ABSTRACT
Bacillus thuringiensis (Bt) Berliner has potential for use in insect management. Its use can be an alternative for the management of Bradysia aff. ocellaris (Comstock), considered one of the main strawberry pests in a soilless system. Therefore, the objective of this work was to evaluate the toxicity of different bacteria on B. aff. ocellaris in laboratory and greenhouse bioassays. The following isolates were used in the experiments: Bacillus circulans (Bc), B. thuringiensis var. oswaldo cruzi (Bto) or B. thuringiensis var. israelensis (Bti) and B. thuringiensis var. kurstaki (Btk) In the laboratory, B. aff. ocellaris larvae showed high susceptibility to Bti isolate (92 % mortality) 14 days after treatment exposure (DAET). In contrast, the isolates Bc, Bto, and Btk showed less than 32 % mortality, not differing from the control treatment (water 22 % mortality). According to the concentration-response curves the values of lethal concentration LC50 and LC90 were 4 x 106 CFU.mL-1 and 4 x 1015 CFU.mL-1. By applying Bti (4 × 1012 CFU.mL-1) at the base of strawberry plants growing in plastic pots containing commercial plant substrate, a reduction of 26 % in the emergence of B. aff. ocellaris was observed. According to these results, the Bti isolate is considered promising for the formulation of bioinsecticides based on Bt for the management of B. aff. ocellaris in strawberry culture.
ABSTRACT
Lycoriella species (Sciaridae) are responsible for significant economic losses in greenhouse production (e.g., mushrooms, strawberries, and nurseries). The current distributions of species in the genus are restricted to cold-climate countries. Three species of Lycoriella are of particular economic concern in view of their ability to invade areas in countries across the Northern Hemisphere. We used ecological niche models to determine the potential for range expansion under future climate change scenarios (RCP 4.5 and RCP 8.5) in the distribution of these three species of Lycoriella. Stable environmental suitability under climate change was a dominant theme in these species; however, potential range increases were noted in key countries (e.g., USA, Brazil, and China). Our results illustrate the potential for range expansion in these species in the Southern Hemisphere, including some of the highest greenhouse production areas in the world.
ABSTRACT
Stratiolaelaps scimitus (Womersley) and Cosmolaelaps brevistilis (Karg) (Acari: Laelapidae) are predatory mites of soil-inhabiting pests, mainly small insects. Fungus gnats fly species are found in greenhouse strawberry production and may be controlled with predatory mites, being important to know their compatibility with the pesticides used in strawberry crops. In this study, the compatibility of seven commercial pesticides used in strawberry cultivation with the predatory mites S. scimitus and C. brevistilis was assessed in laboratory conditions. Survival and oviposition rates were evaluated between 0.5 and 120 h after treatment (HAT). The results demonstrate that lambda-cyhalothrin treatment resulted in the lowest survival rate for both mites in the first evaluations, being moderately harmful, while spinetoran was slightly harmful to C. brevistilis. On the other hand, abamectin, azadirachtin, azoxystrobin + difenoconazole, iprodione and thiamethoxam were harmless for both mites and, oviposition rate was significantly different only at 72 and 120 HAT for S. scimitus and C. brevistilis respectively. These results may be used to develop guidelines for the adoption of selective pesticides in integrated pest management programs that conserves predatory mites.
Subject(s)
Fragaria/physiology , Mites/physiology , Pest Control, Biological/methods , Pesticides , Animals , Predatory Behavior/drug effectsABSTRACT
Interaction between Musca domestica L. and its predator Muscina stabulans (Fallén) (Diptera, Muscidae): Effects of prey density and food source abundance. The objective of this work was to evaluate the influence of prey density and food source abundance on the predatory behavior of Muscina stabulans over M. domestica. Three predator/prey proportions were evaluated (1:1, 1:3 and 1:6), using 100 third instar predator larvae against second instar prey larvae. Each proportion was maintained using three different levels of food substrate (25, 50 and 100 g). The experiments were carried out in triplicate in BOD incubators (25ºC, UR 70% ± 10% and 12 h photoperiod). The mortality of the M. domestica larvae was 100% under all conditions, except in the 1:6 predator/prey proportion, at the 50g and 100g food substrate levels, where it was 99.99% and 99.22%, respectively. There was a significant increase in the development period of M. stabulans in relation to the increase in prey density and decrease in quantity of food substrate. An increase in the proportion of individuals and a reduction in the amount of resource slowed down larval development. Muscina stabulans pupal weight was proportional to the increase in prey density and the amount of food substrate. The proportion or the density influenced the survival of M. stabulans, with no difference in relation to the amount of food source and consequently in the interaction of the factors. There was no difference between the 1:1 and 1:3 predator-prey densities, with both differing from the 1:6 density.
ABSTRACT
To evaluate the population fluctuation of Coleoptera from a poultry farm in Pelotas, Rio Grande do Sul, Brazil, two sampling methods were used: a tube-type trap and a sandwich trap. The analyses of polynomial regression were applied independent of the type of sampling method used. The experiment was carried out for twelve months, from April 2002 to March 2003, in a broiler barn aviary at the Conjunto Agrotécnico Visconde da Graça/UFPEL. A total of 43.945 Coleopterans were captured from the following species: Alphitobius diaperinus, Carcinops troglodytes, Euspilotus rubriculus, Gnathocerus cornutus, Mezium americanum and Somotrichus unifasciatus. Among these, Alphitobius diaperinus was present in all months of the year, with larval population peak in February (235) and lowest capture in August (01). The adult population peak was in March (12,020) and the lowest capture in July (27). The remaining captured Coleopterans did not occur in all twelve months, however they also had population peaks in the months of February and March, which also were the months with the highest temperatures.
Para avaliação da flutuação populacional de Coleoptera, em granja avícola, em Pelotas, Rio Grande do Sul, Brasil, foram utilizados dois métodos de coleta: armadilha do tipo tubo e do tipo sanduíche, durante doze meses. A análise de regressão polinomial foi aplicada independentemente do tipo de método de coleta utilizado. O experimento foi conduzido durante 12 meses, de abril de 2002 a março de 2003, em um aviário de aves poedeiras do Conjunto Agrotécnico Visconde da Graça da Universidade Federal de Pelotas (UFPEL). Foram capturados 43.945 Coleopteros das espécies Alphitobius diaperinus, Carcinops troglodytes, Euspilotus rubriculus, Gnathocerus cornutus, Mezium americanum e Somotrichus unifasciatus. Entre esses Coleopteros, Alphitobius diaperinus esteve presente em todos os meses do ano, com pico populacional de larvas em fevereiro (235) e menor índice de captura em agosto (01), sendo que o pico populacional de adultos foi em março (12.020) e o menor índice de captura ocorreu em julho (27). Os outros Coleopteros capturados não ocorreram durante os 12 meses de captura, porém, eles também tiveram pico populacional nos meses de fevereiro e março, que foram os de temperatura mais alta.