No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Impact of Solenopsis invicta Buren Suppression on Arthropod Ground Predators and Pest Species in Soybean
Abstract
The red imported fire ant, Solenopsis invicta Buren, reportedly contributes to the biological control of key soybean pests. However, S. invicta may negatively affect ground-dwelling natural enemies such as ground beetles and earwigs. Information on the interactions between natural enemies is important for anticipating the success of biological control in agroecosystems with multiple interacting entomophagous species. Ground arthropods were monitored in soybean using pitfall traps in the 2000 and 2001 growing seasons to determine their response to selected fire ant controls. Three treatments were examined: an untreated check, Amdro™ (hydramethylnon) bait (ant-specific), and Lorsban™ (chlorpyriphos) (broad spectrum) plus Amdro. Fire ant captures in pitfall traps were lower in the Amdro and in the Amdro plus Lorsban treatments compared to the untreated control. Reduced fire ant density plus chemical treatment impacted the abundance of certain ground predators. Spiders, primarily Lycosidae, were significantly more abundant in the untreated control plots on some sampling dates; whereas, the earwig Labidura riparia Pallas was more abundant in the Lorsban and Amdro plots, presumably due to the removal of fire ants and other natural enemies. Ground beetles (Carabidae) were not different between treatments on any sampling dates. This study supports the assumption that spiders are compatible with fire ants as natural enemies and that earwigs are not compatible with fire ants. Numbers of lesser cornstalk borer, Elasmopalpus lignosellus Zeller, were not affected by the suppression of fire ant predation or the chemical treatments in 2000, the only year when they were captured. Crickets (Gryllidae), mole crickets (Gryllotalpridae), click beetles (Elateridae), scarab beetles (Scarabaeidae), and false darkling beetles (Melandryidae) also were not different between the fire ant suppression treatments.
... Our study demonstrates that tectocepheids beneÞt from Þre ants, possibly due to their small size (200 Ð300 m) relative to that of other oribatids. The positive associations between Þre ants and both staphylinids and spiders also were not expected because past research has shown that Þre ants have either negative or no effect on these groups in cotton (Vinson 1991, Eubanks et al. 2002, Diaz et al. 2004); however, there is evidence to suggest that spider abundances increase in the presence of Þre ants in soybean (Seagraves et al. 2004). An alternative explanation for the positive response of some invertebrates to Þre ants may be that these taxa instead responded negatively to the application of hydramethylnon in Þre ant exclusion plots. ...
... K.Koch] orchard by using s-methoprene (Extinguish). Similarly, Seagraves et al. (2004) observed an increase in L. riparia abundance under Þre ant suppression in soybean. In both cases, the authors suggested that the increase in the abundance of L. riparia in the absence of Þre ants was caused by a release from predation or competitive exclusion by S. invicta. ...
The red imported fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae), has been studied extensively in its role in aboveground food webs of agroecosystems of the southern United States. There is also a limited body of evidence suggesting that S. invicta may significantly influence the soil fauna. This study examined the influence of fire ants on the arthropod communities at the soil surface of cotton, Gossypium hirsutum L., fields at two field sites operated by the University of Georgia in Athens and Tifton, GA (1 yr at each location). Fire ant abundance was suppressed in large plots with ant-specific hydramethylnon-based bait, and arthropods were collected from treatment and control plots by using pitfall traps during multiple week-long sample periods to measure the abundance of epigeic arthropods. Sampling was conducted from June through September 2006 in Athens and from July through September 2007 in Tifton. Although fire ant suppression decreased the abundance of erythraeid mites and nitidulid beetles at both sites, the majority of effects were site-specific. Other taxa positively associated with fire ants included oribatid mites and gnaphosid and linyphiid spiders. In contrast, the abundance of springtails, earwigs, endomychid beetles, and thrips increased with fire ant suppression. This study demonstrates that S. invicta can significantly influence both pest and beneficial epigeic arthropods and that although fire ants exert clear effects on specific taxa, their effects are not uniform within a given trophic group as members from the same guild were differentially impacted.
... We used hot water instead of other control methods, such as insecticidal baits or mound treatments, because our variables of interest (species richness and abundance of co-occurring ants) are affected by non-specific poisons (Summerlin, Hung & Vinson 1977;Seagraves, McPherson & Ruberson 2004). Regardless of the manner (or caution, for example mound drenches) of application, insecticides persist and enter the arthropod food chain. ...
... Experiments on the fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae), one of the most studied social insects, have almost universally relied on poison baits to remove or reduce populations of this ant. A few examples will suffice: Seagraves et al. (2004) killed fire ants with three different bait treatments to test their effect on arthropod ground predators; Allen (1995) reduced fire ant populations with Amdro® bait to determine their effect on bobwhite quail; and Reagan et al. (1972) reduced fire ants with Mirex® bait to determine their effect on sugar cane pests. ...
... To date, both negative and positive effects of insecticides on L. riparia in the field have been reported; Price and Shepard (1978) reported that the application of organophosphorus insecticides reduced the population of L. riparia, whereas others (Gross and Spink, 1969;Tryon, 1986;Seagraves et al., 2004) have reported that the application or residues of insecticides promoted the population growth of L. riparia through reduction of predaceous ant populations. This implies that the effects on L. riparia differ among insecticides and that L. riparia is less susceptible to insecticides than other predaceous insects like ants; however, the difference in the susceptibility of L. riparia to various insecticides has not been studied to date. ...
Using a direct spraying test in the laboratory, nine Bt insecticides, a Beauveria bassiana insecticide, two IGRs (methoxyfenozide and chromafenozide), and a synthetic insecticide (pyridalyl) were determined to be harmless and a synthetic insecticide (dinotefuran) was determined to be slightly harmful to second instar Labidura riparia nymphs, which are regarded as an important natural mortality factor against insect pests in various crop fields. The use of these insecticides should be recommended in IPM programs to control cabbage insect pests, since they are regarded as being compatible with the conservation of L. riparia in the field.
... Experiments on the fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae), one of the most studied social insects, have almost universally relied on poison baits to remove or reduce populations of this ant. A few examples will suffice: Seagraves et al. (2004) killed fire ants with three different bait treatments to test their effect on arthropod ground predators; Allen (1995) reduced fire ant populations with Amdro® bait to determine their effect on bobwhite quail; and Reagan et al. (1972) reduced fire ants with Mirex® bait to determine their effect on sugar cane pests. ...
Ecological experiments on fire ants cannot, or should not, use poison baits to eliminate the fire ants because such baits are not specific to fire ants, or even to ants. Hot water is an extremely effective and specific killing agent for fire ant colonies, but producing large amounts of hot water in the field, and making the production apparatus mobile have been problematical. The construction and use of a charcoal-fired kiln made from a 55-gal. oil drum lined with a sand-fireclay mixture is described. An automobile heater fan powered from a 12-v battery provided a draft. Dual bilge pumps pumped water from a large tank through a long coil of copper tubing within the kiln to produce 4 to 5 l. of hot water per min. The hot water was collected in 20 l. buckets and poured into fire ant nests previously opened by piercing with a stick. The entire assembly was transported in and operated from the back of a pickup truck.
Five experimental plots containing 32 to 38 colonies of the fire ant, Solenopsis invicta, Buren (Hymenoptera: Formicidae), were treated with hot water over a period of two years. All colonies on the treatment plots were treated twice with hot water early in 2004, reducing their numbers to zero. However new colonies were formed, and mature colonies expanded into the plots. A third treatment was made in the spring of 2005, after which fire ant populations were suppressed for over a year. Whereas the 5 control plots contained a total of 166 mostly large colonies, the 5 treatment plots contained no live colonies at all. Averaged over a two-year period, a 70% reduction in total number of colonies was achieved (P < 0.001) on the treatment plots, and a 93% reduction of large, mature colonies. Over this same time span, the number of colonies in control plots remained stable. The reduction in colony numbers on the treatment plots was reflected in the pitfall trap samples that recorded a 60% reduction in fire ants.
... We used hot water instead of other control methods, such as insecticidal baits or mound treatments, because our variables of interest (species richness and abundance of co-occurring ants) are affected by non-specific poisons (Summerlin, Hung & Vinson 1977; Seagraves, McPherson & Ruberson 2004). Regardless of the manner (or caution, for example mound drenches) of application, insecticides persist and enter the arthropod food chain. ...
The fire ant, Solenopsis invicta , is a globally distributed invasive ant that is largely restricted to disturbed habitats in its introduced range. For more than half a century, biologists have believed its success results from superior competitive abilities relative to native ant species, as well as an escape from their natural enemies.
We used large volumes of hot water to kill fire ant colonies, and only fire ant colonies, on experimental plots in pastures, and found that populations and diversity of co‐occurring ants did not subsequently increase.
These results are contrary to classical predictions and indicate that S. invicta is not a superior competitor that suppresses native ants, and that the low diversity and abundance of native ants in degraded ecosystems does not result from interaction with fire ants. Instead, other factors such as prior disturbance and recruitment limitation may be the primary limiting factors for native species in these habitats.
The red imported fire ant, Solenopsis invicta Buren, has been reported to contribute to the biological control of key arthropod pests in soybean, Glycine max (L.) Merrill, and other crops. Solenopsis invicta also has been implicated as a major disrupter of biological control and a direct crop pest associated with reduced yields. In 2000 and 2001, fire ant foraging, survival of sentinel lepidopteran eggs and pupae, seasonal abundance of common foliage-dwelling soybean arthropods, and crop yield were assessed under three different fire ant suppression treatments at two test sites in Tift Co., GA. The treatments included an untreated control, hydramethylnon ant bait, and hydramethylnon bait in combination with the broad spectrum insecticide chlorpyriphos. Fire ant foraging was reduced in the chemically-treated plots in comparison to the control, based on fire ant numbers on hot dog baits after a 1-h field exposure in the early morning. Survival of soybean looper, Pseudoplusia includens Walker, eggs in 2000 and corn earworm, Helicoverpa zea Boddie, eggs in 2001 was lower in the untreated plots after a 24-h field exposure, where S. invicta foraging rates were high. Soybean looper pupal survival was 34 and 88% lower on foliage and the ground, respectively, in the control compared to those with reduced fire ant foraging. The seasonal abundance of foliage-dwelling soybean arthropods was primarily unaffected by the fire ant suppressing treatments. However, in 2001, green cloverworms, Hypena scabra F., and spiders were significantly lower (38.6 and 40.5%, respectively) in the chlorpyriphos plus hydramethylnon bait treatment in comparison to the other treatments. Season-long suppression of fire ants had no effect on soybean yield. The results of this study suggest that S. invicta, at naturally-occurring levels, is an active predator on some common soybean lepidopteran pests.
From scorching, barren deserts to humid tropical forests, from deep in the soil, to high in the tree canopies, ants are everywhere! Comprising a substantial part of living biomass on earth, ants are integral to the functioning of terrestrial ecosystems. More than 12,000 species have been described to date, and it is estimated that perhaps as many still await classification. Their social structure provides a rich ground for exploring how division of labour affects the acquisition of resources, foraging and defensive behaviours, and coevolution with the flora and fauna with which they interact. The study of ants has led to significant advances in our understanding of insect evolution, global diversity patterns, competitive interactions, mutualisms, ecosystem's responses to change, and biological invasions. Ant Ecology explores these and other key ecological issues and new developments in myrmecology across a range of scales. The book begins with a global perspective on species diversity in time and space and explores interactions at the community level before describing the population ecology of these social insects. The final section covers the recent ecological phenomenon of invasive ants: how they move across the globe, invade, affect ecosystems, and are managed by humans. Each chapter links ant ecology to broader ecological principles, provides a succinct summary, and discusses future research directions. The Synthesis and Perspectives highlights contributions of ant ecology to ecology more broadly, and outlines promising areas for future research.
The impact of the imported fire ant (IFA) is complex, in large part, because several very different species of "Fire Ants" have invaded and one of these has two forms, all of which are hard to separate by the public, as well as, some investigators not focused on the ant. Each of these different "IFA" species and forms differ in their impact. Further, these ants impact a number of "things" ranging from the environment and wildlife (plants and animals) as well as people, their environment and infrastructure. In addition, they can not only lead to death of living things (including people), but they can destroy many aspects of our environment and infrastructure at the cost of millions of dollars. But there are some beneficial aspects and some people can make many thousands of dollars due to their presence. This is an attempt to look at these issues.
Foraging activity of the red imported fire ant, Solenopsis invicta Buren, was monitored at bait traps for 1 yr to determine how weather and season affected foraging. Soil temperature at 2 cm was the best individual predictor of foraging rates at our study site (R2 = 59%); workers foraged from 15 to 43°C, with maximal rates between 22 and 36°C. Season explained another 19% of sample variation in a multiple regression with soil temperature; this was because foraging was unusually low in late fall. Rain reduced foraging rates by ca. 40% and explained an additional 3% of the variation. Workers did not exhibit a tendency to forage more at night because neither time of day nor night/day were significantly correlated with foraging rates. Relative humidity, saturation deficits, soil moisture, and wind were also unrelated to foraging. Average weight of individual foragers increased ca. 30% with increasing soil temperature and decreased 15% with the advancing season. Soil-temperature data were used to calculate periods of foraging activity for an open pasture, a nearby shaded woodlot, and seven additional locations in the southeastern United States. Activity periods were distinctly shorter in shady habitats and higher latitudes. Low temperatures limited activity much more frequently than high temperatures.
The red imported fire ant, Solenopsis invicta Buren, is an important predator in some cropping systems in the United States, particularly sugarcane and cotton, where it preys on key pests such as the sugarcane borer, Diatraea saccharalis (F.), and beet armyworm, Spodoptera exigua (Hübner). A study was undertaken to characterize the prey items collected by foraging S. invicta in an Oklahoma peanut field. From June to September 1999, 19 h of collecting yielded 1,276 foraged items. The largest percentage of foraged items (>20%) (other than unidentifiable fragments [39%]) were lepidopteran larvae, of which 87% were Stegasta bosqueella Chambers, the rednecked peanutworm. Overall, S. invicta collected approximately seven times more pest arthropods than beneficial arthropods. Forager success rates were ≈3.8 times higher for solids than liquids. Refuse piles in the field contained a large percentage of Coleoptera (≈26%) and did not mirror foraged material collections. Percent damaged pods on plants growing within S. invicta mounds was significantly (approximately three times) lower than on plants not within mounds. Additional data are presented on forager success rates and foraging/temperature relations.
Temperature and seasonal effects on foraging activity of Solenopsis invicta Buren (red imported fire ant) in Oklahoma were investigated by periodically quantifying the number of ants captured in baited vials for 2 yr. All temperature parameters (soil surface, 2 cm, 15 cm, mound surface, mound 5 cm deep, and mound 10 cm deep) except ambient at 1 m above soil surface were significant predictors of foraging activity; soil temperature at 15 cm was the best individual predictor, explaining 34% of variability in foraging activity. A combined quadratic model including mound surface temperature and season (weeks) explained 63% of the variability in foraging activity. Comparison with a similar study conducted in Florida revealed differences in the percentage of the year favorable for maximal foraging (≈25% in Oklahoma versus 42-59% in Florida). These data suggest that recommendations for timing of insecticidal bait applications against S. invicta that are appropriate in more southern portions of the fire ant range may not be appropriate for Oklahoma.
Invasive ant species represent a serious threat to the integrity of many ecological communities, often causing decreases in the abundance and species richness of both native ants and other arthropods. One of the most in-depth and well-known studies of this type documented a severe impact of the imported red fire ant, Solenopsis invicta, on the native ant and arthropod fauna of a biological field reserve in central Texas (USA) during the initial invasion in the late 1980s. I sampled the community again in 1999, 12 years later, utilizing the same methodology, to compare the short-and long-term impacts of this invasion. Pitfall traps and baits were used to obtain quantitative measures of the ant and arthropod community, and hand collecting was additionally employed to determine the overall ant species composition. Although the abundance and species richness of native ants and several other arthropod groups decreased precipitously immediately after the S. invicta invasion, all measures of native ant and arthropod species diversity had returned to preinvasion levels after 12 years. Solenopsis invicta was still the most abundant ant species, but not nearly as abundant as it was during the initial phase of the invasion. The results of this study indicate that the impact of such invasive ants may be greatest during and shortly after the initial phase of an invasion.
A method is presented for partitioning estimates of total larval mortality into that attributable to arthropod predators and that attributable to other factors. Mark-release-recapture and direct observation techniques are used in combination to derive estimates of mortality inflicted by all predators and to identify the predator species responsible for the mortalities on small and medium larvae. Daily rates of arthropod predation on velvetbean caterpillar, Anticarsia gemmatalis Hübner, larvae ranged from 0-25% per day for small larvae and 0-73% per day for medium larvae in 2 soybean fields. Nabids consumed the greatest proportion of small and medium larvae in one field, whereas imported fire ants, Solenopsis invicta Buren, were the major consumer of small and medium larvae in the other field. Results demonstrate that the total mortality inflicted by all predators can be the same for predator complexes with different species composition. /// Se presenta un método de seccionar las estimaciones de la mortalidad total de las larvas a la porción que se atribuye a los predadores y la que se atribuye a otros factores. Técnicas de marcarliberar-recapturar y de observar se usan en combinación para derivar las estimaciones de la mortalidad inflijida por todos predadores y para identificar la especie de predador responsable para las mortalidades de las larvas pequeñas y de medio tamaño. Rangos diarios de la predación de artrópodos sobre larvas de Anticarisia germmatalis Hubner variaban desde 0-25% por día para las larvas pequeñas, 0-73% por día para las larvas de medio tamaño en 2 campos de frijol de soya. En un campo, los nábidos consumieron la porción mas grande de las larvas pequeñas y de medio tamaño, mientras que en otro campo Solenopsis invicta Buren fue el consumidor major de las larvas pequeñas y las de medio tamaño. Los resultados demonstraron que la mortalidad inflijida por todos los predadores puede ser equal para los complejos con diferentes composiciones de especies.
The presence of a few red imported fire ants, Solenopsis invicta Buren, workers on aphid bearing cotton plants reduced aphid predator effectiveness in the laboratory. The predators Hippodamia convergens Guerin-Meneville adults and 3rd instar larvae were effective in reducing Aphis gossypii Glover populations as did 3rd instar larval Chrysopa carnea Stephens, Scymnus louisianae Chapin and Syrphus sp. larvae. However, all of these predators were ineffective in the presence of fire ants which were capable of killing all species although both Scymnus and Syrphus larvae sometimes escaped. Although predators may be killed they may prefer areas of low ant encounters in the field thus surviving and reducing their impact on fire ant tended aphid populations. /// En condiciones de laboratorio, la presencia de obreras de la hormiga de fuego Solenopsis invicta Buren en plantas de algodón infestadas con áfidos, redujo la eficiencia de los predatores de estos áfidos. Entre los más comunes predatores se encuentran:adultos y larvas del tercer estadío de Hippodamia convergins Guerin-Meneville, larvas del tercer estadío de Chrypopa carnea Stephens, larvas de Scymnus louisianae Chopin y larvas de Syrphus sp. Estos predatores mostraron ser eficientes en la reducción de las poblaciones de pulgones del algodonero. Sin embargo, fueron inefectivos en la presencia de la hormiga de fuego, las cuales atacaron y mataron a estos predatores. En contadas ocaciones, algunas larvas de Scymnus y Surphus pudieron escapar el ataque de estas hormigas; así que debido al riesgo de ser atacados, los predatores prefieren áreas en las que la frecuencia de encuentro con hormigas es baja, lo que reduce el impacto de éstos en las poblaciones de áfidos protegidos por la hormiga de fuego.
Moderate to heavy infestations of the imported fire ants (IFA), Solenopsis invicta Buren and S. richteri Forel, have reduced soybean production in the southern United States. In early surveys of crop damage, Wilson & Eads (1949) attributed a loss of about three percent of the soybean crop in three south Alabama counties to the ants. Adams et al. (1976, 1977) reported that 16.8 to 49.1 kg/ha of soybeans in Georgia and North Carolina were not harvested because of physical interference of S. invicta mounds with combine operation. Subsequent studies in Florida and Mississippi showed that IFA feeding on the germinating seed reduced the plant stand with an ultimate reduction of up to 600 kg/ha in soybean yield (Lofgren and Adams 1981, Adams et al. 1983). Apperson & Powell (1983) found that increased numbers of IFA correlated positively with reduced soybean yield in North Carolina
An overwintering population of Cardiochiles nigriceps Viereck (Hymenoptera: Braconidae) was studied in Central Texas in 1979-1980 in a plot of pigeon peas infested by a large, late-season population of the tobacco budworm, Heliothis virescens (F.). Emergence from overwintering started in early June, and no adults emerged after late June 1980. Overwintering C. nigriceps cocoons were collected from December 1979 through June 1980 and incubated at 26.7°C to determine the number of days required for adult emergence. Results indicated that adults had the potential to emerge from overwintering throughout the summer. In the field, however, predation of the cocoons by imported fire ants, coupled with an extremelydry summer that caused the soil to get extremely hard, interfered with the emergence of adult parasites over an extended period.
Seven species of insects including ground beetles, tiger beetles, earwigs, and the red imported fire ant, Solenopsis invicta Buren, were identified in laboratory feeding trials as pupal predators of velvetbean caterpillar, Anticarsia gemmatalis Hübner. The survivorship and predation of velvetbean caterpillar pupae were studied in soybean fields in Louisiana. Two descriptive categories of predatory feeding action were identified, “partial” and “complete”. Predation was the principal mortality factor, accounting for 52.5 to 95.2% mortality in plots with fire ants. The red imported fire ant was a primary predator, accounting for 77.5 to 96.5% of total predator mortality for pupae under the soil surface in plots with fire ants. Our studies also indicated that the red imported fire ant seemed to reduce other ground-dwelling pupal predators of velvetbean caterpillar.
Infestations and damage to sugarcane by the sugarcane borer, Diatraea saccharalis (F.), increased 53% and 69%, respectively, following one application of mirex to sugarcane field plots for control of the red imported fire ant, Solenopsis invicta Buren. Decrease in populations of arthropod predators, especially S. invicta, carabids, and staphylinids was responsible for increased sugarcane borer populations. Mirex did not appear to affect spider populations, but decreased numbers of crickets. Azinphozmethyl applied for sugarcane borer control decreased both spiders and crickets. S. invicta was the only ant species collected in experimental plots. These data show that mirex is not as specific to the red imported fire ant as previous reports have indicated.
Field experiments were conducted during 1966 and 1967 in the Bayou Sec area of Assumption Parish near Napoleonville, La., to (1) evaluate, quantitatively, the relative importance of arthropod predators of Diatraea saccharalis (F.) by correlation between numbers of these predators and the degree of egg and larval mortality of the borers; (2) obtain qualitative evidence of predation through frequent and widespread field observations; and (3) study the feeding behavior and habits of the predators concerned. Average percent egg predation was higher during August and September than during June and July. Percent eggs destroyed by sucking predators was significantly higher than those destroyed by chewing predators. More predation was recorded during the night than during the day. Positive correlation coefficients were found between total numbers of predators (ant and spider populations) and percent egg predation. Spiders were found to be more closely associated with percent egg predation than ants. Percent recovery of sugarcane borer larvae was significantly higher in July than in June. Numbers of predators and percentages of hatchability had a more significant effect on percentages of larval recovery than numbers of sugarcane plants per stool. Predators that were observed feeding on the different stages of the sugarcane borer belong to the following taxa: Formicidae, Carabidae, Forficulidae, Elateridae, Chrysopidae, and Araneida.
Five dominant spider families were found on Virginia soybeans, two on the ground (Lycosidae and Linyphiidae) and three on the foliage (Oxyopidae, Thomisidae, and Salticidae). Total foliage-dwelling spiders peaked in early August and again in early September 1981, and in early to mid-August in 1982. Ground spiders peaked in June with the greatest abundance of Lycosidae. While higher spider populations were collected from foliage in soybeans double-cropped after barley harvest and in full-season soybeans that were drill-planted, the ground spiders were more numerous in both barley- and wheatsoybean double-cropped systems. Over 25,000 spider specimens from 17 different families were observed in soybean ecosystems during this 2-year study.
Pitfall traps were used to monitor the seasonal abundance of predators in conventionally tilled, irrigated, and nonirrigated peanut (Arachis hypogaea L.) fields in Alabama in 1987 and 1988. A dverse fauna of predaceous arthropods was captured; Labidura rlparia (Pallas) (Dermaptera: Labiduridae) was the most abundant. Solenopsls invicta Buren (Hymenoptera: Formicidae), Geocorls spp. (Hemiptera: Lygaeidae), carabids, staphylinids, and Iycosids were also common. Traps placed between plant rows and those within rows yielded similar averages. All predaceous groups were captured throughout the peanut-growing season but in varied densities. Predator abundance peaked 70-100 d after planting, depending on the group. Capture of most predators increased exponentially for part or all of the growing season.
The effects of the predator complex in suppressing defoliating caterpillars of soybean were evaluated in Louisiana by chemical exclusion techniques. The total number of defoliators on a season-long basis was found to differ significantly (P < 0.05) between chemically treated plots and unidisturbed checks. Additionally, there were significant changes in numbers of total foliage and total ground predators. Populations of the velvetbean caterpillar, Anticarsia gemmatalis Hübner, the primary pest, were significantly higher (P < 0.05) in plots With predator groups removed than in untreated checks though the level of pests remained below the economic threshold.
Field populations of striped earwigs Labidura riparia (Pallas) in Baton Rouge arc resistant to chlorinated hydrocarbon insecticides and are not killed by these chemicals at rates recommended for control of imported fire ants, Solenapsis saevissima richteri Forel. Striped earwig populations developed to a significant higher level in suburban yards treated with 10% granular heptachlor than in untreated yards. Heptachlor-treated field plots covering 2800 square feet developed higher populations of striped earwigs than did either mirex-treated (0.025% bait) or untreated field plots of equal size. Heptachlortreated field plots situated 100 or more feet from suburban yards had significantly fewer earwigs than did heptachlor-treated suburban yards. Imported lire ants and thief ants, S. molesta (Say), were the only predators observed feeding on eggs of the striped earwig when eggs were exposed overnight in 0.5-dr vials situated in untreated field plots. Within heptachlor-treated field plots where fire ant populations were reduced to a minimum, cannibalism by 5th and 6th instar and adult earwigs on eggs of their own species was frequently observed.
The efficacy of the red imported fire ant (Solenopsis invicta Buren) as a predator of larval stages of the boll weevil (Anthonomus grandis Boheman) was evaluated in 2 areas of Texas. In the Trinity River area the ants consumed up to 85% of the weevils with a weekly avg of 66%. Ants never consumed more than 37% of the weevils in the Brazos-Navasota River area and averaged 22% in Aug. The fire ant exhibits characteristics that may make it a valuable predator of cotton insect pests. It tends to disperse fairly uniformly across cotton fields at high densities and tends to increase in abundance as the growing season progresses.
In the presence of the red imported fire ant, Solenopsis invicta Buren, adult emergence of the parasitoid Lysiphlebus testaceipes Cresson from laboratory colonies of the corn leaf aphid, Rhopalosiphum maidis (Fitch), was reduced. Parasitoids abandoned an attack when ants were within a few millimeters and searched elsewhere, increasing search time. However, the increased searching time in the laboratory was compensated by a reduction in parasitoids' resting time resulting in similar levels of parasitism between the controls and the ant-infested containers. A major effect of the red imported fire ant was the removal and destruction of parasitized aphids. Ants began detecting parasitized aphids 6 d after parasitization and removed them to the ant colony. Honeydew production was reduced in parasitized aphids by 6 d and they resembled starved aphids. However, in contrast to parasitized aphids, starved aphids were moved to healthy plants, when available.
Large numbers of the red imported fire ant, Solenopsis invicta Buren, were unable to pauperize the predator arthropod fauna of a cotton field in east Texas. None of the 47 taxa sampled was significantly reduced as a result of S. invicta predation. Because of its predatory habits on boll weevils, Anthonomus grandis grandis Boheman and Heliothis spp., and its failure to simplify the predator fauna, S. invicta must be considered an important predator in cotton agroecosystems where it is abundant. The evidence suggests that S. invicta is a fairly specialized predator though probably a polyphagous scavenger.
Direct field observations and use of radioactive phosphorus (32P) as a tracer showed 18 insect and 6 spider species, representing 6 orders and 19 families, to be predators of Nezara viridula (L.) in a soybean ecosystem in Louisiana. Solenopsis invicta Buren was the dominant egg predator during the vegetative stages of soybean development, while cannibalism of eggs by adults and nymphs of N. viridula was also frequently observed during this stage. Grasshoppers were the more important egg feeders during the reproductive stages of plant development. Life tables developed for N. viridula in field cages showed that survival to adult was 0.5% during the vegetative and flowering stages and 4.5% during pod set, but it increased significantly to 38.2% when seeds were formed. Under field conditions during the latter period, survival to fourth-instar nymphs declined to 8.7%, from which it was concluded that, in this particular ecosystem, 33.6% mortality was caused by predation and 57.7% was due to other factors.
Red imported fire ants,Solenopsis invicta Buren, are effective predators of the boll weevil,Anthonomus grandis Boheman, in east Texas cotton fields. Boll weevils caused no economic loss in 11 years due to mortality attributed primarily
to ants. Removal of the ants resulted in an increase in crop damage by the boll weevil. Insecticides used for cotton pests
greatly reduce the abundance of the ants. To capitalize on this effective predation of boll weevils by ants, unnecessary applications
of insecticides should be eliminated.
Les fourmis importées,Solenopsis invicta Buren sont des prédateurs efficaces du charançon du coton,Anthonomus grandis Boheman dans les champs de coton de l'est du Texas.
Les charançons n'ont pas causé de dommages économiques en 11 ans à cause de la mortalité attribuée essentiellement à l'action
des fourmis. La suppression de celles-ci a provoqué une augmentation des dégâts dus au charançon. Les insecticides employés
contre les ravageurs du coton réduisent beaucoup l'abondance des fourmis. Pour préserver cette efficace prédation des charançons
par les fourmis, il convient de supprimer les applications d'insecticides qui ne sont pas nécessaires.
Red imported fire ants, Solenopsis invicta Buren (Hymenoptera: Formicidae), are usually considered serious pests. S. invicta workers, however, are voracious predators and are frequently among the most abundant predators in agroecosystems within their range. Unfortunately, fire ant workers may also attack beneficial insects and arthropods. The goal of this study was to quantify the relationship between the abundance of fire ant workers and the abundance of insect pests and their natural enemies in cotton and soybean. In addition, I used path analysis to estimate the direct and indirect effects (potential loss of pest control due to suppression of other natural enemies) of fire ants. Densities of S. invicta workers were negatively associated with all 16 herbivore taxa sampled in cotton and 13 of the 16 herbivore taxa sampled in soybean. These data suggest that red imported fire ants are important predators of the major insect pests of these crops. The abundance of fire ants, however, was also negatively correlated with the densities of 22 of 24 natural enemy taxa in cotton and 14 of 16 natural enemy taxa in soybean. It appears that fire ants are significant intraguild predators of some of the most important biological control agents in these crops. These indirect interactions were often complex because fire ants not only suppressed populations of beneficial natural enemies (i.e., natural enemies that had negative impacts on pest populations), but also suppressed natural enemies that interfered with biological control (i.e., intraguild predators that had net positive effects on pest populations). Detailed experimental work is needed to determine whether the benefits of pest suppression by fire ants outweigh the negative impact of fire ants on natural enemies.
Environmental factors affecting relative distribution of foraging red imported fire ants in a soybean field on soil and plants
- K A Kidd
- C S Apperson
Kidd, K. A. and C. S. Apperson. 1984. Environmental factors affecting relative distribution of
foraging red imported fire ants in a soybean field on soil and plants. J. Agric. Entomol. 1:
212-218.
The economic importance and control of imported fire ants in the United States
- C S Lofgren
Lofgren, C. S. 1986. The economic importance and control of imported fire ants in the United
States. In S. B. Vinson [ed.], Economic impact and control of social insects. Praeger. New
York. 421 pp.
Reduction of red imported fire ant populations by tillage
- W L Morrill
- G L Greene
Morrill, W. L. and G. L. Greene. 1975. Reduction of red imported fire ant populations by tillage.
J. Georgia Entomol. Soc. 10: 162-164.