Life Table Parameters of Tetranychus merganser Boudreaux (Acari: Tetranychidae) on Five Host Plants.

The quality of the host plant affects the life history parameters of tetranychid mites. The biology and fertility life tables of Tetranychus merganser on five host plants (Carica papaya, Phaseolus vulgaris, Capsicum annuum var. glabriusculum, Helietta parvifolia, and Rosa hybrida) were assessed under laboratory conditions at 28 ± 1 °C and 70-80% relative humidity (RH) with a photoperiod of 12:12 h (L:D). The development period of immature females differed among the tested host plants and ranged from 9.32 days on P. vulgaris to 11.34 days on H. parvifolia. For immature males, it ranged from 9.25 days on P. vulgaris to 11.50 days on H. parvifolia. The female survival rate varied from 53.97% on H. parvifolia to 94.74% on P. vulgaris. The highest total fecundity rate was recorded on P. vulgaris (125.40 eggs/female) and the lowest on H. parvifolia (43.92 eggs/female). The intrinsic rate of increase (rm) varied from 0.271 (H. parvifolia) to 0.391 (P. vulgaris). The net reproductive rate (RO) was higher on P. vulgaris than on the other host plants. The longest mean generation time (GT) was calculated on C. annuum var. glabriusculum and the shortest on Rosa hybrida. The demographic parameters suggest the unsuitability of H. parvifolia as the host for the development of red spider mites, and the best performance of T. merganser was on P. vulgaris.

Evaluation of Ethanolic Powdered Extract of Magnolia tamaulipana Vazquez against Oligonychus punicae Hirst (Trombidiformes: Tetranychidae).

Avocado bronze mite (ABM), Oligonychus punicae Hirst (Trombidiformes: Tetranychidae) has potential for development in several plant species of agricultural importance. ABM is one of the most economically important pests in avocado cultivars, causing major damage to fruit and defoliation. At present, the control of ABM depends mainly on agrochemicals. Therefore, it is necessary to find alternatives to agrochemicals that can help minimize environmental impact and health risks for humans and mammals. The aim of this research was to assess the effect of different concentrations (5, 10, 50, 100, 250, 500, 1000 µg/mL) of ethanolic powdered extract of M. tamaulipana leaves against adult ABM females. The different concentrations of M. tamaulipana extract did not cause mortality of O. punicae. Females treated with 5 and 1000 µg/mL of the extract showed a decrease in the number of eggs laid per female at 24 (5.17 and 1.27), 48 (5.07 and 1.17), and 72 h (4.97 and 0.80), compared to the control treatment (5.20, 6.60 and 6.87), respectively, which led to a reduction in the growth rate. Percentage of feeding damage decreased with the increasing concentration of the extract. The ethanolic powdered extract of M. tamaulipana leaf has potential to control O. punicae.

Evaluation of Resistance of Eleven Maize Races (Zea mays L.) to the Red Spider Mite (Tetranychus merganser, Boudreaux).

At least 59 maize races (Zea mays L.) have been registered in Mexico. The feeding damage caused by insects and mites to maize crops generates up to ~30% of maize yield losses. Spider-mite-resistant plants are needed. The red spider mite, Tetranychus merganser Boudreaux (Acari: Tetranychidae), is distributed in the United States, China, Mexico, and Thailand. It is considered a potential pest in Mexican agriculture. The aim of this study was to evaluate the resistance mechanisms (antixenosis and antibiosis) of 11 native maize populations, representative of each race of maize grown in Tamaulipas, Mexico, to T. merganser under laboratory conditions. The aim was also to obtain information on the chemical composition and some morphological characteristics of these maize races and to identify resistant maize races for incorporation into a breeding program. Antixenosis was assessed by non-preference for oviposition and feeding. Antibiosis was measured by growth rate (ri). The presence of secondary metabolites in the 11 maize races were different. In the 11 maize races, quantitative analysis of total phenol concentration, total flavonoid concentration, and antioxidant capacity were significantly different. The multivariate analysis of variance showed that there is evidence of antixenosis noted by maize race differences in egg laying and percentage feeding damage but not of antibiosis noted by growth rate. Red spider mites laid significantly more eggs on the Celaya (24 h: 25.67 ± 17.04, 48 h: 42.67 ± 26.86, 72 h: 49.33 ± 28.54) race than on Raton (24 h: 7.00 ± 5.00, 48 h: 12.67 ± 8.02, 72 h: 14.67 ± 9.29) and Elotes Occidentales × Tuxpeño (24 h: 9.67 ± 5.85, 48 h: 15.33 ± 10.69, 72 h: 17.67 ± 10.97) races. However, the growth rate and mortality of T. merganser in the 11 corn races were similar. The Vandeño (24 h: 11.67 ± 2.89, 48 h: 27.67 ± 7.64, 72 h: 30.00 ± 18.03) and Tabloncillo × Tuxpeño (24 h: 18.33 ± 7.64, 48 h: 25.00 ± 8.66, 72 h: 25.00 ± 8.66) races were the most resistant to red spider mite damage, whereas the most susceptible race was Celaya (24 h: 26.67 ± 15.28, 48 h: 48.33 ± 29.30, 72 h: 65.00 ± 30.00). Further analysis by PCA at 24, 48, and 72 h found the Celaya race positively correlated to growth rate and oviposition of T. merganser and to a lesser extent with the percentage of feeding damage, suggesting that the Celaya race was most susceptible to T. merganser. At 24 h, the Vandeño race was most resistant, given a negative correlation to growth rate and oviposition by T. merganser. The PCA at 48 and 72 h noted the Elotes Occidentales × Tuxpeño race was most resistant to red spider mite, with negative relationships to growth rate and oviposition and, to a lesser extent, to feeding damage. This resistance is due to the differences in both its morphological characteristics and the secondary metabolites present in their leaves.

The Resistance of Seven Host Plants to Tetranychus merganser Boudreaux (Acari: Tetranychidae).

Red spider mites, Tetranychus merganser Boudreaux (Acari: Tetranychidae), is an agricultural pest that causes economic losses in papaya and nopal crops in Mexico. The aim of this research was to assess antibiosis and antixenosis as resistance mechanisms in seven host plants (Thevetia ahouai, Carica papaya, Phaseolus vulgaris, Moringa oleifera, Pittosporum tobira, Helietta parvifolia, Capsicum annuum var. glabriusculum) to red spider mites. Antixenosis was evaluated by non-preference for oviposition and feeding, antibiosis by infinitesimal rate of increase, finite rate of increase and doubling time, and the percentage of spider mites mortality. Oviposition and damage by feeding of T. merganser were significantly greater on C. papaya than on the other host plants. The growth rate of the spider mite was significantly lower in P. tobira and T. ahouai than in the other host plants. The percentage of hatched eggs of T. merganser was significantly higher in P. vulgaris than in the other plant species. Based on the demographic parameters, survival, food intake, and oviposition, these results indicated that compared with C. papaya, P. tobira and T. ahouai were more resistant. These results may be due to the fact that they were plants species of different families. The resistant plants can be studied as alternatives in the management of T. merganser.

Bioacaricidal Potential of Moringa oleifera Ethanol Extract for Tetranychus merganser Boudreaux (Acari: Tetranychidae) Control.

The Tetranychidae family includes mites causing severe damage to agricultural fields. The red spider mite, Tetranychus merganser Boudreaux (Acari: Tetranychidae), causes severe damage to several plant species grown as cash crops. Current red spider mite control depends mainly on chemical insecticides. There is a need for alternate control measures that are environmentally friendlier than chemical pesticides. The aim of the study was to assess the effects of Moringa oleifera leaf ethanolic extract at different concentrations (0.1, 0.5, 1, 5, 10, 15, and 20% (v/v)) against T. merganser females. Such effects can serve as a basis to include this compound in integrated pest management programs for the control of red spider mites. Mites treated with 20% (v/v) killed 86.67%, 13.70%, and 96.30% at 24, 48, and 72 h, respectively, as compared to the control treatment. Oviposition, egg hatching, and the damage caused by red spider mites were all reduced at high concentrations. Moringa oleifera leaf ethanolic extract can be used as a powerful bioacaricide for the control of T. merganser.

Evaluation of Ethanol Extract of Moringa oleifera Lam. as Acaricide against Oligonychus punicae Hirst (Trombidiformes: Tetranychidae).

Tetranychidae family is a major group of mites causing serious damage in agricultural, vegetable and ornamental crops. Avocado bronze mite (ABM), Oligonychus punicae Hirst (Acari: Tetranychidae) causes major crop damage, defoliation and fruit abortion. At present, the control of this mite depends mainly on agrochemicals. Therefore it is necessary to find alternatives to synthetic pesticides that can help minimize environmental impact and health risks for the consumers. The aim of this research was to assess the effect of different concentrations (0.1, 0.5, 1, 5, 10, 15 and 20% (v/v)) of ethanolic extract of Moringa oleifera leaves against adult ABM females. Mites treated with 0.1 and 20% (v/v) of the extract showed mortality of 0.00% and 46.67%, 6.67% and 86.67%, 13.70% and 96.67%, at 24, 48 and 72 h, as compared to the control treatment, respectively. The number of eggs laid and hatch, as well as ABM feeding rates, depended on the extract concentration, which led to a reduction in the growth rate. M. oleifera leaf ethanolic extract has potential to control O. punicae.

Diversidad y caracterización de maíces nativos de la Reserva de la Biósfera "El Cielo", Tamaulipas, México / Diversity and characterization of native maize from the "El Cielo" Biosphere Reserve, Tamaulipas, Mexico

Resumen La diversidad del maíz en México se fundamenta por la presencia de 59 a 64 razas; Tamaulipas como estado productor contribuye a mantener la variabilidad entre razas, especialmente en las regiones aisladas. La reserva de la Biósfera "El Cielo" localizada en una región montañosa, que comprende los municipios de Jaumave, Ocampo, Gómez Farías y Llera de Canales, ha sido escasamente estudiada, a pesar de que existen riesgos de degradación o extinción de poblaciones nativas de maíz, por factores como cambios de uso de suelo y fenómenos naturales. El objetivo de este trabajo fue analizar la diversidad morfológica de poblaciones nativas de maíz de la Reserva de la Biósfera "El Cielo". Durante los meses de febrero, marzo y abril del 2016, se realizaron recolectas de maíces nativos en los municipios que comprenden la reserva. El tamaño de la muestra varió, entre 20 y 30 mazorcas de cada población, y de estas, se eligieron 10 mazorcas para registrar variables cuantitativas y cualitativas. Se utilizaron los métodos multivariados de análisis de componentes principales y conglomerados. El 62.45 % correspondió a la variación total, la cual fue explicada por los dos primeros componentes principales, y las variables con mayor contribución a la variación fueron longitud de mazorca, número de granos por hilera, peso de mazorca, peso y volumen de 100 granos, diámetro de mazorca y de olote, número de hileras por mazorca y la relación diámetro/longitud de mazorca. En las poblaciones nativas de maíz que aún se cultivan en la Reserva de la Biósfera "El Cielo", se encontró amplia diversidad morfológica de mazorca, así como variación en la combinación de colores de grano y olote, lo que sugiere que las poblaciones nativas representan un amplio potencial como acervo genético y reservorio de genes.

Abstract The diversity of maize in Mexico is based on the presence of breeds that range from 59 to 64 varieties. Tamaulipas is a corn-producing state that contributes to sustain this enormous variation of breeds, especially in isolated regions. The biosphere ecological reserve "El Cielo" is located in a mountainous region, which comprises Jaumave, Ocampo, Gómez Farías and Llera de Canales municipalities. This region has been scarcely studied in spite of the degrada tion or extinction risks of native populations of maize due to factors such as changes in land use and natural phenomena. The objective of this work was to analyze the morphologic diversity of native maize varieties of "El Cielo" biosphere ecological reserve. Native maize harvests were collected in the municipalities that comprise the reserve during the months of February, March and April of 2016. The sample size ranged between 20 and 30 cobs of each variety, out of this sample 10 cobs were selected in order to register quantitative and qualitative variables. A multivariate analysis method of main components and conglomerates was used. Results show that 62.45 % of the samples were correspondent with total variation, which was explained by the first two main compo nents. The variables with greater contribution to the variation were cob length, number of grains per row, cob weight, weight and volume of 100 grains, cob diameter, number of rows per hob and the relation of diameter/length in each cob. The native maize populations that are still cultivated at the biosphere ecological reserve "El Cielo" there was a wide morphological diversity of cob, as well as variation in the com bination of grain and corncob color. This sug gests that native populations possess a substantial potential as a gene pool and gene reservoir.