Although whiteflies Tetraleurodes perseae (Nakahara) (Hemiptera: Aleyrodidae) are considered a secondary pest of avocado crops, their presence and the damages that they cause can decrease crop vigor and affect production. The objective of the present work was to determine the population fluctuation and altitudinal distribution of the T. perseae Nakahara whitefly in avocado trees, as well as to determine the number of possible generations in one year. The study was done in three orchards in Morelos state, located at different altitudes, from February 2014 to April 2015. Samplings were done every 21 days from 10 randomly chosen trees in each orchard. The samples were taken randomly from the middle stratus (1.6 m in height) of each tree; in buds or young leaves for the number of adults and leaves only for nymphs. Additionally, two yellow traps (7 × 14 cm) with glue were placed in each tree for adult samplings. Data were collected regarding vegetative budding, rainfall, relative humidity, and temperature. T. perseae was present in all three sampled orchards, with a greater presence in the lowest orchard, during the whole study period. In the orchard with the lowest altitudinal gradient (1,736 masl), 11 whitefly generations developed; 10 generations developed in the medium gradient orchard (1,934 masl); and 8 generations developed in the highest orchard (2,230 masl). The adults showed a positive relationship with regard to vegetative buds, while the nymphs had a negative relationship with regard to relative humidity. The rest of the parameters showed diverse effects on the species depending on the altitude of the orchard.

No abstract

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

-Spiromesifen is an insecticide that inhibits the synthesis of lipids and, in Mexico, its use against the Tomato-Potato Psyllid, Bactericera cockerelli (Sulc), on chili pepper (Capsicum annum), tomato (Lycopersicon sculentum) and potato (Solanum tuberosum) began in 2005; however more information is needed to understand its toxicity on this insect pest. The aim of this research was to determine the toxicity of spiromesifen against each of the biological stages of tomato-potato psyllid, its effect on fertility and viability of eggs deposited by treated females, as well as the female preference to lay eggs on treated and non treated plants. The relative toxicity at 95% mortality (highest LC 95 value /LC 95 value of the respective biological stage) of spiromesifen in egg, nymph 1, nymph 2, nymph 3, nymph 4, and nymph 5 were 517.5; 31316.2; 2950.1; 315.6; 18.2 and 1-fold, respectively. There were no differences in the toxicity of spiromesifen between adult males and females. The number of laid eggs was reduced as the spiromesifen concentration used to treat female increased and egg hatch was reduced in all tested doses. In the "no choice" test, females deposited 38.6 ± 2.01 eggs by leaf of non treated chili pepper type jalapeño, while in the treated with 360 mg L -1 we observed 0.3 ± 0.08 eggs by leaf. In the "choice" test, the oviposition decreased as the dose increased. There were no eggs on plants treated with 2400 mg L -1 of spiromesifen.

-In two fi eld-collected populations of de Bemisia tabaci (Gennadius) B biotype previously selected with the neonicotinoid insecticide thiamethoxam (NEO-R, NEO-N), and a population susceptible to insecticides (SUSC), the level of response to the insecticide thiametoxam, as well as the life and fertility tables were determined. At LC 95 , the NEO-R population showed a resistance ratio (RR 95 ) value of 8.8-fold, an intrinsic rate of increase (r m ) of 0.72. The fi tness of the NEO-R and NEO-N populations in relation to the SUSC was 1.5 and 2.0, respectively. The RR 95 value for NEO-N was 1.9-fold; it´s r m value was 0.082, while in the SUSC population was 0.041. The developmental time of egg and adult were longer in NEO-R population, while the nymph and pupa lasted longer in the NEO-N and SUSC populations. The developmental time was different in the three NEO-R, NEO-N, and SUSC populations with 19.7 d (315.84 degree days or dd), 15.7 d (250.4 dd) and 18.5 d (296.6 d), respectively. The populations previously selected with thiamethoxam did not reproduce faster than their susceptible counterpart.

Seven technical grade insecticides were evaluated against a susceptible population and against two field populations of the potato tuberworm Phthorimaea operculella (Zeller) by topical application to third-instar larvae. Using a standard susceptible laboratory colony, we calculated median lethal doses (LD50) of 0.39, 0.059, 0.12, 0.00022, 0.18, 0.010 and 0.0007 μg/larvae for the insecticides DDT, methyl parathion, ethyl parathion, azinphosmethyl, malathion, carbaryl and permethrin, respectively. By comparison, we found that a wild population from Oyameles, Puebla was susceptible to the insecticides while a population from Leon, Guanajuato was susceptible to DDT, methyl parathion, ethyl parathion, malathion and permethrin, but was resistant to azinphosmethyl and carbaryl.

No abstract

The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is one of the most important pests of cultivated plants. Its control is mainly based on the application of acaricides with concomitant adverse environmental and human health effects. Consequently, we examined the potential of using temperature as an alternative. To that end, we conducted bioassays of the temperature-mortality response of eggs, larvae, protonymphs, deutonymphs, and adult females of T. urticae. Groups of 20 individuals from each stage were placed on 4-cm diameter bean leaf (Phaseolus vulgaris L.) discs. A stream of air at the designated temperature was passed over the disc at a rate of 3.7 ± 1 m s–1) for 2 ± 1 s. Mortality was evaluated at 24 h (larva, protonymph, deutonymph, and female) or 72 h (egg) after exposure. Based on preliminary mortality responses, we selected 10 temperatures with a response range between 0 and 100% mortality. Those were 30, 35, 40, 45, 47, 50, 53, 55, 60, and 65°C [SD, ± 1.5 for each]). In total, 30 replications were conducted, and each repetition included these temperatures and untreated controls. The median lethal temperature ranged from 41.8°C for adult females to 46.9°C for eggs. The lethal temperature to kill 95% of the exposed individuals ranged from 55°C for females to 62.5°C for eggs. There were no survivors at 65°C (eggs), 60°C (larva, protonymph, and deutonymph), or 55°C (adult females).