Heat Tolerances of Four Species of Fire Ants (Hymenoptera: Formicidae: Solenopsis)

Abstract

Minor workers of the four fire ants species found in Texas, Solenopsis aurea Wheeler, S. geminata (Fabricius), S. invicta Buren, and S. xyloni McCook were exposed for one hour to upper critical temperatures. Solenopsis aurea and S. xyloni are typically desert adapted ants whereas S. geminata and S. invicta are found in mesic regions. We predicted that those species from hot desert regions would have higher temperature tolerances than their more mesic congeners. Mortality rates were not siginificantly affected by relative humidity conditions (0% or 100%), indicating that the ants did not die from dehydration. The responses of ants acclimated at I2°C, 2~C, and 32°C were significantly different, although biologically the differences were negligible. The LDSO values were between 40.8°C and 44.0°C and the LD95 values between 4!U °C and 47.3°C. MATERIALS AND METHODs.-Four species of fire ants were collected in Texas: Solenopsis aurea Wheeler and S. xyloni McCook from Garza Co., S. geminata (Fabricius) from Kimble and Val Verde Cos., and S. invicta Buren from Bandera Co. Colonies of ants were collected, separated from the soil, and housed following the methods of Banks et aL (1981). All colonies were maintained with similar regimens of food, water, and light. Ants were fed cockroaches, Nauphoeta cinerea (Saussure), and mea1worms, Tenebrio sp. Free water and a 1:1 solution of honey and water were

Bait Insecticides and Hot Water Drenches Against the Little Fire Ant,Wasmannia auropunctata(Hymenoptera: Formicidae), Infesting Containerized Nursery Plants

“…Hot water treatment at 45°C for 10 min resulted in >99% mortality of W. auropunctata both in vitro and in infested potted plants; however, in order to meet quarantine requirements and consistently achieve 100% mortality, drenching at a higher temperature or for longer duration is necessary to adequately treat plants that may be root-bound or in media that does not allow adequate heat conduction. Francke et al (1985) reported that temperature tolerance (LD95) for four fire ant species, Solenopsis aurea Wheeler, S. geminata (Fabricus), S. invicta Buren, and S. xyloni McCook, previously acclimated for 2 wk at 22°C under similar conditions as this study, were reported in the range of 43.8-45.7°C (1 h exposure). Upper lethal temperature limit of desert honey ant workers, Myrmecocystus spp., was determined to be between 40-45°C (2 h exposure) (Kay & Whitford 1978).…”

Thermal Tolerances of Three Tramp Ant Species (Hymenoptera: Formicidae)

“…In our experiments, T. bicarinatum was the largest species and proved the least tolerant. Francke et al (1985) hypothesized that tolerance to different temperatures in ants can be influenced by worker age, ambient humidity, previous thermal regime, and colony diet, apart from colony location (Angilletta et al 2007). As all three species were reared under the same room conditions and the tests employed only workers found outside the colonies -which are regarded as the oldest (Hölldobler & Wilson 1990) -we think the observed differences between species directly reflect their intrinsic temperature tolerances.…”

Effect of Carbohydrate Supplementation on Investment into Offspring Number, Size, and Condition in a Social Insect

“…For eusocial organisms, a colony’s investment in the size and condition of its individual members can influence colony fitness through colony maintenance, survival, and reproduction [ 13 – 15 ]. For example, body size affects worker metabolism [ 16 , 17 ], thermal tolerance [ 18 , 19 ], locomotion [ 20 , 21 ], longevity [ 16 , 22 ], and foraging/prey selection [ 23 – 25 ]. Consequently, body size plays an important role in determining how organisms interact with the biotic and abiotic environment [ 19 , 25 – 27 ].…”