The maize weevil, Sitophilus zeamais Motschulsky, is considered one of the most important pests of stored grains. Plant powders from nine seasoning spices were tested in the laboratory to control S. zeamais at 0.5, 1, 2 and 4% (w/w). The variables evaluated were mortality and emergence (F1) of adult insects, grain weight loss and grain germination. The experimental design was completely randomized, with four replicates, and the group of treatments was repeated three times. The highest mortality percentages were obtained with Piper nigrum L. at 1% (83.4%), 2% (97.6%) and 4% (100%). The lowest adult insect emergence was obtained with the same treatments more Capsicum annuum var. longum Sendtn., Cinnamomum zeylanicum Blume and Pimpinella anisum L. at 4% (w/w). No significant differences were recorded as regard grain weight loss and germination. All the plant powders tested had a repellent effect on Sitophilus zeamais and no fumigant effect was recorded.

The maize weevil (Sitophilus zeamais Motschulsky) is one of the most widespread pests and causes heavy losses of stored grain throughout the world. Control of this insect is primarily dependent upon continued applications of organophosphorus and pyrethroid insecticides and fumigants as phosphine but the increasing problems with current insecticides drive the need for research and to develop new control methods. The insecticidal effect of leaf powder of tepa, Laureliopsis philippiana (Looser) Shodde, was evaluated against maize weevil under laboratory conditions. The parameters evaluated were adult mortality and emergence, grain weight loss and germination, and residual, repellent and fumigant effect. The highest levels of insect mortality were registered with treatments at 1, 2, and 4%, with values from 94.7 to 100%. Also, it was obtained 0% of adult insect emergence with these concentrations. In all treatments grain weight was less than 5.8 g. Seed germination was not affected. The powder of L. philippiana exhibited repellent effect in all concentrations and did not show fumigant effect. Insecticidal effect of powder remained for 14 d. Finally, we concluded that powder of L. philippiana has great potential for controlling S. zeamais.

The use of acaricides of high toxicity in the production and handling of ornamental plants should be a matter of consumer concern. The susceptibility of two populations of Tetranychus urticae was assessed: one collected from Primula obconica Hance and the other from Convolvulus arvenis L. as susceptible reference strain to the acaricides dicofol, abamectin alone and mixed with the surfactant phosphatidylcholine, azadirachtin, sulfur, pyridaben and fenazaquin. The evaluated parameters were mortality, lethal concentration 50% (LC 50) and 90% (LC 90), lethal time 50% (LT 50) and 90% (LT 90), effectiveness and index of resistance (IR). The experimental design was completely at random. Each treatment had 1 /4, 1 /2, 1, 2 and 4X of the doses indicated by the manufacturer, five replicates and were sprayed with a Potter spray tower. The results showed that the LC 50 for azadirachtin and sulfur was significantly high. Regarding the population from P. obconica, abamectin alone and in mixture with phosphatidylcholine and fenazaquin showed the highest efficiency. Azadirachtin and sulfur were the acaricides showing the slowest activity and the resistance index indicated that the population collected in P. obconica should be considered susceptible to all the evaluated acaricides.

RESUMENEl pimiento boliviano (Schinus molle L.) es un árbol del cual se han identificado metabolitos secundarios con actividad insecticida. El objetivo fue evaluar, en condiciones de laboratorio, la actividad insecticida e insectistática del polvo y aceite esencial de frutos de S. molle sobre Sitophilus zeamais. En los bioensayos de toxicidad por contacto la mayor mortalidad se obtuvo con el aceite esencial al 8,0 % con 96,3% de insectos muertos con una CL 50 de 3,82 mL aceite esencial 100 g -1 maíz (3,82%). A la misma concentración el polvo mostró un 63,8% de mortalidad y una CL 50 de 7,95 g polvo 100 g -1 maíz (7,95%). Ambos tratamientos no afectaron significativamente la germinación ni la pérdida de peso del grano. El aceite esencial en la concentración de 8,0% provocó una completa inhibición en la emergencia mostrando una F 1 de 0% de insectos adultos. Todos los tratamientos fueron repelentes y el mayor efecto antialimentario del aceite esencial se registró con la concentración de 16% con 71,2% de inhibición. Se concluyó que el polvo y aceite esencial de S. molle presentan toxicidad insecticida por contacto y efecto repelente e inhibidor de la alimentación sobre S. zeamais. Palabras clave: pimiento boliviano, gorgojo del maíz, monoterpenos ABSTRACTThe pepper tree (Schinus molle L.) has secondary metabolites with insecticidal activity. The objective of this study was to assess under laboratory conditions the insecticidal and insectistatic activity of fruit powder and essential oil of S. molle against Sitophilus zeamais. In contact toxicity bioassays, the highest mortality was observed with essential oil at a concentration of 8.0%, recording 96.3% of dead insects with an LC 50 of 3.82 mL essential oil 100 g -1 maize (3.82%). Powder at the same concentration showed a 63.8 % of mortality with an LC 50 of 7.95 g powder 100 g -1 maize (7.95%). None of the treatments affected germination or grain weight loss. The essential oil at a concentration of 8.0% caused a complete inhibition of F 1, resulting in 0% of adult insects. All treatments had repellent effects. The highest antifeeding effect observed with the essential oil was recorded at a concentration

The maize weevil (Sitophilus zeamais Motschulsky) and the red flour beetle (Tribolium castaneum Herbst) are two key pests of stored-grain products worldwide. The insecticidal activity of boldo (Peumus boldus Molina) powder, liquid ethanolic and hexanic extracts against S. zeamais and T. castaneum were evaluated under laboratory conditions. The evaluated variables were mortality, emergence of adult insects (F 1 ), and grain weight loss. The experimental design was completely randomized. The mortality in S. zeamais was 100% even at the lowest powder concentration (0.5% w/w), whereas emergence of F 1 adult insects was 0% and grain weight loss was ≤ 0.08%. For T. castaneum, only 8 and 16% w/w powder concentrations reached 100% mortality. The liquid ethanolic and hexanic extracts caused 100% mortality of S. zeamais, whereas only the ethanolic extract reached this value for T. castaneum. Therefore, the powder and the evaluated extracts of P. boldus were toxic for S. zeamais and T. castaneum and are promising against these and other stored-grain pests.