Queen control of sex ratio in fire ants

The haplodiploid sex-determination system of ants gives rise to conflict between queens and workers over colony sex ratios, and the female-biased allocation ratios seen in many species suggest that workers often prevail in this conflict. We exchanged queens between male- and female-specialist colonies of the fire ant Solenopsis invicta. These exchanges quickly reversed the sex-ratio biases of adopting colonies. The sex ratio of queen-laid eggs differed strongly between male- and female-specialist colonies. These findings suggest that queens can force workers to raise male sexuals by limiting the number of female brood and help to explain why sex investment ratios lie between the queen and worker equilibria in this and many other ant species.     

Pheromonal control of dealation and oogenesis in virgin queen fire ants

In the fire ant Solenopsis invicta, sexually mature virgin females are prevented from shedding their wings and becoming functional egg layers by the presence of the mated queen. Experimental data suggest that this inhibitory effect results from the action of a relatively nonvolatile primer pheromone (or pheromones) produced by the mated queen and distributed by the workers. Target ants are both virgin queens and workers.     

External morphology and microstructure of the compound eye of fire ants, Solenopsis invicta Buren

The external morphology of the compound eye of the winged female and male Solenopsis invicta Buren and its microstructure in light and dark adaptations were observed using scanning electron microscopy and optical microscopy. The results indicated that the compound eye located on the lateral side of its head, is the a shape of a half ellipsoid and composed of approximately 510 ommatidia in the female, and a near hemisphere with about 805 ommatidia in the male. The ommatidium was made of a corneal lens, crystalline cone, 8 to 9 retinula cells and basement membrane. The cornea was a colorless, transparent and double convex lens. The crystalline cone, with an inverted cone shape, was approximately 14.50m long, formed by four equal parts, and surrounded by many pigment granules. The rhabdom beneath the crystalline cone, was about 75.00m long, with a thicker middle part and thinner ends. More pigment granules were scattered in the distal and proximal ends and less in the middle, and the basement membrane was on the most bottom area of the ommatidium. The primary pigment cells moved horizontally along the crystalline cone from its distal to proximal end during dark adaptation or moved reversely during light adaptation. There was no significant difference between the pigment granule distribution and the structure of the crystalline cone between female and male ommatidium under the same light or dark adaptation. It is concluded that the fire ant compound eye is an apposition eye, whose light-tuning mechanism is accomplished by the change of crystalline cone and the movement of the pigment cells.     

惠州市主要体育场馆红火蚁疫情及防控效果初报

调查了惠州市奥林匹克体育馆、金山湖体育馆等周边绿化区红火蚁疫情,并进行防控处理。调查表明,奥林匹克体育场与体育人才训练基地红火蚁疫情达到五级,属于严重危害区;金山湖游泳跳水馆红火蚁达到四级,属于中度危害区;金山湖体育馆红火蚁疫情为三级,属于轻度危害区。同时,采用诱饵法对防控效果进行了监测,随着施药时间的增长,防控效果愈高。药后7 d,红火蚁蚁丘减退率为77.9%~82.0%,工蚁诱集量减退率为60.0%~88.0%;药后15 d,蚁丘减退率上升至88.3%~91.0%,工蚁诱集量减退率高达88.6%~90.0%。药后40 d监测,防控效果均达100%,完全消除了红火蚁的蚁害威胁。