Toxicity and Metabolism of Zeta-Cypermethrin in Field-Collected and Laboratory Strains of the Neotropical Predator Chrysoperla externa Hagen (Neuroptera: Chrysopidae).

Resistance to pesticides has been studied in several insect pests, but information on the natural enemies of pests-including the Neotropical predator Chrysoperla externa Hagen (Neuroptera: Chrysopidae), a major biological control agent in South America-is lacking. We report here a comparative study between a field-collected strain of C. externa subjected to monthly sprayings of pyrethroids and neonicotinoids and a laboratory strain without exposure to pesticides. The tolerance of both strains against zeta-cypermethrin was similar, and addition of the synergist piperonyl butoxide increased the toxicity by 30% in both strains. Gas-chromatography analyses and mixed-function-oxidase measurements indicated similar values in both strains and also confirmed the key role of oxidative metabolism in this species. Because C. externa has maintained a tolerance to zeta-cypermethrin without previous pesticide exposure, this species could potentially be mass-reared and released in fields in the presence of pesticide pressure.

Biological activity of three alkyl cinnamates on young larvae of Tuta absoluta.

The "tomato moth," Tuto absoluta (Meyrick) (Lepidoptera: Gelechiidae), is a neotropical oligophagous insect considered a key pest of tomato crops. It was detected in Europe seven years ago and quickly spread to several regions of Asia and North Africa. In Argentina, its control is done by chemical pesticides mainly. The indiscriminate use of chemical broad spectrum pesticides have caused several problems in the control of this pest due to resistance mechanism involved to several insecticides including pyrethroids, organophosphates and biopesticides. In this context, the searching and evaluation of new compounds- compatible with integrated pest management programs- has become relevant. Within the phenylpropanoids, alkyl cinnamates, whether natural or synthetic, have been reported with biological activity: repellence, antifeedant and insecticide. Therefore, the cinnamates could be a valuable alternative to replace the conventional insecticides. The aim of this work was to study the antifeedant effect of three alkyl cinnamates (methyl, ethyl and propyl cinnamate) on the consumption rate patterns of second instar larvae of T. absoluta. A series of concentrations of each compound (100, 250 and 500 micrograms/milliliter) were prepared using acetone (analytical grade) - distilled water as solvent and a surfactant (Tween 80) was added to each solution to improve the wet of leaves. Tomato leaf disks of 2 cm diameter were treated by immersion in each solution during 15 seconds. Afterward, the treated discs were dried under fume hood and each disk was placed in a plastic capsule. A larva with 6-8 hours of starvation was added to each experimental unit. Each treatment was replicated between 24-30 times. The area consumed by each larva was measured after 24, 48 and 72 hours post-treatment. We also evaluated development time, weight of the pupa, adult emergence, fecundity and fertility as sublethal effects. The results were analyzed using ANOVA test. None of the compounds tested at the aforementioned concentrations exhibited insecticidal effect. However, ethyl cinnamate showed a strong antifeedant effect. The results observed on the leaf consumption and other sublethal effects assessed will be discussed. According to these preliminary results, further studies are needed to complete its toxicological profile by other exposure methods.

Toxicity of cypermethrin on the neotropical lacewing Chrysoperla externa (Neuroptera: Chrysopidae).

The generalist predator Chrysoperla externa (Neuroptera: Chrysopidae) is distributed in the Neotropical Region and presents a strong potential as a biological control agent due to its easily rearing, high voracity and tolerance to several pesticides. This species feeds on relevant pests such as aphids, whiteflies, trips and various lepidopterans. In Argentina, an indiscriminate chemical control with broad spectrum pesticides is still the first option for controlling pests causing resistance problems and reduction of beneficial organisms. Therefore, it would be desirable that predators or parasitoids develop tolerance or resistance as phytophagous pests for their maintenance in the agricultural ecosystems. The objective of this work was to evaluate the tolerance of C. externo to the pyrethroid cypermethrin by topical exposure in laboratory conditions. The symptoms evaluated were tremors, movement, knockdown, inability to walk due to being glued. Recovery from poisoning symptoms was also evaluated. Six different concentrations of the pesticide, including the full field one, were tested. The exposure method was by topical applications on third larval instar. A low toxicity on larvae at 24 h post-treatment was observed, even at the highest concentration evaluated. Most of treated individuals looked normal at 24 h post-treatment; those who were knocked down showed a complete recovery between 48 and 72 h post-treatment. C externa demonstrated a high tolerance to pyrethroids. This could be due to the activity involved in pyrethroids biotransformation (for example, esterases and mixed-function oxidases), or to a low sensitivity of the molecular target. Future studies should be addressed at biochemical and molecular levels to complete our knowledge about insecticide effects on this predator.

Preliminary studies of effectiveness and selectivity of Movento on Bemisia tabaci and its parasitoid Eretmocerus mundus.

The Bemisia tabaci Gennadius (Homoptera:Aleyrodidae) biotype complex is a key pest of several worldwide crops. The management and control of this pest has become difficult mainly due to its high reproductive rate and capacity to develop resistance to broad spectrum insecticides. In Argentina B. tabaci whitefly, causes economic losses in most areas of agricultural production. Eretmocerus mundus Mercet (Hymenoptera:Aphelinidae) is the most important parasitoid of B. tabaci and is commercialized as a biocontrol agent, mainly in Europe. Conservation of this biological control agent in Argentinean orchards requires the adoption of sustainable pest management practices due the negative impact of traditional pesticides on non-target organisms. Spirotetramat (Movento) belongs to a new class of pesticides that acts as a lipid biosynthesis inhibitor and claims to be selective towards natural enemies. The objectives of this work were 1) to evaluate the effectiveness of spirotetramat on eggs and nymphs of B. tabaci and 2) to determine the selectivity of spirotetramat towards E. mundus. Whitefly's eggs and nymphs (first nymphal settled instar) were exposed to the insecticide by foliar immersion whereas parasitoid adults (6 days old) were exposed to the insecticide by residual method for one hour, to simulate exposure of the parasitoid to the insecticide in the field. Lethal and sublethal effects of the insecticide were recorded daily. These preliminary studies have shown a high effectiveness of spirotetramat on the first nymphal instar of B. tabaci as well as a high selectivity for the pest in comparison to the parasitoid adults showing a low acute toxicity to them. These results suggest Movento could be included in Integrated Pest Management programs although more studies are required to complete its ecotoxicological profile.

Side-effects of glyphosate on the life parameters of Eriopis connexa (Coleoptera: Coccinelidae) in Argentina.

In Argentina, transgenic soybean crop (Roundup Ready, RR) has undergone a major expansion over the last 15 years, with the consequent increase of glyphosate applications, a broad-spectrum and post emergence herbicide. Soybean crops are inhabited by several arthropods. Eriopis connexa Germar (Coleoptera: Coccinelidae) is a predator associated to soybean soft-bodies pest and have a Neotropical distribution. Nowadays, it is being considered a potentially biological control agent in South America. The objectives of this work were to evaluate the side-effects of glyphosate on larvae (third instar) and adults of this predator. Commercial compound and the maximum registered concentrations for field use were employed: GlifoGlex 48 (48% glyphosate, 192 mg a.i./litre, Gleba Argentina S.A.). The exposure was by ingestion through the treated prey (Rophalosiphum padi) or by drinking treated water during 48 h for treatment of the adult. The herbicide solutions were prepared using distilled water as solvent. The bioassays were carried out in the laboratory under controlled conditions: 23 +/- 0.5 degrees C, 75 +/- 5% RH and 16:8 (L:D) of photoperiod. Development time, weight of pupae, adult emergence, pre-oviposition period, fecundity and fertility were evaluated as endpoints. Larvae from glyphosate treatment molted earlier than controls. In addition, the weight of pupae, longevity, fecundity and fertility were drastically reduced in treated organisms. The reductions were more drastic when the treatments were performed at the third larval stage than as adult. The reproduction capacity of the predator was the most affected parameter and could be related to a hormonal disruption by glyphosate in the treated organisms. This work can confirm the deleterious effects of this herbicide on beneficial organisms. Also, it agrees with prior studies carried out on other predators associated to soybean pest, such as Chrysoperla externa (Neuroptera: Chrysopidae) and Alpaida veniliae (Araneae: Araneidae).

Compatibility of a Melia azedarach extract with Eriopis connexa (Coleoptera: Coccinellidae).

The integrated pest management (IPM) premises claim for a joint use of beneficial organisms (parasitoids and predators) and selective pesticides. Botanical pesticides are being considered as selective pesticides. During the last 20 years of the 20th century, the plant family Meliaceae was identified as a promising source of compounds with insect-control properties. The Chinaberry tree, Melia azedarach L., is a deciduous tree native to Persia, India, and China, but has been cultivated in many countries including Africa, Australia, and the Americas. It is a source of tetranortriterpenoid compounds called meliatoxins, which have similar structures and insecticidal activities compared to azadirachtin. Eriopis connexa Germar (Coleoptera: Coccinelidae) is a native predator from the Neotropical Region. It is a beneficial organism associated to several agro-ecosystems, feeding on soft-bodies pest such as aphids, whiteflies and thrips. In horticultural crops, it has been observed to feed on worldwide important pest such as Bemisia tabaci Gennadius (Heteroptera: Aleyrodeidae) and Myzus persicae L. (Heteroptera: Aphididae), both of them considered as virus vectors. The objectives of this work were to evaluate the side-effects of M. azaderach (Meliaceas) extract on eggs, larvae and adults of Eriopis connexa. Extracts from unripe fruits (1%, w/w, obtained by the CEPROCOR, Cordoba-Argentina) were employed for ecotoxicological bioassays. The exposure method was by immersion for eggs and by ingestion of drinking water for adults. The botanical extract solutions were prepared using distilled water as solvent and a tensioactive (Tween 20) for topical application. The bioassays were carried out in the laboratory under controlled conditions: 23 +/- 0.5 degrees C temperature, 75 +/- 5% RH and 16:8 (L:D) photoperiod. Hatching, development time, adult emergence, pre-oviposition period, fecundity and fertility were evaluated as endpoints. No detrimental effects were observed in treated organisms irrespective of the exposure way and development stage. According to these preliminary results, M. azaderach fruit extracts can be compatible with E. connexa for pest control. However, future studies should be addressed to conclude about its toxicity on beneficial organisms.

Sindrome de Sjogren y linfoma. A proposito de dos casos / Sjogren Syndrome and lymphoma

El conocimiento de las enfermedades hematologicas malignas asociadas a enfermedades reumaticas es fragmentario e incompleto. Se presentan dos casos de linfoma coexistiendo con Sindrome de Sjogren. El primer caso se trata de un linfoma de celulas grandes de alto grado de malignidad asociado a un sindrome de Sjogren secundario a enfermedad mixta del tejido conectivo. El segundo caso es el de un linfoma nodal de pequeñas celulas y bajo grado de malignidad, que plantea diagnostico diferencial entre asociacion de patologia autoinmune y linfoma, o bien de un cuadro Sjogren like producido por enfermedad hematologica primaria

Sindrome de Sjogren y linfoma. A proposito de dos casos / Sjogren Syndrome and lymphoma

El conocimiento de las enfermedades hematologicas malignas asociadas a enfermedades reumaticas es fragmentario e incompleto. Se presentan dos casos de linfoma coexistiendo con Sindrome de Sjogren. El primer caso se trata de un linfoma de celulas grandes de alto grado de malignidad asociado a un sindrome de Sjogren secundario a enfermedad mixta del tejido conectivo. El segundo caso es el de un linfoma nodal de pequeñas celulas y bajo grado de malignidad, que plantea diagnostico diferencial entre asociacion de patologia autoinmune y linfoma, o bien de un cuadro Sjogren like producido por enfermedad hematologica primaria (AU)