Abstract. The sugarcane borer Diatraea saccharalis is an important pest of sugarcane and ants are one of its main predators. The practice of burning sugarcane straw in situ after harvest has been gradually replaced in Brazil by other practices. However, it is unknown whether ants can control the abundance of this borer in the presence of straw. In this study, we assessed the diversity and species composition of ants attacking different stages of the pest's life cycle. Specifically, we asked whether the species richness and abundance of ants varies during the course of day and a year. We established one-hectare plots at random locations in a sugarcane plantation. Once a month, we collected 20 samples of each stage of the D. saccharalis life cycle and randomly distributed these samples as bait on plants spaced 20 m apart within a plot. Ants were collected daily in the morning and afternoon over a period of 12 months. We identified several aspects of ant feeding behaviour that may affect their biological control of the borer: (1) the greatest number of ants were collected from baits consisting of the immature stages of the sugarcane borer, (2) ants were most active in the morning and (3) their activity varied from month to month. Solenopsis saevissima and morphotypes of Crematogaster sp.7 and Pheidole sp.35 are potentially important predators of borers in sugarcane crops in which the straw is not burnt.
The increase in the use of flat slabs and the need of the openings for the passage of installations, such as hydraulic and electrical, which significantly reduces the punching shear resistance capacity of the slab, makes the understanding of the influence of openings in this type of structure extremely necessary. The influence in the structural behaviour of flat slabs with openings at different distances from the column was investigated through five square slabs (1,800 mm x 1,800 mm x 130 mm) supported on square columns (150 mm x 150 mm) tested until failure. The results obtained experimentally were compared with results available in the literature, as well as with responses predicted from the normative instructions. The results confirm high stresses concentration in the region between the column and the opening and that opening situated at 3d from the column have no influence on the failure load for the tested slabs.
Light and temperature are important factors affecting development and sporulation of entomopathogenic fungi. This paper is a study of the behaviour of Metarhizium anisopliae isolate SPL‐3B, under 3 temperatures and 4 photoperiods, utilizing F15‐T12/LD lamps.
It was concluded that amongst the 12 combinations of temperature and photoperiod tested, a temperature of 28 °C and photoperiod of 16 hours is the regime most suitable for development and sporulation of this isolate of Metarhizium anisopliae.
Zusammenfassung
Zum Einfluß der Photoperiode und Temperatur auf die Entwicklung und Sporulation von Metarhizium anisopliae (Metsch.) Sorok.
Licht und Temperatur sind wichtige Faktoren, die auch die Entwicklung und Sporulation von entomophagen Pilzen beeinflussen. Es wurde das Verhalten des M. anisopliae‐Isolats SPL‐3B bei 3 Temperatur‐ und 4 Photoperiode‐Stufen unter Verwendung von F 15‐T 12/LD‐Lampen untersucht. Von den 12 Temperatur‐Photoperiode‐Kombinationen erwiesen sich 28°C + 16 h Licht als für die Entwicklung und Sporulation des M. anisopliae‐Isolats am günstigsten.
-The effect of combinations of the entomopathogenic nematodes Heterorhabditis indica Poinar, Karunakar & David, 1992 (strain IBCB-n5) and Steinernema sp. (strain IBCB-n6) at doses of 2.4;12 and 60 IJ/cm 2 , with sub-doses of the chemical insecticides fipronil, thiamethoxam and imidacloprid were tested in laboratory conditions against adults and larvae of the sugarcane billbug, Sphenophorus levis Vaurie, 1978. Firstly, the effect of fipronil (200 g A.I./ha), thiamethoxam (250 g A.I./ha) and imidacloprid (700 g A.I./ha) were evaluated on the nematode viability. The insecticides were compatible with the nematodes, not affecting the viability of the infective juvenile after 24 hours. For the experiments with adults, the treatments containing nematodes and insecticides tested separately showed mortality below 25%, except for the two highest doses of Steinernema sp. (at 12 and 60 IJ/cm 2 ), with mortality levels of 33.3% and 50% respectively. For the mixtures of the nematodes with sub-doses of thiamethoxam (62.5 g A.I./ha), the mortality levels increased significantly, reaching up to 66.7%, with the mixture of H. indica at 60 IJ/cm 2 , and 70% to 83.3% at all doses of Steinernema sp., showing synergistic effect at these combinations. The combination of H. indica and Steinernema sp. (12 IJ/cm 2 ) with thiamethoxam (62.5 g A.I./ha) against larva, the nematodes tested alone or in mixture with the insecticides showed mortality levels between 75% and 87.5%, indicating no advantage of the mixture for improving the insect mortality.KEYWORDS -integrated pest management, Heterorhabditis indica, Steinernema sp., sugarcane billbug, microbial control.
RESUMO -Foi testado em laboratório, o efeito de combinações dos nematóides entomopatogênicos
The harvest of sugarcane is still traditionally done manually with the burning of straw in most cultivated areas in Brazil. However, burning has been gradually eliminated with the relatively recent use of mechanical harvesting. This will result in significant changes in the agroecosystem, as the straw will remain in the field. No investigation on Formicidae found in sugarcane plantations in Southeastern Brazil harvested by this new system has been done yet. Because of their feeding habits, many species of this family may act as predators of several sugarcane pests. In this study, the sampling efficacy of pitfall traps, baits, and underground traps with two types of attractants were evaluated. Pitfall traps gave the largest richness, while abundance was the highest from baiting. Community composition and structure differed in relation to the sampling methods used. The myrmecofauna collected with the same method with different baits was similar. Pitfall trapping was the most efficient method in this type of ecosystem; and sardine, the best attractant, due to its easy handing in the field.
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