Sex-specific alterations in adaptive responses of Chironomus columbiensis triggered by imidacloprid chronic and acute sublethal exposures.

The use of imidacloprid is a common pest control practice in the Neotropical region. However, the imidacloprid unintended sublethal effects on Neotropical aquatic non-target arthropods and undesirable consequences for aquatic environments remain unclear. Here, we assessed the susceptibility of Chironomus columbiensis (Diptera: Chironomidae) larvae to the neonicotinoid imidacloprid and evaluated whether sublethal exposure types would trigger sex-dependent adaptive responses (e.g., emergence, body mass, reproduction, wing morphology). We conducted a concentration-mortality curve (96 h of exposure) and established chronic and acute sublethal exposure bioassays. While chronic sublethal exposures consisted of exposing individuals during their entire larval and pupal stages, the acute sublethal exposures represented a single short duration (24 h) exposure episode during either the first or fourth larval instar. Our results revealed that chronic sublethal exposure reduced the body mass of males, while acute sublethal exposures during the first instar resulted in heavier males than those that were not exposed to imidacloprid. Chronic exposure also reduced the reproduction of males and females, while the acute sublethal exposure only affected the reproduction of individuals that were imidacloprid-exposed on their later larval instar. Chronic and acute sublethal exposures did differentially affect the wing properties of C. columbiensis males (e.g., increased size when chronically exposed and highly asymmetric wings when acutely exposed in early larval phase) and females (e.g., highly asymmetric wings when chronically and acutely exposed). Collectively, our findings demonstrated that imidacloprid can cause unintended sublethal effects on C. columbiensis, and those effects are dependent on sex, exposure type, and developmental stage.

Exposures to deltamethrin on immature Chironomus columbiensis drive sublethal and transgenerational effects on their reproduction and wing morphology.

Sublethal exposure to insecticides can trigger unintended responses in non-target insects that may disrupt reproductive and developmental performances of these organisms. Here, we assessed whether sublethal exposure to the pyrethroid insecticide deltamethrin in early life had sublethal and transgenerational effects on the reproduction (i.e., fecundity and fertility) and wing morphology of Chironomus columbiensis, an aquatic insect used as a water quality indicator. We first conducted concentration-response bioassays to evaluate the susceptibility of C. columbiensis larvae to deltamethrin. Our results revealed that deltamethrin toxicity was approximately 7-fold higher when C. columbiensis larvae where exposed to 96 h (LC50 = 0.17 [0.15-0.20] µg/L) than to 24 h (LC50 = 1.17 [0.97-1.43] µg/L). Furthermore, the sublethal exposures (at LC1 = 0.02 µg/L or LC10 = 0.05 µg/L) of immature C. columbiensis resulted in lower fecundity (e.g., reduced eggs production) and morphometric variation wing shapes. Further reduction in fertility rates (quantity of viable eggs) occurred at deltamethrin LC10 (0.05 µg/L). Almost 80% of the fecundity was recovered with only a single recovery generation; however, two subsequent recovery generations were not sufficient to fully recover fecundity in C. columbiensis. Specimens recovered from 98.5% of wing morphometric variation after two consecutive generations without deltamethrin exposure. Collectively, our findings demonstrates that sublethal exposure to synthetic pyrethroids such as deltamethrin detrimentally affect the reproduction and wing shape of C. columbiensis, but also indicate that proper management of these compounds (e.g., concentration and frequency of application) would suffice for these insects' population recovery.

Anatomy of male and female reproductive organs of stink bugs pests (Pentatomidae: Heteroptera) from soybean and rice crops / Anatomia dos órgãos reprodutivos em machos e fêmeas de percevejos praga (Pentatomidae: Heteroptera) das culturas de soja e arroz

Abstract: Pentatomidae comprises a diverse group of stink bugs widely distributed in the Neotropical region. Many species are phytophagous and cause injuries to plants, and can thus be defined as agricultural pests. In this study, the anatomy of the female and male reproductive tracts of three important agricultural pests in Colombia is described: Piezodorus guildinii Westwood, 1837 and Chinavia ubicaRolston 1983, found on soybeans, and Oebalus insularis Stål, 1872, found in rice crops. For that, light microscopy techniques were used. The anatomy of the reproductive tract of sexually mature males of the three species studied consisted of a pair of testes, vas deferens, seminal vesicles, ejaculatory bulb, an ejaculatory duct that opens into an aedeagus, and paired accessory glands. The reproductive tract of females consisted of a pair of ovaries, each with seven telotrophic-meroistic ovarioles, a pair of lateral oviducts, common oviduct, spermatheca, and a genital chamber. Telotrophic ovarioles were comprised of terminal filament, tropharium, vitellarium, and pedicel. Differences in size, color, and position of structures along the reproductive tract were observed between the species examined. Reproductive biology of insects provides informative characters for behavioral and evolutionary studies, as well as useful data for pest control strategies.

Resumo: Pentatomidae compreende um diverso grupo de percevejos amplamente distribuídos na região Neotropical. Muitas espécies são fitófagas e causam algum tipo de injúria em plantas, podendo se configurar como pragas agrícolas. Neste trabalho, descrevemos a anatomia do trato reprodutor de machos e fêmeas em três importantes pragas agrícolas da Colômbia: Piezodorus guildinii (Westwood 1837) e Chinavia ubica (Rolston 1983) na cultura de soja e Oebalus insularis (Stål 1872) na cultura do arroz. Para isto, foram utilizadas técnicas de microscopia de luz. A anatomia do trato reprodutor em machos sexualmente maduros nas três espécies consistiu de um par testículos, vasos deferentes, vesículas seminais, bulbo ejaculatório, um ducto ejaculatório que se abre em um aedeagus e glândulas acessórias pareadas. O trato reprodutor das fêmeas consistiu de um par de ovários, cada um com sete ovaríolos telotróficos-meroísticos, um par de ovidutos laterais, uma espermateca e a câmara genital. Os ovaríolos telotróficos possuíam quatro diferentes regiões: filamento terminal, germário, vitelário e pedicelo. As diferenças entre as espécies foram observadas no tamanho, cor e posição das estruturas ao logo do trato reprodutivo. A biologia reprodutiva de insetos gera caracteres que fornecem informações para trabalhos envolvendo evolução, comportamento e estratégias de controle de pragas.

Trade-off and adaptive cost in a multiple-resistant strain of the invasive potato tuber moth Tecia solanivora.

BACKGROUND: Resistance to pesticides is an evolutionary process that entails, in most cases, substantial consequences to the biology of the resistant populations. In this study we focus on the life history traits of the potato tuber moth Tecia solanivora, an invasive and voracious pest for which resistance to pyrethroid insecticides was recently reported. Marginally resistant and multiple-resistant populations were selected from eight sampled localities in Colombia; the use of a fully susceptible population was not possible since none was recognized in the laboratory or field. The multiple-resistant Siachoque population exhibited a 42-fold resistance to the carbamate insecticide carbofuran, and low levels of resistance to chlorpyrifos, a trend observed in six of the eight tested populations. This population also exhibits 24-fold resistance to permethrin. The marginally resistant population of Gualmatán showed 4-fold resistance to chlorpyrifos. RESULTS: The multiple-resistant population exhibited a 3.8-day shorter developmental time than the susceptible population, but with higher larval mortality. The peak of egg-laying was delayed in the resistant population in 9 days and the population growth rate was lower than that of the susceptible population. CONCLUSION: We hypothesize that the short developmental time of the multiple-resistant population may be an adaptation to minimize exposure to insecticides, which are applied to the soil. This adaptation is likely to require the surviving adults to compensate for the smaller nutrient amounts accumulated by the larvae in investing part of its adult life in securing the necessary resources for late-life egg production. © 2018 Society of Chemical Industry.

Pyrethroid resistance is associated with a kdr-type mutation (L1014F) in the potato tuber moth Tecia solanivora.

BACKGROUND: The Guatemalan potato tuber moth, Tecia solanivora, has been the most important pest species in Hispanico-American potato fields since its first record on potatoes in 1956 in Guatemala. This insect pest has been spreading to other parts of the world, including the Canary Islands in Europe. Tuber moth control relies heavily on the use of insecticides, including pyrethroids. Here, we assessed the likelihood of control failures and performed concentration-response bioassays in five Colombian strains of T. solanivora to evaluate their susceptibilities to the pyrethroid permethrin. RESULTS: Evidence of control failures was observed in four strains tested, which exhibited moderate resistance levels (i.e. ranging from 5.4- to 24.4-fold). However, no spatial dependence was observed between the permethrin LC50 values and the geographic distances among the tuber moth strains. In order to evaluate whether permethrin resistance was mediated by potential mutations in the para-type sodium channels of T. solanivora, the IIS4-IIS6 region of the para gene was PCR amplified and sequenced from the five strains tested. As demonstrated across a range of different arthropod species that exhibited knockdown resistance (kdr), we observed a single point substitution (L1014F) at high frequencies in the para gene of all four resistant strains. CONCLUSION: This is the first identification of a target-site-alteration-based resistance in the Guatemalan potato tuber moth T. solanivora, which is widespread and exhibits high frequencies among geographically distant strains, indicating that pyrethroids are probably becoming ineffective for the control of this pest species. © 2016 Society of Chemical Industry.

New and little known Orthoptera (Ensifera and Caelifera) from the Ñambí River Natural Reserve, Nariño, Colombia.

A preliminary checklist of the Orthopterans from the Ñambí River Natural reserve is presented. A total of 26 species were studied, five new species are herein described: Championica nambiensis n. sp., Cocconotus awa n. sp., Cocconotus levyi n. sp. (Tettigoniidae: Pseudophyllinae), Antillicharis kwaiker n. sp. (Gryllidae) and Brachybaenus nariniensis n. sp. (Gryllacrididae). Three species are recorded from Colombia for the first time (Legua crenulata, Uvaroviella (Holacla) nebulosa and Anabropsis alata) and seven species are new records for Nariño department (Allotettix peruvianus, Ripipteryx ecuadoriensis, Neoconocephalus affinis, Anaulacomera poculigera, Orophus conspersus, Orophus tessellatus and Neocurtilla hexadactyla). Further comments on species distribution and taxonomy are given.

DIAGNÓSTICO DEL USO Y MANEJO DE PLAGUICIDAS EN FINCAS PRODUCTORAS DE CEBOLLA JUNCA Allium fistulosum EN EL MUNICIPIO DE PASTO / DIAGNOSTICS OF PESTICIDES USE AND MANAGEMENT IN PRODUCTIVE GREEN ONION Allium fistulosum FARMS IN THE MUNICIPALITY OF PASTO

El control de plagas y enfermedades en el cultivo de la cebolla en Nariño, se caracteriza por el uso del control químico. Por lo tanto, el objetivo de esta investigación fue identificar las condiciones de uso y manejo de plaguicidas de este cultivo en el corregimiento Buesaquillo, del municipio de Pasto. Para determinar el tipo de productos utilizados se realizó recolección y clasificación de envases vacíos de agroquímicos durante 6 meses. En la zona de estudio se realizaron 200 encuestas con 38 preguntas relacionadas con aspectos socioeconómicos, manejo de cultivo, uso y manejo de plaguicidas y sus riesgos potenciales. Los datos fueron sometidos a análisis de correspondencia múltiple. Se recolectaron 4710 envases vacíos, de los cuales el 46,3% correspondieron a fungicidas, el 12,4% a fertilizantes y el 9,3% a insecticidas. El principal criterio para aplicación fue el recomendado por los almacenes de expendio de agroquímicos (72%), la frecuencia de aplicación depende de las condiciones ambientales que va entre 8 y 15 días, el periodo de carencia en el 80% de los encuestados es de 15 días antes de la cosecha. El 74% de los agricultores expuestos a los plaguicidas son hombres y la mayoría (85,5%) tiene estudios primarios, el 53,5% no entiende la etiqueta del producto y algunos de los encuestados (19%) dicen haber sufrido síntomas de intoxicación, y la mayoría (70%) de los productores queman los envases de los plaguicidas. Bajo las condiciones del presente estudio se concluye que el uso de los plaguicidas es similar entre los encuestados, caracterizándose por su manejo inadecuado, el cual pone en riesgo la salud de los agricultores y amenazan con el equilibrio de este agroecosistema.

Pests and diseases control in green onion cultivation in the department of Nariño is characterized by the use of chemical control. Therefore, the objective of the investigation was to identify the use and management conditions of pesticides on this crop in the small township of Buesaquillo, municipality of Pasto. To determine the type of products used, an empty agrochemical containers collection was carried out during six months. Two hundred surveys, with 38 questions related to socio-economic aspects, crop management, pesticide use and management and its potential risks, were carried out in the study zone. The data were submitted to multiple correspondence analyses. A total of 4710 empty containers were recollected, of which 46.3% corresponded to fungicides, 12.4% to fertilizers, and 9.3% to insecticides. The main criterion of application was the one recommended by the agrochemicals warehouse sale (72%); frequency of application depends on environmental conditions ranging between 8 and 15 days, and the grace period in 80% of the surveys is 15 days prior to the harvest. 74% of farmers exposed to pesticides are men and most of them (85.5%) have completed their primary school studies; 53.5% do not understand the product's label, some of them (19%) claim to have suffered intoxication symptoms and most producers (70%) burn the pesticide containers. Under the conditions of this study it can be concluded that the use of pesticides is similar among the surveyed farmers, and is characterized by inadequate management, which puts farmers' health at risk and threatens this agro ecosystem equilibrium.