populations through unit standard deviation shocks to endogenous variables. Specifically, this research examined the dynamic causal relationships between major pest occurrences and environmental variables in 3 groundnut-growing states of India-Andhra Pradesh, Gujarat, and Tamil Nadu, using cointegration and Vector Error Correction Model techniques. The analysis incorporated key environmental variables, including temperature, relative humidity, and rainfall. Results from the Johansen test indicated a strong long-term equilibrium relationship between pest populations and climatic conditions, confirming the presence of at least one cointegrating vector at the 5% significance level. Granger causality tests further revealed that temperature and relative humidity had a unidirectional causal influence on the pest occurrence. Additionally, impulse response analysis further revealed that shocks to temperature and relative humidity produced significant and persistent effects on pest incidence over time.

Old World climbing fern, Lygodium microphyllum (Cav.) R. Br., is one of the worst invasive weeds of natural areas of southern and central Florida, United States. The climbing fern forms thick mats that shade native shrubs and trees. Old World climbing fern invades the southern peninsula of Florida, where cost-effective, sustainable control methods are needed. Here, we report the results of greenhouse studies that examined the performance of Lygomusotima stria Solis & Yen larvae, a potential biological control agent of L. microphyllum. We examined the impact of larval feeding on the target weed when grown at a range of fertilizer and herbivore levels. Furthermore, we applied these treatments to guide post-release mass rearing protocols. The results indicate that larvae had greater survival when fed plants at the highest fertilizer level. Two generations of feeding by L. stria larvae decreased rachis weights at the lowest fertilizer levels and fiddlehead numbers. At higher fertilizer conditions, the plants were able to tolerate L. stria herbivory, resulting in no significant changes in plant tissue allocations. The increased larval survival when fed plants grown at high fertilizer levels will benefit both laboratory and field mass production of agents. By impacting rachises and fiddleheads, these results suggest this insect will impede the ability of L. microphyllum to climb substrates, especially in lower resource conditions.