Population Fluctuation of Disonycha teapensis Blake (Coleoptera: Chrysomelidae) in Crotalaria longirostrata Hook. & Arn. (Fabales: Fabaceae) in Huimanguillo, Tabasco, Mexico

Objective: To establish the population fluctuation of Disonycha teapensis adults and larvae and to determine its relationship with the amount of damaged foliage, temperature, and precipitation. Methodology: The study was carried out in a n=48 Crotalaria longirostrata plant crop. The following data was recorded every week: number of adults and larvae, damaged leaflets percentage, plant phenology, temperature, and precipitation. Based on these data, monthly averages were calculated, and correlation analysis were performed between the population fluctuation of D. teapensis and the fluctuation of the damaged foliage percentage, temperature, and precipitation. Results: All the phenological stages of C. longirostrata were affected by the pest, which showed a constant population growth. The population fluctuation resembled the fluctuation of the damaged foliage percentage, with a significant positive correlation between both variables. Regarding temperature and precipitation, the correlation was negative but not significant; therefore, the relationship between population fluctuation and these climatic factors is not clear. Study Limitations: It was not possible to conduct the study for a full year. Conclusions: The population development of D. teapensis depends on the increase in the amount of foliage of its host plant. This insect attacks plants in all their phenological stages and the amount of damaged foliage is considerable.

Flutuação populacional e eficiência de panos de batida na coleta de Spodoptera frugiperda na cultura da soja em Espumoso/RS / Population fluctuation and efficiency of beat cloths in the collection of Spodoptera frugiperda in soybean crop in Espumoso/RS

A cultura da soja é amplamente difundida no Brasil. Entre as pragas mais importantes da cultura está a lagarta-do-cartucho Spodoptera frugiperda, responsável por altos danos na cultura. O monitoramento periódico nas lavouras é fundamental para realização do manejo integrado de pragas (MIP). O objetivo do trabalho foi avaliar a incidência de S. frugiperda e sua flutuação populacional durante o desenvolvimento da cultura da soja, durante o ano agrícola de 2020/2021, bem como verificar o método de coleta mais adequado para esta espécie. O experimento foi conduzido durante a safra 2020/2021 em Espumoso/RS. Utilizou-se a cultivar BMX Lança, semeada em 28/11/2020. O delineamento inteiramente casualizado (DIC). Foram utilizados panos de batida horizontal e vertical para quantificar a espécie. Os resultados foram submetidos à análise de variância e ao teste Tukey a 5% de probabilidade de erro. A presença de S. frugiperda foi recorrente a partir de estádio reprodutivo e seu pico populacional ocorreu em R5.3, justificando controle químico.O uso de pano de batida horizontal é o mais indicado para a espécie em questão. O monitoramento periódico faz-se necessário durante o ciclo da cultura.

How soil abiotic factors affect the population fluctuation of Leitneria pugio (Acari: Mesostigmata: Halolaelapidae)

Abiotic factors, such as temperature, humidity, soil elements, along with biotic factors affect terrestrial arthropod communities. Since the application of agricultural fertilizers with the entrance of different elements causes changes in the soil physicochemical conditions, fertilizers may cause fluctuation in the population density of edaphic arthropods. Given this opinion, in this research, the effect of common fertilizers on the population fluctuation and distribution pattern of the predatory mite Leitneria pugio (Karg) was investigated. The experimental treatments were granular urea fertilizer with two doses (200 and 400 kg per ha), poultry manure, zinc sludge (to simulate the accumulation of zinc sulfate fertilizer in the soil), and control in five blocks. Humidity, pH, temperature, NO3– and NO2–, and elements (organic Carbon, K, Na, P, Fe, Cu, Pb, Cr, Cd, Ni, Zn, and As) of soil were measured, and their relationship with the predatory mite population was determined by Pearson correlation coefficient. Iwao's patchiness, Taylor's power law, and Morisita's coefficient of dispersion were used for determining the spatial distribution pattern of L. pugio. The spatial pattern of L. pugio was aggregated, and the highest population density of the predator was observed in December in zinc sludge and control treatments, and in May, in zinc sludge treatment, on the average 60, 35, and 110 per m2, respectively. The relationship between mite's population and Cu and Pb was significantly positive, and L. pugio had a significantly negative relationship with P, NO3– and soil temperature. Nevertheless, the application of different fertilizers did not affect the spatial distribution pattern of the predator.

Entomofauna asociada al cultivo de Solanum sessiliflorum Dunal, en el municipio de Lloró, occidente de Colombia

En tres parcelas de 6 m x 10,5 m se evaluó la entomofuana asociada al cultivo de Solanum sessiliflorum Dunal. Los insectos se colectaron aplicando captura manual y trampa. Las manuales, se efectuaron con el apoyo de jamás, pinzas y guantes de carnaza, las capturas con trampa, se realizaron por medio de trampas pitfall sin atrayentes, la intensidad de muestreo fue de 308 horas/hombre para las capturas manuales y 1344 horas/hombre para capturas con trampas pitfall. Se colectaron en total 386 individuos distribuidos en 38 géneros, 22 familias y cinco órdenes. La composición trófica sugiere a los insectos fitófagos y zoófagos como los más abundantes. La fluctuación poblacional de los insectos asociados, estuvo muy relacionada con la fenología del cultivo, ya que el registro de colectas de los insectos sugiere un aumento de la población en la etapa de floración del cultivo. The entomophuana associated with the Solanum sessiliflorum Dunal crop was evaluated in three 6 m x 10.5 m plots. The insects were collected by manual capture and trapping. The manual captures were carried out with the support of a pair of tweezers and gloves, the trapping was done with pitfall traps without attractants, the sampling intensity was 308 man-hours for manual captures and 1344 man-hours for captures with pitfall traps. A total of 386 individuals were collected, distributed in 38 genera, 22 families and five orders. The trophic composition suggests phytophagous and zoophagous insects as the most abundant. The population fluctuation of the associated insects was closely related to the phenology of the crop, since the record of insect collections suggests an increase in the population during the flowering stage of the crop.

Population Fluctuation and Diurnal Time Budgeting of White-Headed Duck (Oxyura Leucocephala) During Winter at Garaet Hadj Tahar (Skikda, North East Algerian)

This study was focused on the ecology and behavior of the White-headed Duck (Oxyura leucocephala) at Garaet Hadj Tahar (Guerbes-Sanhadja, North East of Algeria). Sampling was carried out during two wintering seasons (2017-2018 and 2018-2019). High number of this duck was recorded in 2018/19 (350 individuals). We observed two Oxyura population, the first sedentary, and the second, hosted the Garaet during the wintering season. Diurnal time budget was dominated by the comfort activities the sleeping with a rate of 39.13%. Following by swimming (37.76%), feeding (17.59%) grooming (4.58%), courtship ritual (0.56%) and flying (0.38%). The feeding of white-headed duck is done exclusively by diving. Beside, this waterbird associated between Feeding by diving and grooming in order to minimized energy. The accessory activities such as: courtship ritual, flying were done by this duck at the end of wintering. This results confirm that Garaet Hadj Tahar is considered as wintering site for this threatened species. Biological Conservation plan (BCP) must be applied at level of this wetland in order to manage bioressources and threatened waterbirds.

Population Fluctuation of Rice Leaffolder, (Cnaphalocrocis medinalis) in Two Consecutive Rice Seasons

Larvae of rice leaffolder, Cnaphalocrocis medinalis attack rice crop at all three phases (from tillering until maturity stages). Their population throughout season was influenced by abiotic and biotic factors. Study on population fluctuation is important to understand the population dynamic and its factors in natural field condition. Thus, a study of population fluctuation of C. medinalis was conducted at rice field in Semanggol, Perak. Larvae were collected from 10 rice hills per plot in three 15 m x 4 m plots started on April 5, 2015 until June 7, 2015 (off season) and from October 25, 2015 until December 27, 2015 (main season). Abiotic data namely temperature, relative humidity (RH) and rainfall were obtained from Department of Meteorology Malaysia. Comparison of C. medinalis population between two seasons at different weeks was analysed using two-way ANOVA. The relationship of C. medinalis population with abiotic factors was analysed using Pearson correlation and stepwise regression. There was a significant interaction effect between season and week (F9,40=2.19; p<0.05). The highest population was recorded at week 55 day after transplanting (DAT) in main season comprised of 17% of total collection, followed by week 62 in off season (14%), week 48-main season (13%) and week 55-off season (13%). There was a positive correlation between C. medinalis population and RH in main and off season with RH was the key factor in regulating population in both seasons. Our results revealed that population of C. medinalis at different weeks was influenced by season. It is due to differences of weather condition between seasons, management practices and plant stages. The highest population recorded during reproductive phase is due to the morphology of rice plant that offers great suitability for larvae feeding and development. The abiotic factors also influenced C. medinalis population. Therefore, the abiotic factors should be considered in management of C. medinalis besides the plant stage and fertilizer effect. Future research on effect of natural enemies on C. medinalis population in field is needed in order to gain a better understanding of the factors that influence the population.

Anastrepha spp. (Diptera: Tephritidae) in Ximenia americana and other tropical fruits in a Brazilian savannah

The aim of this work was to evaluate the infestation of Anastrepha species in several fruit tree species and A. alveata in wild plum Ximenia americana L. (Olacaceae), as well as the fruit fly community in a Savannah area using faunal indexes and population fluctuation. For this, we installed McPhail traps and carried out collections at Palmeiras home garden, municipality of São Pedro of Piauí, state of Piaui, northeastern Brazil. We noted high infestation of A. alveata in wild plum, with 144.2 puparia/kg, 216.1 puparia/kg and 321.6 puparia/kg for the years 2014, 2015 and 2016. The infestation indexes of A. obliqua in red mombin (Spondias purpurea) were 146.1 puparia/kg in 2016 and 479.2 puparia/kg in 2017, and in umbu-hog plum (Spondias sp.) 607.3 puparia/kg in 2017, both from the Anacardiaceae family. The species that composed the fruit fly community were A. alveata, A. ethalea (predominant), A. obliqua, A. zenildae (dominant and accessory), A. sororcula, A. fraterculus and Anastrepha sp. (accidental). The population fluctuation of A. ethalea occurred from March to October, while A. alveata presented population peaks in the fruiting of wild plum, between October and December