Jerónimo Landeros

Effect of different densities of the twospotted spider mite Tetranychus urticae on CO2 assimilation, transpiration, and stomatal behaviour in rose leaves.

The effect of population density of Tetranychusurticae Koch on CO2 assimilation, transpiration and stomatal behaviour in rose leaves and on the diameter and length of stems and flower buds was investigated under greenhouse conditions. The investigation was performed in order to gain more insight into integrated control systems in rose crops grown under greenhouse conditions. Physiological processes, such as photosynthesis and transpiration, as well as stomatal behaviour and chlorophyll content, were studied as they form part of the plants nutrition mechanism and therefore affect the quantity and quality of the flowers. Information related to the effect of spider mite population density on bloom quality, diameter and length of stems and flower buds was also collected. The data indicate that increased mite density coincides with a decrease in the net photosynthetic rate, transpiration and chlorophyll content. Higher mite densities on leaves cause stomata to remain open for longer periods, which allows a greater loss of water. Spider mite densities of 10 and 50 mites per leaf cause a reduction in flower stem length of 17 and 26%, respectively, as compared to plants with no mites present.

Temperature-based life history and life table parameters of Texas citrus mite on orange (Acari: Tetranychidae)

Abstract The effect of five different constant temperatures on life history and life table parameters of the Texas citrus mite Eutetranychus banksi (McGregor) on sweet orange (Citrus sinensis (L.) Osbeck) leaves was studied under controlled laboratory conditions. The intrinsic rates of natural increase were -0.0649, 0.1723, 0.1759, 0.1973, and -0.0711; net reproductive rates, 0.30, 8.25, 7.24, 9.21, and 0.44; mean generation times, 19.21, 12.79, 11.74, 11.52, and 11.64 days at 20, 25, 30, 32.5, and 35°C, respectively. In general, the durations of each immature instar as well as combined immature stages, declined with increasing temperature up to 32.5°C and then increased at 35°C. As regards the adult stages, the durations of preoviposition, oviposition, and postoviposition periods, as well as adult longevity, decreased with rising temperature in the range of 25–30°C. With the exception of the preoviposition period, temperature of 20°C had an opposite effect on the durations of the remaining adult phases.Mean total andmean daily fecundities generally but irregularly declined with ascending temperatures.Mean total developmental times declined curvilinearly with rising temperature; however, the rate of development had a positive curvilinear relationship with increasing temperatures. Threshold temperature of development (°C) and thermal constants (degree-days) for egg, larva, protonymph, deutonymph, combined immature stages, preoviposition, oviposition, postoviposition, and adult longevity were: 5.82, 127.66; 3.29, 14.08; 4.33, 41.91; 3.69, 53.28; 4.08, 279.02; 5.35, 34.39; 3.06, 86.78; 3.75, 28.14; and 2.89; 139.52, respectively. From the data it was calculated that there are 22–23 annual generations of the Texas citrus mite in Tamaulipas, Mexico. Temperatures in the range of 28 to 31°C constitute the optimal range for development of this mite species.

Genetically modified maize resistant to corn earworm (Lepidoptera: Noctuidae) in Sinaloa, Mexico

Abstract Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), the corn earworm, is a key pest causing damage to corn Zea mays L. (Poales: Poaceae). The development of hybrids expressing Cry1Ab, Vip3Aa20, and mCry3A protein of Bacillus thuringiensis Berliner (Bt) (Bacillales: Bacillaceae) is an option to control this insect. Corn hybrids Agrisure™ 3000 GT, Agrisure® Viptera™ 3110, and Agrisure® Viptera™ 3111 were tested for corn earworm suppression in the agricultural region of Sinaloa during the 2011, 2012, and 2013 autumn—winter growing seasons, and compared with their respective isolines. Gallery length on the ear and the number of damaged ears were evaluated. The genetically modified hybrids demonstrated the effectiveness of inserted proteins to confer resistance to the corn earworm by killing the pest or reducing its growth and damage to the ear. Based on the results, Agrisure™ 3000 GT, Agrisure® Viptera™ 3110, and Agrisure® Viptera™ 3111 are useful elements for an integrated pest management program on corn in Sinaloa, Mexico.

Evaluation of Foliar Damage by Spodoptera frugiperda (Lepidoptera: Noctuidae) to Genetically Modified Corn (Poales: Poaceae) in Mexico

Abstract The fall armyworm, Spodoptera frugiperda Smith & Abbot (Lepidoptera: Noctuidae), is a key pest of corn, Zea mays L. (Poales: Poaceae), in Mexico. The development of genetically modified (GM) corn hybrids for resistance to this insect, with the inclusion of several genes coding for proteins Cry1Ab, Vip3Aa20, and mCry3A of Bacillus thuringiensis Berliner (Bacillales: Bacillaceae) (Bt), offer an alternative to conventional insecticides to control this pest. Resistance to fall armyworms of the GM corn hybrids Agrisure 3000 GT, Agrisure Viptera 3110, and Agrisure Viptera 3111 was evaluated in 4 locations at Sinaloa for a 3 yr period. Damage evaluation showed that the maize hybrids with the Bt gene insertion were not affected by the fall armyworm as compared with their respective isolines, which were seriously damaged. The results reaffirm the insect control benefits provided by this technology and provide a baseline for resistance management.

Comparison of the Level of Damage by Spodoptera frugiperda (Lepidoptera: Noctuidae) on Genetically-Modified and Conventional Maize Plants in Northern Mexico

Resumen. Se evaluó el nivel de daño ocasionado por el gusano cogollero, Spodoptera frugiperda (J.E. Smith), bajo condiciones de campo en tres híbridos de maíz genéticamente modificado (GM) y un híbrido convencional como testigo, todos con y sin aplicación de insecticidas. Las variedades GM Agrisure 3110® que expresa las proteínas de Bacillus thuringiensis Cry1Ab y Vip3Aa20, Agrisure Viptera 3111® que expresa Cry1Ab, Vip3Aa20, y mCry3A, mostraron un alto nivel de resistencia con valores en la Escala de Davis igual a 1 con y sin control de insecticida. Agrisure 3000 GT® que expresa las proteínas Cry1Ab y mCry3A tuvo un daño foliar de 2.3 y 3.3 con y sin control de insecticida, mientras que el daño fue mayor en el testigo con y sin control de insecticida con valores de 7.2 y 9, respectivamente. Estos resultados muestran que la tecnología es altamente efectiva para controlar esta plaga clave y podría traer considerables beneficios a los agricultores de México.

Abamectin Effect on Chrysoperla carnea (Stephens)1 Functional Response

Abstract. The effect of abamectin was evaluated on the functional response of green lacewing, Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae), at seven egg densities of tobacco budworm, Heliothis virescens (Fabricius), and fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), using Holling s disc equation. Functional response of green lacewing was Type II, indicating that as prey density increased, predation rate also did. However, the predation rate of the three larval instars of green lacewing on tobacco budworm eggs was significantly less because of the insecticide effect, decreasing 48.0, 46.1 and 47.3% on first, second and third instar respectively. The same response was observed with fall armyworm decreased 64.5, 36.2 and 23.6% on first, second and third instar larvae respectively. Functional response parameters such as attack rate (a´), handling time (Th), total handling time (Tht), searching time (Ts), and search efficiency (E) were affected by reducing predation, causing a negative effect on predator behavior by increasing the time to identify and consume prey. This affected efficacy of green lacewing as a biological control agent.

Susceptibility of Genetically Modified Maize Hybrids to Sugarcane Borer, Diatraea saccharalis (F.)1, at Sinaloa, Mexico

Abstract. Use of genetically modified hybrids of maize, Zea mays L., is a pest management tool with special significance when a pest such as sugarcane borer, Diatraea saccharalis (F.) (Lepidoptera: Crambidae), becomes less responsive to conventional control methods. Resistance of genetically modified maize hybrids ‘AgrisureTM 3000 GT’ and ‘Agrisure® VipteraTM 3111’ were evaluated against stalk borers and compared with conventional hybrids with or without insecticide. During evaluation, few borers were found, especially during the first year (2012), but, in most cases, stalk damage by larvae was less in AgrisureTM 3000 GT and Agrisure® VipteraTM 3111 than in their conventional isolines. Insecticide did not prevent damage by the pest and even treated conventional maize was damaged. Use of AgrisureTM 3000 GT and Agrisure® VipteraTM 3111 hybrids can be a management tool to prevent damage by sugarcane borer in maize.