Effects of contaminants on bait acceptance by Solenopsis invicta (Hymenoptera: Formicidae)

Three commonly used fire ant baits, Amdro (0.73% hydramethylnon [AI]), Ascend (0.011% abamectins [AI]), and Maxforce (1.0% hydramethylnon [AI]), were exposed to potential, volatile contaminants. The contaminants included the insecticides Orthene Fire Ant Killer (75.0% acephate [AI] ), Cyren (44.6% chlorpyrifos [AI]), and Tempo 2 (24.3% cyfluthrin [AI]); cigarette smoke; gasoline (unleaded, 89 octane); and fertilizer (10-10-10). Fire ant baits previously exposed for 48 h to these contaminants were analyzed using gas chromatography analysis. Orthene Fire Ant Killer, Cyren, Tempo 2, cigarette smoke, and gasoline had volatile components transferred to the baits. Baits exposed to these products were used in a field evaluation of bait acceptance by Solenopisis invicta Buren, the red imported fire ant. Uncontaminated Amdro was significantly preferred by S. invicta over Amdro contaminated by smoke, Cyren, Tempo 2, and gasoline. Uncontaminated Maxforce was significantly preferred over Maxforce contaminated by Tempo 2, Cyren, and gasoline, and uncontaminated Ascend was preferred over Tempo 2- and Cyren-contaminated Ascend. Orthene-exposed Amdro, Maxforce, and Ascend baits, and smoke-exposed Maxforce and Ascend baits were not significantly different from the control. These results indicate that volatile insecticides and products can contaminate fire ant baits. Some insecticides and products, such as gasoline, can significantly affect bait palatability and may adversely impact control.     

Preference of food particle size among several urban ant species

Appropriate particle size may be a critical characteristic for effective granular ant baits. We examined the particle size preference of six species of pest ants to an anchovy-based bait. We also examined head capsule widths of Argentine ants, Linepithema humile (Mayr) (mean = 0.54 mm), California harvester ants, Pogonomyrmex californicus (Buckley) (mean = 1.63 mm), red imported fire ants, Solenopsis invicta Buren (mean = 0.9 mm), and southern fire ants, Solenopsis xyloni McCook (mean = 0.76 mm) and compared them with the first and second most preferred particle size. There were differences between particle size of which the most mass was removed and of which there were more particles removed by ants. California Argentine ants, southern fire ants, and Alabama Argentine ants removed more 840 to 1,000-microm particle mass of the anchovy diet but had more visits to dishes containing 420 to 590 microm particles. California harvester ants and Allegheny mound ants, Formica spp., removed more >2,000 microm particle mass but visited dishes containing 1,000 to 2,000 microm particles more often. Red imported fire ants also removed more >2,000 microm particle mass but visited dishes with 590 to 840-microm particles most often. Pharaoh ants, Monomorium pharaonis (L.), removed and visited 420 to 590-microm particles more than any other size. A linear regression model determined that particle size preferred by each ant species relates to forager head width. The majority of particles of commercial ant bait, including Amdro, Ascend, Award, Bushwhacker, Max Force with fipronil, and old and new formulations of Max Force with hydramethylnon, were 1,000 to 2,000 microm, but the majority of Niban particles were <420 microm. Altering the size of particles of toxic ant baits to fit the particle size preference of each pest ant species may increase the efficacy of ant baits.     

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.     

Speed of efficacy and delayed toxicity characteristics of fast-acting fire ant (Hymenoptera: Formicidae) baits

Efficacy and speed of action of fire ant (Hymenoptera: Formicidae) baits that claim fast control of colonies were compared with a standard bait. More than 85% of red imported fire ant, Solenopsis invicta Buren, laboratory colonies provided bait containing the active ingredient indoxacarb died within 3 d, and all colonies were dead in 6 d. Standard bait containing hydramethylnon resulted in death of 60% of the colonies in 9 d. Bait containing spinosad did not cause colony death. Under field conditions, one-half of the areas treated with the indoxacarb bait did not have any active fire ant nests within 3 d, whereas 11 d was needed to reach the same level of control with the hydramethylnon bait. Spinosad had a maximum of 17% of the treated areas without nests after 3 d. The delay in death of S. invicta adults treated in the laboratory with the indoxacarb and spinosad baits was shorter than the standard hydramethylnon bait, which had mortality similar to the traditional delayed toxicity criterion of < 15% mortality after 24 h and > 89% mortality over the test period. Indoxacarb caused mortality of 57% at 24 h and 100% at 48 h; however, visual symptoms of toxicity were not readily observed for at least 8 h before the abrupt increase in death. Spinosad caused 96% mortality by 24 h, and initial mortality became apparent at 4 h. Time required for death of 15% of a treated population (LT15) of spinosad, indoxacarb, and hydramethylnon was 3, 9, and 16 h, respectively. Delayed toxicity characteristics of the fast-acting indoxacarb bait may be useful for the development of other fast-acting ant baits.     

Susceptibility and behavioral response of red imported fire ant (Hymenoptera: Formicidae) to selected entomogenous nematodes (Rhabditida: Steinernematidae & Heterorhabditidae).

Pathogenicity of infective juveniles of selected Steinernema spp. and Heterorhabditis spp. toward developing and reproductive stages of the red imported fire ant, Solenopsis invicta Buren, was tested under laboratory conditions. At 10(3)-10(5) infective juveniles per Petri dish, mortality of reproductive larvae, pupae, and alates ranged from 28 to 100% at higher doses after 96 h at 23-25 degrees C. Steinernema carpocapsae All was the most consistent species tested; this nematode caused mortality of fire ant larvae, pupae, and alates of 82-94, 64-96, and 38-99%, respectively. Although not susceptible to nematode infection, worker ants vigorously preened nematodes from brood, alates, and themselves. In a field study, S. carpocapsae (5 x 10(6) and 2 x 10(6) drench, 2 x 10(6) infective juvenile infection) was applied to active fire ant mounds in 3.8-liter suspensions. Hydramethylnon (75 ml), a water drench, a water injection, and untreated fire ant mounds were marked and treated. Overall activity in mounds treated with nematodes of hydramethylnon ranged from 40 to 48%. Satellite mound activity accounted for 32-44% of overall activity in mounds treated with nematodes 2 wk after treatment. However, 6 wk after treatment, activity in mounds treated with hydramethylnon was 44%; activity of mounds treated with nematodes ranged from 52 to 80%. Satellite mound activity accounted for 0-24% of overall activity. Whereas a soil drench of S. carpocapsae showed potential as a control method for the red imported fire ant, colony relocation after nematode treatment could limit overall efficacy unless application techniques are developed to overcome or take advantage of the movement.     

Native ant responses to Solenopsis invicta buren reduction using broadcast baits

A pilot study was conducted to investigate the impact of Solenopsis invicta management with an insect growth regulator bait (s-methoprene) on native ant species and to determine the responses of these species to S. invicta reduction. This invasive species alters the diversity and structure of different trophic levels of arthropod assemblages. Despite advances in S. invicta management using biological control agents, poison baits remain as the primary tool for effective fire ant management. However, the effect of these products on native ants is relatively unknown. Understanding these effects is critical to the development of S. invicta management strategies that include conservation of native ants. Native ants compete with S. invicta to some degree and can bolster efforts to release and establish exotic biological control agents to more effectively manage S. invicta. The study was carried out in Mumford, TX. Two treatments were used: a bait treatment that reduced S. invicta densities and a control. The treatments were randomly assigned to 1.33-ha blocks, replicated four times, and periodically inspected using complementary sampling techniques (pitfall traps, baited vials, manual collections, and nest surveys). Sixteen ant species were found among the two treatments. After S. invicta reduction, significant increases in densities of several other ant species were observed. Species within the assemblage shifted from the dominance by S. invicta to the dominance of the native pyramid ant, Dorymyrmex flavus McCook, which showed the most significant increase in bait treated blocks and was found to persist at densities significantly higher than the control for >2 yr after the last bait treatment. A temporary change in diversity was observed, indicating that use of a poison bait for S. invicta management benefited numerous resident species in the ant assemblage.     

不同浓度茚虫威对红火蚁的防治效果

为探索适合防治红火蚁的茚虫威浓度,利用丙酮溶解茚虫威原药,使用雾化手段与载体和配方其他试剂充分混合,干燥后保存,进行野外试验测定其防治红火蚁的药效。结果表明,研制的0.025%茚虫威饵剂综合防治效果达85.30%,0.05%茚虫威饵剂达100%,0.1%茚虫威饵剂达100%。3个浓度的茚虫威饵剂拥有良好的防治红火蚁药效,0.05%浓度最适合研制红火蚁饵剂。     

Lack of interactions between fire ant control products and white grubs (Coleoptera: Scarabaeidae) in turfgrass

Insecticides are widely used to manage turfgrass pest such as white grubs (Coleoptera: Scarabaeidae). Red imported fire ants, Solenopsis invicta (Buren) are important predators and pests in managed turfgrass. We tested the susceptibility of white grub life stages (adults, egg, and larvae) to predation by S. invicta and determined if insecticides applied for control of S. invicta would result in locally greater white grub populations. Field trials over 2 yr evaluated bifenthrin, fipronil, and hydramethylnon applied to large and small scale turfgrass plots for impacts on fire ant foraging and white grub populations. Coincident with these trials, adults, larvae, and eggs of common scarab species were evaluated for susceptibility to predation by S. invicta under field conditions. Field trials with insecticides failed to show a significant increase in white grub populations resulting from treatment of turfgrass for fire ants. This, in part, may be because of a lack of predation of S. invicta on adult and larval scarabs. Egg predation was greatest at 70% but < 20% of adults and larvae were attacked in a 24 h test. Contrary to other studies, results presented here suggest that fire ants and fire ant control products applied to turfgrass have a minimal impact on white grub populations.     

Field suppression of the invasive ant Wasmannia auropunctata (Hymenoptera: Formicidae) in a tropical fruit orchard in Hawaii

The little fire ant, Wasmannia auropunctata (Roger) (Hymenoptera: Formicidae), is an invasive ant that forms supercolonies when it successfully invades new areas. W. auropunctata was first reported in Hawaii in 1999, and it has since invaded a variety of agricultural sites, including nurseries, orchards, and pastures. Amdro (hydramethylnon; in bait stations), Esteem (pyriproxyfen; broadcast bait), and Conserve (spinosad; ground spray) were tested for their efficacy against W. auropunctata in a rambutan, Nephelium lappaceum L. and mangosteen, Garcinia mangostana L., orchard by making treatments every 2 wk for 16 wk. Relative estimates of ant numbers in plots was determined by transect sampling using peanut butter-baited sticks. Significant treatment effects were observed on weeks 13-17, with reductions in ant counts occurring in the Amdro and Esteem treatments. During this period, the reduction in ant numbers from pretreatment counts averaged 47.1 and 92.5% in the Amdro and Esteem plots, respectively, whereas ant numbers in the untreated control plots increased by 185.9% compared with pretreatment counts. Conserve did not cause a reduction in ant counts as applied in our experiment. No plots for any of the treatments achieved 100% reduction. Pseudococcidae were counted on branch terminals at 4-wk intervals. The two predominant species, Nipaecoccus nipae (Maskell) and Nipaecoccus viridis (Newstead) were significantly lower in the Amdro and Esteem treatments on week 16 compared with controls. Many W. auropunctata were found nesting in protected sites in the orchard trees, which may have compromised the ground-based control methods. Absolute density estimates from shallow core samples taken from the orchard floor indicated the W. auropunctata supercolony exceeded 244 million ants and 22.7 kg wet weight per ha.     

广东省草皮种植场和城市草坪红火蚁发生为害程度调查

[背景]在防控红火蚁的工作中,有效控制该虫传播途径、降低传播风险是预防的关键。随草皮调运传播是红火蚁扩散的重要方式之一。[方法]采用活蚁巢密度、诱集比率、诱集工蚁数量、发生率等多个指标,调查评价了广东省主要草皮种植地区广州石基、广州增城、深圳南山、惠州博罗等草皮种植场和城市绿化草坪红火蚁发生程度。[结果]广东省草皮种植场红火蚁发生普遍,携带该虫扩散传播的风险极大。不同地区草皮种植场红火蚁发生程度存在明显差异。惠州博罗草场红火蚁发生程度最重,活蚁巢密度、诱集比率、诱集工蚁数量和发生率分别为0．0085个·m^-2、56．75％、16．80头·个^-1和83．60％;深圳南山发生程度最轻,各项指标分别为0．0011个·m^-2、9．62％、0．92头·个^-1和24．50％。城市绿化草坪红火蚁发生较为普遍。调查的3个城市中惠州发生程度最重,活蚁巢密度、诱集比率、诱集工蚁数量和发生率等均最高,分别为0．0149个·m2、10．46％、14．30头·个-1和62．86％。不同品种草坪草红火蚁发生程度不同,以假俭草最高,以上4个指标分别为0．0140个·100m^-2、6．85％、5．57头·个^-1和51．43％。城区类型不同红火蚁发生程度不同,老城区红火蚁发生较轻,新城区较重,发生点常在移植草坪、绿化苗木区域。[结论与意义[广东省主要草皮种植区和城市草坪红火蚁发生均较为普遍,运输携带该虫传播的风险极大,研究结果可为加强草皮检疫、防止携带红火蚁传播提供依据。     

灭蚁威对不同生境下红火蚁的药效评价

在红火蚁发生区域选农田、山坡地、绿化带、草坪等4个不同生境地块,采用灭蚁威毒饵进行防治试验,并对其药效进行调查。结果显示,药后10 d,灭蚁威对红火蚁蚁巢的防效较差,且表现出不同生境而有所差异;但在药后35 d时,其对蚁巢和工蚁的校正防效均在95%以上,表现出良好的防治效果。本试验结果表明,灭蚁威的药效需一个月后才能充分发挥;在红火蚁发生区,对不同的生境均可采用灭蚁威饵剂进行防治。     

Comparing electroantennogram and behavioral responses of two Pseudacteon phorid fly species to body extracts of Black, Red and Hybrid imported fire ants, Solenopsis spp

Several phorid fly species were introduced to the southern United States for biological control of the invasive imported fire ants, Solenopsis richteri (Black), Solenopsis invicta (Red), and their Hybrid S. richteri×S. invicta (Hybrid). It has been previously reported that the Jaguariuna biotype of Pseudacteon tricuspis and the Formosan biotype of Pseudacteon curvatus could distinguish among the three fire ant species with greater preference for Hybrid and Red fire ants. We hypothesized that phorid flies might use host derived chemical cues to differentiate ant species. To determine possible differential olfactory sensitivity of phorid fly species to different fire ant species, we compared electroantennogram (EAG) and behavioral responses of both sexes of P. tricuspis and P. curvatus to body extracts of Black, Red and Hybrid fire ants. As worker sizes of Black and Hybrid fire ants used in this study were much larger than that of Red fire ant (the average weight for Black, Red and Hybrid workers was 1.707, 0.863, 1.223mg per ants, respectively), at doses of 0.01, 0.1, 1 worker equivalent, body extracts of Black and Hybrid fire ant elicited significantly greater EAG response in both sexes of P. tricuspis than that of Red fire ant. Similarly, the EAG response in female P. curvatus to body extract of Black fire ant was significantly greater than to body extract of Red fire ant. To eliminate worker size influence on EAG response in phorid flies, we conducted a second EAG study using a dose of 1mg ant equivalent (body extract from 1mg of worker). No difference in EAG responses was recorded to body extract obtained from the same amount of workers among the three fire ant species (we consider viable Hybrid fire ant as a species in this paper), suggesting that worker size differences contributed to difference in EAG response in the first EAG study. In both EAG studies, male P. tricuspis showed significantly greater EAG responses than male P. curvatus to all three fire ant species. In four-way olfactometer bioassay, worker body extracts of all three fire ant species were equally attractive to P. tricuspis and P. curvatus (i.e. both phorid fly species did not show any preferences among the three fire ant species). Together, the results of the EAG and behavior studies suggest that parasitic phorid flies utilize host derived non-polar compounds from worker ants extracted out by hexane for host location but not for host preference, since both fly species are not able to distinguish among the body extracts of the three fire ant species. Future study will investigate possible involvement of polar compounds and/or non-chemical cues in mediating host preference by phorid flies.     

氟磺酰胺复配毒饵对红火蚁的田间防治效果

在深圳市龙岗区和宝安区对氟磺酰胺复配毒饵进行药效评价,试验结果表明,施药后3～15d,龙岗实验区蚁巢周围均有死亡工蚁陆续出现。第7d时,0.75%氟磺酰胺复配毒饵防治效果为16.99%,第28d时防治效果达47.43%,在试验结束的第140d时防治效果达97.93%;对照药剂0.5%氟磺酰胺毒饵对红火蚁Solenopsis invicta Buren的防除效果迅速,在第7d防治效果达50%以上。在宝安实验区,蚁巢的防治效果也随施药后时间的延长而增加,第28d的防治效果为51.65%,试验结束时防治效果达到94.72%;对照药剂0.5%氟磺酰胺毒饵42d防治效果达最大值为92.88%。上述结果显示,0.75%氟磺酰胺复配毒饵具有较快压低红火蚁种群密度,持效控制实验区红火蚁种群的特点。     

Evidence of intracolony transmission of Thelohania solenopsae (Microsporidia: Thelohaniidae) in red imported fire ants (Hymenoptera: Formicidae) and the first report of spores from pupae.

Red imported fire ant, Solenopsis invicta, colonies were infected horizontally by introducing live brood (mainly larvae and pupae) infected with Thelohania solenopsae. Live, infected brood introduced into uninfected colonies were adopted and raised to adulthood instead of being executed by the recipient colony. Introductions of infected larvae with uninfected pupae, which eclose into adult worker caste fire ants, resulted in an 80% infection rate of the inoculated colonies. Infections from introductions of infected pupae with uninfected larvae resulted in a 37.5% infection of inoculated colonies. Infections were also detected in 11.6 and 3.7% of the adult worker caste ants that eclosed from uninfected large larvae and pupae, respectively, that were held with infected adult workers. Microscopic examination of infected brood revealed sporoblasts and large numbers of spores of T. solenopsae in S. invicta pupae.     

Interspecific competition between Solenopsis invicta and two native ant species, Pheidole fervens and Monomorium chinense

This study was designed to understand the effects of the interspecific competition between red imported fire ant, Solenopsis invicta Buren and two native ant species, Pheidole fervens Smith and Monomorium chinense Santschi, by conducting colony interference and individual confrontation tests under laboratory conditions. The colony interference test showed that both native ant species, owing to their numerical advantage, killed the Solenopsis invicta virus-1 (SINV-1)-infected or healthy queens of S. invicta. Significantly less time was required for M. chinense to kill all SINV-1-infected S. invicta compared with the time required to kill the healthy S. invicta. Compared with healthy S. invicta, SINV-1-infected S. invicta spent a longer time eliminating the P. fervens colonies. In confrontation tests, M. chinense killed a significantly higher number of infected S. invicta minors than they did healthy minors, but the number of S. invicta majors (either infected or healthy) killed was substantially less. This study found that the viral infection weakened the competitive ability of S. invicta and made them prone to be eliminated by M. chinense but not by P. fervens.     

家蝇作为饲料添加剂对清远良种鸡肉质和风味的影响

测定蝇蛆和蝇蛹作为饲料添加剂对清远良种鸡肉质和风味的影响,为家蝇Musca domestica L.作为添加饲料改善鸡的肉质和风味,以及代替鱼粉成为新的蛋白质来源提供数据。150只清远鸡雏鸡随机等分成5组,以鱼粉或商业饲料加入不同比例的家蝇幼虫或蝇蛹作为添加饲料加以饲养。结果显示,饲喂不同食料的清远鸡的增重、脾重和法氏囊重影响差异不显著,但饲喂蝇蛆和蝇蛹的鸡群的死亡率明显低于仅饲喂鱼粉或商业饲料的鸡群;饲喂蝇蛆或蝇蛹的鸡肉的系水力(用失水率表示)和风味评价明显提高,氨基酸含量差异显著。说明家蝇幼虫作为动物蛋白可提高鸡的抗疾病能力及改善鸡肉风味。     

红火蚁入侵对广东多种生境中蚂蚁类群的影响

采用陷阱法和诱饵诱集法研究了深圳红火蚁发生区和未发生区蚂蚁的类群多样性和相似性.结果表明:草坪和荒草地红火蚁发生区域的蚂蚁物种数明显减少,且草坪中蚂蚁种类减少的程度(6种)大于荒草地 (3种).红火蚁入侵后荔枝园、荒草地和草坪的蚂蚁优势种发生了明显改变,红火蚁替代了原来的优势蚂蚁种类,在数量上占据了主导地位,在荒草地和草坪这种优势种的改变更为明显.对蚂蚁类群指数的分析表明:红火蚁入侵荒草地和草坪后蚂蚁类群的多样性、均匀度降低,优势度明显增大;而荔枝园中蚂蚁类群多样性指数、均匀度指数均增大,优势度指数降低.荔枝园、荒草地和草坪的红火蚁发生区和未发生区蚂蚁类群相似性系数不同,分别为0.6316、0.5882和0.2941.     

Developmental rates and host specificity for Pseudacteon parasitoids (Diptera: Phoridae) of fire ants (Hymenoptera: Formicidae) in Argentina

This study extends our comparative knowledge of Pseudacteon interactions with Solenopsis fire ant workers. Reported in this work are development times for seven Argentinean parasitoid species reared on two hosts, Solenopsis richteri Forel and Solenopsis invicta Buren, under laboratory temperature regimes comparable with those of the climatic zones occupied by these host species. Developmental times spanned 31-66 d across phorid species, and in general did not differ between genders or host species, but were longer at lower temperatures. The size distribution of flies reared was bimodal, with a group of large (Pseudacteon borgmeieri, Pseudacteon nocens, Pseudacteon obtusus and Pseudacteon tricuspis) and small (Pseudacteon cultellatus, Pseudacteon curvatus, and Pseudacteon nudicornis) species. P. borgmeieri was exceptional with respect to length of developmental time. Also reported are results of initial oviposition and developmental studies of some of these phorid species on other Argentinean Solenopsis ant species; P. curvatus was the only species able to complete its development on nonhost fire ants. These results support the concept of incorporating several complementary species of Pseudacteon in the biological control of pest fire ants.     

Behavioral and Electroantennogram Responses of Phorid fly <Emphasis Type="Italic">Pseudacteon tricuspis</Emphasis> (Diptera: Phoridae) to Red Imported Fire Ant <Emphasis Type="Italic">Solenopsis invicta</Emphasis> Odor and Trail Pheromone

The phorid fly, Pseudacteon tricuspis is an introduced parasitoid of the red imported fire ant, Solenopsis invicta in the United States. Previous studies show that phorid flies are attracted to host ant workers at disturbed colonies, to colonies exhibiting aggressive interspecific interactions, and to fire ant mating flights. In a series of behavioral and electroantennogram (EAG) experiments, we confirm the possible use of fire ant odor as cues for host location by P. tricuspis. We tested the response of P. tricuspis of different sex and mating status to several host-related odor stimuli including live fire ant workers, extracts of worker whole body, head, thorax, and abdomen, and (E,E)-α-farnesene, a trail pheromone component of Solenopsis fire ants. Results from Y-tube olfactometer bioassays demonstrated the attraction of mated female P. tricuspis to live S. invicta workers. In addition, extracts of S. invicta worker whole body and thorax elicited strong olfactometer response in female flies (mated and unmated) and mated males, but not in unmated males. Pseudacteon tricuspis did not show significant attraction to extracts of S. invicta worker head and abdomen, or to (E,E)-α-farnesene, irrespective of sex and mating status. In EAG experiments, female and male P. tricuspis showed significant EAG response to extracts of worker whole body, head, and abdomen, and to a less extent, thorax extract, but not to (E,E)-α-farnesene. Females showed slightly greater EAG response than males, but EAG response was not affected by mating status. These results suggest that fire ant thorax is likely the source of kairomones used as host location cues by P. tricuspis, and support the hypothesis that fire ant worker trail pheromones are not likely used by P. tricuspis for host location.