Analía Salvatore

Toxic effects of lemon peel constituents on Ceratitis capitata

A series of experiments were conducted to evaluate the toxicity of lemon peel extracts incorporated into mediterranean fruit fly Ceratitis capitata diet. Extracts were obtained with different solvents: diethyl ether, ethyl acetate, and methanol. All three extracts were toxic to some extent; the diethyl ether extract was selected for further studies. Ether extracts of lemon peel were prepared weekly over a 2-month period, from fruits collected on the 1st d of the bioassay. Weekly GC-MS and UV analyses of the extracts demonstrated that the concentration of citral and coumarins decreased in the peel after harvest. We conducted a series of bioassays to evaluate the toxicity of the ether extract, and mixtures of this extract with citral, 5,7-dimethoxycoumarin, and linalool incorporated to C. capitata larvaes natural diet (lemon slices endocarp) at a concentration of 250 μg/g of diet. Significant larvicidal activity can be obtained from a fresh lemon peel extract; however, when the extract was obtained from stored lemons, toxicity decreased. Addition of small amounts of citral or 5,7-dimethoxy- coumarin, and linalool to the stored lemon peel extract would bring back the toxicity to the rates of fresh lemons extracts. Finally, female adults of C. capitata fed on diets containing additional amounts of ether extract, 5,7-dimethoxycoumarin, and linalool, were exposed to different photoperiods to test for phototoxicity. The treatment was toxic and affected the oviposition capacity of females depending on photoperiod.

Effects of p-Vinylphenyl Glycosides and Other Related Compounds on the Oviposition Behavior of Ceratitis capitata

Elaphoside-A [p-vinylphenyl (β-d-glucopyranosyl)-(1→3)-β-d-allopyranoside], a Mediterranean fruit fly oviposition deterrent, was previously isolated from an Argentine collection of the fern Elaphoglossum piloselloides. In order to establish the structural requirements for the observed oviposition inhibition, we synthesized and characterized 4 known and 21 new aromatic glycosides structurally related to elaphoside-A. Their effects on the oviposition behavior of Ceratitis capitata females are discussed.

Trichogramma (Hymenoptera: Trichogrammatidae) species, egg parasitoids of Diatraea saccharalis (Lepidoptera: Crambidae) on sugarcane (Poales: Poaceae) in Argentina.

Summary The aim of this study was to identify egg parasitoids of Diatrea saccharalis F., sensu Guenée (Lepidoptera: Crambidae) in sugarcane in Tucumán, Argentina. We report a new host—parasitoid association of Trichogramma atopovirilia Oatman & Platner (Hymenoptera: Trichogrammatidae) attacking D. saccharalis and the first record of Trichogramma galloi Zucchi from Argentina. Additionally, Trichogramma pretiosum Riley was recorded in this survey. Sumario El objetivo de este estudio fue identificar los parasitoides de huevos de Diatraea saccharalis F., sensu Guenée (Lepidoptera: Crambidae) en caña de azúcar en Tucumán, Argentina. Se reporta una nueva asociación hospedero parasitoide de Trichogramma atopovirilia Oatman & Platner (Hymenoptera: Trichogrammatidae) sobre D. saccharalis y es el primer registro de Trichogramma galloi Zucchi para Argentina. Además, se registró la presencia Trichogramma pretiosum Riley en este relevamiento.

Insecticidal effects of Vernonanthura nebularum against two economically important pest insects

Vernonanthura nebularum (Cabrera) H. Rob. (Asteraceae), an endemic species from the north of Argentina, is a rich source of elephantopus-type sesquiterpene lactones. These compounds have proved to be promising antiparasitic agents, but there is no report about their action against pest insects. In this work we studied for the first time the antifeedant and toxic effects of V. nebularum natural products against the fall army warm Spodoptera frugiperda Smith and the oviposition deterrent activity against the fruit fly Ceratitis capitata Wiedemann. As a result, we found that extracts, fractions composed of sesquiterpene lactones and pure sesquiterpene lactones altered larval feeding behavior in the food choice test. Nutritional parameters of S. frugiperda larvae were also affected. Fraction II (300 μg/g of diet.), containing compounds 1, 2 and 3, was the most toxic substance with 80% pupal mortality and wing malformations in adults. In oviposition deterrent experiments against Ceratitis capitata, we observed a moderate effect at 30 μg/cm2 of the test compound. The most active substances were the methanolic extract, dichloromethane subextract and lactone 2. According to our results, V. nebularum natural products could be used for maximizing the effectiveness and specificity in future insecticide design with specific or multiple target sites, while ensuring the economic and ecological sustainability, in addition to combat the increasing resistance rates developed by synthetic pesticides.

Acrotomopus atropunctellus (Coleoptera: Curculionidae) preference for large sugarcane shoots mitigates damage to sugarcane crop

Summary The sugarcane weevil, Acrotomopus atropunctellus (Boheman) (Coleoptera: Curculionidae) is an increasingly important sugarcane pest in Argentina. Its emergence period overlaps with early stages of sugarcane phenology. This research assessed the preference of A. atropunctellus for shoot size and the effect of damage on shoot survival. Acrotomopus atropunctellus preferred to feed on large- and mediumsized shoots, regardless of sex. However, older plants were resistant to injury. Also, the number of punctures produced by females was 1.6 times greater than that produced by males. Avoiding late planting or harvest dates could be a useful tactic for mitigating A. atropunctellus incidence in sugarcane crops.

Impacts of Crop Residue on Damage by Sugarcane Pests During the Tillering Phase in Argentina

Abstract One of the most important recent changes in sugarcane cultural practices in Tucumán, Argentina, is the adoption of the practice of green-cane harvesting, which involves harvesting the sugarcane crop in the absence of burning. The objective of this study was to assess the impact of the post-harvest crop residue (also sometimes known as “trash blanket”) on Elasmopalpus lignosellus (Zeller) (Lepidoptera: Pyralidae) and Pseudaletia unipuncta Haworth (Lepidoptera: Noctuidae) population dynamics in sugarcane. The study was conducted in ratoon crops for 3 growing seasons (2011, 2012, and 2013) and at 3 locations in the state of Tucumán, Argentina. The treatments consisted of rows with the crop residue burned and the crop residue retained. Removal of the crop residue by burning, compared with retention, resulted in significantly greater crop damage by E. lignosellus in all locations and years. In contrast, damage by P. unipuncta was observed exclusively on plots where crop residue was retained. Comparing the pest status of 2 insects, E. lignosellus seems to be more consistently deleterious to sugarcane yield than P. unipuncta, and chemical control of this species is not very effective. Therefore, leaving the crop residue in place seems to be the most appropriate crop management approach, although it is important also to monitor P. unipuncta populations in order to implement control should it be necessary.