Identification of potential predators of western bean cutworm (Striacosta albicosta) in field corn through molecular gut‐content analysis

An understanding of population dynamics and insect biology is important for effective crop management strategies. Biotic factors such as pathogens play a large role on the fitness and dynamics of insect populations. Microsporidia are obligate intracellular parasites that infect more than 150 insect species and range from sublethal and chronic to fast acting and deadly. The western bean cutworm, Striacosta albicosta (Smith) (Lepidoptera: Noctuidae), is a pest of both corn (Zea maize L. [Poales: Poaceae]) and dry beans (Phaseolus sp L. [Fabales: Fabaceae]) that is infected by a microsporidian parasite from the genus Nosema (Microsporidia: Nosematidae). Unfortunately, little is known about the interactions between the Nosema sp. (Microsporidia: Nosematidae) infecting the western bean cutworm and its prevalence and effects on the host population. This is especially true for the western bean cutworm population that has settled in the Great Lakes region over the last two decades. Using field caught samples and phase contrast microscopy, no consistent trends in pathogen load were observed over the course of the western bean cutworm flight season. A weak, but statistically significant relationship was observed between male body weight and pathogen load. Overall, we found a 100% prevalence of infection in the adult western bean cutworm population in Michigan.

Seven spot ladybird beetle, (Coccinella septempunctata) is a widely distributed natural enemy of soft-bodied insect pests especially aphids worldwide. Both the adult and larvae of this coccinellid beetle are voracious feeders and serve as a commercially available biological control agent around the globe. Different techniques are adopted to enhance the mass rearing and storage of this natural enemy by taking advantage of its natural ability to withstand under extremely low temperatures and entering diapause under unfavorable low temperature conditions. The key objective of this study was to develop a cost effective technique for enhancing the storage life and predatory potential of the larvae of C. septempunctata through cold storage in conjunction with the use of nuclear techniques, gamma radiations. Results showed that the host eating potential of larvae was enhanced as the cold storage duration was increased. Gamma irradiation further enhanced the feeding potential of larvae that were kept under cold storage. Different irradiation doses also affected the development time of C. septempuntata larvae significantly. Without cold storage, the lower radiation doses (10 and 25 GY) prolonged the developmental time as compared to un-irradiated larvae. Furthermore, the higher dose of radiation (50GY) increased the developmental time after removal from cold storage. This study first time paves the way to use radiation in conjunction with cold storage as an effective technique in implementation of different biological control approaches as a part of any IPM programs

The western bean cutworm, Striacosta albicosta (Smith) (Lepidoptera: Noctuidae), is a recent pest of corn, dry,and snap beans, in the Great Lakes region, and best practices for its management in beans need to be established.Insecticide efficacy and application timing field studies, conducted in 2011–2013, determined that lambda-cyhalothrin and chlorantraniliprole were capable of reducing western bean cutworm feeding damage in dry beans from 2.3 to 0.4% in preharvest samples, and in snap beans from 4.8 to 0.1% of marketable pods, respectively. The best application timing in dry beans was determined to be 4–18 d after 50% egg hatch. No economic benefit was found when products were applied to dry beans, and despite high artificial inoculation rates, damage to marketable yield was relatively low. Thiamethoxam, methoxyfenozide, and spinetoram were also found to be effective at reducing western bean cutworm damage in dry bean to as low as 0.3% compared to an untreated control with 2.5% damaged pods. In snap beans, increased return on investment between CAD$400 and CAD$600 was seen with multiple applications of lambda-cyhalothrin, and with chlorantraniliprole applied 4 d after egg mass infestation.

Western bean cutworm, Striacosta albicosta (Smith) (Lepidoptera: Noctuidae), is a native pest of dry beans (Phaseolus vulgaris L.) and corn (Zea mays L.). Historically, the western bean cutworm was distributed in the western United States, but since 1999 eastward expansion has been observed. In corn, economic impact is caused by larval ear feeding. Information on western bean cutworm biology, ecology, and economic impact is relatively limited, and the development of economic injury levels (EILs) and economic thresholds (ETs) is required for more effective management. Studies during 2008-2011, across three ecoregions of Nebraska, sought to characterize western bean cutworm survival and development of EILs and ETs. Calculations of EILs and ETs incorporated the dynamics of corn price, management cost, and pest survival. The results from the current study demonstrated low larval survival of this species (1.51-12.82%). The mean yield loss from one western bean cutworm larva per plant was 945.52 kg/ha (15.08 bu/acre), based on 74,100 plants per ha. Economic thresholds are expressed as a percentage of plants with at least one egg mass. This study is the first study that explicitly incorporates variable management costs and crop values into western bean cutworm EIL calculations, and larval survival into ET calculations.

Transgenic crops expressing insecticidal toxins could soon provide safe, clean and effective means of pest control, but their usefulness will be short-lived if insects adapt to the toxins. Two planting strategies are among those that have been recommended to delay crop failure: susceptible insects could be conserved by planting either ‘refugia’, i.e. separate fields of toxic and toxin-free crop, or ‘seed mixtures’ of toxic and toxin-free plants in the same fields. However, we show that if insects can move from plant to plant, seed mixtures may actually hasten insect resistance compared with pure stands of toxic plants. Insect movement causes an increase in effective genetic dominance which can counteract reduced selection due to the mixture. This failure of seed mixtures is likely under just those conditions, low genetic dominance of resistance, which predict a good chance for resistance to the toxin to evolve slowly. Seed mixtures, unlike refugia, are therefore failure prone. This result also suggests potential problems with a third strategy, tissue-specific expression of toxins, which essentially provides a mixture of toxin-free and toxin-containing tissues on the same plant. However, better information and modelling are urgently required to evaluate alternative means of slowing insect adaptation to resistant crop plants. Legislation for toxinfree refugia may provide one of the best available means for conserving insect susceptibility.

A series of bioassays were conducted to determine the relative toxicities and residual activities of insecticides labeled for use in blueberry (Vaccinium corymbosum L.) on natural enemies, to identify products with low toxicity or short duration effects on biological control agents. In total, 14 insecticides were evaluated using treated petri dishes and four commercially available natural enemies (Aphidius colemani Viereck, Orius insidiosus [Say], Chrysoperla rufilabris [Burmeister], and Hippodamia convergens [Guérin-Menéville]). Dishes were aged under greenhouse conditions for 0, 3, 7, or 14 d before introducing insects to test residual activity. Acute effects (combined mortality and knockdown) varied by insecticide, residue age, and natural enemy species. Broad-spectrum insecticides caused high mortality to all biocontrol agents, whereas products approved for use in organic agriculture had little effect. The reduced-risk insecticide acetamiprid consistently caused significant acute effects, even after aging for 14 d. Methoxyfenozide, novaluron, and chlorantraniliprole, which also are classified as reduced-risk insecticides, had low toxicity, and along with the organic products could be compatible with biological control. This study provides information to guide blueberry growers in their selection of insecticides. Further research will be needed to determine whether adoption of a pest management program based on the use of more selective insecticides will result in higher levels of biological control in blueberry.

The western bean cutworm, Striacosta albicosta (Smith), is a pest of corn and dry beans in North America. Before the late 1990s, economic infestations of the insect were restricted mostly to the western Great Plains and Idaho. During 1999–2009, it greatly expanded its range and moved across the central and eastern regions of the Corn Belt, eventually reaching northeastern Atlantic coast states. Greenpeace Germany issued a 2010 report claiming that the dramatic range expansion of the western bean cutworm was due entirely to “pest replacement” that resulted from the adoption of genetically engineered Bt corn, which suppressed one pest species and allowed another species—the western bean cutworm, in this case—to take its place. We maintain that the scientific literature does not provide empirical field-collected data to support the Greenpeace Germany claim that Bt corn is the sole factor that influenced the range expansion of the western bean cutworm. We propose broader ecological and agronomic factors to explain why the western bean cutworm has recently expanded its geographic range to include all of the major corn-growing areas in the central and eastern United States. These additional factors may include insect biology, insect and corn phenology synchrony, reduced insecticide use, conservation tillage, soil type, glyphosate-resistant crops, insect genetics, insect pathogens, preexisting insect population densities, and climate change.

The western bean cutworm, Striacosta albicosta (Smith) (Lepidoptera: Noctuidae) is native to the western United States, where it was first described as a pest of dry beans (Phaseolus vulgaris L.) and corn (Zea mays L.) (3). On corn, fourth and fifth instar larvae feed in the ear, reducing yield and grain quality. Since 2000, the western bean cutworm has spread eastward through Iowa, Minnesota, Illinois, and Missouri (1,2,4), into Indiana in 2005, and Wisconsin in 2006 (6). Before 2006, there were no records of western bean cutworm in the Michigan State University A. J. Cook Arthropod Collection or in collections at The Ohio State University, nor reports of larval injury to corn in Michigan or Ohio. In the summer of 2006, five and ten pheromone traps were set up in Michigan and Ohio, respectively (Fig. 1). Each trap was constructed from a one-gallon plastic milk jug cut to leave open side panels (5), and baited with a Scentry western bean cutworm pheromone lure (Great Lakes IPM, Vestaburg, MI) hung under the cap (Fig. 2). Traps were filled with a 50:50 mixture of water and commercial antifreeze and hung 1.5 m above the ground near corn. Traps were checked once per week from 1 July through late August; lures were changed once in late July. In Ohio, a total of three adults were captured, one in each of three counties during the first week of July (Fig. 1A). In Michigan, adults were captured later in the season, one each during the weeks of 8 to 14 and 15 to 21 July in Van Buren Co. and on the night of 24 July in Kalamazoo Co. (Fig. 1A). These were the first western bean cutworm adults recorded from either state.

Fungal entomopathogens are widespread in nature and contribute to the natural regulation of insects. They can be exploited for pest management as biological control agents of pests in attempts to improve the sustainability of crop protection. Four types of biological control are recognized: classical, inoculation, inundation, and conservation biological control. Classical biological control is the intentional introduction and permanent establishment of an exotic biological agent for long-term pest management. Inoculation biological control is the intentional release of a living organism as a biological control agent with the expectation that it will multiply and control the pest for an extended period, but not permanently. Inundation biological control is the release of large numbers of mass-produced biological control agents to reduce a pest population without necessarily achieving continuing impact or establishment. Conservation biological control is a modification of the environment or existing practices to protect and enhance specific natural enemies or other organisms to reduce the effect of pests. The traditional and the most popular approach in biological control with entomopathogenic fungi has been to apply the fungal material to the cropping system (as biopesticide), using an inundation biological control strategy. The term biopesticide is used for microbial biological pest control agents that are applied in a similar manner to chemical pesticides. The use of biopesticides can substitute for some (but not all) chemicals and provide environmentally safe and sustainable control of pests but EU legislation and prohibitive registration costs are discouraging the development and commercialization of many promising new products.

The western bean cutworm (Striacosta albicosta) is a primary pest of corn and dry edible bean, for which control measures are often warranted. Inundative releases of Trichogramma ostriniae have been used to control lepidopterous pests, such as the European corn borer (Ostrinia nubilalis), in eastern North America (e.g., New York, Virginia). However, no prior field studies have assessed T. ostriniae as a biological control agent in the North American Great Plains. Objectives for this study were (i) to determine the suitability of S. albicosta as a host for T. ostriniae and (ii) to assess the feasibility of T. ostriniae as a biological control agent of S. albicosta in Nebraska corn and dry edible bean fields. Dispersal and parasitism were monitored with yellow sticky cards and sentinel egg masses (O. nubilalis, S. albicosta, and Ephestia kuehniella) at 36 locations surrounding a central release point. Trichogramma ostriniae adults tended to be concentrated near the point of release. However, egg parasitism was so low that the minimum rates of T. ostriniae needed for effective control could not be determined. Our evidence indicates that the low parasitism measured in this study may indicate low suitability of T. ostriniae to Western Nebraska and, possibly, the Great Plains.

The western bean cutworm, Striacosta albicosta (Smith) is a native North American pest of corn and dry beans. The historical geographic range of the western bean cutworm covered the western Great Plains states including Colorado, Nebraska, and Wyoming. Since 1999, the geographic range of the western bean cutworm has rapidly expanded eastward across the U.S. Corn Belt and eastern Canada, causing significant and economic damage to corn Zea mays (L.) and dry edible beans Phaseolus spp., in parts of this region. Since 2010, increasing challenges related to managing this pest in its new range prompted numerous research studies that provided new insights into the biology and management of western bean cutworm. This revision of a previous Journal of IPM profile summarizes new information regarding the ecology and biology of western bean cutworm, and discusses updated recommendations for scouting and management in corn and dry beans, with an emphasis in the expanded geographic range of the Great Lakes region.

Opinions about the value of biological control are often extreme. Colloquially, biological control most often refers to classical biological control, in which one species is introduced from another region to control pests such as arthropod herbivores in agricultural systems, or weeds in managed and natural systems.1 As such, biological control has the potential to be a low-cost, chemical free, means to control pests. Numerous biological control programs have been unqualified successes (Bellows 2001), such as the control of cacti in Australia with the moth Cactoblastis cactorum (Raghu and Walton 2007), of cottony-cushion scale (Icerya purchasi) in California with the vedalia lady beetle, Rodolia cardinalis (Caltagirone and Doutt 1989), and of glassy-winged sharpshooters in French Polynesia with the egg parasitoid Gonatocerus ashmeadi (Grandgirard et al. 2009). Yet, classical biological control, as with any introduction of a species into a new area, necessarily involves the unknown and therefore carries some inherent risk (Simberloff and Stiling 1996) – what will these organisms actually do in a novel ecosystem? The most unpredictable element in biological control is the extent to which the realized niche is modified in the new environment. This effect has been responsible for some disastrous outcomes of classical biological control, many of which occurred during an era when vertebrates were being introduced around the world by Europeans for a variety of reasons (e.g., introducing the birds of Shakespeare to America, Mirsky 2008), including for biological control (Howarth 1991). The introductions as biological control agents of cane toad to Australia (Crossland et al. 2000) and mongoose to Hawaii (Hays and Conant 2007) are notorious. Introductions of generalist invertebrate agents also have had dire consequences, such as the introduction of predatory snails to French Polynesia (Murray et al. 1988; Coote 2007). In retrospect, some of the unintended consequences of biological control could have been avoided with more ecological knowledge (McEvoy and Coombs 2000) or more societal appreciation for native species (which has developed with time, Henneman and Memmott 2001), but with other introductions, it would have been impossible to know ahead of time what the risks would be (e.g., gall fly agents of knapweeds providing supplementary food to mice that harbor hantavirus, Pearson and Callaway 2006). Many of the unknown outcomes of biological control are purely ecological – what is the risk that a wasp, introduced to parasitize an agricultural pest, will also be able to feed on a native insect? Other unknowns involve evolution – will a herbivore adapt over time to be able to feed on a new nontarget host or hybridize with a closely related species? This volume explores the evolutionary aspects of biological control. Although often overlooked, evolutionary considerations are critical to all stages of classical biological control, from agent selection, to quarantine, release, establishment, and ultimately success in pest control (Ehler et al. 2004). Many questions are unresolved. For example, should agents be chosen that have a long history with the host or are ‘new associations’ more likely to succeed (Hokkanen and Pimentel 1989)? Can one improve effectiveness through artificial selection (Hopper et al. 1993)? Will postcolonization adaptation of the agent increase the likelihood of success, and/or are hosts equally likely to evolve resistance over time (Roderick 1992; Holt and Hochberg 1997; Hufbauer 2001)? Are generalist consumers more likely to survive in novel environments or are specialists more effective (Murdoch et al. 1985; Waage 1990; Brodeur 2012)? More recently, concern for the environment, as well as theory examining the reasons for success of generalist predators, prompted a shift to the release of specialized consumers typically preceded by extensive testing aimed at delimiting the host range of candidate biological control agents. While this approach has clearly made biological control more predictive ecologically, research focused on host range currently lacks measures of genetic variation in host use and responses of those hosts, and thus evolutionary uncertainties remain.

The western bean cutworm (WBC), Striacosta albicosta (Smith, 1888) (Lepidoptera: Noctuidae), is a corn (Zea mays L., 1753) and dry edible beans (Phaseolus vulgaris L.) insect pest increasingly present in Canada, mainly in Ontario and more recently in Quebec, and causing an increasing number of cases of ear damage each year. The main objective of this study was to acquire knowledge (impact of biotic and abiotic factors) on WBC to eventually develop and implement integrated management of the pest in field corn. Over the summers and autumns of 2021-2022 (between mid-July and mid-October), we carried out moth tracking and egg mass scouting, analyzed the database of the Quebec pest monitoring network (Réseau d’avertissements phytosanitaires (RAP)) for the period 2010-2022, evaluated the impact of WBC on corn ears, and evaluated the effectiveness of different control methods, including the use of Bt corn hybrids producing the Vip3A protein and the use of insecticides, in several fields in different regions of Quebec. Our results demonstrate that among the ten agri-environmental factors studied, only the area cultivated with dry edible beans around the monitored corn fields, the region, and the soil texture influence the presence and abundance of WBC moths and the presence of egg masses in a field. In addition, WBC does not seem to affect ear growth (length and width), but the larvae favor the development of the corn ear rot. Finally, Bt Vip3A hybrids and insecticides appear to be effective methods to manage the WBC.

Ladybirds (Coleoptera: Coccinellidae) provide services that are critical to food production, and they fulfill an ecological role as a food source for predators. The richness, abundance, and distribution of ladybirds, however, are compromised by many anthropogenic threats. Meanwhile, a lack of knowledge of the conservation status of most species and the factors driving their population dynamics hinders the development and implementation of conservation strategies for ladybirds. We conducted a review of the literature on the ecology, diversity, and conservation of ladybirds to identify their key ecological threats. Ladybird populations are most affected by climate factors, landscape composition, and biological invasions. We suggest mitigating actions for ladybird conservation and recovery. Short-term actions include citizen science programs and education, protective measures for habitat recovery and threatened species, prevention of the introduction of non-native species, and the maintenance and restoration of natural areas and landscape heterogeneity. Mid-term actions involve the analysis of data from monitoring programs and insect collections to disentangle the effect of different threats to ladybird populations, understand habitat use by taxa on which there is limited knowledge, and quantify temporal trends of abundance, diversity, and biomass along a management-intensity gradient. Long-term actions include the development of a worldwide monitoring program based on standardized sampling to fill data gaps, increase explanatory power, streamline analyses, and facilitate global collaborations.

The influence of microsporidian pathogens from commercially available lady beetles on larval development of the green lacewing, Chrysoperla carnea, in the absence of infection.