Red imported fire ant (Hymenoptera: Formicidae) control with a corn grit bait of fenoxycarb without soybean oil.

The standard fenoxycarb fire ant bait formulation (Logic), composed of pregel defatted corn grits and soybean oil toxicant, was modified by eliminating the soybean oil. This formulation without soybean oil contained greater than 2 times more fenoxycarb and was as effective as the standard bait formulation against laboratory colonies of red imported fire ant, Solenopsis invicta Buren. In field tests, the modified and standard baits were equally effective in controlling fire ants after 6, 12, and 18 wk. Individual worker ants obtained from plots treated with fenoxycarb baits without soybean oil had greater than 47 times less fenoxycarb than did workers from the plots treated with the standard fenoxycarb baits containing soybean oil.

Fly pupae as attractant carriers for toxic baits for red imported fire ants (Hymenoptera: Formicidae).

Eight laboratory-reared ant species were fed baits of house fly, Musca domestica L., pupae treated with hydramethylnon. Two fire ant species, Solenopsis invicta Buren and Solenopsis geminata (F.), and Pheidole morrissi (Forel) were killed; average percentage of mortality of the five other species was less than 20%. In contrast, all species that were fed the commercial fire ant bait containing hydramethylnon (Amdro) died or were adversely affected. In the field, applications of house fly pupae and eye gnat, Hippelates pusio Loew, pupae dipped in acetone solutions of fenoxycarb significantly reduced population indices of the red imported fire ant, S. invicta, compared with commercial formulations of fenoxycarb (Logic) and hydramethylnon (Amdro). Field observations showed that the pupae of either species can be carried or moved by one or two worker ants. The smooth, hard cuticle of the pupae make them easy to handle and apply with application equipment. The current cost of house fly pupae is considerably more than the cost of a granular carrier, pregel defatted corn grits. However, if mass-production methods reduce this price differential, fly pupae could become an effective and more species-specific fire ant bait carrier.

Biochemical and behavioral evidence foe hybridization between fire ants,Solenopsis invicta andSolenopsis richteri (Hymenoptera: Formicidae).

Behavioral and biochemical evidence is presented for hybridization between the fire ants,Solenopsis richteri andS. invicta. The response of the two species to extracts of their trail pheromones presented as a point source is clearly species-specific; however, hybrid workers responded to parental Dufour's gland extracts and parental workers responded to Dufour's gland extracts of the hybrid. The behavioral evidence for hybridization was confirmed by gas Chromatograph comparison of the Dufour's gland extracts of the three fire ant forms, which showed a pattern for the hybrid that was intermediate to the two parental species.

Isolation of the trail recruitment pheromone ofSolenopsis invicta.

TheSolenopsis invicta trail pheromone is synthesized by the Dufour's gland and is released through the sting apparatus. The recruitment subcategory of theS. invicta trail pheromone was shown to be composed of a mixture of the orientation pheromone, (Z,E)-α-farnesene and an unidentified homosesquiterpene consisting of three rings and one double bond (C-1). C-1 is present in worker Dufour's glands at only 75 pg per worker equivalent. This is the first report that demonstrates that different exocrine products from the same gland control different subcategories of behavior related to mass recruitment.

Genetic method for the preferential elimination of females of anopheles albimanus.

Recent field experiments demonstrated the possibility of using the sterile male method for the control of Anopheles albimanus Wiedemann, the most important vector of human malaria in Central America. Until now there was no practical method for excluding females from the releases of sterile males. A genetic method was developed for the preferential elimination of females during any of the four life stages. This genetic sexing system utilizes propoxur (o-isopropoxyphenyl methyl-carbamate) susceptibility as a recessive conditional lethal a T(Y:2R) translocation, and an In(2R)inversion. The propoxur resistance allele (dominant) was linked to the Y chromosome via a radiation-induced translocation, and genetic recombination was suppressed by inversions. In one of the strains produced, 99.7 percent of the females are eliminated when treated with propoxur, without male loss.

Mirex residues in nontarget organisms after application of 10-5 bait for fire ant control, northeast Florida--1972-74.

The 10-5 bait formulation of mirex insecticide was applied to a 20,000-acre area of northeast Florida. For 24 months after application, samples of a wide variety of fauna were collected and analyzed for mirex content. Insects accumulated mirex to the greatest extent in the first 6 months after application; most residues had decreased greatly by 12 months. Other invertebrates showed low mirex levels during the first 9 months after application and none after 12 months. Fish possessed low levels of insecticides for 9 months; amphibians showed mirex residues for 12 months after application. In general, reptiles had low levels throughout the 24-month period and mammals had higher levels, particularly in fat tissues. Birds consistently had low to moderate mirex levels. After a single application of 10-5 mirex bait, only relatively low levels of insecticide were detected in exposed fauna. After 24-months, mirex was found infrequently and at low levels.

Mirex residues in nontarget organisms after application of experimental baits for fire ant control, southwest Georgia--1971-72.

Mirex, the only compound approved for control of the red imported fire ant (Solenopsis invicta) and the black imported fire ant (Solenopsis richteri), is normally applied at a rate of 1.40 kg/ha. (1.25 lb/acre). Influenced by recent studies showing that low levels of mirex are toxic to certain nontarget organisms, particularly estuarine species, authors report here on a monitoring study of mirex in three large treatment areas of southwest Georgia. Four formulations of bait were applied aerially in 1971-72. Low-level residues were observed in small terrestrial vertebrates and invertebrates and in fresh-water inhabitants. Levels detected were about the same for all baits. Maximum residues were detected 1-3 months after treatment and gradually declined to low levels of 0.02-1.16 ppm 1 year after treatment.