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Many factors affect the host range of baculoviruses. Chrysodeixis includens and Trichoplusia ni are two closely related members of the lepidopteran subfamily Plusiinae that are important insect pests of different crops worldwide. In Brazil, C. includens has recently become a major defoliating pest of soybean. In this study, we compared the susceptibility of C. includens and T. ni to an alphabaculovirus isolated from a C. includens population in Brazil named Chrysodeixis includens nucleopolyhedrovirus isolate GO (ChinNPV-GO). Our results showed that ChinNPV-GO infects and kills C. includens at low oral doses, whereas T. ni larvae exhibited much lower levels of susceptibility to oral infection. In contrast, ChinNPV-GO very similarly infected and killed C. includens and T. ni larvae after budded viruses were injected into the hemocoel. Altogether, we conclude that T. ni is much less susceptible to ChinNPV-GO due to a reduced ability of this virus to establish a primary infection in the midgut. Our results further support that ChinNPV-GO and other plusiinae-associated SNPVs studied to date exhibit restricted host ranges even though known hosts are phylogenetically closely related.

Evolutionary studies of insect pests improve our ability to anticipate problems in agricultural ecosystems, such as pest outbreaks, control failures, or expansions of the host range. Here, we investigated the mechanisms underlying the evolutionary processes behind the recent census size expansion and local adaptation of Chrysodeixis includens. First, we sequenced mitochondrial markers to conduct a phylogeographic investigation of C. includens historical processes. Then, we combined a de novo genotyping‐by‐sequencing approach with a study of agricultural landscapes to uncover recent processes of adaptation. Primarily, we found low genetic diversity across all markers and clear indications of a recent demographic expansion. We also found a lack of significant isolation by distance (IBD), and weak or absent genetic structure considering geographic locations. However, we did find initial signs of population differentiation that were associated with host plant types (i.e., soybean and cotton). Agricultural landscape attributes, including soybean crops, were significantly associated with putative markers under positive selection. Moreover, positive selection associated with host differentiation was putatively linked to digestive enzymes. This study showed how landscape composition and host plants can affect the evolutionary process of agricultural pest insects such as C. includens.

Soybean looper (SBL), Chrysodeixis includens (Walker) (Lepidoptera: Noctuidae), is an important pest of soybean and cotton in Brazil. The use of insecticides is one of the main control tactics against this pest. To support Integrated Pest Management (IPM) and Insect Resistance Management (IRM) programs, we characterized the susceptibility of Brazilian populations of SBL to insecticides. Field populations were collected from soybean fields during the 2016–2017 and 2017–2018 crop seasons. In the laboratory, late L2/early L3 larvae were exposed to insecticides in diet-overlay or topical bioassays. Field populations of SBL showed high susceptibility to spinetoram (LC50 = 0.074–0.25 μg a.i. per cm2), indoxacarb (LC50 = 0.46–0.94 μg a.i. per cm2), thiodicarb (LC50 = 9.14–36.61 μg a.i. per cm2), chlorantraniliprole (LC50 = 0.15–0.57 μg a.i. per cm2), flubendiamide (LC50 = 0.45–2.01 μg a.i. per cm2), and chlorfenapyr (LC50 = 0.15–0.25 μg a.i. per cm2); the resistance ratios were less than 16-fold. In contrast, SBL populations have reduced susceptibility to lambda-cyhalothrin (LC50 = 3.71–9.54 μg a.i./cm2), methoxyfenozide (LC50 = 0.67–4.23 μg a.i. per cm2), novaluron (LC50 = 27.52–77.63 μg a.i. per cm2), and teflubenzuron (LC50 = 13.41–73.02 μg a.i. per cm2). The resistance ratios relative to a Lab population (susceptible of reference) was up to 38-, 63-, 1,553-, and 5,215-fold, respectively. These high resistance ratios can be associated with resistance evolution. Implications of these findings to IPM and IRM programs are discussed.

Chrysodeixis includens (Walker, [1858]) is one of the most important defoliator of soybean in Brazil because of its extensive geographical distribution and high tolerance to insecticides compared with other species of caterpillars. Because of this, we conducted bioassays to evaluate the efficacy of pyrethroid λ-cyhalothrin on a C. includens resistant strain (MS) and a susceptible (LAB) laboratory strain. High throughput RNA sequencing (RNA-seq) of larval head and body tissues were performed to identify potential molecular mechanisms underlying pyrethroid resistance. Insecticide bioassays showed that MS larvae exhibit 28.9-fold resistance to pyrethroid λ-cyhalothrin relative to LAB larvae. RNA-seq identified evidence of metabolic resistance in the head and body tissues: 15 cytochrome P450 transcripts of Cyp6, Cyp9, Cyp4, Cyp304, Cyp307, Cyp337, Cyp321 families, 7 glutathione-S-transferase (Gst) genes, 7 α-esterase genes from intracellular and secreted catalytic classes, and 8 UDP-glucuronosyltransferase (Ugt) were overexpressed in MS as compared with LAB larvae. We also identified overexpression of GPCR genes (CiGPCR64-like and CiGPCRMth2) in the head tissue. To validate RNA-seq results, we performed RT-qPCR to assay selected metabolic genes and confirmed their expression profiles. Specifically, CiCYP9a101v1, CiCYP6ae149, CiCYP6ae106v2, CiGSTe13, CiCOE47, and CiUGT33F21 exhibited significant overexpression in resistant MS larvae. In summary, our findings detailed potential mechanisms of metabolic detoxification underlying pyrethroid resistance in C. includens.

Chrysodeixis includens is a polyphagous pest restricted to the American continent. The occurrence of C. includens is allied, among other factors, by favorable conditions such as temperature, humidity, presence of hosts, and migratory behavior. In this work, we built spatiotemporal species distribution models at continental and global levels for the distribution of C. includens using CLIMEX to determine times and regions favorable for year-round survival and migration of this species and in case of invasion on other continents to apply timely and right phytosanitary measures. Our models estimated high climate suitability for C. includens in Central and large proportions of South America throughout the year. Moreover, there is suitability for C. includens growth in all months of the year in Central and northern part of South America. In the northern hemisphere, these conditions range from April to October, while in mid-southern parts of South America, favorable periods comprise October through June. The countries with the highest suitability for C. includens outside the American continent are located on the African and Asian continents. Our results show variable climate suitability for C. includens during the year that help to understand likely migration pattern in North America. This information would direct efforts for appropriate C. includens management during warm and moist periods of the year. Furthermore, our models notify the need for the development of strategies for the inspection and interception of C. includens especially in central Africa, India, South and Southeast Asia, and Northeast Australia.

The soybean looper, Chrysodeixis includens , is a primary soybean pest that reduces crop productivity. This work examined control of C. includens populations with methanolic extract of Serjania erecta , a native Cerrado plant, while minimizing risks to pollinators, natural enemies and the environment. Serjania erecta specimens were collected, identified, and subjected to methanol extraction. Bioassays were performed using newly hatched and second-instar caterpillars and different extract concentrations on the diet surface to obtain IC 50 values. Two replicates, containing 10 caterpillars, were established in triplicate. The IC 50 values were 4.15 and 6.24 mg of extract mL −1 for first-instar and second-instar caterpillars, respectively. These growth inhibition results informed the extract concentrations assessed in subsequent development inhibition assays, in which the pupal weight was higher under the control than under the treatments. Extract treatments increased the duration of the larval, pupal and total development. The potential of different concentrations of S. erecta extract to inhibit the enzymes carboxylesterases was also evaluated. Carboxylesterases activity decreased by 41.96 and 43.43% at 7.8 and 15.6 μg mL −1 extract, respectively. At 31.3 μg mL −1 extract, enzymatic activity was not detected. Overall, S. erecta leaf methanolic extract showed inhibitory potential against carboxylesterases.

The subfamily Plusiinae of the moth family Noctuidae is made up 400 species worldwide. Two species of the subfamily, the soybean looper, Chrysodeixis includens (Walker), and the cabbage looper, Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae), are important defoliating insect pests of various field crops and have been the subject of previous Plusiinae surveys in the Southern U.S. Soybean fields were sampled in the Mississippi Delta from 2010 to 2012 to determine the temporal occurrence of various Plusiinae species on soybean. As in previous surveys, C. includens was the most common Plusiinae species in soybean during the 3-yr survey, especially in late season collections (July–September). Rachiplusia ou (Guenée) (Lepidoptera: Noctuidae) was the predominant species observed in early season collections (May–early July). Populations of R. ou during the first sample dates during 2010 were much higher than those observed during the other years of the survey. Only three collected larvae successfully developed into T. ni adults, one each collected during May, June, and July. Although R. ou was not commonly reported in previous studies on soybean, it occurred in low numbers during June and July during the 3-yr study.The temporal occurrence and species composition followed a predictable pattern in all 3 yr of the study.

Hemp (Cannabis sativa L.) is a reemerging crop in the United States with increasing outdoor acreage in many states. This crop offers a potential host for polyphagous, defoliating lepidopteran pests currently present in Louisiana. The ability of soybean looper [Chrysodeixis includens (Walker)] (Lepidoptera: Noctuidae), fall armyworm [Spodoptera frugiperda (J.E. Smith)] (Lepidoptera: Noctuidae), and beet armyworm [Spodoptera exigua (Hübner)] to develop and reproduce on hemp was investigated in this study. Insects were reared on two hemp varieties, Maverick and Pipeline, as well as documented host plants soybean [Glycine max (L.) Merr.] (Fabales: Fabaceae) variety UA5414RR and cowpea [Vigna unguiculata (L.)] (Fabales: Fabaceae) variety Quickpick Pinkeye. Larvae of all three species reared on ‘Maverick’ had significantly faster preadult developmental times compared to the other hosts. Chrysodeixis includens larvae fed excised leaves of ‘Maverick' and ‘Pipeline’ experienced higher intrinsic and finite rates of increase, higher net reproductive rates, and faster mean generation and doubling times. Spodoptera frugiperda larvae reared on ‘Maverick’, ‘Pipeline’, and ‘UA5414RR’ had higher intrinsic and finite rates of increase, higher net reproductive rates, and faster mean generation and doubling times compared to ‘Quickpick Pinkeye’. Spodoptera exigua larvae had the highest survivorship on ‘Maverick’ and similar, positive lifetable statistics when reared on ‘Maverick’ and ‘Pipeline’. The results of this study indicate hemp is an alternative host plant that has the potential to influence the population dynamics of C. includens, S. frugiperda, and S. exigua in Louisiana agroecosystems they co-occur in.

A meridic diet overlay bioassay using empty, positively charged zein nanoparticles ((+)ZNP) was performed on soybean looper (Chrysodeixis includens (Walker)), tobacco budworm (Heliothis virescens (F.)), and velvetbean caterpillar (Anticarsia gemmatalis Hübner) (Lepidoptera: Noctuidae). Assessment of effects on mortality and development weights 7 d after ingestion of (+)ZNP were evaluated on larvae of each species. Treatments involved different concentrations, with H. virescens and A. gemmatalis offered 0 and 3,800 ppm (+)ZNP, whereas C. includens colonies were offered 0, 630, 1,260, and 2,520 ppm (+)ZNP. Mortality of A. gemmatalis and C. includens increased after ingestion of the highest (+)ZNP concentrations, while H. virescens neonate mortality was unaffected. Neonate and third-instar weights of A. gemmatalis and C. includens, and neonate H. virescens, decreased with high (+)ZNP concentrations. Following mortality results from A. gemmatalis neonates, a concentration response test was performed using a range of (+)ZNP concentrations.The LC50 for A. gemmatalis was 1,478 ppm.The potential of (+)ZNP as a pest management tactic is discussed.

Soybean production is a cornerstone of Brazilian agriculture but is heavily threatened by insect pests such as the soybean looper Chrysodeixis includens, capable of reducing yields by up to 70% if uncontrolled. Reliance on chemical insecticides is increasingly unsustainable due to environmental impacts and resistance, highlighting the need for eco-friendly alternatives. The alphabaculovirus Chrysodeixis includens nucleopolyhedrovirus (ChinNPV) is an important biocontrol agent largely used in Brazilian fields because of its host specificity and safety, although its persistence is limited by ultraviolet (UV) sensitivity. Here, we characterize two ChinNPV isolates, CNPSo-168 (C168) and Tabatinga (Tb), using genomic and phenotypic analyses. Whole-genome sequencing revealed circular dsDNA genomes of 139,290 bp (154 ORFs) for C168 and 139,131 bp (153 ORFs) for Tb, both encoding the 38 baculovirus core genes and sharing >98.9% identity with reference genomes. Comparative genomics identified 431 SNPs, including 132 nonsynonymous changes in structural, regulatory, and infection-related genes. At low concentrations, C168 showed an approximately 2-fold lower LC50 than Tb (higher potency), while both achieved near-complete mortality within 8 days at higher concentrations. This greater potency at lower concentrations reinforces the efficacy-based rationale for selecting isolate C168 for biocontrol applications. Infection reduced larval growth, pupation, and adult emergence, often with developmental impairments. Despite genetic differences, both isolates were highly UV-sensitive, and formulation tests indicated that titanium dioxide combined with kaolin conferred partial protection. These results provide insights into ChinNPV diversity and support its development as a sustainable tool for soybean pest management.