Impaired associative learning after chronic exposure to pesticides in young adult honey bees

Neonicotinoids are the most widespread insecticides in agriculture, preferred for their low toxicity to mammals and their systemic nature. Nevertheless, there have been increasing concerns regarding their impact on non-target organisms. Glyphosate is also widely used in crops and, therefore, traces of this pesticide are likely to be found together with neonicotinoids. Although glyphosate is considered a herbicide, adverse effects have been found on animal species, including honey bees. Apis mellifera is one of the most important pollinators in agroecosystems and is exposed to both these pesticides. Traces can be found in nectar and pollen of flowers that honey bees visit, but also in honey stores inside the hive. Young workers, which perform in-hive tasks that are crucial for colony maintenance, are potentially exposed to both these contaminated resources. These workers present high plasticity and are susceptible to stimuli that can modulate their behaviour and impact on colony state. Therefore, by performing standardised assays to study sublethal effects of these pesticides, these bees can be used as bioindicators. We studied the effect of chronic joint exposure to fieldrealistic concentrations of the neonicotinoid imidacloprid and glyphosate on gustatory perception and olfactory learning. Both pesticides reduced sucrose responsiveness and had a negative effect on olfactory learning. Glyphosate also reduced food uptake during rearing. The results indicate differential susceptibility according to honey bee age. The two agrochemicals had adverse effects on different aspects of honey bee appetitive behaviour, which could have repercussions for food distribution, propagation of olfactory information and task coordination within the nest.Fil: Mengoni Goñalons, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Farina, Walter Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentin

Effects of Sublethal Doses of Imidacloprid on Young Adult Honeybee Behaviour

Imidacloprid (IMI), a neonicotinoid used for its high selective toxicity to insects, is one of the most commonly used pesticides. However, its effect on beneficial insects such as the honeybee Apis mellifera L is still controversial. As young adult workers perform in-hive duties that are crucial for colony maintenance and survival, we aimed to assess the effect of sublethal IMI doses on honeybee behaviour during this period. Also, because this insecticide acts as a cholinergic-nicotinic agonist and these pathways take part in insect learning and memory processes; we used IMI to assess their role and the changes they suffer along early adulthood. We focused on appetitive behaviours based on the proboscis extension response. Laboratory reared adults of 2 to 10 days of age were exposed to sublethal IMI doses (0.25 or 0.50ng) administered orally or topically prior to behavioural assessment. Modification of gustatory responsiveness and impairment of learning and memory were found as a result of IMI exposure. These outcomes differed depending on age of evaluation, type of exposure and IMI dose, being the youngest bees more sensitive and the highest oral dose more toxic. Altogether, these results imply that IMI administered at levels found in agroecosystems can reduce sensitivity to reward and impair associative learning in young honeybees. Therefore, once a nectar inflow with IMI traces is distributed within the hive, it could impair in-door duties with negative consequences on colony performance.Fil: Mengoni Goñalons, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Farina, Walter Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentin

Geographical Range and Laboratory Studies on Apanteles opuntiarum (Hymenoptera: Braconidae) in Argentina, a Candidate for Biological Control of Cactoblastis cactorum (Lepidoptera: Pyralidae) in North America

La polilla de la tuna, Cactoblastis cactorum (Berg) (Lepidoptera: Pyralidae), es una plaga que amenaza las Opuntia spp. nativas de América del Norte. Se han implementado varias estrategias para su control, erradicándola de México pero no de los Estados Unidos, donde ha continuado incrementando su distribución geográfica con éxito. Por lo tanto, se propone un enfoque integrado que incluya al control biológico para regular las poblaciones de C. cactorum en América del Norte. Se realizaron relevamientos de campo del parasitoide recientemente descrito, Apanteles opuntiarum Martínez & Berta, dentro del área de distribución nativa de C. cactorum en Argentina, y se realizaron estudios de laboratorio para desarrollar un protocolo de cría del parasitoide. Apanteles opuntiarum fue el parasitoide más común de C. cactorum y sus distribuciones en el campo coincidieron ampliamente. En el laboratorio, el éxito reproductivo del parasitoide se maximizó cuando una o dos avispas estuvieron expuestas a 30 larvas dentro de un recipiente de 500 ml. Hembras criadas en laboratorio fueron menos exitosas parasitando hospedadores que hembras provenientes del campo. A pesar del éxito logrado en la cría de los parasitoides, obtuvimos una proporción de sexos sesgada hacia machos en los experimentos. Como este sesgo podría estar relacionado a la presencia del parásito reproductivo Wolbachia, tanto la colonia de laboratorio como individuos provenientes del campo fueron analizados y poseían Wolbachia. El presente estudio proporcionó información útil de campo y laboratorio para (1) estandarizar una técnica de cría en laboratorio; (2) realizar estudios de especificidad de hospedadores en condiciones de cuarentena; y (3) seleccionar las poblaciones de parasitoides que mejor coinciden con el clima de las áreas invadidas por C. cactorum en América del Norte.The cactus moth, Cactoblastis cactorum (Berg) (Lepidoptera: Pyralidae), is a pest that threatens native Opuntia spp. in North America. Control tactics developed and implemented against this invasive pest successfully eradicated the moth in Mexico and on barrier islands in the United States. However, with the cancellation of the regional management program in the United States, no control tactics are being implemented to mitigate the expansion of the moth's geographical range. Hence, an integrated approach including biological control is proposed to regulate the population of C. cactorum in North America. Field surveys of the recently described parasitoid, Apanteles opuntiarum Martínez & Berta, were carried out within the C. cactorum native range in Argentina, and laboratory studies were conducted to develop a parasitoid rearing protocol. Apanteles opuntiarum was the most common parasitoid of C. cactorum and their field distributions were similar. In the laboratory, the parasitoid's reproductive success was maximized when one or two female wasps were exposed to 30 host larvae within a 500 ml container. Laboratory reared females were less successful at parasitizing hosts than field collected females. In spite of the success achieved with laboratory rearing, male bias was observed throughout the experiments. Because this bias might be related to the presence of the reproductive parasite Wolbachia, both laboratory colony and field collected individuals were screened and Wolbachia was detected. This study provides useful field and laboratory information on (1) laboratory rearing techniques for A. opuntiarum; (2) developing host specificity test protocols for studies under quarantine conditions; and (3) selecting parasitoid populations that best match the climatic conditions present in the C. cactorum invaded areas of North America.Fil: Mengoni Goñalons, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Varone, Laura. Fundación para el Estudio de Especies Invasivas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Logarzo, Guillermo Alejandro. Fundación para el Estudio de Especies Invasivas; ArgentinaFil: Guala, Mariel. Fundación para el Estudio de Especies Invasivas; ArgentinaFil: Rodriguero, Marcela Silvina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Hight, Stephen D.. United States Department Of Agriculture. Agriculture Research Service; Estados UnidosFil: Carpenter, James E.. United States Department Of Agriculture. Agriculture Research Service; Estados Unido

Effects of the herbicide glyphosate on honey bee sensory and cognitive abilities: Individual impairments with implications for the hive

The honeybee Apis mellifera is an important pollinator in both undisturbed and agricultural ecosystems. Its great versatility as an experimental model makes it an excellent proxy to evaluate the environmental impact of agrochemicals using current methodologies and procedures in environmental toxicology. The increase in agrochemical use, including those that do not target insects directly, can have deleterious effects if carried out indiscriminately. This seems to be the case of the herbicide glyphosate (GLY), the most widely used agrochemical worldwide. Its presence in honey has been reported in samples obtained from different environments. Hence, to understand its current and potential risks for this pollinator it has become essential to not only study the effects on honeybee colonies located in agricultural settings, but also its effects under laboratory conditions. Subtle deleterious effects can be detected using experimental approaches. GLY negatively affects associative learning processes of foragers, cognitive and sensory abilities of young hive bees and promotes delays in brood development. An integrated approach that considers behavior, physiology, and development allows not only to determine the effects of this agrochemical on this eusocial insect from an experimental perspective, but also to infer putative effects in disturbed environments where it is omnipresent.Fil: Farina, Walter Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental. Laboratorio del Grupo de Estudio de Insectos Sociales; ArgentinaFil: Balbuena, María Sol. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental. Laboratorio del Grupo de Estudio de Insectos Sociales; ArgentinaFil: Herbert, Lucila Thomsett. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental. Laboratorio del Grupo de Estudio de Insectos Sociales; ArgentinaFil: Mengoni Goñalons, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental. Laboratorio del Grupo de Estudio de Insectos Sociales; ArgentinaFil: Vázquez, Diego Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental. Laboratorio del Grupo de Estudio de Insectos Sociales; Argentin

Effect of acute imidacloprid (IMI) ingestion on olfactory learning and memory of young honeybee workers.

<p>Bees were submitted to a classical conditioning protocol one hour after being fed with sucrose solution alone (DMSO control; light gray, hollow circles) or with 0 (IMI control; dark gray, hollow circles), 0.25 (darker gray, filled circles) or 0.50 ng (black, filled circles) of IMI dissolved in DMSO. The percentage of bees that extended their proboscis (PER%) towards the odour was quantified over the course of five training trials (Acquisition, left) and a single testing trial fifteen minutes after training (Retention, right). Individuals used were <b>a)</b> 2/3 days old, <b>b)</b> 5/6 days old or <b>c)</b> 9/10 days old. Numbers inside bars indicate sample size. Different letters stand for statistical differences between IMI treatments (<i>p</i> < 0.05).</p

Survival of young honeybee workers after acute exposure to imidacloprid (IMI).

<p>Harnessed bees were exposed to IMI either by contact or orally. Individuals used were 2/3, 5/6 or 9/10 days of age. When bees were topically exposed to IMI, survival was measured 15 minutes and 2 hours after exposure. When they were orally exposed to IMI, survival was measured 2, 20 and 24 hours after exposure. The <i>p</i>-values indicate significance of the factor IMI (two way RM ANOVA).</p><p>Survival of young honeybee workers after acute exposure to imidacloprid (IMI).</p

Relationship between learning performance and sucrose sensitivity of young honeybee workers after having ingested IMI.

<p>Gustatory Response Scores (GRS) plotted against Learning Indexes (LI) obtained during the acquisition phase of the olfactory PER conditioning. Values of each variable correspond to the mean of different groups of bees. Each symbol represents the combination of GRS and LI values for two groups under the same experimental conditions Age group x IMI treatment.</p

Effect of acute imidacloprid (IMI) contact on olfactory learning and memory of young honeybee workers.

<p>Bees were submitted to a classical conditioning protocol fifteen minutes after being topically exposed to 0 (light gray), 0.25 (dark gray) or 0.50 ng (black) of IMI dissolved in DMSO. The percentage of bees that extended their proboscis (PER%) towards the odour was quantified over the course of five training trials (Acquisition, left) and a single testing trial fifteen minutes after training (Retention, right). Individuals used were <b>a)</b> 2/3 days old, <b>b)</b> 5/6 days old or <b>c)</b> 9/10 days old. Numbers inside bars indicate sample size. Different letters stand for statistical differences between IMI treatments (<i>p</i> < 0.05).</p

Insulin effects on honeybee appetitive behaviour

Worker honeybees (Apis mellifera) carry out multiple tasks throughout their adult lifespan. It has been suggested that the insulin/insulin-like signalling pathway participates in regulating behavioural maturation in eusocial insects. Insulin signalling increases as the honeybee worker transitions from nurse to food processor to forager. As behavioural shifts require differential usage of sensory modalities, our aim was to assess insulin effects on olfactory and gustatory responsiveness as well as on olfactory learning in preforaging honeybee workers of different ages. Adults were reared in the laboratory or in the hive. Immediately after being injected with insulin or vehicle (control), and focusing on the proboscis extension response, bees were tested for their spontaneous response to odours, sucrose responsiveness and ability to discriminate odours through olfactory conditioning. Bees injected with insulin have higher spontaneous odour responses. Sucrose responsiveness and odour discrimination are differentially affected by treatment according to age: whereas insulin increases gustatory responsiveness and diminishes learning abilities of younger workers, it has the opposite effect on older bees. In summary, insulin can improve chemosensory responsiveness in young workers, but also worsens their learning abilities to discriminate odours. The insulin signalling pathway is responsive in young workers, although they are not yet initiating outdoor activities. Our results show strong age-dependent effects of insulin on appetitive behaviour, which uncover differences in insulin signalling regulation throughout the honeybee workeŕs adulthood.Fil: Mengoni Goñalons, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Guiraud, Marie. Universitéde Toulouse; FranciaFil: De Brito Sanchez, María Gabriela. Universitéde Toulouse; FranciaFil: Farina, Walter Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentin

Insulin effects on honeybee appetitive behaviour

Data corresponding to the manuscript submitted: Insulin effects on honeybee appetitive behaviou