Resumen El uso de insectos depredadores ha ganado interés para el manejo confiable y ambientalmente seguro de la polilla del tomate, Phthorimaea absoluta (Meyrick) (Lepidoptera: Gelechiidae), una plaga de este cultivo en todo el mundo. Por medio de un estudio con el programa EthoVision® y de ensayos de opción múltiple, repor tamos el comportamiento de búsqueda de presas y la preferencia alimentaria del mírido neotropical Tupiocoris cucurbitaceus Spinola (Hemiptera: Miridae), un agente de control biológico de P. absoluta, cuando se le presentan huevos de la plaga y simultáneamente otras dos especies de presas. T. cucurbitaceus exhibe un comportamiento alimentario generalista. Las ninfas del depredador mostraron inicialmente preferencia por las ninfas de Trialeurodes vaporariorum (Westwood) (Hemiptera: Aleyrodidae) pero consumieron más huevos de P. absoluta y Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) al cabo de 24 h. Los machos de T. cucurbitaceus prefirieron a T. vaporariorum mientras que las hembras no mostraron preferencia por ningún tipo de presa. Además, los individuos no causaron daños directos a las hojas. Los hallazgos enfatizan la importancia de evaluar la oferta de diferentes presas para conocer la efectividad de los agentes de control biológico en el campo. La investigación aporta valiosos conocimientos sobre los hábitos alimentarios de T. cucurbitaceus, respaldando su potencial como agente de control biológico para P. absoluta.

Abstract The use of predatory insects has gained interest for reliable and environmentally safe pest management to control the South American tomato leafminer, Phthorimaea absoluta (Meyrick) (Lepidoptera: Gelechiidae), a pest of tomato crops worldwide. Based on video tracking using EthoVision® software and static feeding multiple-choice tests, we report the prey-searching behavior and feeding preference of the Neotropical mirid bug Tupiocoris cucurbitaceus Spinola (Hemiptera: Miridae), a biological control agent of P. absoluta when presented with its eggs and other two prey species. T. cucurbitaceus exhibits generalist feeding behavior; the nymphs initially showed a preference for Trialeurodes vaporariorum Westwood (Hemiptera: Aleyrodidae) nymphs but consumed more P. absoluta and Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs after 24 h. T. cucurbitaceus males preferred T. vaporariorum throughout the experiment while females showed no preference for any prey. Furthermore, they did not cause significant damage to the leaves. The findings emphasize the importance of evaluating the simultaneous offer of multiple prey types to understand the effectiveness of biocontrol agents in the field. Overall, the research contributes valuable insights into the feeding habits of T. cucurbitaceus, supporting its potential as a biological control agent for P. absoluta in tomato crops.

Abstract Caenorhabditis elegans is a free-living nematode, belonging to the bacterivorous trophic group. Although it was cited in several countries, in different types of ecosystems and in associations with other organisms, the wild habitats of this nematode have not yet been precisely defined. In Argentina, C. elegans was recently isolated from the hoverfly Allograpta exotica, a voracious predator with potential biological control against aphids in horticultural crops. In this frame, the objectives of this study were (i) to characterize it molecularly and morphologically (ii) to report a wild strain of C. elegans for the first time from Argentina, (iii) to present a new ecological niche by associating it with A. exotica and (iv) to evaluate the pathogenicity against these insects. The results of the morphological and molecular analyses made it possible to determine that the isolated nematode was C. elegans, thus establishing the ARGLP1900 wild strain as the first record of this nematode for Argentina. A new association was described, since there are no records of interaction between C. elegans and A. exotica, providing information on a new ecological niche. The new wild strain found in this work, could be appropriate for comparative genomic studies with other C. elegans strains.

ABSTRACT Population variations of predatory hoverflies in agroecosystems depend mainly on the resources that crops and wild vegetation provides them as well as death caused by natural enemies. We identified I) aphidophagous hoverfly species in lettuce and broccoli crops in Buenos Aires, II) the seasonal variations of the immature stages and their larval parasitism, and III) the wild plants, surrounding the crops, visited by adults. Fortnightly, 30 leaves were randomly selected in both crops during 2018-2019 and immature stages of syrphids and aphids per leaf were recorded. Adults were manually collected in patches of the wild plants (during 10 min of direct observations), and plants visited by adults were determined. The hoverflies were Allograpta exótica Wiedemann and Toxomerus duplicatus Wiedemann. Only A. exótica was recorded in crops. The dominant aphids were Myzus persicae (Sulzer) in lettuce and Brevycorine brassicae (L.) in broccoli. Parasitism rates ranged between 8 and 100% and the species were Diplazon laetatorius (Fabricius), in both crops, and Pachyneuron aff. nelsoni only in broccoli. Galinsoga parviflora Cav. and Matricaria chamomilla L. were the wild plants most often visited by hoverflies. This work provides basic information for the control of aphids by hoverflies in the framework of conservation biological control.

RESUMEN Las variaciones poblacionales de sírfidos depredadores en los agroecosistemas dependen principalmente de los recursos ofrecidos por los cultivos y la vegetación silvestre, así como de la mortalidad causada por sus enemigos naturales. En este trabajo identificamos I) las especies de sírfidos afidófagos en lechuga y brócoli, II) las variaciones estacionales de los estados inmaduros y el parasitismo larval, y III) las plantas aledañas a los cultivos más visitadas. Se registraron los estados inmaduros de los sírfidos y los áfidos colectando quincenalmente 30 hojas al azar en cada cultivo durante 2018-2019. Los adultos de sírfidos registrados por observación directa durante 10 minutos en parches de vegetación silvestre, fueron colectados manualmente y se determinaron las plantas visitadas. Los sírfidos fueron Allograpta exótica Wiedemann y Toxomerus duplicatus Wiedemann; solamente la primera especie fue registrada en los cultivos. Los áfidos más abundantes fueron Myzus persicae (Sulzer) en lechuga y Brevycorine brassicae (L.) en brócoli. El parasitismo larval varió entre 8 y 100%, registrándose Diplazon laetatorius (Fabricius) en ambos cultivos, y Pachyneuron aff. nelsoni solo en brócoli. Galinsoga parviflora Cav. y Matricaria chamomilla L. fueron las plantas silvestres más visitadas. Estos conocimientos son relevantes para el control biológico de áfidos por sírfidos en el marco del control biológico por conservación.

Abstract Antagonistic interactions among predators have the potential to dampen top-down impacts on a shared pest. Strong cannibalism by adults and larvae on eggs along with a stronger intraguild predation by Eriopis connexa on Cycloneda sanguinea (Coccinellidae) than vice versa had been documented. The intensity and direction of these interactions could vary with the larval instar. We calculated aggressiveness, attack, and predation rates between larvae in the laboratory and studied both larval mortality and within-plant distribution in plants. Despite high attack rates, larvae of both species usually escaped from predation, except for the fourth vs. second–instar combinations, where the smaller larvae were more vulnerable to predation than the larger. Successful predation by E. connexa fourth-instars on C. sanguinea second-instars frequently occurred. All interactions between larvae became relaxed when extraguild prey were present. The larval mortality within the plants was influenced by the availability of extraguild prey only. Larvae of both species promptly dispersed outside the plant when prey became unavailable. With the extraguild prey present, the larvae of both species initially preferred the plant upper stratum in both combinations, but then dispersed. This study suggests that the defensive capability and larval dispersal could prevent cannibalism and intraguild-predation interactions.

Abstract Laboratory trials were performed to determine the impact of three Neotropical predatory coccinellids (Cycloneda sanguinea, Eriopis connexa and Coleomegilla quadrifasciata) and a minute pirate bug (Orius insidiosus) on Chaetosiphon fragaefolii, an important strawberry aphid pest. The predation on C. fragaefolii nymphs and adults, as well as the time to the first attack of all predators were compared with predation on Aphis gossypii. Predator preferences for prey and aphid defensive behavior were also evaluated. Moreover, the effect of coccinellids on C. fragaefolii population growth was assessed in experimental greenhouse conditions. The predation rate varied among predators, being significantly lower for O. insidiosus than for the coccinellids. Consumption was higher on A. gossypii than on C. fragaefolii, regardless of the aphids developmental stage. The time to the first attack of all predators was longer in the presence of C. fragaefolii. Walking away and cornicle secretion were the most common antipredator behaviors of aphid against coccinellids and O. insidiosus, respectively. Coccinellids preferred A. gossypii over C. fragaefolii, while O. insidiosus showed indifference. Cycloneda sanguinea and E. connexa exhibited the highest suppression effect on the growth rate of C. fragaefolii. Thus, the four predators evaluated could contribute to reduce strawberry aphid populations, especially C. sanguinea and E. connexa.

The blueberry, Vaccinium corymbosum L. (Ericaceae), is a shrub native to the northern Hemisphere introduced in Argentina, where it occupies small cultivated areas mainly in the provinces of Buenos Aires, Entre Ríos and Tucumán. At present, little is known about insects associated with this crop in Argentina. The aim of this study was to identify the species of Chrysomelidae present in blueberry crops in different regions of Argentina, and to present new chrysomelids-blueberry associations. Identification diagnosis, geographical distribution, association with other plants and aspects of their biology is given for each species. Seven species of crop-damaging Chrysomelidae were recorded in blueberry crops of Buenos Aires and Entre Rios. They belong to the subfamilies Galerucinae: Diabrotica speciosa (Germar), Disonychodes exclamationis (Boheman), Caeporis stigmula Germar, and Cacoscelis melanoptera Germar; Eumolpinae: Percolaspis varia (Lefèvre), and Spintherophyta semiaurata (Klug); and Cryptocephalinae: Lexiphanes coenobita Suffrian.

El arándano, Vaccinium corymbosum L. (Ericaceae), es un arbusto nativo del hemisferio Norte, que fue introducido en la Argentina donde ocupa pequeñas áreas cultivadas, principalmente en las provincias de Buenos Aires, Entre Ríos y Tucumán. Hasta la actualidad, se conoce poco sobre los insectos asociados con este cultivo. El objetivo de este trabajo es relevar las especies de crisomélidos presentes en los cultivos de arándano de diferentes regiones, y aportar nuevas asociaciones crisomélidos-arándano para la Argentina. Para cada especie registrada, se brinda la diagnosis para su reconocimiento, su distribución geográfica, la asociación con otras plantas y algunos aspectos de su biología. Se registraron siete especies de Chrysomelidae que utilizan el arándano como recurso alimenticio en las provincias de Buenos Aires y Entre Ríos: subfamilia Galerucinae: Diabrotica speciosa (Germar), Disonychodes exclamationis (Boheman), Caeporis stigmula Germar, Cacoscelis melanoptera Germar; subfamilia Eumolpinae: Percolaspis varia (Lefèvre) y Spintherophyta semiaurata (Klug); y subfamilia Cryptocephalinae: Lexiphanes coenobita Suffrian.

We report for the first time in Argentina the presence of Syncharina lineiceps (Spinola) and it is cited as new record for blueberries crops. For each species of the genus Syncharina Young we provide updated information referred to geographic distribution and plants hosts. A key to identify the species of the genus is presented.

Se cita por primera vez para la Argentina la especie Syncharina lineiceps (Spinola) y se da a conocer como nuevo registro para los cultivos de arándanos. Para cada especie del género Syncharina Young, se proporciona información actualizada referida a la distribución geográfica y las plantas huéspedes. Se propone una clave para identificar las especies del género.