Grass Infusions in Autocidal Gravid Ovitraps to Lure Aedes Albopictus.

Aedes albopictus is a vector of several pathogens of significant public health concern. In this situation, gravid traps have become a common surveillance tool for Aedes spp., which commonly use hay infusions as an attractant. Diverse grass infusions have been assessed to enhance the attraction to this vector mosquito. However, these studies have focused on the oviposition effect, and the attraction potential to gravid Ae. albopictus females has not been evaluated yet. Here we report the attractiveness of infusions of 4 different botanical species (Cenchrus purpureus, Cyanodon dactylon, Megathyrus maximus, Pennisetum ciliare) as baits in sticky ovitraps and autocidal gravid ovitraps (AGOs) under laboratory, semifield, and field conditions. In the laboratory, Cynodon dactylon showed attractiveness, whereas in semifield conditions, both C. dactylon and Megathyrsus maximus were similarly attractive for gravid Ae. albopictus. None of the infusions conducted with AGOs were able to lure Ae. albopictus and other species of mosquitoes in a 14-wk field experiment. Our results demonstrate the feasibility of finding more attractive infusions for Ae. albopictus females to improve the efficacy of AGO traps, but further testing of infusions in AGOs in field settings is needed.

Mortality of Phyllophaga vetula larvae by the separate and combined application of Metarhizium anisopliae, Steinernema carpocapsae and Steinernema glaseri.

Phyllophaga spp. are a complex of edaphic insect pests that are present in the corn crops (Zea mays) in México, which are usually controlled with increasing dosages of broad-spectrum chemical insecticides. Several entomopathogenic nematode species can produce acceptable control levels of these larvae. However, the synergistic interaction between fungi and entomopathogenic nematodes (EPN) could improve the control of this insect. This study investigates the mortality of larvae of Phyllophaga vetula by the effect of the separate or combined application of the fungus Metarhizium anisopliae M1cog strain (Ma) and the nematodes Steinernema carpocapsae All strain (Sc) or Steinernema glaseri NJ-43 strain (Sg). In laboratory, dosages of 1 × 106 or 1 × 108 spores/larva and 250 infective juveniles were applied on medium or large size P. vetula larvae contained in vials with sterilized agricultural soil as the assay arena. The separate application of Ma did not kill any larvae, but Sg and Sc killed 40 and 80% of the larvae, respectively. However, the Ma and Sc combination had an important antagonistic interaction that decreased the mortality to 40%, but the combination Ma and Sg had a slight additive interaction that increased the mortality to 47%. The most determining factor in larvae mortality was the nematode used, with Sg as the species with best performance in 6 of the 12 treatments evaluated and with a maximum effectivity of 80% on medium-size larvae if combined with a low dosage of Ma. The combined application of an entomopathogenic fungus and EPN showed no consistent effects on the mortality percentage of P. vetula, mostly because the fungus was not isolated from Phyllophaga larvae.Phyllophaga spp. are a complex of edaphic insect pests that are present in the corn crops (Zea mays) in México, which are usually controlled with increasing dosages of broad-spectrum chemical insecticides. Several entomopathogenic nematode species can produce acceptable control levels of these larvae. However, the synergistic interaction between fungi and entomopathogenic nematodes (EPN) could improve the control of this insect. This study investigates the mortality of larvae of Phyllophaga vetula by the effect of the separate or combined application of the fungus Metarhizium anisopliae M1cog strain (Ma) and the nematodes Steinernema carpocapsae All strain (Sc) or Steinernema glaseri NJ-43 strain (Sg). In laboratory, dosages of 1 × 106 or 1 × 108 spores/larva and 250 infective juveniles were applied on medium or large size P. vetula larvae contained in vials with sterilized agricultural soil as the assay arena. The separate application of Ma did not kill any larvae, but Sg and Sc killed 40 and 80% of the larvae, respectively. However, the Ma and Sc combination had an important antagonistic interaction that decreased the mortality to 40%, but the combination Ma and Sg had a slight additive interaction that increased the mortality to 47%. The most determining factor in larvae mortality was the nematode used, with Sg as the species with best performance in 6 of the 12 treatments evaluated and with a maximum effectivity of 80% on medium-size larvae if combined with a low dosage of Ma. The combined application of an entomopathogenic fungus and EPN showed no consistent effects on the mortality percentage of P. vetula, mostly because the fungus was not isolated from Phyllophaga larvae.

Survival and Infectivity of Entomopathogenic Nematodes Formulated in Sodium Alginate Beads.

An alternative control method to the use of chemical insecticides against soil dwelling insect pests is the application of entomopathogenic nematodes formulated in alginate beads for enhanced shelf life. The aim was to compare the benefit on nematode survival and infectivity of: (i) pre-conditioning of juveniles, and (ii) coating of alginate beads. The nematodes Steinernema glaseri , Steinernema carpocapsae, and Heterorhabditis bacteriophora were reproduced in last instar larvae of the wax moth Galleria mellonella and the infective juveniles emerged were subjected to two capture treatments: white traps and plaster of Paris, the latter was utilized as a pre-conditioning treatment. A total of 1,000 infective juveniles were formulated in each sodium alginate bead with or without an alginate coating. The beads were stored at 23 ± 3°C and a bidistilled water suspension of nematodes was set as a control. The survivorship of these formulates and their infectivity on Galleria mellonella larvae were evaluated every 7 d post-formulation (dpf). In beads without pre-conditioning juveniles nor coating, Steinernema carpocapsae had the higher survival rate (58.8%), the longest survival time (28 dpf) and the higher infectivity (100%) as well. Pre-conditioning improved the survival and infectivity of Steinernema glaseri by 22.5% at 21 dpf and 70.0% at 14 dpf, respectively. Alginate coating increased survival (21.7%) and infectivity (95%) of Heterorhabditis bacteriophora for up to 28 dpf. The combination of pre-conditioning and coating slightly favored the survival (10% for up to 14 dpf) of Steinernema glaseri and infectivity (100% for up to 35 dpf) of Steinernema carpocapsae . Non pre-conditioned Steinernema carpocapsae formulated in uncoated beads was the combination with better performance in survivorship (58.8%) and infectivity (100%) at 28 dpf. It was concluded that non pre-conditioned Steinernema carpocapsae formulated in uncoated beads was the combination with better survivorship and infectivity.

Population Fluctuation and Altitudinal Distribution of Tetraleurodes perseae (Nakahara) (Hemiptera: Aleyrodidae) in Avocado (Lauraceae) in Morelos, Mexico.

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.

Logrank test and Interval Overlap Test for Bactericera cockerelli (Hemiptera: Triozidae) under different fertilization treatments for 7705 tomato hybrid.

It is known that some nutrients can have both negative and positive effects on some populations of insects. To test this, the Logrank test and the Interval Overlap Test were evaluated for two crop cycles (February-May and May-August) of the 7705 tomato hybrid, and the effect on the psyllid, Bactericera cockerelli (Sulc.) (Hemiptera: Triozidae), was examined under greenhouse conditions. Tomato plants were in polythene bags and irrigated with the following solutions: T1-Steiner solution, T2-Steiner solution with nitrogen reduced to 25%, T3-Steiner solution with potassium reduced to 25%, and T4-Steiner solution with calcium reduced to 25%. In the Logrank test, a significant difference was found when comparing the survival parameters of B. cockerelli generated from the treatment cohorts: T1-T2; T1-T3; T1-T4; T2-T3; and T3-T4, while no significant differences were found in the T2-T4 comparison in the February-May cycle. In the May-August cycle, significant differences were found when comparing the survival parameters generated from the treatment cohorts: T1-T2; T1-T3; and T1-T4, while no significant differences were found in the T2-T3; T2-T4; and T3-T4 comparisons of survival parameters of B. cockerelli fed with the 7705 tomato hybrid. Also, the Interval Overlap Test was done on the treatment cohorts (T1, T2, T3, and T4) in the February-May and May-August cycles. T1 and T2 compare similarly in both cycles when feeding on the treatments up to 36 d. Similarly, in T1 and T3, the behavior of the insect is similar when feeding on the treatments up to 40 and 73 d, respectively. Comparisons T2-T3 and T2-T4 are similar when feeding on both treatments up to 42, 38 and 37, 63 d, respectively. Finally, the T3-T4 comparison was similar when feeding in both treatments up to 20 and 46 d, respectively.

Estudio de las condiciones de mezclado en fermentador para la producción de blastosporas de Beauveria bassiana / Study of the mixing conditions in bioreactor for blastospores production of Beauveria bassiana

Se caracterizaron tres fermentadores: New Brunswick M-19 de 14 litros, Applikon Biocontroller 1035 de 7 litros y New Brunswick Bioflo III de 7 litros, determinando el coeficiente volumétrico de transferencia de oxígeno (KLa), la retención de gas (RG) y el tiempo de mezclado (tM). El fermentador New Brunswick Bioflo III tuvo los mejores valores con una relación de diámetro del impulsor/diámetro del tanque (DI/DT) de 0.43, KLa = 9.5-208 h-1 y tM = 1.0-3.0 s, por lo que fue seleccionado para realizar la producción de blastosporas de Beauveria bassiana, utilizando melaza como fuente de carbono. Se estudiaron las condiciones de mezclado, utilizando diferentes combinaciones de impulsores tipo Rushton, Maxflo y Lightnin, bajo un diseño experimental factorial 32. El tiempo de propagación fue de 4 días, el volumen de trabajo 4 litros, 10% de inóculo (1x106 blastosporas/ml), temperatura 30°C, agitación de 400-500 rpm, aireación de 0.5-1.0 vvm, y pH de 5.4.El hongo se desarrolló mejor utilizando la combinación de impulsores Rushton-Maxflo a 400 rpm y 1.0 vvm (F = 10.324, p ≤ 0.0123) (DMS=0.585), obteniendo una concentración de 1.2x109 blastosporas/ml, 2.2 g/l de biomasa y 2.48 g/l de consumo de sustrato (Y x/s=0.89). Las condiciones de mezclado y los parámetros obtenidos pueden ser aplicados en otros fermentadores para optimizar la producción de blastosporas de B. bassiana en la elaboración experimental de bioinsecticidas.

In this work three fermenters were characterized: New Brunswick M-19 of 14 liters, Biocontroller Applikon 1035 of 7 liters and New Brunswick Bioflo III of 7 liters, determining the volumetric coefficient oxygen transfer (KLa), gas hold up (GH) and the mixing time (tM). The fermenter New Brunswick Bioflo III had the best values with a ratio of diameter of the impeller/vessel (DI/DT) of 0.43, KLa = 9.5-208 h-1 and tM = 1.0-3.0 s, so it was selected for the production of blastospores of Beauveria bassiana, using molasses as carbon source. We studied the mixing conditions, using different combinations of impellers, type Rushton, Lightnin and Maxflo under a factorial experimental design 32. The propagation time was of 4 days, working volume 4l, 10% inoculum (1x106 blastospores/ml), temperature 30°C, agitation of 400-500 rpm, aeration 0.5-1.0 vvm, and pH of 5.4. The fungus growth better using a combination of impellers Rushton-Maxflo at 400 rpm and 1.0 vvm (F = 10.324, p ≤ 0.0123) (LSD = 0.585) obtaining a concentration of 1.2x109 blastospores/ml, 2.2 g/l biomass and 2.48 g/l of substrate consumption (Y x/s = 0.89). The mixing conditions and the parameters obtained can be applied to optimize the blastospore productions of B. bassiana to fermenter level in the experimental production of bioinsecticides.