Specificity of the Red Imported Fire Ant Phagostimulant Response to Carbohydrates
The red imported fire ant, Solenopsis invicta Buren, is considered an oil-loving feeder, however, carbohydrates are essential ingredients in the diet of the fire ant also. Comprehensive screening of mono-, di-, and tri-saccharides demonstrated that glucose, fructose, fucose, sucrose, maltose, turanose and raffinose were significant phagostimulants for fire ant workers. It was also found that while D-glucose and L-fucose, the naturally occurring isomers, were active, the opposite diastereomers were not. Any structural modification of the glucose molecule resulted in loss of activity. None of the sugar alcohols evaluated were active. The fire ant is an agricultural pest and the many reports of fire ant damage to food crops may be linked to their need for dietary carbohydrates. A knowledge of carbohydrate phagostimulants may help to understand specificity of fire ant /plant interactions.
Red imported fire ants (Hymenoptera: Formicidae): frequency of sting attacks on residents of Sumter County, Georgia.
A survey of the human sting attack rate of the red imported fire ant, Solenopsis invicta , on a sample population in Sumter Co., Georgia, USA, was conducted over a 12-month period. Seventy-seven families (310 individuals) initially participated in the program, but dropouts reduced the average study population to 272 individuals per month. A total of 213 sting attacks were recorded for 95 individuals. A majority (179) of these were recorded for rural residents. The greatest contact occurred from April to September, with the total sting attacks ranging from 18–35 per month. The highest sting attack rate occurred in persons under 20 years of age (50%); the number of stings declined with increased age. Females reported being stung at a slightly higher rate than males. Two individuals (1%) classified their sting reactions as severe, 26 (12%) as moderate, and 183 (87%) as mild.
Design of reinforced concrete lining in pressure tunnels, considering thermal effects and jointed rockmass
Abstract Jaeger's theory (Jaeger, Rock Mechanics and Rock Engineering , Cambridge University Press, 1972) of the design of the lining for a pressure tunnel applies to a tunnel located in an isotropic, homogeneous and elastic medium. The theory is derived from the elasticity equations for the plane stress condition. In this paper, Jaeger's theory is extended to a plane strain situation. Also included is a discussion of the effects of a uniform increase (or decrease) in the lining temperature, jointed rockmass, cracking of the tunnel lining, and cracking of the rockmass around the opening. Tables are presented for the modulus of subgrade reaction for various rockmass conditions and for rock sharing pressures for various lining conditions. The reduction factor to include the effect of joints in rockmass is derived by the analysis of a numerical model of the lined tunnel by the finite-infinite-interface element method.