Experiments were conducted to determine the impact of twospotted spider mite, Tetranychus urticae Koch, on cotton injury and yield. Artificial infestations were initiated at the three leaf stage of cotton growth and removed after specified durations of infestation. Yields were reduced for durations of infestation 21 days or greater. In a second experiment, the interactions between twospotted spider mite, thrips, at-planting insecticides, and foliar insecticides were studied to determine their impact on cotton yields. Twospotted spider mites and thrips reduced cotton yield. In a third experiment, twospotted spider mites were released from a central point in 0.024 hectare blocks of cotton and injury was recorded at various distances from that point. Injury was clearly visible seven meters from the infestation point within 16-28 days after infestation. Twospotted spider mites caused significant yield losses in cotton in all of these experiments.

Gorse, Ulex europaeus, is a serious weed of agriculture and forestry in New Zealand. The mite Tetranychus lintearius feeds on gorse in Europe and was released in New Zealand during autumn 1989 as a potential biological control agent. The aim of my laboratory study was to increase available knowledge on its development and aggregation. As the quality of gorse declined as a food resource (as indicated by chlorophyll content) a significant decline in egg production, and an increase in development time of mites was found. Mean egg production at 15℃ ranged from 37.8 to 45.2 eggs/female over 10 days in the experimental treatments and development time from 39.2 to 43.3 days. Density of adult female mites (1, 2, 5, 10, 15, 20/spine) also had a significant effect on the number of eggs produced/female over ten days (mean daily egg production/female, 0.78-0.88). Mean development time from egg to adult decreased from 40.6 to 39 days as density increased from 1 to 50 mites/spine. The resident New Zealand strain of T lintearius, imported originally from Cornwall, is now widely established but has not established successfully on the west coast of the South Island or in the north of the North Island. Four new strains recently introduced from coastal Portugal and Spain, areas climatically similar to these New Zealand regions, may be more successful. Thus, although egg production and survival of all strains were significantly reduced when subjected to daily periods of simulated rainfall in laboratory experiments, those of the newly introduced strains were least affected. Laboratory experiments with the resident New Zealand and Cambados strains also showed that individuals aggregated actively at 10-20℃, but the latter aggregated more strongly at these temperatures. This strong aggregation behaviour may increase survival in warm, wet climates and suggests that Cambados strain mites could become established and so increase gorse control in Westland and Northland.

Gorse, Ulex europaeus, is a serious weed of agriculture and forestry in New Zealand. The mite Tetranychus lintearius feeds on gorse in Europe and was released in New Zealand during autumn 1989 as a potential biological control agent. The aim of my laboratory study was to increase available knowledge on its development and aggregation. As the quality of gorse declined as a food resource (as indicated by chlorophyll content) a significant decline in egg production, and an increase in development time of mites was found. Mean egg production at 15℃ ranged from 37.8 to 45.2 eggs/female over 10 days in the experimental treatments and development time from 39.2 to 43.3 days. Density of adult female mites (1, 2, 5, 10, 15, 20/spine) also had a significant effect on the number of eggs produced/female over ten days (mean daily egg production/female, 0.78-0.88). Mean development time from egg to adult decreased from 40.6 to 39 days as density increased from 1 to 50 mites/spine. The resident New Zealand strain of T lintearius, imported originally from Cornwall, is now widely established but has not established successfully on the west coast of the South Island or in the north of the North Island. Four new strains recently introduced from coastal Portugal and Spain, areas climatically similar to these New Zealand regions, may be more successful. Thus, although egg production and survival of all strains were significantly reduced when subjected to daily periods of simulated rainfall in laboratory experiments, those of the newly introduced strains were least affected. Laboratory experiments with the resident New Zealand and Cambados strains also showed that individuals aggregated actively at 10-20℃, but the latter aggregated more strongly at these temperatures. This strong aggregation behaviour may increase survival in warm, wet climates and suggests that Cambados strain mites could become established and so increase gorse control in Westland and Northland.

Thesis (B.Sc.(Hons.)) -- University of Adelaide, Dept. of Entomology, 1972.

Thesis (Ph.D.) -- University of Western Sydney, Hawkesbury, 2000. / "A thesis presented in fulfilment of the requirement for the degree of Doctor of Philosophy" Bibliography : leaves 160-183.

Tez (Yüksek Lisans) - Süleyman Demirel Üniversitesi, Fen Bilimleri Enstitüsü, Bitki Koruma Anabilim Dalı, 2008. / Bibliyografya var.

Doctor of Philosophy / Department of Entomology / David C. Margolies / James R. Nechols / Foraging traits such as prey consumption rate and the efficiency with which predators convert their prey into offspring are important determinants of local predator-prey dynamics. However, in environments with patchy prey distribution, predator dispersal and aggregation in response to prey-induced volatile cues becomes more critical. My dissertation addressed predator-prey population dynamics in response to variation in four foraging traits in the predatory mite, Phytoseiulus persimilis (Acari: Phytoseiidae): consumption rate, conversion efficiency, dispersal, and olfactory response related to prey. The dispersal response and olfactory sensitivity in predatory mites is modified by prey-related cues. For example, the dispersal response increased with decreasing prey density in a patch and increasing prey-related volatiles from outside the prey patch. The olfactory response of predatory mites also increased with increasing numbers of prey per plant or with the length of time a plant was infested by prey. These results formed the basis for development of bioassays used to examine genetic variation in dispersal and olfactory response of predatory mites. Through artificial selection I documented additive genetic variation in all four traits. After relaxation of selection, high-level phenotypes were stable compared to their low counterparts. There were significant genetic correlations between some of the foraging traits. However, there were no correlations between foraging traits and life-history traits. The existence of genetic variation and covariation among the foraging traits suggests that predatory mites must be able to adopt different foraging strategies in the evolution of prey-finding in a tritrophic system. High consumption, high conversion efficiency and high dispersal response phenotypes interacted differently with prey in a spatially complex landscape. All foraging traits were comparable in terms of predator-prey densities and plant damage; but they were lower than the unselected control. Spatial association and correlation analysis showed that all foraging traits were positively associated with prey; but the strongest association was observed for the high conversion efficiency and dispersal lines. The variability in foraging behaviors of the predatory mite affects its ability to locate patchily distributed prey, thereby influencing foraging efficiency and population dynamics. This research provides new information about the critical link between predator foraging and population dynamics relevant to biological control.

Temperature effects on the biology of Tetranychus cinnabarinus (Boisduval) and Typhlodromus occidentalis (Nesbitt) (Acarina: Phytoseiidae) were studied in the laboratory. Temperature had a definite effect on the developmental time, longevity and survival of adult females, and duration and rate of oviposition in both T. occidentalis and T. cinnabarinus. Increases in temperature significantly decrease developmental time, pre-oviposition periods, oviposition duration and rate, and the longevity and survival rates of both adult females. However, the daily consumption rate of T. occidentalis protonymph, deutonymph and adult gravid female increased significantly with an increase in temperature. Mean generation times decreased for both mites with an increase in temperature. The intrinsic rate of natural increase rose with each temperature increase. However, the r(m) of T. occidentalis was less than that for T. cinnabarinus at all temperature regimes, and it decreased from the 26.6° C regime to the 30.5° C regime. Of the three temperatures studied, 22.7°, 26.6°, and 3.5° C, 22.7° C proved to be the optimum for the predator to maintain control over the prey.

Los campos de cultivo agrícola se ven afectados en la producción por diversos factores, entre los cuales se encuentra el ataque de plagas de insectos, siendo una medida para su control y exterminio el uso de insecticidas sintéticos, sin embargo, la mayoría genera una alta contaminación ambiental. Debido a esto, los bioinsecticidas de origen vegetal surgieron como una alternativa menos contaminante por su rápida degradación en el ambiente y baja peligrosidad para el hombre. El presente trabajo evaluó la toxicidad de los extractos acuosos, etanólicos y hexánicos de las hojas de Minthostachys mollis (Lamiaceae) “muña” y semillas de Annona muricata (Annonaceae) “guanábana”, Lupinus mutabilis (Fabaceae) “tarwi” y Chenopodium quinoa (Chenopodiaceae) “quinua” sobre hembras adultas del ácaro Tetranychus urticae (Trombidiformes: Tetranychidae) “arañita roja” y larvas del primer instar de Chrysoperla externa (Neuroptera: Chrysopidae) “león de áfidos”. Se emplearon dos concentraciones para todos los extractos: 10% y 20% (p/v), en un periodo de exposición entre las 24 y 72h. Los datos obtenidos fueron sometidos al análisis de varianza (ANDEVA) y la prueba post hoc de Duncan con un nivel de significancia de p≤0,05. Los parámetros de toxicidad se observaron en los valores NOEC (Concentración sin efecto observado) y LOEC (Concentración más baja con efecto observado). Se realizó el screening fitoquímico de los extractos botánicos empleados en los bioensayos. El extracto acuoso de M. mollis y el extracto etanólico de C. quinoa, ambos al 20% de concentración, causaron mortalidades en T. urticae del 28,98% y 29,63%, respectivamente. Los extractos hexánicos de A. muricata y M. mollis no presentaron actividad acaricida. El extracto etanólico de M. mollis registró la mayor toxicidad de todos los extractos evaluados a las 72h de exposición en C. externa, con una mortalidad del 75,76%. El extracto hexánico de A. muricata no produjo mortalidad en este insecto a las 24, 48 y 72h de exposición. La diferenciación en toxicidad (mayor a menor) de los extractos vegetales para C. externa fue: etanólico> acuoso> hexánico. Según el CR (cociente de riesgo) obtenido a las 48h de exposición, los extractos acuosos no representaron un riesgo en la mortalidad de C. externa. La secuencia de mayor a menor toxicidad del CR de los extractos acuosos fue: L. mutabilis˃ A. muricata˃ C. quinoa˃ M. mollis.Agricultural crops have been affected by several factors among which are plague of insects attack, being an effective measure for its control and extermination: synthetic insecticides use, however the majority of them produce high levels of environmental pollution. Due to this, bioinsecticides of plant origin emerging as alternative less polluting because of rapid degradation in the environment and low danger to man. This work analizes the toxicity of hexanic, ethanolic and aqueous extracts of leaves of Minthostachys mollis (Lamiaceae) “muña” and seeds of Annona muricata “guanábana” (Annonaceae), Lupinus mutabilis “tarwi” (Fabaceae) and Chenopodium quinoa “quinua” (Chenopodiaceae) on adult female mite of Tetranychus urticae (Trombidiformes: Tetranychidae): "red spider mite" and the first instar stage larva of Chrysoperla externa (Neuroptera: Chrysopidae): "lacewings". Two concentrations were used for all extract: 10% and 20% (w/v) in an exposure period between 24 and 72h. Analysis of variance (ANOVA) and post-hoc test of Duncan were performed with a significant level p ≤ 0.05. Toxicity endpoints were observed with values in NOEC (No Observed Effect Concentration) and LOEC (Lowest Observed Effect Concentration). Phytochemical screening of botanical extracts used in bioassays was performed. Aqueous extract of M. mollis and ethanolic extract of C. quinoa both at concentration of 20% causing losses in T. urticae of 28,98% and 29,63% respectively. Hexanic extracts of A. muricata and M. mollis did not show acaricide activity. Ethanolic extract of M. mollis registered the greater toxicity of all evaluated extracts at 72 hours in exposure of C. externa with mortality 75,76%. Hexanic extract of A. muricata had no significant effect on mortality in this insect at 24, 48 and 72 hours of exposure. Differentiation in toxicity (to a greater up lesser) of vegetal extracts for C. externa was: ethanol> aqueous> hexane. According to obtained quotient risk (CR) at 48 hours of exposure, aqueous extracts did not represent an increased risk of mortality of C. externa. The descending sequence of toxicity of CR of aqueous extracts was: L. mutabilis˃ A. muricata˃ C. quinoa˃ M. mollis.

The spider mite family (Tetranychidae) is a well known pest group in agriculture. Within this family, Willamette spider mite (Eotetranychus willamettei) causes physical harm and potential damage to grapevines (Vitis vinifera) along the central and north coast of California as well as Washington and Oregon. Willamette spider mite prefers cooler climates and feeds by puncturing the plant leaf tissue; therefore removing plant nutrients in the early stages of plant growth. Amending soils with fertilizer is a common cultural practice used in commercial vineyards, but no study has documented the interaction between the effects fertilizer concentrations have on Willamette spider mite. This project consisted of a field study (at Cambria Vineyards & Winery, Santa Maria, CA) and a laboratory study (at a California Polytechnic State University, San Luis Obispo campus greenhouse). The field study tested the effects potassium, nitrogen, and control (unfertilized) treatments had on Willamette spider mite on ‘Chardonnay’ grapes. Field results showed no significant difference among the three treatments, but suggest a response, given that mite density peaked highest in the potassium treatment and had a second high peak in the nitrogen treatment. In addition, egg density peaked highest in the potassium treatment. The lab study tested the effect four different nitrogen treatments had on Willamette spider mites. Treatments ranged from High N (1500 ppm N fertilizer), Med-High N (1500 ppm N fertilizer), Med–Low N (500 ppm N fertilizer), and Low N (0-50 ppm N fertilizer). Four parameters were tested: male and female days to maturation, male and female survivorship to adult, adult female longevity and oviposition. Longevity and oviposition lab results indicate that Willamette spider mite has a non-linear response to grape N concentration. Performance was better within the two medium treatments compared to High N and Low N treatments. Survivorship suggests the same as days to maturation although not statistically significant.