Search

The application of synthetic insecticides remains the most used tool for the management of spotted‐wing drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae). However, management of this pest in the organic production of soft‐skinned fruits is a complex task due to the restricted number of registered products. Here, we assess the toxicity of lime sulfur and evaluate whether lime sulfur‐treated strawberry plants affected the oviposition and development of D. suzukii. Lime sulfur exhibited adequate toxicity to D. suzukii (LC50 = 26.6 mL L−1) without phytotoxicity to strawberry plants. When D. suzukii females were exposed to lime sulfur‐treated plants in no‐choice bioassays, oviposition was significantly (t‐test, P < 0.05) reduced compared with that on untreated plants. In free‐choice bioassays, D. suzukii females laid significantly (paired t‐test, P < 0.05) more eggs on untreated plants. Furthermore, in the free‐choice bioassays, immature development was slower for adults that originated from eggs laid on lime sulfur‐treated plants than from those laid on untreated plants. Lime sulfur showed adequate control and, therefore, has potential for use as a management tool against D. suzukii infestations in organic production systems. This old, alternative insecticide preparation not only caused adult fly mortality, but also reduced the number of eggs laid on lime sulfur‐treated plants.

We propose a shift in the traditional way to teach Entomology for undergraduate and postgraduate courses. We envisage a system in which undergraduate and postgraduate students interact, discussing Entomology outside the classroom. This would get them to actively seek for knowledge, rather than being paternalistically told how they should learn. Such a system does not preclude lectures as a didactic strategy, nor it rules out lecturers as responsible for instructorship. On the contrary, we believe lectures and discussion outside classroom are complementary for effective teaching. Our results show that undergraduate and postgraduate students who interact outside classroom are able to get better grades even when submitted to traditional written tests. Moreover, it seems that postgraduate students who get involved in such a system get permanent jobs faster than those postgraduates not taking part in it. Apparently, the key here was that when discussing outside classroom, students are allowed to think freely, rather than simply accumulating information taught in classroom. In doing so, they transform information into knowledge, and therefore, are able to solve even unforeseen problems.

La concentración letal (CL) es usada para estimar la toxicidad de plaguicidas a artrópodos. Sin embargo, la CL es una medida incompleta de los efectos de los productos sobre poblaciones, pues analiza solamente la mortalidad como parámetro de toxicidad. Se sabe que individuos que sobreviven a la exposición a plaguicidas pueden sufrir efectos subletales. Objetivo: En este trabajo fue estudiado en laboratorio los efectos letales y subletales del caldo sulfocálcico en el crecimiento poblacional de los ácaros T. evansi y T. urticae. Metodología: Los efectos letales fueron estimados a través de test de toxicidad aguda con obtención de curvas dosisrespuesta y sus respectivas concentraciones letales, y los efectos subletales a través de la estimativa de la tasa instantánea de crecimiento poblacional (ri). Resultados: Las concentraciones letales y subletales del caldo sulfocálcico para T. evansi fueron 0,2 y 1,03% del producto, respectivamente, mientras que para T. urticae fueron 5,68 y 23,44% del producto. Conclusiones: El caldo sulfocálcico se presenta como una alternativa para el control de T. evansi, mientras que para T. urticae no es viable económicamente su utilización.AbstractThe lethal concentration (CL) is used to estimate the toxicity of pesticides for arthropods. However, the CL is an incomplete measurement of the effects of products on populations because it analyzes only mortality as a parameter of toxicity. It is known that individuals that survive to exposure of pesticides may suffer sublethal effects. Objective: The lethal and sublethal effects of lime sulfur on the population growth of dust mites T. evansi and T. urticae were studied in laboratory conditions,. Methodology: Lethal effects 63 Luna Azul ISSN 1909-2474 No. 37, julio - diciembre 2013 ©Universidad de Caldas were estimated by using acute toxicity tests to obtain dosageresponse curves and their respective lethal concentrations and sublethal effects were estimated by means of the instantaneous population growth rate (ri). Results: The lethal and sub-lethal concentrations of lime sulphur against T. evansi were 0.2 and 1.03%, respectively, whereas for T. urticae, concentrations were 5.68 and 23.44%. Conclusions: Lime sulfur represents a valuable alternativefor T. evansi control; while for T. urticae is not a viable economically option to be recommended. La concentración letal (CL) es usada para estimar la toxicidad de plaguicidas a artrópodos. Sin embargo, la CL es una medida incompleta de los efectos de los productos sobre poblaciones, pues analiza solamente la mortalidad como parámetro de toxicidad. Se sabe que individuos que sobreviven a la exposición a plaguicidas pueden sufrir efectos subletales. Objetivo: En este trabajo fue estudiado en laboratorio los efectos letales y subletales del caldo sulfocálcico en el crecimiento poblacional de los ácaros T. evansi y T. urticae. Metodología: Los efectos letales fueron estimados a través de test de toxicidad aguda con obtención de curvas dosisrespuesta y sus respectivas concentraciones letales, y los efectos subletales a través de la estimativa de la tasa instantánea de crecimiento poblacional (ri). Resultados: Las concentraciones letales y subletales del caldo sulfocálcico para T. evansi fueron 0,2 y 1,03% del producto, respectivamente, mientras que para T. urticae fueron 5,68 y 23,44% del producto. Conclusiones: El caldo sulfocálcico se presenta como una alternativa para el control de T. evansi, mientras que para T. urticae no es viable económicamente su utilización.AbstractThe lethal concentration (CL) is used to estimate the toxicity of pesticides for arthropods. However, the CL is an incomplete measurement of the effects of products on populations because it analyzes only mortality as a parameter of toxicity. It is known that individuals that survive to exposure of pesticides may suffer sublethal effects. Objective: The lethal and sublethal effects of lime sulfur on the population growth of dust mites T. evansi and T. urticae were studied in laboratory conditions,. Methodology: Lethal effects 63 Luna Azul ISSN 1909-2474 No. 37, julio - diciembre 2013 ©Universidad de Caldas were estimated by using acute toxicity tests to obtain dosageresponse curves and their respective lethal concentrations and sublethal effects were estimated by means of the instantaneous population growth rate (ri). Results: The lethal and sub-lethal concentrations of lime sulphur against T. evansi were 0.2 and 1.03%, respectively, whereas for T. urticae, concentrations were 5.68 and 23.44%. Conclusions: Lime sulfur represents a valuable alternativefor T. evansi control; while for T. urticae is not a viable economically option to be recommended.

In Brazil, smallholders produce the physic nut Jatropha curcas in association with crops such as pumpkin and corn, besides weeds. We evaluated the suitability of pumpkin and corn pollens, as well as pollen from a weed species (Peltaea riedelii), present in physic nut crop, as alternative food to predatory mites Euseius concordis and Iphiseiodes zuluagai. These species are natural enemies of Polyphagotarsonemus latus and Tetranychus bastosi, two important mite pests on J. curcas plants. The survival and oviposition rate of E. concordis and I. zuluagai were evaluated for five days on leaf discs supplied with pollen of pumpkin, corn or P. riedelii. Castor bean pollen (Ricinus communis) was provided to the predators as a control of suitable food. No significant difference on the oviposition rate of both I. zuluagai and E. concordis was observed when they fed with pollen from the three plants. However, the source of pollen affected the survival of the predatory mites. Pumpkin pollen was the worst food for both predatory mites while corn and P. riedelii was a better food. These results indicate the non-suitability of pumpkin pollen as alternative food to I. zuluagai and E. concordis. Corn and P. riedelli are sources of supplementary food to the predatory mites and can sustain predator populations when prey is scarce. En Brazil los pequeños agricultores producen el piñón Jatropha curcas L. asociado con plantaciones de zapallo, maíz, y muchas veces con malezas. Evaluamos la adecuación del polen de zapallo y maíz, así como de la maleza (Peltaea riedelli), frecuente en los cultivos del piñon, como fuente de alimento alternativo para los ácaros E. concordis y I. zuluagai. Estas especies son los enemigos naturales de Polyphagotarsonemus latus y Tetranychus bastosi, dos principales ácaros plagas de plantas de jatropha. La tasa de sobrevivencia y desove de los ácaros E. concordis y I. zuluagai fue evaluada por un período de cinco días en discos de hojas provistas con polen de zapallo, maíz o de P. riedelii. Polen de la planta Ricinus communis fue previsto para los depredadores, como control de alimentación adecuada. No hubo diferencia estadística en la tasa del desove de ambos I. zuluagai y E. concordis cuando alimentados con el polen de las especies evaluadas. No obstante, la fuente de polen afecta la sobrevivencia de los ácaros depredadores. El polen de zapallo fue el peor alimento para ambos ácaros depredadores, contrario al del maíz y la maleza P. riedelii, que fueron los mejores. Los resultados indican que el polen de zapallo es inadecuado como alimento alternativo para I. zuluagai y E. concordis. El maíz y la maleza P. riedelli representan una fuente alimenticia suplementaria para los ácaros depredadores y puede ser importante para sustentar poblaciones de depredadores, por lo menos algunos días, cuando la presa está ausente o escasa.