Insect herbivores and plant-parasitic nematodes are global, economically devastating pests that are present in nearly every crop and natural system worldwide. Although they may be spatially separated, they indirectly interact with each other by altering both plant chemical defense and nutrition. However, the outcome of these interactions is highly variable across different focal species. We performed a meta-analysis to determine how plant and nematode traits influence insect herbivore growth and reproduction, as well as nematode abundance and reproduction. We investigated how interactions between plant-parasitic nematodes and insect herbivores influence plant biomass, carbon, and nitrogen in the roots and shoots. We found no overall effect of nematodes on insect herbivores or insect herbivores on nematodes. However, while phloem-feeding insect reproduction was not affected by nematode feeding guild or plant family, chewing insect growth increased in the presence of cyst nematodes and decreased in the presence of gall nematodes. The effect of nematodes on chewing insect herbivore growth was also affected by the focal plant family. Nematode presence did not alter plant biomass when plants were exposed to aboveground insect herbivory, but carbon and nitrogen were higher in roots and nitrogen was higher in shoots of plants with nematodes and insects compared to plants with insects alone. Our results indicate that the mechanisms driving the outcome of aboveground–belowground interactions are still unclear, but those chewing insects may have more variable responses to nematode damage than phloem-feeders.

Understanding the movement and distribution of insects inside a grain bin is crucial to develop an effective stored grain management protocol. The three-dimensional movement and distribution of adult Cryptolestes ferrugineus (Stephens) at 20 and 30°C were determined in a 0.7 × 0.7 × 0.7 m³ (internal dimensions) wooden box filled with wheat of uniform moisture contents (12.5 ± 0.1%, 14.5 ± 0.1%, and 16.5 ± 0.1% wet basis). The wheat at a constant moisture content was filled into 343 mesh cubes (0.1 × 0.1 × 0.1 m³) and placed inside the wooden box. The center mesh cube in the box had one hundred adult insects introduced at the beginning of the movement. After 24 h, the 343 mesh cubes were removed from the wooden box in less than 45 min. Finally, the contents of each mesh cube were sieved, and the insects counted. Each experiment was replicated three times. A maximum of 17% of insects stayed at the introduced cube (center of the wooden box). About 50–88% of the introduced adults moved downward from the introduction location at the studied temperatures and moisture contents. This 24 h study showed that C. ferrugineus movements in three dimensions follow a diffusion pattern in the horizontal direction and move downward due to the ‘drift’ effect and geotaxis in the vertical direction.

Plastic mulch of different colors and ultraviolet (UV) reflectivity individually or combined with released arthropod predators is an important component of an integrated pest management strategy. In 2015 and 2016, we evaluated the density and within-plant distribution of a released predatory mite, Amblyseius swirskii Athius-Henriot (Acari: Phytoseiidae) in snap bean (Phaseolus vulgaris L.), cucumber (Cucumis sativus L.), yellow squash (Cucurbita pepo L.), eggplant (Solanum melongena L.), Jalapeno pepper (Capsicum annuum L.), and tomato (Solanum lycopersicum L.) grown on different plastic mulches. The mulch treatments evaluated were: metalized top and black bottom, metalized top and white bottom, black-on-black, black-on-white, white-on-black, and bare soil with no mulch. Crop species had a significant effect on the density of A. swirskii. Eggplant and cucumber had higher numbers of A. swirskii than the other crops tested in 2015. In 2016, the density of A. swirskii was higher on eggplant than on cucumber. There was a variation in the distribution of A. swirskii in different strata of the plant canopies with the highest number in the bottom stratum of each crop, which was positively correlated with the population of Thrips palmi Karny (Thysanoptera: Thripidae). Mulch type had no effect on the density or distribution of A. swirskii in any strata of any of the crops tested.The results of this study indicate that releasing A. swirskii is compatible with the use of UV-reflective mulch. This information about host preference and within-plant distribution of A. swirskii should be of value in pest management programs for the crops studied.

Most parasitoid wasps parasitize herbivorous insects, so nectar from flowers is readily available. However, parasitoid wasps are also an important component of the rich invertebrate communities at livestock facilities in large accumulations of manure, where flowers are largely absent. Little is known about adult parasitoid diet and nutrition in these communities. The present study examined this in Spalangia cameroni Perkins, a pupal parasitoid of filth flies. Like many parasitoid wasps, S. cameroni feed on host fluids, and in the laboratory readily feed on honey or a sucrose solution, which increases their longevity. Here adult longevity in the presence of six potential food sources, bovine manure, sorghum silage, bovine milk, buckwheat inflorescence (Polygonaceae), sweet alyssum inflorescence (Brassicaceae), or dandelion inflorescence (Asteraceae), was compared to that with water or honey. Only parasitoids given buckwheat lived as long as parasitoids given honey, and parasitoids given honey or buckwheat lived longer than parasitoids given water. Parasitoids readily ate buckwheat nectar, avoiding pollen grains. Diet affected the amount of free sugars, glycogen, and lipids in complex ways. Compared to parasitoids that were given just water, parasitoids with access to honey or sucrose had higher sugar and glycogen levels, but not detectably higher lipid levels. Access to buckwheat had no detectable effect on a parasitoid's free sugar, glycogen, or lipid levels; however, then after 4 d with just water, sugar levels were lower and glycogen levels were higher compared to parasitoids that had been given access to only water the entire time.

Predator diversity in a system can have different results on the biological control of pests. Positive results can arise if natural enemies have niche complementarity, whereas negative effects can occur when one enemy interferes with heterospecifics—e.g., via intraguild predation—resulting in weaker pest suppression. Nevertheless, a coexistence is possible if enemies use the resource differentially leading to resource partitioning, and/or if the intraguild prey has some competitive advantage over the intraguild predator—i.e., is better at exploiting the shared resource or exhibits avoidance behavior. In this study, we conducted a series of field-sampling and semifield experiments to elucidate the spatiotemporal association patterns of the coccinellids Eriopis connexa (Germar) and Cycloneda sanguinea L. (Coleoptera: Coccinellidae) and determine how the trophic interactions between them could affect the biological control of aphids. We found that both coccinellid species coexist in sweet-pepper crops over time, and this coexistence could be explained by a temporal niche complementarity. Despite cooccurring spatially, they were segregated at the leaf level, which segregation can be explained by an avoidance behavior to prevent negative trophic interactions, such as cannibalism and intraguild predation. Under semifield conditions, the possible negative trophic interactions did not affect the control of aphids when both species were present, but the density of C. sanguinea was reduced at the end of the experiment. These results suggest that biological control strategies that include both species would be positive for the control of aphids on the basis of these considerations.

Aphids that attack canola (Brassica napus L.) exhibit feeding preferences for different parts of canola plants, which may be associated with brassica-specific glucosinolates. However, this idea remains untested. Furthermore, canola aphid species employ different strategies for tolerating glucosinolates. While the green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae), excretes glucosinolates, the cabbage aphid Brevicoryne brassicae (L.) (Hemiptera: Aphididae) sequesters them. Given the different detoxification mechanisms, we predicted that both aphid species and aphid feeding location would affect prey suitability for larvae of the predator, Hippodamia convergens (Guérin-Méneville) (Coleoptera: Coccinellidae). We hypothesized that aphids, specifically glucosinolate-sequestering cabbage aphid, reared on reproductive structures that harbor higher glucosinolates concentrations would have greater negative effects on predators than those reared on vegetative structures which have lower levels of glucosinolates, and that the impact of aphid feeding location would vary depending on the prey detoxification mechanism. To test these predictions, we conducted experiments to compare 1) glucosinolates profiles between B. brassicae and M. persicae reared on reproductive and vegetative canola structures, 2) aphid population growth on each structure, and 3) their subsequent impact on fitness traits of H. convergens. Results indicate that the population growth of both aphids was greater on reproductive structures, with B. brassicae having the highest population growth. B. brassicae reared on reproductive structures had the highest concentrations of glucosinolates, and the greatest adverse effects on H. convergens. These findings suggest that both aphid-prey species and feeding location on canola could influence populations of this predator and, thus, its potential for biological control of canola aphids.

Following the adventive arrival, subsequent spread, and ensuing impact of Adelges tsugae Annand (Hemiptera: Adelgidae), the hemlock woolly adelgid (HWA) in the eastern United States, a robust initiative was launched with the goal of decreasing ecosystem impacts from the loss of eastern hemlock (Pinales: Pinaceae). This initiative includes the use of biological control agents, including Laricobius spp. (Insecta: Coleoptera). Laboratory production of these agents is limited by subterranean mortality and early emergence. Therefore, the subterranean survivorship and timing of emergence of a mixture of Laricobius spp. was investigated. PVC traps internally lined with a sticky card and covered with a mesh screen were inserted into the soil to measure the percent emergence of adults based on the number of larvae placed within. The number of emerged adults in the field and laboratory-reared larval treatments was adjusted based on emergence numbers in the control and used as the response variable. Independent variables included in the final model were: treatment (field-collected vs. laboratory-reared), organic layer depth (cm), soil pH, and April-to-December mean soil moisture. No differences were found in survivorship between field-collected and laboratory-reared treatments. As pH and organic layer increased survivorship decreased, significantly. Although the majority of emergence occurred in the fall, emergence also occurred in spring and summer. The occurrence of spring and summer emergence and low survivorship (17.1 ± 0.4%) in the field across all treatments suggests that these are characteristics of Laricobius spp. field biology in their introduced range and not artifacts of the laboratory rearing process.

Ceratapion basicorne (Illiger) is a recently approved univoltine biological control agent that develops inside the rosette of yellow starthistle (Centaurea solstitialis L.), an invasive annual plant. Adult weevils normally emerge in early summer, and females are thought to be in reproductive diapause until the following spring, when they oviposit in rosettes. The long period of reproductive diapause constrains mass-rearing this weevil because only one generation per year can be produced. Determining the environmental conditions that regulate diapause termination may enable shortening diapause under laboratory conditions to increase production of adults to release. We tested three hibernating conditions (greenhouse [ambient temperature and photoperiod], glass door refrigerator [5°C and ambient photoperiod], and growth chamber [5°C and 24 h dark]) for three durations (4, 8, 11 wk). The highest proportion of females laying eggs came from the growth chamber, with 40% terminating diapause after 4 wk, 80% after 8 wk, and 95% after 11 wk of exposure. Our study demonstrates that duration of cold temperature is an important stimulus to terminate reproductive diapause of C. basicorne, and that exposure to ambient light had no effect at 5°C. However, 47% of females held at ambient greenhouse conditions, without any chilling period, completed diapause within 11 wk. Thus, a cold period can accelerate diapause development, but it is not necessary for its completion. Reducing the winter diapause period from about 6 mo to 11 wk should enable the production of multiple generations per year to increase the number of insects available to release.

Invasive black and pale swallow-worts (Vincetoxicum nigrum (L.) Moench, and Vincetoxicum rossicum Kelopow), which are related to milkweeds, can act as ecological traps for monarch butterflies (Danaus plexippus L. (Lepidoptera: Nymphalidae)) as they lay eggs on them that fail to develop. A recently approved biological control agent against swallow-worts, Hypena opulenta Christoph, occupies the same feeding guild on swallow-worts as monarch larvae and could be perceived as a competitor to monarchs. We tested how the presence of this defoliating moth on swallow-worts may influence monarch host selection. In a two-year field experiment, we placed pale swallow-wort plants that were either infested with H. opulenta or noninfested as well as common milkweed (Asclepias syriaca L.), into monarch habitats to assess oviposition rates. In the laboratory, monarchs were either given a choice or not between milkweeds and black swallow-worts with or without H. opulenta. While monarchs strongly preferred common milkweed in the field, up to 25% of the eggs we observed were laid on pale swallow-wort, without preference for swallow-wort with (10.7%) or without (14.3%) H. opulenta. In laboratory choice and no-choice tests, monarchs did not lay any eggs on black swallow-wort, likely because of the long-term laboratory rearing on common milkweeds. Our results confirm that pale swallow-wort may act as an oviposition sink to monarchs in Michigan as well. Since the biological control program is still in its infancy, the nature of interactions between monarchs and H. opulenta may change as the biocontrol agent becomes more widespread.

In 2016, we conducted three experiments to clarify the effects of 2,3-hexanediols isomers on trap catches of Neoclytus acuminatus (F.) (Coleoptera: Cerambycidae). We also noted the effects of the isomers on trap catches of other cerambycids and associated species of predators and competitors. Catches of N. acuminatus in traps baited with ethanol + syn-2,3-hexanediol + racemic 3-hydroxyoctan-2-one were reduced with the addition of anti-2,3-hexanediol, an attractant for Curius dentatus Newman (Coleoptera: Cerambycidae). A fourth experiment conducted in 2017 verified that racemic 3-hydroxyoctan-2-one increases catches of N. acuminatus in traps baited with ethanol + syn-2,3-hexanediol.The addition of anti-2,3-hexanediol increased catches of Knulliana cincta (Drury) (Coleoptera: Cerambycidae) in traps baited with ethanol + racemic 3-hydroxyoctan-2-one, whereas attraction of Neoclytus scutellaris (Olivier) to traps baited with ethanol + racemic 3-hydroxyhexan-2-one was reduced by syn-2,3-hexanediol. Trap catches of the beetle predators Chariessa pilosa (Forster), Enoclerus ichneumonus (F.), and Madoniella dislocata (Say) (Coleoptera: Cleridae) were affected by 2,3-hexanediol isomers, whereas other common predators were unaffected by the isomers. Attraction of the bostrichid Xylobiops basilaris (Say) (Coleoptera: Bostrichidae) was increased by the 2,3-hexanediols; the relative effect of the two isomeric blends was dependent on trap co-baits of 3-hydroxy-2-ketones.The two enantiomeric blends of 2,3-hexanediol had minimal effects on catches of most species of ambrosia beetles, whereas the 3-hydroxy-2-ketones affected trap catches of some species.

Insects harbor bacterial endosymbionts that provide their hosts with nutritional benefit or with protection against natural enemies, plant defenses, insecticides, or abiotic stresses.We used directed sequencing of 16S rDNA to identify and compare endosymbionts of Bactericera maculipennis (Crawford) and the western, central, and northwestern haplotypes of B. cockerelli (Šulc) (Hemiptera: Psylloidea: Triozidae). Both species are native to North America, are known to harbor the plant pathogen ‘Candidatus Liberibacter solanacearum’ and develop on shared host plants within the Convolvulaceae. The Old-World species Heterotrioza chenopodii (Reuter) (Psylloidea: Triozidae), now found in North America, was included as an outgroup. 16S sequencing confirmed that both Bactericera species harbor ‘Candidatus Liberibacter solanacearum’ and revealed that both species harbor unique strains of Wolbachia and Sodalis. However, the presence of Wolbachia and Sodalis varied among haplotypes of B. cockerelli. The central and western haplotypes harbored the same strains of Wolbachia, which was confirmed by Sanger sequencing of the wsp and ftsZ genes. Wolbachia was also detected in very low abundance from the northwestern haplotype by high-throughput sequencing of 16S but was not detected from this haplotype by PCR screening. The northwestern and central haplotypes also harbored Sodalis, which was not detected in the western haplotype. Heterotrioza chenopodii harbored an entirely different community of potential endosymbionts compared with the Bactericera spp. that included Rickettsia and an unidentified bacterium in the Enterobacteriaceae. Results of this study provide a foundation for further research on the interactions between psyllids and their bacterial endosymbionts.

Rice water weevil, Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curculionidae), is a destructive insect pest of rice in the United States. The pruning of rice roots by L. oryzophilus larvae can cause up to 25% yield loss. Currently, insecticidal seed treatments are used in the Louisiana rice industry as a pre-emptive means of controlling this weevil species. Our objective was to gain a better understanding of the spatial distribution of L. oryzophilus in Louisiana rice fields. Thirteen untreated commercial rice fields in Louisiana were mapped using GPS software, and surveyed for L. oryzophilus larvae over two years (2017 and 2018). An ANOVA, spatial interpolation, hotspot analysis, and multiple linear regression were used to determine where populations of L. oryzophilus were concentrated and whether distributions of the pest were related to edge effects. The results showed that L. oryzophilus larvae are typically aggregated along the edges of rice fields, with populations decreasing toward the center of rice fields. Lissorhoptrus oryzophilus densities were 3.3- and 2.2- fold greater along field edges than in field centers in 2017 and 2018, respectively. Hotspot spatial analysis revealed 59% and 32% of low-density clusters occurred at or near field centers, respectively. Multiple linear regression revealed larval densities decline with increasing distance from overwintering sites and alternative habitats (such as tree lines and levees containing bunch grasses and other alternative noncrop plants).These results suggest potential for insecticidal seed treatments to be applied selectively within rice fields to control this pest.

Graphical Abstract

The larger grain borer, Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae), is a serious pest of stored maize in Mozambique and in other African countries. This study investigated the influence of abiotic and biotic factors on populations of P. truncatus at four sites over a two-year period (2013–2014) in Mozambique. Fourteen 250 × 250 m quadrants were selected at each site. Plant species diversity, temperature, precipitation, and relative humidity data were recorded. Pheromone-baited Uni-traps were used to monitor P. truncatus inside each quadrant. In addition, plant species were identified using visual observation and measurement of morphological features of leaves and fruits, and quantified, after which the percentage of host plant species of P. truncatus was determined out of all species in each quadrant. Multiple regression analysis and generalized linear models showed that host plant species dominance, maximum and minimum temperature, relative humidity, and rainfall influenced the variations in P. truncatus abundance. The development of these models of P. truncatus flight activity provides a baseline for further studies predicting dispersal and potential areas of invasion by this pest.

Characterizing the temperature-dependent development rate requires empirical data acquired by rearing individuals at different temperatures. Many mathematical models can be fitted to empirical data, making model comparison a mandatory step, yet model selection practices widely vary.We present guidelines for model selection using statistical criteria and the assessment of biological relevance of fits, exemplified throughout a Lepidoptera pest dataset. We also used in silico experiments to explore how experimental design and species attributes impact estimation accuracy of biological traits. Our results suggested that the uncertainty in model predictions was mostly determined by the rearing effort and the variance in development times of individuals. We found that a higher number of tested temperatures instead of a higher sample size per temperature may lead to more accurate estimations of model parameters. Our simulations suggested that an inappropriate model choice can lead to biased estimated values of biological traits (defined as attributes of temperature dependent development rate, i.e., optimal temperature for development and critical thresholds), highlighting the need for standardized model selection methods. Therefore, our results have direct implications for future studies on the temperature-dependent development rate of insects.

Developmental time of the predatory mite Neoseiulus cucumeris (Oudemans) fed on cattail and almond pollen was determined under laboratory conditions at nine constant temperatures: 10, 15, 20, 25, 27, 30, 32, 35 and 38°C. No development was observed at 10°C. The lower temperature threshold (T₀) was estimated to be 10. 97 and 10. 29°C for the almond and cattail pollen, respectively, using the Ikemoto linear model. Thermal constant (K) for pre-adult development of N. cucumeris was 112.8 and 123.5 DD fed on almond and cattail pollen, respectively, using the Ikemoto linear model. The interaction between diet and temperature had a significant effect on the developmental rate of N. cucumeris. The nonlinear Pradhan-Taylor, Janisch/Kontodimas, Briere-1, and Janisch/Rochat models best described the developmental rate of pre-adult stages of N. cucumeris. The estimated Tfast by Pradhan-Taylor model was 31.9 and 33.9°C when fed on almond and cattail pollen, respectively, which was similar to the observed shortest developmental time at 32°C. Our results revealed that N. cucumeris could develop over a wide temperature range (15–35°C), which is a desirable characteristic for a biocontrol agent in biological control programs.

Anoplophora chinensis (Forster) is a xylophagous invasive cerambycid whose larvae feed on the lower bole and exposed roots of many tree species in orchard, urban, and forested habitats. Larval survival and development of A. chinensis from Italy and China were evaluated at eight constant temperatures (5, 10, 15, 20, 25, 30, 35, and 40°C). Development was slow or did not occur at temperatures ≤10 and >35°C. The T_Min for the first six instars and the pupa was <10°C, while T_Min for the higher instars was closer to 12°C. The ultimate instar for both populations was insensitive to temperature. When the T_Max thresholds could be estimated they were between 31 and 41°C. Temperature also influenced larval weight gain; larvae held at 25–30°C generally weighed the most from the fourth instar on. The number of degree days for 50% of the population to molt to the next instar increased with increasing instar for both populations up through the sixth instar. Anoplophora chinensis may use wood moisture content in conjunction with temperature as a cue as to when to pupate. These responses of A. chinensis to temperature can be used for developing phenological models to predict timing of stages for management or eradication efforts.

Dendroctonus armandi (Tsai and Li) (Coleoptera: Curculionidae: Scolytinae) is considered to be the most destructive forest pest in the Qinling and Bashan Mountains of China. Low winter temperatures limit insect's populations, distribution, activity, and development. Insects have developed different strategies such as freeze-tolerance and freeze-avoidance to survive in low temperature conditions. In the present study, we used gene cloning, real-time polymerase chain reaction (PCR), RNA interference (RNAi), and heterologous expression to study the function of the D. armandi antifreeze protein gene (DaAFP). We cloned the 800 bp full-length cDNA encoding 228 amino acids of DaAFP and analyzed its structure using bioinformatics analysis. The DaAFP amino acid sequence exhibited 24–86% similarity with other insect species. The expression of DaAFP was high in January and in the larvae, head, and midgut of D. armandi. In addition, the expression of DaAFP increased with decreasing temperature and increasing exposure time. RNAi analysis also demonstrated that AFP plays an important role in the cold tolerance of overwintering larvae. The thermal hysteresis and antifreeze activity assay of DaAFP and its mutants indicated that the more regular the DaAFP threonine-cystine-threonine (TXT) motif, the stronger the antifreeze activity. These results suggest that DaAFP plays an essential role as a biological cryoprotectant in overwintering D. armandi larvae and provides a theoretical basis for new pest control methods.

Graphical Abstract

Black soldier fly (Hermetia illucens L. [Diptera: Stratiomyidae]) has gained huge popularity in different industrial and commercial sectors because of its excellent potential to treat organic waste and high biomass production. As the industrial application of BSF is expanding at accelerated rates, there is a need to optimize its mass scale production where the organic substrates play a very crucial role in optimal growth and development. The present study deals with the investigation of different life history attributes of BSF such as larval and adult weights, survival, pupation rate, and the development time as the function of different organic substrates [fruits and vegetable mix (T1); wheat bran, soy, and corn meal mix (T2); and the dairy manure (T3)]. The larval, pupal, and adult weights differed across all three treatments (P < 0.05). There was no significant difference in the survival rate of larvae among T1 and T2 however, T3 differed significantly from T1 and T2. Likewise, the pupation rate and the development time differed significantly between the three treatments. Results indicated that the BSF development was least in dairy manure treatment and therefore, higher percent mortality and higher development time were observed. However, to deal with the problems of waste management and treatment, BSF larvae can be successfully employed for the treatment of any type of waste since it showed significant treatment efficiencies.

Graphical Abstract

The Douglas-fir beetle (Dendroctonus pseudotsugae Hopkins) occasionally colonizes western larch [Larix occidentalis Nutt. (Pinales: Pinaceae)] growing in close proximity to its primary host, Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco (Pinales: Pinaceae)], but brood have never been found to survive in live western larch. Western larch produces the monoterpene 3-carene in higher concentrations than Douglas-fir. In this study, the toxicity and repellency of 3-carene to Douglas-fir beetle was evaluated in a series of laboratory and field tests. In a laboratory bioassay, 3-carene was one of the most toxic monoterpenes to Douglas-fir beetles among those tested. In a field trial, addition of 3-carene to multiple-funnel traps baited with frontalin (the primary component of Douglas-fir beetle aggregation pheromone) or frontalin and α-pinene significantly reduced the number of Douglas-fir beetles collected. In another field study, live western larch, felled western larch, live Douglas-fir, felled Douglas-fir, and live Douglas-fir surrounded by 3-carene releasers were baited with Douglas-fir beetle aggregation pheromones. There were significantly fewer Douglas-fir beetle entrance holes and egg galleries excavated on both live western larch and live Douglas-fir surrounded by 3-carene compared with live Douglas-fir. Most egg galleries excavated in live western larch were heavily impregnated with resin and no eggs hatched. There were no significant differences in egg galleries excavated or eggs hatched between felled western larch and felled Douglas-fir. Collectively, these data support the hypothesis that 3-carene slows the colonization process in live western larch allowing more time for host trees to respond to a colonization attempt and a higher likelihood of successfully resisting infestation.

Cultivar resistance is a key management strategy for the sugarcane borer, Diatraea saccharalis (F.), the primary pest in Louisiana sugarcane, but mechanisms of resistance are not well understood. This research evaluated the potential mechanisms of cultivar resistance to D. saccharalis among commercially produced sugarcane cultivars and experimental lines through three field screenings, two greenhouse experiments, and one diet incorporation assay. The resistant standards HoCP 85-845, HoCP 04-838, and L 01-299 were among the cultivars with the lowest D. saccharalis injury levels in both field and greenhouse trials. Cultivars HoCP 00-950 and L 12-201 were among the most heavily injured in both trials. Differences in oviposition among cultivars in the greenhouse choice study were not detected, suggesting adult preference is not a key factor in resistance. This was also supported by the no-choice greenhouse experiment in which up to 9-fold differences in neonate establishment among cultivars were detected. Larval injury among cultivars in greenhouse experiments was consistent with field studies suggesting traits that affect neonate establishment (e.g., rind hardness) help to confer resistance in the field. In the diet incorporation assay, lower larval weights and longer time to pupation were observed on resistant cultivar Ho 08-9003, but no differences were found among current commercial cultivars. Continuous evaluation of cultivar resistance to D. saccharalis is important in developing effective integrated pest management strategies for this pest. More research into plant characteristics (e.g., leaf sheath tightness and pubescence) associated with resistance is needed.

Pristine sub-Antarctic islands terrestrial ecosystems, including many endemic species, are highly threatened by human-induced cosmopolitan plant invasion. We propose that native plant suppression could be further facilitated by the subsequent invasion by generalist pest species that could exacerbate their competitive exclusion through the process of apparent competition. By comparing the biological parameters of an invasive aphid species, Myzus ascalonicus, on one native (Acaena magellanica) and one invasive (Senecio vulgaris) plant species, we showed that survival and fecundity were higher and development time lower on the native plant species than on the invasive one. Moreover, comparing the effect of a temperature increase on the population dynamics of M. ascalonicus on the two plants, we showed that the relative profitability of the native species is further amplified by warming. Hence, while pest population doubling time is 28% higher on the invasive plant under current temperature, it would become 40% higher with an increase in temperature of 3°C. Consequently, our findings demonstrate that global warming could exacerbate competitive exclusion of native plants by invasive plants in sub-Antarctic islands by its indirect effect on the apparent competition mediated by generalist phytophagous pests.

The grapevine phylloxera Daktulosphaira vitifoliae (Fitch) is the pest insect of greatest importance in grapevine. The objective of study was to evaluate the occurrence of overwintering eggs in seedlings of ‘Paulsen 1103’ (Vitis berlandieri × Vitis rupestris) and evaluate the biology and fertility life table of D. vitifoliae on five grape cultivars: ‘Bordô’ (Vitis labrusca), ‘Cabernet Sauvignon’ (Vitis vinifera), ‘BRS Lorena’ (Vitis vinifera × Seyval [Seibell 5656-Rayon d'Or]), ‘Magnolia’ (Vitis rotundifolia), and ‘Paulsen 1103'. In the field, overwintering eggs were found to be present in 78% of ‘Paulsen 1103' seedlings, on the trunk of the seedlings. In the laboratory, phylloxera was found to complete the biological cycle (egg to adult) in roots of ‘BRS Lorena', ‘Bordô', and ‘Cabernet Sauvignon'. Nymphs did not complete development on roots of ‘Paulsen 1103' and ‘Magnolia’, with 100% first instar mortality. Adult females feeding on ‘Bordô’ roots showed the lowest total fecundity (20.9 eggs per female), differing from insects feeding on ‘Cabernet Sauvignon’ roots (207.8 eggs per female). Based on the fertility life table, roots of ‘Cabernet Sauvignon’ provided the best reproduction rate (R_o = 219), intrinsic rate of increase (r_m = 0.197 d) and time between generations (T = 21.5 d). The presence of overwintering eggs on the trunk of the rootstock ‘Paulsen 1103’ may promote the survival and dispersal of the insect. Lignified roots of the rootstock ‘Paulsen 1103’ and the cultivar ‘Magnolia’ do not allow the development of D. vitifoliae, with ‘Cabernet Sauvignon’ being the most suitable for the development of the insect.

Wild Callery pear (Pyrus calleryana Decne.) results from a cross between various cultivars of P. calleryana and any other Pyrus individual.While many cultivars of this species are still commercially produced and sold for horticultural purposes in the United States, Callery pear is a detrimental invasive species that encroaches on many managed and natural areas, damages equipment and injures people, pets, and livestock with its thorny branches, and likely causes detrimental ecological impacts. Despite its importance as an invasive species, the mechanisms behind Callery pear's invasion and spread are unclear. To identify potential drivers of invasion, we quantified feeding of generalist and specialist herbivores on Callery pear and four native tree species, based on insect host ranges, with choice and no-choice experiments followed by field surveys of herbivory on these same tree species. Feeding by all herbivores was lower on Callery pear than on native tree species in no-choice assays. Specifically, feeding on Callery pear was moderate by generalists and very low by specialists. Specialist feeding on Callery pear was comparable to native species in choice assays but was significantly reduced in no-choice assays. Reduced specialist feeding along with moderate generalist feeding on Callery pear in the field provides evidence for the Enemy Release Hypothesis as a potential driving mechanism behind its invasion success.

The invasive spotted lanternfly, Lycorma delicatula, (White Hemiptera: Fulgoridae) continues to spread throughout the Eastern United States. This species exhibits a broad host range, with tree of heaven, Ailanthus altissima (Mill.) Swingle, commonly referred to as the preferred host. Here, we evaluated 2-wk survivorship of early nymphal instars, late nymphal instars, and adult L. delicatula on single diets of ten wild and cultivated hosts: tree of heaven; apple, Malus domestica; peach, Prunus persica; black cherry, P. serotina Ehrh; black locust, Robinia pseudoacacia L.; black walnut, Juglans nigra L.; common hackberry Celtis occidentalis L.; mulberry Morus alba L.; sugar maple Acer saccharum Marshall; white oak, Quercus alba L.. Among them, early and late instars had significantly greater survivorship on tree of heaven and black walnut and adults had greatest survivorship on tree of heaven. Additionally, we evaluated development and survivorship of L. delicatula from newly hatched nymphs to adulthood on single diets of tree of heaven, black walnut, grapevine, apple, and peach, and mixed diets of tree of heaven plus one other host. Single host diets that supported L. delicatula development to adulthood were tree of heaven and black walnut. Interestingly, mixed diets also supported development, and reduced development time to adults by up to 12% compared with the single tree of heaven diet. Our results suggest that within agroecosystems and across landscapes, L. delicatula can develop on single hosts such as tree of heaven, but also on multiple host plants, yielding adults earlier in the growing season.

The Rio Grande in Texas is the geopolitical boundary between the United States and Mexico. Considered one of the world's most at-risk rivers, it has been impacted by intensified management by both countries sharing its watershed. Invasion by Arundo donax (Linnaeus) (Poales: Poaceae), giant reed, has been extensive in the riparian corridor, with potential impacts on native wildlife. A need exists to better understand the ecological communities in these habitats to support strategies for enhancing resources for pollinators. We sampled bee and flowering plant communities monthly over 2 yr along a 3.22 km stretch of the lower Rio Grande in Webb County, TX. Bee and plant richness and abundance were bimodal with peaks in March–April and September in both riparian and upland habitats. The bee community was similar across habitats and sampling dates and dominated by a few common species. Anthophora occidentalis (Cresson) (Hymenoptera: Apidae) and Lasioglossum sp. L (Curtis) (Hymenoptera: Apidae) were indicator species of the riparian habitat, and Halictus ligatus (Say) (Hymenoptera: Halictidae) was an indicator species of the upland habitat. Three plant species were indicator species in riparian habitats, spiny pricklepoppy (Argemone sanguinea Greene) (Papaverales: Papaveraceae), spotted beebalm (Monarda punctata Linnaeus) (Lamiales: Lamiaceae), and Pennsylvania cudweed (Gamochaeta pensylvanica Willdenow) (Asterales: Asteraceae). Analysis showed a positive relationship between bee richness and abundance with flowering plant diversity, increasing bee richness within an optimal temperature range 25–30°C, and higher bee abundance with increased average monthly precipitation. This geographically extensive riparian corridor could be managed using ecological restoration to enhance resources for pollinators.

Wild and managed bee populations are in decline, and one of many environmental causes is the impact of pesticides on developing bees. For solitary bees, delayed larval development could lead to asynchronous adult emergence, unhealthy and inefficient adult pollinators, and decreased brood production and survival. We examined a methodology for testing Osmia lignaria Say (Hymenoptera: Megachilidae) larval responses to pesticide exposure using a laboratory bioassay. We created two provision types: a homogenized blend of O. lignaria provisions from an apple orchard and homogenized almond pollen pellets collected by honey bees plus sugar water. Pesticides were administered to the provisions to compare toxic effects. We recorded larval developmental durations for second–fifth instar and for fifth instar to cocoon initiation for larvae fed provisions treated with water (control) or doses of three pesticides and a representative spray-tank mixture (acetamiprid, boscalid/pyraclostrobin, dimethoate, and acetamiprid plus boscalid/pyraclostrobin). All larvae survived to cocoon initiation when only water was added to provisions. Impacts of pesticide treatments significantly differed between the apple and almond homogenates. The greatest treatment effects occurred when the homogenized almond provision was mixed with acetamiprid alone and when combined with boscalid/pyraclostrobin. Optimizing bioassays through the use of appropriate larval food for exposing solitary bee larvae to agrochemicals is crucial for assessing risks for pollinators.

The phenology and voltinism of bean leaf beetle, Cerotoma trifurcata (Forster), were examined in three counties in 2010 and two counties in 2011 in Ontario soybean, Glycine max (L.) Merr., fields. Soil samples from within cages containing field-collected beetles revealed one cycle of eggs, larvae, and pupae. Observed degree-day (DD) accumulations for C. trifurcata life stage events (egg hatch, egg hatch to pupation, and oviposition to peak adult) in field experiments were compared with thermal constants determined in a temperature-dependent development laboratory experiment where C. trifurcata were reared under five constant temperatures. Observed and predicted DDs for all life stage events were nearly identical. Mean DD accumulations from first oviposition to peak adult emergence in the field studies was 589 ± 67 DD (base 10.3°C), which was nearly identical to the model prediction (581 ± 40 DD, base 10.3°C).

Perilla seed bugs (Nysius sp.) are considered to be the emerging pests causing nutritional and yield losses in perilla and cereal crops. A survey of perilla seed bugs on weeds and perilla crops was conducted over the course of 2 yr in Korea to determine the species composition, abundance, and seasonal dynamics of perilla seed bugs. Three species of Heteroptera (Nysius plebeius, Nysius hidakai, and Nysius inconspicuus), nymphs of Nysius species, and several parasitoid species were collected from weeds and perilla crops. Nysius hidakai was the most abundant perilla seed bugs. In 2019, adult perilla seed bugs, nymphs of perilla seed bugs, and parasitoid species were more abundant in weed species than in perilla crops. An early peak with a greater number of adult perilla seed bug (N. hidakai) was observed in weeds in 2020. However, an identical peak with a similar number of perilla seed bug (N. hidakai) was found in perilla crops in both years. Peak perilla seed bugs densities were observed in the 4th week of June, 2020 in weeds. Parasitoid species from Aphidiidae (1), Braconidae (11), Eulophidae (7), Figitidae (5), Ichneumonidae (7), Platygastridae (1), and Pteromalidae (5) subfamilies were collected. Perilla seed bugs seem to be a serious and increasingly important pest in several field crop species including perilla crops grown on the southern Korean peninsula. Monitoring and early detection of insect species are vital to predicting seasonal colonization and population build-up of perilla seed bugs on perilla crops from a climate change perspective, and essential for developing appropriate management techniques. Thus, continuous monitoring of perilla seed bugs in alternative weed hosts is needed to protect perilla crops from perilla seed bug infestation.

We investigated the effects of various foods and different rearing temperatures on the survival and development of the redlegged ham beetle Necrobia rufipes (De Geer) (Coleoptera: Cleridae), a serious pest of dry-cured hams. The diets tested were dried pet food, finely shredded copra, shredded cheese, dry-cured ham, ground fish meal, and mature larvae of Tribolium castaneum (Herbst) (Coleoptera:Tenebrionidae). As indicated by the growth index and k-values, N. rufipes populations grew fastest on the pet food and slowest on the copra. On the other hand, N. rufipes fed both ham and T. castaneum larvae produced significantly heavier larvae. The adult beetles lived significantly longer on cheese compared to other foods. Studies conducted to determine the developmental rates of N. rufipes fed pet food at temperatures of 22, 25, 28, and 31°C showed that the total developmental time and longevity of N. rufipes significantly varied at different temperatures tested. The shortest developmental time (93.32 d) was observed at 28°C. Oviposition rate was highest for females reared at 25°C while lowest at 22°C. Based on the development, reproduction, and thermal requirements, the most suitable temperature for N. rufipes was between 28 and 31°C. The results also revealed that larval cannibalism prevailed among adult beetles.

Hemlock woolly adelgid (HWA; Adelges tsugae Annand (Hemiptera: Adelgidae)) is the cause of widespread mortality of Carolina and eastern hemlock (Tsuga caroliniana Engelmann and T. canadensis (L.) Carrière) throughout the eastern United States (U.S.). Since its arrival in the northeastern U.S., HWA has steadily invaded and established throughout eastern hemlock stands. However, in 2018, anecdotal evidence suggested a sharp, widespread HWA decline in the northeastern U.S. following above-average summer and autumn rainfall. To quantify this decline in HWA density and investigate its cause, we surveyed HWA density in hemlock stands from northern Massachusetts to southern Connecticut and analyzed HWA density and summer mortality in Pennsylvania. As native fungal entomopathogens are known to infect HWA in the northeastern U.S. and rainfall facilitates propagation and spread of fungi, we hypothesized high rainfall facilitates fungal infection of aestivating nymphs, leading to a decline in HWA density. We tested this hypothesis by applying a rain-simulation treatment to hemlock branches with existing HWA infestations in western MA. Our results indicate a regional-scale decline and subsequent rebound in HWA density that correlates with 2018 rainfall at each site. Experimental rain treatments resulted in higher proportions of aestivating nymphs with signs of mortality compared to controls. In conjunction with no evidence of increased mortality from extreme winter or summer temperatures, our results demonstrate an indirect relationship between high rainfall and regional HWA decline. This knowledge may lead to better prediction of HWA population dynamics.

Whiteflies (Bemisia tabaci) represent an insect pest in horticulture. It serves as a vector for transmitting phytopathogens that inhibit the correct development of plants, affecting crop performance. In this research, whitefly population model was proposed to provide a tool that predicts the pest spread within a crop under greenhouse conditions. The analysis, calibration, and validation of the models, based on logistic functions, were implemented for the three stages (egg, nymph, and adult) of the life cycle of this organism. Temperature (°C), relative humidity (%), initial population (number/cm²), and Growing Degree-Day (GDD) were considered as input variables to describe each development stage. The statistical analysis for the model validation included the coefficient of determination (R²), the percentage standard error of prediction (%SEP), the average relative variance (AVR), and the efficiency coefficient (E). The first period for calibration consisted of 43 d (204.3 GDD), and the second period for validation consisted of 36 d (171.1 GDD). The model efficiently predicts the population growth for the egg, nymph, and adult stages since the values of R² were 0.9856, 0.9918, and 0.9436, and the values of %SEP were 12.4, 11.9, and 75.1% for the egg, nymph, and adult stages, respectively. Moreover, the validation model obtained an R² of 0.9287 for the egg stage, 0.9645 for the nymph stage, and 0.9884 for the adult stage. Meanwhile, the values of %SEP were 10.38, 16.89, and 32.59% for the egg, nymph, and adult stages, respectively. In both cases, the values suggest an adequate fit for the model.