Sociobiology: Volume 54, Number 3, 2009

Feature Articles:

Fitness Costs and Benefits of Ant Attendance and Soldier Production for the Social Aphid Pseudoregma bambucicola (Homoptera: Aphididae: Hormaphidinae)

By Harunobu Shibao, Masahiro Morimoto, Yukako Okumura & Masakazu Shimada

ABSTRACT

We investigated ecological and behavioral aspects of the symbiotic interaction between ants and P. bambucicola in Kagoshima, Southern Japan, for one year. In particular, we evaluated the effects of ants and soldiers on colony growth, predator abundance, and colony persistence to understand the fitness costs and benets of ant attendance and soldier production for Pseudoregma bambucicola. Although many aphid colonies were initially attended by the ants Lasius japonicus or Crematogaster osakensis, most colonies were abandoned by the ants and failed to obtain long-term ant attendance. Unattended colonies, including those abandoned by ants, often produced numerous soldiers and achieved larger colony size. In contrast, colonies continuously attended by ants usually had no soldiers and attained smaller colony size. In a laboratory test, in which aphids were reared in the absence of ants for 48 hrs, it was confirmed that aphids from ant-attended colonies produced no or far fewer soldiers than those from unattended colonies, and that both types of aphid produced about the same number of progeny. These results suggest that ants frequently prey upon the aphids they attend, and that the aphids invest less in soldiers when they are attended by ants. In ant-attended colonies, aphids have a smaller body size and were reproductively less active than in colonies without ant attendance. Nonetheless, ant-attended colonies were rarely attacked by natural enemies, and showed greater longevity than unattended colonies, although sterile soldiers contributed to the long lifespan of unattended colonies. These data indicate that the symbiotic relationship between ants and P. bambucicola is facultatively mutualistic, and that ants confer a fitness benefit on the aphid colonies by providing more effective protection than sterile soldiers, even though ant attendance has a negative inuence on the growth and reproduction of the aphids. It is conceivable that P. bambucicola has two defensive strategies: association with ants as a first choice; and then soldier production. When the aphids fail to secure long-term ant protection, they may resort to costly soldier production, thereby increasing the colony-level fitness.

KEY WORDS: social aphid, soldier, ant attendance, mutualism, cost-benet analysis

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Colony Development of Two Bumblebees, Bombus eximius and B. sonani, Reared in Captivity in a Subtropical Area of Taiwan (Hymenoptera, Apidae, Bombini)

By Ching-Hao Chiang, I-Hsin Sung, Kai-Kuang Ho & Ping-Shih Yang

ABSTRACT

Two bumblebee species, Bombus eximius and B. sonani, were reared artificially to investigate the characteristics of colony development under laboratory conditions in Taiwan. A total of 53 queens of B. eximius and 37 queens of B. sonani were collected in the field during 2007 and 2008. B. eximius has a longer period for colony initiation, immature stages in each caste, and a larger colony size (63 – 271 workers) than B. sonani (21 – 68 workers). Under the laboratory conditions, queens of B. eximius laid 4 – 6 eggs in each eggcup, while B. sonani laid 2 – 3 eggs. The queen production point (QP) of B. eximius started before the switch point (SP), and the queen production eggs were laid in Phase 3. However, queen production eggs of B. sonani were probably laid during the Phase 2 and Phase 3. It was found that B. eximius has a longer period of colony development than B. sonani, and the main difference between the two species was the number of third worker brood during Phase 3. In the field, the endemic species B. sonani is considered to adapt to the temperate climate, while B. eximius is adapted to the subtropical climate in Taiwan. The colony development and seasonal occurrence of B. eximius is expected to be from September –/October to April or later, and from April to August or later in B. sonani. The results showed no differences between the two species in the queen nesting rate, successful colonization rate, successful mating rate of laboratory-reared queens, and egg laying rate of laboratory-reared queens. We strongly suggest that B. eximius has great merit for pollination programs of commercial utilization, while B. sonani can only serve as a substitute species for pollinations in Taiwan.

KEY WORDS: Bumblebee, colony development, pollinator, seasonal occurrence, Taiwan

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Three New Species of Parasitoid Phoridae (Diptera) From the Neotropical Region

By Brian V. Brown

ABSTRACT

One species of ant-decapitating fly, Apocephalus (Apocephalus) meekerjensenae n. sp. from Costa Rica, and two species of bee-killing flies, Melaloncha (Udamochiras) stoneorum n. sp. and M.(Melaloncha) eminara n. sp. from Bolivia, are described.

KEY WORDS: Apocephalus, Melaloncha, Phoridae, new species, Neotropical, parasitoid

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Susceptibility of Seven Termite Species (Isoptera) to the Entomopathogenic Fungus Metarhizium anisopliae

By Thomas Chouvenc, Nan-Yao Su & Alain Robert

ABSTRACT

Seven termite species (Isoptera) from five families were tested for disease susceptibility against the entomopathogenic fungus Metarhizium anisopliae using a standard protocol: Mastotermes darwiniensis (Mastotermitidae), Hodotermopsis sjoestedti (Termopsidae), Hodotermes mossambicus (Hodotermitidae), Kalotermes flavicollis (Kalotermitidae), Reticulitermes flavipes and Prorhinotermes canalifrons (Rhinotermitidae), and Nasutitermes voeltzkowi (Termitidae). Our results showed a large diversity in disease susceptibility against M. anisopliae among the different species tested and we suggest that the evolution of disease resistance mechanisms in Isoptera may be influenced by the selective pressure of the nesting ecology of each species.

KEY WORDS: termite, Metarhizium anisopliae, disease resistance, pathogen, nesting ecology

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Effect of Distance Between Cellulose and Soil on Bait Discovery in Reticulitermes flavipes and Reticulitermes malletei (Blattodea: Rhinotermitidae) in Laboratory Assays

By James G. Fredericks, Susan King & Charles E. Mason

ABSTRACT

The effect of distance between cellulose bait and soil on time to bait station discovery in two subterranean termite species (Reticulitermes flavipes (Kollar) and Reticulitermes malletei Clément) was evaluated. Worker and soldier termites of each species were introduced into plastic tubs containing moistened builder’s sand and a cylindrical, plastic bait station. Cardboard cylinders of varying diameters were inserted into the stations, resulting in a gap between the cellulose/sand interface of 0.0 mm or 6.0 mm. Time to discovery was determined for each species and each diameter cellulose cylinder. No difference in time to discovery was observed between the 0.0 mm and 6.0 mm distances. However, R. flavipes workers discovered the cellulose significantly faster (2.45 d) than R. malletei (3.2 d). Further investigation is suggested for identifying differences between the two species.

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New Records of Social Wasps (Hymenoptera, Vespidae) in the Brazilian Tropical Savanna

By Fábio Prezoto, Marcos M. de Souza, Abner Elpino-Campos & Kleber Del-Claro

ABSTRACT

Although very diversified and abundant in Brazil, there is little knowledge on distribution of social wasps in the major part of Brazil. Here we report the first records for eight species of social wasps in Minas Gerais state: Mischocyttarus araujoi Zikán, M. funerulus Zikán, M. tricolor Richards, M. confusus Zikán, M. cerberus styx Richards, M. artifex (Ducke), Polistes pacificus flavopictus Ducke and Polybia striata (Fabricius). These species occurred in tropical savanna and semi deciduous forest.

KEY WORDS: Mischocyttarus spp., Polistes sp., Polybia sp., inventory, diversity

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Interspecific Agonism and Foraging Competition Between Coptotermes formosanus and Coptotermes gestroi (Blattodea: Rhinotermitidae)

By Sean Y. Uchima & J. Kenneth Grace

ABSTRACT

We investigated interactions between Coptotermes gestroi (Wasmann) (formerly known as C. vastator) and Coptotermes formosanus Shiraki in forced encounters and in foraging competition. In agonistic assays, termites from each species, with a fixed worker-to-soldier ratio of 9:1, were placed in filter paper-lined petri dishes and allowed to interact over a 24-hour period. Coptotermes gestroi suffered more mortality in all but one interspecific encounter, although only one of these occurrences was statistically significant. There was no significance difference in mortality in any combination of intraspecific, intercolonial pairings within the same species. To investigate foraging competition, termites from colonies of both species were introduced into arenas with a single, centrally located wood food source. Neither species demonstrated an ability to monopolize the food source. There was significant mortality in trials containing both species in comparison to single-species controls; although there was no statistical difference in mortality when the two species were compared with each other.

KEY WORDS:

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Biology and Ecology of Macrotermes barneyi (Isoptera: Termitidae)

By Zhengyan Wang, Jianchu Mo & Yujie Lu

ABSTRACT

Macrotermes barneyi, one of the subterranean fungus-growing termites, is distributed in Vietnam and the central and southern areas of China. It is a destructive termite to dams, dikes and living plants. There are only primary reproductives and no supplementary reproductives in the colony of this termite. In different development stages of the colony, workers, soldiers and alates are differentiated. Alates begin to appear in colonies after 5-8 years of new colony establishment. Timing of alate swarming is from 23:00 to 6:00 of the next day from late April to early July at 20.1-28.2ºC, 70-85% R.H and 98.1-99.6 kPa atmospheric pressure. After the new colony is settled, it would sequentially undergo the stages of unilocular nest without fungus combs, unilocular nest with a fungus comb, unilocular nest with the royal cell, multilocular nest without empty chambers, multilocular nest with empty chambers, and senescence. Foraging behavior of workers occurs mostly at 20-28ºC and 80-95% R.H. from 23:00 to 4:00 of the next day. Termitomyces albuminosus can grow above-ground from fungus combs during the period of June to August after heavy rain.

KEY WORDS: Macrotermes barneyi, caste differentiation, colony development, swarming, climate, symbiotic fungus

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Laboratory Assessment of two Active Ingredients for Control of Coptotermes gestroi (Isoptera: Rhinotermitidae)

By Fabiana Elaine Casarin, Ana Maria Costa-Leonardo & Odair Correa Bueno

ABSTRACT

The subterranean termite Coptotermes gestroi Wasmann (Isoptera: Rhinotermitidae) is a pest of major economic importance in urban environments of southeastern Brazil. Compared to using pesticides for termite control, termite bait products target termites more specifically and also address environmental contamination issues. In this point of view, we performed two different bioassays in order to evaluate the efficacy of boric acid and fipronil against different populations of C. gestroi. The results showed that concentrations between 2000 and 3000 ppm of boric acid caused approximately 100 percent mortality in termites. Concentrations between 0.01 and 0.0001 ppm of fipronil resulted in 100% termite mortality after 2 wk exposure. The data displayed a fast mortality of termites contaminated with fipronil, even with small concentrations, and therefore it is not a suitable product to be used in baits against C. gestroi. The present study showed a delayed toxicity of boric acid against the subterranean termite C. gestroi which suggests a need for further field tests.

KEY WORDS: bait, boric acid, control, fipronil, subterranean termites

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Attractiveness of Different Citrus Pulps to the Leaf-Cutting Ant Atta sexdens rubropilosa (Hymenoptera: Formicidae)

By Amanda A. Carlos , Luiz Carlos Forti, Roberto S. Camargo, Sinara Maria Moreira, Sandra S. Verza & Eduardo Arrivabene Diniz

ABSTRACT

The most common control method uses toxic baits consisted of dehydrated citrus pulp as carrier and attractant. However, the portion of the citrus fruit that is attractive to ants is still unknown, despite its importance in chemical control. This study compared the attractiveness of different fruit parts of citrus pulps to Atta sexdens rubropilosa workers. Three treatments: pellets of industrial citrus pulp, albedo (mesocarp), and whole citrus pulp were offered randomly to ants and the removal of these substrates by workers was observed. The three pulps were equally attractive to this species (F = 0.8033; p = 0.4633). Although the whole pulp included the epicarp, it was as attractive as the other treatments, possibly because, the material was heated during processing, eliminating any volatile substance that could repel ants.

KEY WORDS: attractiveness, Atta sexdens, leaf-cutting ants, citrus pulp

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Usurpation of a Mischocyttarus cerberus stix Nest by Polistes versicolor (Hymenoptera: Vespidae)

By Fábio Barros Britto, Thalita Rocha & Thiago A. Ortega Pietrobon

ABSTRACT



KEY WORDS: nest usurpation, paper wasp, Epiponini, Polistini

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Worldwide Spread of the Penny Ant, Tetramorium bicarinatum (Hymenoptera: Formicidae)

By James K. Wetterer

ABSTRACT

Tetramorium bicarinatum (Nylander, 1846) (formerly misclassified as Tetramorium guineense (Fabricius)) has long been recognized as one of the world’s most broadly distributed ant species. To evaluate the worldwide spread of T. bicarinatum, I compiled published and unpublished specimen records from >1000 sites. I documented the earliest known T. bicarinatum records for 148 geographic areas (countries, island groups, major Caribbean islands, US states, and Canadian provinces), including several areas for which I found no previously published records: Aruba, Barbuda, Belize, Comoro Islands, Grenada, Îles Eparses, Mascarene Islands, Missouri, Montserrat, Nepal, Sweden, and Tobago.

Tetramorium bicarinatum is widespread throughout much of the tropics and subtropics, except for continental Africa and West Asia, where it is largely absent. In addition, T. bicarinatum is found in temperate areas inside greenhouses and heated buildings. In the past, many authors have assumed T. bicarinatum to be African in origin. However, analysis of its known distribution and those of its closest relatives indicates that T. bicarinatum originated in the Indo-Pacific.

Currently, the most widely used common name for T. bicarinatum is “Guinea ant,” a name based solely on the erroneous 19th century synonymy of Tetramorium bicarinatum with Pheidole guineensis (Fabricius) described from Guinea, West Africa. This ill-chosen common name perpetuates the misconception that T. bicarinatum is from Africa. This problem is further compounded by the coincidental existence a secondary homonym Tetramorium guineense (Bernard, 1953), the valid name of an unrelated species known only from Africa. Therefore, I propose a new common name for T. bicarinatum: the penny ant, based primarily on the ant’s copper-brown color, similar to that of a copper penny.

KEY WORDS: biogeography, biological invasion, exotic species, Formicidae, invasive species

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Observation of Nuptial Flights of the Red Imported Fire Ant, Solenopsis invicta (Hymenoptera: Formicidae) in Mainland China

By Yi-juan Xu, Jun Huang, Yong-yue Lu, Ling Zeng & Guang-wen Liang

ABSTRACT

To discover the reproductive characteristics of Solenopsis invicta in Guangdong province, we observed the nuptial flight of field colonies. The results showed that the nuptial flights typically occurred throughout the year, but were more frequent two days after rainy days in Spring and Summer. They often occurred on a sunny day and began to decline after June. Generally, nuptial flights of S. invicta occurred from 9:00 AM to 3:00 PM, there were no nuptial flights observed at night. The duration of the nuptial flight for each nest was generally more than 30min and no more than 2-3hours, and the peak of the winged alate numbers on the mound surface mostly occurred 90min after nuptial flights began.

KEY WORDS: Solenopsis invicta, nuptial flight, Guangdong

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A Mathematical Model for Caste Differentiation in Termite Colonies (Isoptera) by Hormonal and Pheromonal Regulations

By Yusuke Ikemoto, Yuki Ishikawa, Toru Miura & Hajime Asama

ABSTRACT

In social insects, the division of labor among castes is one of the fundamental natures for establishing social behaviors. In termites, because of their hemimetaboly, the regulations of postembryonic development should be important to regulate appropriate caste ratios in a colony. Although the caste differentiation can be triggered by social interactions among colony members, the interactions via primer pheromones and the physiological mechanisms underlying caste determination or differentiation are poorly understood. In this study, therefore, we propose a model for the regulatory mechanism controlling caste differentiation, focusing on the physiological states and inhibitory interactions among individuals. The proposed model incorporates an internal physiological system like JH and ecdysone actions, together with two types of inhibitory interactions by pheromones secreted by soldiers and alates. The results of computer simulations based on the proposed model suggested that the two types of interactions were sufficient to enable a colony to maintain the appropriate caste ratio. These results should help to find the primer pheromones and to infer their functions in the caste differentiation in termites.

KEY WORDS: lower termites, caste differentiation, inhibitory pheromones, mathematical model

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Some Organic Acids Acting as Stimulants of Recruitment and Feeding for the Formosan Subterranean Termite (Isoptera: Rhinotermitidae)

By Juan A. Morales-Ramos, M. Guadalupe Rojas, and David Nimocks III

ABSTRACT

The feeding stimulating properties of 3 organic acids (salicylic, oxalic, and glucuronic acids) and 2 nitrogen containing compounds (uric acid, and glucosamine) for the Formosan subterranean termite were tested. A two choice test between cellulosic matrices with the compounds and blanks showed that Coptotermes formosanus Shiraki significantly preferred matrices with 50 ppm of oxalic acid, salicylic acid, or a blend of equal parts of these 2 compounds plus uric acid and glucosamine. Uric acid and glucosamine did not stimulate feeding or recruitment when added alone at concentrations of 50 ppm. The blend of 4 compounds including oxalic, salicylic, and uric acids and glucosamine was most effective stimulating feeding of C. formosanus at concentrations of 50 and 200 ppm, but the blend became a feeding deterrent at 400 ppm. Glucoronic acid induced feeding stimulation at 450 ppm, but it induced feeding deterrence at 675 ppm. Results indicate that the feeding stimulating properties of these organic acids occur between narrow ranges of concentrations, which may differ significantly among different organic acids.

KEY WORDS: Subterranean termites, feeding stimulants, baits, nutritional ecology, control

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Feeding Response of Coptotermes curvignathus and Coptotermes gestroi (Isoptera: Rhinotermitidae) to Different Wood of Hevea Species

By Ahmad Said Sajap, Mohd. Hamami Sahri & Mohamad Roslan Mohd Kasim

ABSTRACT

Rubber wood, Hevea brasiliensis, is one the most important resources for the timber industry in Malaysia. In an effort to increase the supply of quality rubber wood to the timber industry in Malaysia, several Hevea species, H. pauciflora, H. spruceana, H. guainensis and H. nitida, from Brazil were introduced into Malaysia and tested for their growth performances and wood properties. In this study, wood blocks from these Hevea species were exposed to subterranean termites, Coptoptermes curvignathus and Coptotermes gestroi in laboratory and field trials. The results show that no significant differences in the daily feeding rates that were detected when the wood blocks were forcefully given to the termites. However, a significant variation in the feeding rates of both termite species was observed in choice and field trials. The results from these trials show that H. pauciflora was the most preferred and Hevea spruceana was the least preferred wood.

KEY WORDS: Rubber wood, Malaysia, termites, feeding

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Further Studies on Ant (Hymenoptera: Formicidae) Assemblages in Hospitals of Mato Grosso do Sul, Brazil

By Vanessa Samúdio dos Santos, Stela de Almeida Soares, Jacques Hubert Charles Delabie & William F. Antonialli Junior

ABSTRACT

The aim of this study was to evaluate the ant assemblages in two hospitals at Ivinhema, State of Mato Grosso do Sul, Brazil. Sample series using attractive baits were taken during the cold/dry season and a second during the hot/flooded season. Our study revealed the occurrence of a total of 15 ant species in the two hospitals, respectively 10 and 12 in each one, with an ant infestation rate of 87.5% and 100% respectively, during the cold/dry season and 75% and 81.25% during the hot/flooded season. The species richness, as well as the infestation rate, were relatively higher than in other similar studies. Because of external and internal conditions, each hospital showed a significantly different ant assemblage, however with no apparent preference in their foraging behavior.

KEY WORDS: inventory, attractive baits, infestation.

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Toxicity of New Pyrethroids to the Social Insects Protonectarina sylveirae, Solenopsis saevissima and Tetragonisca angustula

By Shaiene Costa Moreno, Marcelo Coutinho Picanço, Flaviano Oliveira Silvério, Elson Santiago de Alvarenga & Geraldo Andrade Carvalho

ABSTRACT

Pyrethroids are among the most potent and effective pesticides identified with great potential for structural variation with retention or enhancement of potency. Our objective was to evaluate the biological activity of novel methyl esters of pyrethroid acids containing an aromatic ring on the acid moiety against the social insects Protonectarina sylveirae (Saussure) (Hymenoptera: Vespidae), Solenopsis saevissima (Smith) (Hymenoptera: Formicidae) and Tetragonisca angustula (Latr.) (Hymenoptera: Apidae: Meliponinae). The compounds showed low toxicity to all species tested. P. sylveirae was the most sensitive to pyrethroids.

KEY WORDS: predatory wasp, jatai bee, fire ant, insecticide activity

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Superparasitism and Host Discrimination by Neodohrniphora elongata (Diptera: Phoridae), a Parasitoid of the Leaf-Cutting Ant Atta sexdens rubropilosa (Hymenoptera: Formicidae)

By Marcos A. L. Bragança, Carlos A. Nogueira, Lucas M. Souza & Terezinha M. C. Della Lucia

ABSTRACT

The leaf-cutting ant Atta sexdens rubropilosa Forel is parasitized by several species of Phoridae flies, one of which is Neodohrniphora elongata Brown. The female of this fly oviposits inside the head of larger workers of the Atta colony, emerging only one fly from each cephalic capsule. The objective of this study was to investigate the occurrence of superparasitism by N. elongata on workers of A. sexdens rubropilosa in the laboratory and to describe if the female of this parasitoid is able to discriminate between non-parasitized and previously parasitized workers by itself and between non-parasitized and previously parasitized workers by another female of the same species. The tests were conducted in a glass observation chamber where 15 parasitized and 15 non-parasitized workers and one fly were released at a time. The flies laid eggs preferentially in non-parasitized workers rather than workers parasitized by themselves (n=11) or parasitized by other females (n=18). In both cases females of N. elongata were able to discriminate the parasitized host, rejecting most of them, but did not avoid superparasitism. Based on the high indices of superparasitism found (29.4% of self superparasitism and 49.5% of conspecific superparasitism), the process of host discrimination by N. elongata seems to be of little efficiency at least under experimental conditions.

KEY WORDS: Phoridae, self superparasitism, conspecific superparasitism, recurrent attack

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Parental and Alloparental Care of Giant Otters (Pteronura brasiliensis) (Carnivora, Mustelidae) in Balbina Hydroelectric Lake, Amazonas, Brazil

By Fernando César Weber Rosas, Márcia Munick Mendes Cabral, Gália Ely de Mattos & Roberta Elise Silva

ABSTRACT

Data collected during 6 years showed that alloparental care, despite not being mandatory, plays an important role in the reproductive success of Pteronura brasiliensis when major threats are present. Threats can also trigger cubs to be transferred from one den to another, inducing the species to leave a babysitter in the new den.

RESUMO

Dados coletados durante 6 anos revelaram que o cuidado aloparental, apesar de não ser obrigatório, desempenha uma função importante no sucesso reprodutivo de Pteronura brasiliensis quando grandes ameaças estão presentes. Perigo eminente também pode servir como gatilho para a transferência de filhotes de uma toca para a outra, induzindo a presença de uma babá na nova toca.

KEY WORDS: Mustelidae; behavior; babysitter; Brazilian Amazon

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Food Resources used by Meliponini (Hymenoptera: Apidae) in Piracicaba County, State of Sao Paulo, Brazil

By Daniela de Almeida-Anacleto, Luís Carlos Marchini, Augusta Carolina de Camargo Carmello Moreti & Vinicius Castro Souza

ABSTRACT

Our results demonstrate that Nannotrigona testaceicornis, Scaptotrigona bipunctata, Trigona clavipes and Tetragonista angustula generalize the use of floral resources, though they intensively use a small number of plants for their food. With an appropriate handling and improvement of the food sources, mainly of the Asteraceae and Fabaceae families, these bees can be maintained indefinitely.

KEY WORDS: Stingless bee, plant, management, food, floral resource

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Product Testing for the Treatment of Argentine Ants (Linepithema humile) in Southern California

By Gail M. Getty, Dina Richman, Robin L. Taylor & Vernard R. Lewis

ABSTRACT

To control the Argentine ant, Linepithema humile Mayr, the effectiveness of three chemical products applied around structures in southern California was evaluated. Three products were tested and included: Demand® CS (lambda-cyhalothrin, Syngenta), Termidor® SC (fipronil, BASF), and TransportTM GHP (bifenthrin and acetamiprid, FMC Corp.). A licensed pest management professional applied each product per label instructions to four buildings. In addition, four untreated checks were included in the study. Post treatment inspections were completed at 3, 14, 28, and 56-days. At 56 days post treatment, the percentage control for each treatment was: Demand® CS 94.05%; Termidor® 93.55%, and TransportTM GHP 98.96%. In all cases, except the untreated checks, surveyed homeowners reported a reduction in ants found in their homes at 90 days post-treatment.

KEY WORDS: Demand® CS, Termidor® SC, TransportTM GHP, Argentine Ant control, bifenthrin, acetamiprid, lambda-cyhalothrin, fipronil, Linepithema humile

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Ant Species Associated With the Dispersal of Eurhizococcus brasiliensis (Hempel in Wille) (Hemiptera: Margarodidae) in Vineyards of the Serra Gaúcha, Rio Grande do Sul, Brazil

By Franciele Sacchett, Marcos Botton & Elena Diehl

ABSTRACT

The ground-pearl, Eurhizococcus brasiliensis (Hempel in Wille), is a hypogeic hemipteran that feeds on plant roots, being one of the major pests of vineyards. Ant species may account for the dispersal of scale insects, since the ants tend first instar nymphs for honeydew. This research was conducted to investigate, under experimental conditions, whether the ants also recognize and carry E. brasiliensis cysts. Therefore, choice experiments were conducted in two vineyards naturally infested with the ground-pearl, in the municipality of Bento Gonçalves, RS. From the 11 ant species observed visiting the cysts only two were actively dispersing them, Linepithema micans (Forel 1908) and an unidentified Pheidole species. This Pheidole species and the L. micans removed and carried E. brasiliensis cysts. The workers of L. micans visited the greatest amount of test plates, but the Pheidole sp.11 workers removed more cysts. Although both species were more active to disperse the hemipteran’s cysts, L. micans workers were dominant in reference to the workers of Pheidole sp.11. Thus, in the vineyards where they occurred together; if the first species is controlled, the second species can become the main E. brasiliensis disperser.

KEY WORDS: Formicidae, Hemiptera, Linepithema, Pheidole, vine-growing areas

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Field Studies of Wasmannia auropunctata Alkylpyrazines: Towards Management Applications

By Elisa J. Troyer, Nathan T. Derstine, David N. Showalter, Eric B. Jang & Matthew S. Siderhurst

ABSTRACT

Field bioassays with Wasmannia auropunctata (Roger) show that the alarm pheromone components 2,5-dimethyl-3-(2-methylbutyl)pyrazine and 3-methyl-2-(2-methylbutyl)pyrazine both attract and arrest ants in a natural environment. Comparisons between lures containing 2,5-dimethyl-3-(2-methylbutyl)pyrazine and 3-methyl-2-(2-methylbutyl)pyrazine singly and in blends (10:1 and 100:1) based on W. auropunctata extracts, failed to show differences in the time required to attract a given number of ants. This indicates a lack of synergistic effects between the compounds under these test conditions. A dose response assay with 2,5-dimethyl-3-(2-methylbutyl)pyrazine showed maximal ant response to a 1 mg pheromone lure, a dose which remained attractive for 8 days under field conditions. Several of the field experiments included peanut butter baits, a lure currently used for detection. However, ant counts at peanut butter baits were not greater than at controls suggesting that peanut butter does not produce volatiles that attract ants. With the aim of developing management applications, a series of bioassays were conducted with 2,5-dimethyl-3-(2-methylbutyl)pyrazine in combination with food baits. A separate assay was conducted with Tanglefoot, a sticky catch material. In feeding bioassays, the alarm pheromone decreased consumption of peanut butter and solutions of protein and sugar. Tanglefoot squares failed to catch W. auropunctata with any of the lures tested. The field responses of W. auropunctata to alarm pheromone lures show a mixed potential for control applications. While the strong attraction and longevity of lures is promising, the inability to increase bait consumption or capture ants with Tanglefoot presents obstacles to using these alarm pheromone components for ant management.

KEY WORDS:

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Partial Disturbance of Resources Foraged by Reticulitermes flavipes

By Thomas G. Shelton, Patrick D. Gerard & Terence L. Wagner

ABSTRACT

The introduction of termiticidal baits over 10 years ago has increased interest in the basic foraging behavior of pest termite species. Due to the amount of interference with foraged cellulose material (bait matrices, both treated and untreated) in bait stations as part of some control programs, the following study was initiated to examine the response of termites to very short term (1 wk) partial disturbances of a foraged resource. Does weekly interruption (disturbance) of 0, 25, 50, 75, or 100% of a foraged resource reduce feeding (or activity) by subterranean termites? Four pre-weighed cubes of southern yellow pine (Pinus spp. L.) in close proximity (1 cm) were provided to groups of Eastern subterranean termites [Reticulitermes flavipes (Kollar)] as foraging choices in two different screw-top jar arena tests. The first study was done in single jars requiring termites to stay confined near the disturbed blocks, while a second study used three connected jars providing the termites with the ability to avoid the jar with the disturbed blocks altogether. Both studies used similar methods, differing only in arena design. In these studies, one, two, three, all or none of the blocks were picked up carefully and the number of termites on the moved block counted weekly. Data from both studies indicated that termites did not permanently leave disturbed blocks, and that between 50 and 75% of the blocks needed to be moved to reduce feeding on the disturbed blocks.

KEY WORDS: termites, Eastern subterranean termites, disturbance, behavior, foraging

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