Forecasting the seasonal dynamics of Trichoplusia ni (Lep.: Noctuidae) on three Brassica crops through neural networks.

The cabbage looper, Trichoplusia ni Hübner (Lep.: Noctuidae), is a destructive pest of Brassica crops. Their larvae defoliate plants, leading to reduced crop yield. Understanding and modeling pest seasonal dynamics is central to management programs because it allows one to set up sampling and control efforts. This study aimed to train, with field-collected data, artificial neural networks (ANN) for T. ni forecasting on Brassica crops. ANNs were used due to their suitability to fit complex models with multiple predictors. Three weather variables (air temperature, rainfall, and relative humidity lagged at different intervals from the day of pest assessment) and three host plants (broccoli, cabbage, and cauliflower) along with another plant-related variable (days after transplanting) were used as input variables to build ANNs with different topologies. Two outputs (T. ni eggs or larvae) were tested to verify which one would yield more precise models. ANNs forecasting T. ni eggs performed better, based on Pearson's correlation (rv) of observed with fitted values. The winning ANN (rv = 0.706) had weather data lagged by 15 days, 2 neurons in the hidden layer, hyperbolic tangent as the activation function, and resilient propagation as the learning algorithm. Broccoli and cauliflower were the hosts with major contributions for T. ni occurrence. Rainfall was the primary environmental predictor and affected T. ni negatively. Therefore, the winning ANN may be used to forecast T. ni egg densities 15 days in advance, allowing for timely management of this pest.

Lethal and antifeedant effects of Bordeaux mixture on the marsh slug (Deroceras laeve).

The marsh slug, Deroceras laeve (Müller), is a generalist pest of agricultural crops. Slugs are mainly managed with synthetic pesticides that can also have high toxicity toward vertebrates and nontarget arthropods. Besides, they are not labeled for use in organic crop systems. Bordeaux mixture (BM) is an alternative product often used in organic crops for controlling plant diseases. The molluscicidal activity of BM has been reported; however, to our knowledge, no study has determined its efficacy to control D. laeve. This study aimed to determine the lethal (concentration- and time-mortality curves, and foliar persistence) and antifeedant (reduction in leaf consumption) effects of BM-treated cabbage leaves on D. laeve. The LC50 of BM was 28.15%, and the LT50 was 8.83 h. The BM LC25 reduced D. laeve leaf consumption by 3.31-fold. Furthermore, high control effectiveness (mortality > 90%) was attained until the 7th day after spraying. These findings reveal that BM reduces damage by killing D. laeve in a fast faction and by reducing foliar consumption. Therefore, BM can be an alternative to D. laeve management in both conventional and organic systems.

Toxicity and Sublethal Effects of Phthalides Analogs to Rhyzopertha dominica.

Phthalides and their precursors have demonstrated a large variety of biological activities. Eighteen phthalides were synthesized and tested on the stored grain pest Rhyzopertha dominica. In the screening bioassay, compounds rac-(2R,2aS,4R,4aS,6aR,6bS,7R)-7-bromohexahydro-2,4-methano-1,6-dioxacyclopenta[cd]pentalen-5(2H)-one (15) and rac-(3R,3aR,4R,7S,7aS)-3-(propan-2-yloxy)hexahydro-4,7-methano-2-benzofuran-1(3H)-one (17) showed mortality similar to the commercial insecticide, Bifenthrin® (≥90 %). The time (LT50 ) and dose (LD50 ) necessary to kill 50 % of the R. dominica population were determined for the most efficacious phthalides 15 and 17. Compound 15 presented the lowest LD50 (1.97 µg g-1 ), being four times more toxic than Bifenthrin® (LD50 =9.11 µg g-1 ). Both compounds presented an LT50 value equal to 24 h. When applied at a sublethal dose, both phthalides (especially compound 15), reduced the emergence of the first progeny of R. dominica. These findings highlight the potential of phthalides 15 and 17 as precursors for the development of insecticides for R. dominica control.

Phthalides as promising insecticides against Tuta absoluta (Lepidoptera: Gelechiidae).

In this study, the insecticide potential of eight phthalides derived from furan-2(5H)-one was evaluated against Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) larvae. The potency of the most active phthalides and the susceptibility of six different T. absoluta populations to these compounds were determined. The toxicity of these molecules to two non-target species (Solenopsis saevissima Smith and Tetragonisca angustula Latreille) was also evaluated. Two phthalides (3 and 4) presented insecticide potential against T. absoluta. Phthalide 4 was as toxic as piperine (positive control) and both phthalides exhibited rapid action (LT50 < 2 hours). The variation in the susceptibility of T. absoluta populations to the phthalides 3 and 4 was low. Neither phthalide presented physiological selectivity for non-target species. Therefore, the phthalides 3 and 4 are promising molecules, or at least, a starting point for a chemical optimization program leading to formulations for the management of the tomato leafminer. The application of such products should be conducted according to the principles of ecological selectivity.

Effects of glyphosate on the non-target leaf beetle Cerotoma arcuata (Coleoptera: Chrysomelidae) in field and laboratory conditions.

This study aimed to assess the glyphosate application effects on the Cerotoma arcuata Oliver (Coleoptera: Chrysomelidae) population in glyphosate-resistant soybean crops. Field studies were conducted with glyphosate and the insecticide endosulfan to observe the effects of these pesticides on C. arcuata, on its damages in the crop and on the populations of natural enemies in glyphosate-resistant soybean crops. Moreover, the lethal and behavioral sublethal response of C. arcuata to glyphosate and endosulfan was conducted in the laboratory. The results of the field and laboratory experiments showed that glyphosate caused moderate toxicity and high irritability in C. arcuata and that endosulfan caused high toxicity and irritability. Therefore, the direct effect of glyphosate on C. arcuata was negative and does not explain the population increases of this pest in glyphosate-resistant soybean. However, the glyphosate also decreased the density of predators. Thus, the negative effect of glyphosate on the predators may be related to population increases of C. arcuata in glyphosate-resistant soybean crops, however, more studies are needed to better evidence this relationship. This study suggests that glyphosate can impact other non-target organisms, such as herbivorous insects and natural enemies and that the use of this herbicide will need to be carefully stewarded to prevent potential disturbances in beneficial insect communities in agricultural systems.

New Pyrethroids for Use Against Tuta Absoluta (Lepidoptera: Gelechiidae): Their Toxicity and Control Speed.

Insect pests are responsible for major losses in crop productivity, and insecticides are the main tools used to control these organisms. There is increasing demand for new products for pest management. Therefore, the aim of this study was to assess the toxicity of pyrethroids with acid moiety modifications to measure the insecticidal activity of these compounds on Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae). First, we synthesized E/Z mixtures of five pyrethroids: [9], [10], [11], [12], and [13]. Then, we separated the cis and trans pyrethroid isomers of [9], [10], [11], and [12]. We assessed the toxicity of these compounds against T. absoluta. The E/Z mixtures of the five pyrethroids (30 µg of substance per mg-1 of insect) caused high (100%) and rapid (<12 h) tomato borer mortality. The cis isomer of pyrethroid [10] was the most toxic to T. absoluta, causing mortality similar to permethrin. The other isomers were less powerful than permethrin.

Toxicity of new pyrethroid in pest insects Asciamonuste and Diaphania hyalinata, predator Solenopsis saevissima and stingless bee Tetragonisca angustula.

There is increasing demand for new products for vegetable pest management. Thus, the aim of this study was to assess the toxicity of pyrethroids with acid moiety modifications to measure the insecticidal activity of these compounds on the lepidopteran vegetable pests Diaphania hyalinata (L.) (Lepidoptera: Pyralidae) and Asciamonuste (Latreille) (Lepidoptera: Pieridae) and evaluate their selectivity for the predatory ant Solenopsis saevissima (F. Smith) (Hymenoptera: Formicidae) and pollinator Tetragonisca angustula (Latreille) (Hymenoptera: Apidae: Meliponinae). Racemic mixtures of five new pyrethroids (30 µg molecule mg-1 insect body weight) resulted in high (100%) and rapid (stable LD50 after 12 h) mortality in D. hyalinata and A. monuste. In A. monuste, the trans-pyrethroid [12] isomer showed similar toxicity to permethrin. For D. hyalinata, the trans-pyrethroid [9] isomer and cis-pyrethroid [10] isomer were as toxic as permethrin. Due to their low selectivity, these new pyrethroids should be applied on the basis of ecological selectivity principles to minimize impacts on nontarget organisms S. saevissima and T. angustula.

Amino-substituted para-Benzoquinones as Potential Herbicides.

Although quinones present a large array of biological activities, a few studies on the herbicidal potential of 2,5-bis(alkyl/arylamino)-1,4-benzoquinones have been reported to date. In this work, starting from benzoquinone, 13 2,5-bis(alkyl/arylamino)-1,4-benzoquinones were prepared in 46 - 93% yield. The products were fully characterized by spectroscopic analyses and their phytotoxicity against Cucumis sativus and Sorghum bicolor seedlings was investigated. At 100 ppm, compounds caused 10 - 88% growth inhibition of the dicotyledonous species, whereas the monocotyledon was less affected. Most compounds exerted little inhibitory effect on a cyanobacterial model strain. However, at 100 µm, compounds 8 - 10 caused about 50% inhibition of algal growth, and compounds 1 and 2 reduced cell viability in the 1 - 10 µm range. The ability of benzoquinone derivatives to interfere with the light-driven ferricyanide reduction by isolated spinach chloroplasts was evaluated. Some substances showed a moderate effect as uncouplers, but no relationship was found between this property and their biological activity, indicating that the herbicidal effect is not associated with the inhibition of the photosynthetic electron transport chain. Phytotoxic compounds were not toxic to insects, strengthening the possibility that they may serve as lead for the development of eco-friendly herbicides.

Active insecticides for Diaphania hyalinata selective for the natural enemy Solenopsis saevissima.

The objective of this study was to determine the toxicity of the nine synthetic dienamides against the insect pest Diaphania hyalinata (melonworm) and the selectivity of these substances for the predator Solenopsis saevissima (fire ant). Four bioassays were conducted. To begin with, the dienamides that caused high mortality of D. hyalinata have been selected. In the second bioassay the dose-mortality curves of the selected dienamides have been constructed. In the third bioassay, the survival curves for D. hyalinata and the elapsed time to kill 50% of their population have been determined. In the fourth biological test, the selectivity of the substances to the predator S. saevissima has been evaluated. The most active (2E,4E)-N-butylhexa-2,4-dienamide 3d has killed 95% of the melonworm, D. hyalinata, and less than 10% of the natural enemy S. saevissima. The results presented by this compound are superior to the outcome displayed by the commercial insecticide Malathion®. Three of the dienamides prepared in this manuscript have proven to be selective in killing the pest, but not the beneficial insect.

Seasonal variation in the populations of Polyphagotarsonemus latus and Tetranychus bastosi in physic nut (Jatropha curcas) plantations.

Studies on the seasonal variation of agricultural pest species are important for the establishment of integrated pest control programs. The seasonality of pest attacks on crops is affected by biotic and abiotic factors, for example, climate and natural enemies. Besides that, characteristics of the host plant, crop management, location and the pests' bioecology also affect this seasonality. The mites Polyphagotarsonemus latus (Prostigmata: Tarsonemidae) and Tetranychus bastosi (Prostigmata: Tetranychidae) are the most important pests in the cultivation of physic nut, Jatropha curcas (Euphorbiaceae). All parts of J. curcas can be used for a wide range of purposes. In addition many researchers have studied its potential for use as neat oil, as transesterified oil (biodiesel), or as a blend with diesel. However studies about physic nut pests have been little known. The objective of this study was to assess the seasonal variation of P. latus and T. bastosi in physic nut. This study was conducted at three sites in the state of Tocantins, Brazil. We monitored climatic elements and the densities of the two mite species and of their natural enemies for a period of 2 years. Attack by P. latus occurred during rainy seasons, when the photoperiod was short and the physic nut had new leaves. In contrast, attack by T. bastosi occurred during warmer seasons with longer photoperiods and stronger winds. Populations of both mites and their natural enemies were greater in sites with greater plant diversity adjacent to the plantations. The predators found in association with P. latus and T. bastosi were Euseius concordis (Acari: Phytoseiidae), spiders, Stethorus sp. (Coleoptera: Coccinellidae) and Chrysoperla sp. (Neuroptera: Chrysopidae).

Physiological selectivity and activity reduction of insecticides by rainfall to predatory wasps of Tuta absoluta.

In this study, we carried out three bioassays with nine used insecticides in tomato crops to identify their efficiency against tomato leaf miner Tuta absoluta, the physiological selectivity and the activity reduction of insecticides by three rain regimes to predatory wasps Protonectarina sylveirae and Polybia scutellaris. We assessed the mortality caused by the recommended doses of abamectin, beta-cyfluthrin, cartap, chlorfenapyr, etofenprox, methamidophos, permethrin, phenthoate and spinosad to T. absoluta and wasps at the moment of application. In addition, we evaluated the wasp mortality due to the insecticides for 30 days on plants that did not receive rain and on plants that received 4 or 125 mm of rain. Spinosad, cartap, chlorfenapyr, phenthoate, abamectin and methamidophos caused mortality higher than 90% to T. absoluta, whereas the pyrethroids beta-cyfluthrin, etofenprox and permethrin caused mortality between 8.5% and 46.25%. At the moment of application, all the insecticides were highly toxic to the wasps, causing mortality higher than 80%. In the absence of rain, all the insecticides continued to cause high mortality to the wasps for 30 days after the application. The toxicity of spinosad and methamidophos on both wasp species; beta-cyfluthrin on P. sylveirae and chlorfenapyr and abamectin on P. scutellaris, decreased when the plants received 4 mm of rain. In contrast, the other insecticides only showed reduced toxicity on the wasps when the plants received 125 mm of rain.

Sampling plans for pest mites on physic nut.

The starting point for generating a pest control decision-making system is a conventional sampling plan. Because the mites Polyphagotarsonemus latus and Tetranychus bastosi are among the most important pests of the physic nut (Jatropha curcas), in the present study, we aimed to establish sampling plans for these mite species on physic nut. Mite densities were monitored in 12 physic nut crops. Based on the obtained results, sampling of P. latus and T. bastosi should be performed by assessing the number of mites per cm(2) in 160 samples using a handheld 20× magnifying glass. The optimal sampling region for T. bastosi is the abaxial surface of the 4th most apical leaf on the branch of the middle third of the canopy. On the abaxial surface, T. bastosi should then be observed on the side parts of the middle portion of the leaf, near its edge. As for P. latus, the optimal sampling region is the abaxial surface of the 4th most apical leaf on the branch of the apical third of the canopy on the abaxial surface. Polyphagotarsonemus latus should then be assessed on the side parts of the leaf's petiole insertion. Each sampling procedure requires 4 h and costs US$ 7.31.

Unveiling the overlooked: Current and future distribution dynamics of kissing bugs and palm species linked to oral Chagas disease transmission.

Chagas disease, a neglected global health concern primarily transmitted through the bite and feces of kissing bugs, has garnered increasing attention due to recent outbreaks in northern Brazil, highlighting the role of oral transmission facilitated by the kissing bugs species Rhodnius robustus and Rhodnius pictipes. These vectors are associated with palm trees with large crowns, such as the maripa palm (Attalea maripa) and moriche palm (Mauritia flexuosa). In this study, we employ maximum entropy (MaxEnt) ecological niche models to analyze the spatial distribution of these vectors and palm species, predicting current and future climate suitability. Our models indicate broader potential habitats than documented occurrences, with high suitability in northern South America, southern Central America, central Africa, and southeast Asia. Projections suggest increased climate suitability by 2040, followed by a reduction by 2080. This study identifies present and future areas suitable for kissing bugs and palm tree species due to climate change, aiding in the design of prevention and management strategies.

Efficacy and Residual Toxicity of Insecticides on Plutella xylostella and Their Selectivity to the Predator Solenopsis saevissima.

We evaluated the efficacy and residual toxicity of nine commercial insecticides on Plutella xylostella and their selectivity to the predator ant Solenopsis saevissima under laboratory and field conditions. First, to test the insecticides' effectiveness and selectivity, we conducted concentration-response bioassays on both species and the mortalities were recorded 48 h after exposure. Next, rapeseed plants were sprayed following label rate recommendations in the field. Finally, insecticide-treated leaves were removed from the field up to 20 days after application and both organisms were exposed to them as in the first experiment. Our concentration-response bioassay indicated that seven insecticides caused mortality ≥80% of P. xylostella: bifenthrin, chlorfenapyr, chlorantraniliprole, cyantraniliprole, indoxacarb, spinetoram, and spinosad. However, only chlorantraniliprole and cyantraniliprole caused mortality ≤30% of S. saevissima. The residual bioassay indicated that four insecticides had a long-lasting effect, causing mortality of 100% to P. xylostella 20 days after application: chlorantraniliprole, cyantraniliprole, spinetoram, and spinosad. For S. saevissima, bifenthrin caused mortality of 100% during the evaluated period. Additionally, mortality rates below 30% occurred four days after the application of spinetoram and spinosad. Thus, chlorantraniliprole and cyantraniliprole are safe options for P. xylostella management since their efficacy favor S. saevissima.

Tamarixia radiata global distribution to current and future climate using the climate change experiment (CLIMEX) model.

The phloem-limited bacteria, "Candidatus Liberibacter asiaticus" and "Ca. L. americanus", are the causal pathogens responsible for Huanglongbing (HLB). The Asian citrus psyllid Diaphorina citri Kuwayama (Hemiptera: Liviidae) is the principal vector of these "Ca. Liberibacter" species. Though Tamarixia radiata Waterston (Hymenoptera: Eulophidae) has been useful in biological control programmes against D. citri, information on its global distribution remains vague. Using the Climate Change Experiment (CLIMEX) model, the potential global distribution of T. radiata under the 2050s, 2070s, and 2090s for Special Report on Emissions Scenarios A1B and A2 was defined globally. The results showed that habitat suitability for T. radiata covered Africa, Asia, Europe, Oceania, and the Americas. The model predicted climate suitable areas for T. radiata beyond its presently known native and non-native areas. The new locations predicted to have habitat suitability for T. radiata included parts of Europe and Oceania. Under the different climate change scenarios, the model predicted contraction of high habitat suitability (EI > 30) for T. radiata from the 2050s to the 2090s. Nevertheless, the distribution maps created using the CLIMEX model may be helpful in the search for and release of T. radiata in new regions.

Modeling climate change impacts on potential global distribution of Tamarixia radiata Waterston (Hymenoptera: Eulophidae).

The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera: Liviidae), is an efficient vector of "Candidatus Liberibacter" species, the causative agents implicated in citrus greening or huanglongbing (HLB). HLB is the most devastating citrus disease and has killed millions of citrus trees worldwide. Classical biological control using Tamarixia radiata Waterston (Hymenoptera: Eulophidae) against ACP has been successful in some regions. Climatic conditions are critical in determining suitable areas for the geographical distribution of T. radiata. However, paucity of information on climate change impacts on the global spread of T. radiata restricts international efforts to manage ACP with T. radiata. We investigated the potential global distribution of T. radiata using 317 native and non-native occurrence records and 20 environmental data sets (with correlation coefficients (|r| > 0.7)). Using the Maximum Entropy model, these data were analyzed for two shared socioeconomic pathways (SSPs) and two time periods (2030s and 2050s). We showed that habitat suitability for T. radiata occurred in all continents except Antarctica. However, the highly suitable areas for T. radiata were found in parts of the Americas, Asia, Africa and Oceania. The climate suitable areas would increase until the 2050s. The predictions showed that mean temperature of coldest quarter and precipitation of warmest quarter were the most important environmental variables that influenced the distribution of T. radiata. The model reliably predicted habitat suitability for T. radiata, which can be adapted in classical biological control programs to effectively manage ACP in an environmentally friendly manner.

Trichomes and hydrocarbons associated with the tomato plant antixenosis to the leafminer.

The objective of this work was to study the density of trichomes and hydrocarbons associated with the resistance by antixenosis of 42 subsamples of tomato plants from the Horticultural Germplasm Bank of the Universidade Federal de Viçosa (HGB-UFV) to Liriomyza trifolii. These subsamples were studied in addition to 'Santa Clara' cultivar, which was used as a standard of susceptibility to leafminers. The evaluated characteristics were the number of mined leaflets per plant, mines per plant, trichome density and chemical compounds in the leaves. Differences were detected among the subsamples in the variables studied. We identified 20 peaks in the chromatograms of leaf hexane extract the subsamples tested. The subsamples HGBs - 216, 813, 985, 987, 991, 992, 993, 1532, 1989, 1991, 2048, 2055, 2064, 2068, 2073, 2075, 2089, 2096 and 2097 were selected as sources of resistance to L. trifolii. The resistance mechanism associated to these subsamples was antixenosis. In addition, the low density of trichomes and the chemical compounds in the subsamples can be possible causes of pest resistance.

Lepidopterans as potential agents for the biological control of the invasive plant, Miconia calvescens.

This work investigated eight species of Lepidoptera associated with Miconia calvescens DC. (Myrtales: Melastomataceae) in Brazil, including six defoliators, Salbia lotanalis Druce (Lepidoptera: Pyralidae), Druentia inscita Schaus (Mimallonidae), Antiblemma leucocyma Hampson (Noctuidae), three Limacodidae species, a fruit borer Carposina cardinata Meyrick (Carposinidae), and a damager of flowers Pleuroprucha rudimentaria Guenée (Geometridae). Based on host specificity and the damage caused to plants, S. lotanalis and D. inscita are the most promising species for biological control of M. calvescens. Furthermore, if C. cardinata and P. rudimentaria have host specificity in future tests, these caterpillars could also be considered as appropriate biocontrol agents.

Synthesis and insecticidal activity of an oxabicyclolactone and novel pyrethroids.

Deltamethrin, a member of the pyrethroids, one of the safest classes of pesticides, is among some of the most popular and widely used insecticides in the World. Our objective was to synthesize an oxabicyclolactone 6 and five novel pyrethroids 8–12 from readily available furfural and D-mannitol, respectively, and evaluate their biological activity against four insect species of economic importance namely A. obtectus, S. zeamais, A. monuste orseis, and P. americana. A concise and novel synthesis of 6,6-dimethyl-3-oxabicyclo[3.1.0]hexan-2-one (6) from furfural is described. Photochemical addition of isopropyl alcohol to furan-2(5H)-one afforded 4-(1'-hydroxy-1'-methylethyl)tetrahydro-furan-2-one (3). The alcohol 3 was directly converted into 4-(1'-bromo-1'-methylethyl)-tetrahydrofuran-2-one (5) in 50% yield by reaction with PBr(3) and SiO(2). The final step was performed by cyclization of 5 with potassium tert-butoxide in 40% yield. The novel pyrethroids 8–12 were prepared from methyl (1S,3S)-3-formyl-2,2-dimethylcyclopropane-1-carboxylate (7a) by reaction with five different aromatic phosphorous ylides. Compounds 6–12 presented high insecticidal activity, with 6 and 11 being the most active. Compound 6 killed 90% of S. zeamais and 100% of all the other insects evaluated. Compound 11 killed 100% of all insects tested.

Concentration-mortality responses of Myzus persicae and natural enemies to selected insecticides.

The toxicity of six insecticides was determined for the peach-potato aphid, Myzus persicae (Hemiptera: Aphididae), and some of its natural enemies - the predatory beetles Cycloneda sanguinea (Coccinellidae) and Acanthinus sp. (Anthicidae), and the wasp parasitoid Diaeretiella rapae (Aphidiidae). Natural enemies from these groups are important natural biological control agents in a number of agroecosystems, and insecticides potentially safe to these non-target organisms should be identified using standardized tests. Thus, concentration-mortality bioassays were carried out with both the aphid and its natural enemies to assess the toxicity and selectivity of acephate, deltamethrin, dimethoate, methamidophos, methyl parathion, and pirimicarb. The latter insecticide was highly selective to all natural enemies tested, and its LC(90) for M. persicae was 14-fold lower than the field rate recommended for control of the aphid in brassica crops. Methyl parathion also showed selectivity to C. sanguinea and Acanthinus sp., but not to D. rapae. Acephate was the least potent insecticide against M. persicae and was equally or more toxic to the natural enemies relative to the aphid. Pirimicarb and methyl parathion were efficient against M. persicae and selective in favor of two of the natural enemies tested. Acanthinus sp. and C. sanguinea were more tolerant to the insecticides than was the parasitoid D. rapae. This study shows that there are selective insecticides that may be compatible with conservation of natural enemies in brassica crops, which is important practical information to improve integrated pest management systems in these crops.