Search

High populations of the spittlebug (Hemiptera: Cercopidae) may reduce yields on sugar cane. This research was aimed to quantify the effect of biotic, abiotic and agronomic factors on adult populations of the spittlebugs. Data collected was related to the number of adults captured in traps, previous-year infestation level of the sampling plot, nymph counts, weed coverage within and on the border of the plots, sampling time, insecticide and entomopathogen applications, precipitation and temperature. Fifteen plots were sampled from July 2 to October 15, 2014 in Veracruz, Mexico. The data was analyzed as a linear mixed model. Most of the captured adults (98%) were Aeneolamia contigua (Walker, 1851). The analysis showed the following significant effects: a positive relationship between adult populations and spittlebug nymphs and previous-year infestation, and a direct relationship between within-plot weed coverage and spittlebug adult populations. Weed coverage on the borders showed fluctuating effects and had not significant effect on adult populations. Temperature had a positive, significant effect as well, but precipitation and sampling time did not affect adult populations. Results are discussed as related to preventive spittlebug management. [ABSTRACT FROM AUTHOR]

• New suitability areas are expected across all CMIP6 model projections. • Future suitability areas move to northern and central regions. • Risk of diaphorina citri will probably increase in future scenarios. • Future projections indicate current suitability areas remain unchanged. Climate change may modify environmental conditions creating suitable environments for phytopathogen vectors in places that were not suitable before. The present study aimed to contrast current and future spatial distribution of Diaphorina citri in Mexico under two climate change scenarios, Shared Socioeconomic Pathways (SSP) 4.5 and 8.5 for years 2050 and 2070. Non-correlated bioclimatic variables from eight General Circulation Models derived from the Coupled Model Intercomparison Project-6 and presence point data were used to generate distribution models with MaxEnt. Future projections showed that current suitable areas, equivalent to a 38.6% of coverage persist across all scenarios, new suitability areas appear, and no reduction is expected. All the models coincide on a potential increase in relation to the current national distribution of 11.1, 14.8, 13.8 and 25.5% for SSP2 4.5–50 SSP2 4.5–70 SSP5 8.5–50, and SSP5 8.5–70 respectively. Most of the new areas are not currently dedicated to citriculture; however, an increase in the risk of Huanglongbing is expected because most of the new areas are contiguous to the current presence areas, and cover urban zones where there may exist rutaceous hosts, from which the vector may spread the disease to the production zones. [Display omitted] [ABSTRACT FROM AUTHOR]

Copyright of Agrociencia is the property of Colegio de Postgraduados and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The article focuses on a study on Sigmodon hispidus' diet composition in Oaxaca, Mexico. It also explores Sigmodon hispidus' relationship with the season variation of food resources accessibility, habitat, and gender of the rodent. It notes that rodents and vegetation sampling were conducted in sugar cane and weeds plots in April and August 2005. It mentions that a histological analysis was performed inorder to identify the stomach content of the captured rodents. It reveals that S. hispidus' diet varies with the season and gender of the rodent. it adds that its diet consist of foliage and stems of eight species of grasses, sugarcane, and six broad-leaved species.

ABSTRACT. The agave weevil, Scyphophorus acupunctatus Gyllenhal, is considered the most important insect pest of the cultivated agaves in Mexico. Recent studies on the chemical ecology of this weevil have shown that males release a pheromone that attracts both sexes; the pheromone is composed of four components. Previous field experiments showed that all components, singled or in blends, were attractive to the weevils, but compounds 2-methyl-4-heptanone (C1) and 2-methyl-4-octanone (C2) were sufficient to obtain captures equivalent to those by the quaternary blend. In this study, we investigated the effect of different ratios (1:1, 1:2, 1:4, 2:1, and 4:1) and doses (50, 100, 150, 200, 350, and 500 mg) of C1 and C2 in the captures of the agave weevils in commercial plantations of Agave tequilana Weber. Our results showed that traps baited with synthetic pheromone captured more weevils than traps baited with adult male weevils but the different ratios of C1 and C2 did not affect the weevils capture. In fact, traps baited with C2 caught more weevils than those baited with the binary blend. Also, we found that weevil's capture was not affected by dose. In general, traps baited with the synthetic pheromonal components caught more females than males. [ABSTRACT FROM AUTHOR]

The spatial and temporal distribution of gastrointestinal nematodes of cattle has been little studied in Mexico. Previous studies have described periods of higher larval presence, vertical and horizontal migration in grasslands, and the frequency of adult nematodes; as well as the effect of pasture trichomes on the migration and survival of Haemonchus larvae. The aim of this study was to determine the time-space layout and spread of gastrointestinal nematode larvae on pasture, and to estimate the effect of ivermectin applied to cattle on the time-dependent abundance of their eggs in a ranch in Veracruz. To determine the spatio-temporal arrangement, monthly morning grass samples were obtained from 30 sampling points from July 2008 to June 2009. Third stage larvae (L3) from each point were counted, and aggregation patterns were estimated through variance/mean and negative binomial K indices. Additionally, the number of eggs per gram in cattle feces was determined, from samples with (CI) and without ivermectin (SI), using standard techniques. A total of 20 276 L(3) larvae were recovered in the pasture, of which an 80% corresponded to Haemonchus contortus. The highest nematode density with more than 5 000L(3)/kgDM was detected in October 2008, and the lowest in February and March 2009. The L3 showed an aggregated spatial pattern of varying intensity throughout the year. The number of eggs in the stool was not reduced with the ivermectin application to cattle, which suggested a failure of control. However, the highest parasite loads were observed from July to November 2008. We concluded that the application of ivermectin was not effective to control nematodes eggs, and that L3 populations fluctuated on pasture for ten months, providing an infection source to grazing animals afterwards.

The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), is an introduced pest in Mexico and a vector of huanglongbing, a lethal citrus disease. Estimations of the habitat distribution and population growth rates of D. citri are required to establish regional and areawide management strategies and can be used as a pest risk analysis tools. In this study, the habitat distribution of D. citri in Mexico was computed with MaxEnt, an inductive, machine-learning program that uses bioclimatic layers and point location data. Geographic distributions of development and population growth rates were determined by fitting a temperature-dependent, nonlinear model and projecting the rates over the target area, using the annual mean temperature as the predictor variable. The results showed that the most suitable regions for habitat of D. citri comprise the Gulf of Mexico states, Yucatán Peninsula, and areas scattered throughout the Pacific coastal states. Less suitable areas occurred in northern and central states. The most important predictor variables were related to temperature. Development and growth rates had a distribution wider than habitat, reaching some of the northern states of México. Habitat, development, and population growth rates were correlated to each other and with the citrus producing area. These relationships indicated that citrus producing states are within the most suitable regions for the occurrence, development, and population growth of D. citri, therefore increasing the risk of huanglongbing dispersion.