Behavioral Response of Two Subterranean Termites (Isoptera: Rhinotermitidae) to Vibrational Stimuli

Behavioral responses to vibrational stimuli were examined in two subterranean termite species, Coptotermes formosanus Shiraki and Reticulitermes flavipes (Kollar). Termites habituated to vibrational stimulation when in social groups, but failed to do so individually, indicating that habituation is a collective action. In assays on termite groups, both species demonstrated a similar pattern of behavioral responses to vibrational stimuli: evanescent cessation of activity and movement, followed by withdrawal from the vibration source. Groups of both species then gradually moved back toward the vibration source as a consequence of continuous exposure. However, it took a significantly shorter period for C. formosanus to return (57 s) to the test arena and to resume (80 s) normal foraging activities in the test arena compared with R. flavipes, which took 97 and 227 s, respectively, when exposed to the vibration frequency of 120 bmpm. High vibration frequency (240 bmpm) increased the time required to return (C. formosanus, 80 s; R. flavipes, 153 s) and to resume regular locomotion (C. formosanus, 186 s; R. flavipes, 263 s). Our experiments demonstrate that workers play a crucial part in adjusting groups of termites to distressful vibrations. Soldiers of R. flavipes demonstrated similar behavioral responses as workers, however, C. formosanus soldiers exhibited a transient positive response before withdrawal. An erratum to this article is available at .     

A Novel Strain of Steinernema riobrave (Rhabditida: Steinernematidae) Possesses Superior Virulence to Subterranean Termites (Isoptera: Rhinotermitidae)

Subterranean termites are major global pests of wood structures and wood products. Among the most economically important subterranean termite species in the US are Heterotermes aureus, Reticulitermes flavipes, and Coptotermes formosanus. In prior studies, the entomopathogenic nematode, Steinernema riobrave strain 355, exhibited a high level of virulence to H. aureus compared with other nematode species. However, S. riobrave 355 was reported to be poorly or only moderately virulent to R. flavipes and C. formosanus, respectively. We hypothesized that other strains of S. riobrave may possess a high level of virulence to all three termite species. Under laboratory conditions we compared three novel strains of S. riobrave (3-8b, 7-12, and TP) with the 355 strain for virulence to H. aureus, R. flavipes, and C. formosanus workers. H. aureus was very susceptible to all the S. riobrave strains, and termites in all nematode treatments were dead after 4 d. The TP strain of S. riobrave caused greater mortality in R. flavipes and C. formosanus compared to the other nematode strains. Specifically, the TP strain caused 75% and 91% mortality in R. flavipes and C. formosanus, respectively, which was more than 300% and 70% higher than the mortality caused by other strains. Additional studies are warranted to determine the ability of S. riobrave (TP) to control the targeted termite species under field conditions.     

Alarm Reaction of European Reticulitermes Termites to Soldier Head Capsule Volatiles (Isoptera, Rhinotermitidae)

The alarm behavior of worker and soldier castes of four European subterranean termite species of the genus Reticulitermes (R. santonensis, R. lucifugus, R. grassei, R. banyulensis) is described. In petri dish bioassays we presented filter papers with squashed soldier heads as an odor source to trigger a alarm reaction. Untreated filter papers were used as controls. The behavioral patterns were alike for all four species. In the control situation (no alarm), only occasional workers and few soldiers were seen walking in the petri dish. When the odor source was presented, a general state of alertness was observed, showing as higher activity and presence, zigzag running, antennation of nestmates, jittering and jerking, mandible snapping, head-banging, and attraction to the odor source. Workers were attracted within a few seconds (6.9–13.4 s); soldiers followed much later (18.5–64.6 s). Both workers and soldiers inspected the odor source only briefly (workers for 8.7–12.8 s, soldiers for 10.0–19.5 s), with the exception of R. santonensis, where soldiers stayed an average of 209.8 s. The number of individuals, of 50 workers and 3 soldiers, near the odor source averaged 6.0–9.2 workers and 1.2–2.3 soldiers. The presence of workers is crucial: without workers, a significant alarm reaction in soldiers could not be induced. The roles of soldier and worker castes of Reticulitermes species within alarm communication and the origin and nature of possible alarm signals are discussed.     

Factors that Affect Aggression Among the Worker Caste of Reticulitermes spp. Subterranean Termites (Isoptera: Rhinotermitidae)

Aggression was observed among both inter- and intraspecific combinations of four colonies of Reticulitermes flavipes (Kollar) and Reticulitermes hageni Banks in laboratory assays each month for 4 consecutive months. Termites were most frequently aggressive toward colonies of a different species. Number of individuals that displayed aggression decreased over the study period, from April to July. There was a slight trend toward reduced aggressive behavior as termites were maintained in the laboratory for 3 months. Passive and aggressive individuals were identified and reexamined for display of aggressive or passive behavior toward nonnestmates. Eighty-nine percent of previously aggressive termites displayed aggression a second time. Eighty-eight percent of previously passive termites were passive upon reexamination. Differences in head capsule size between passive and aggressive individuals provided no correlation between the presence of aggressiveness and the head capsule size in the worker caste.     

Feeding Preference of Native Subterranean Termites (Isoptera: Rhinotermitidae: Reticulitermes) for Wood Containing Bark Beetle Pheromones and Blue-Stain Fungi

Surprisingly little research has been conducted to investigate interactions between subterranean termites and bark beetles. Facilitative interactions between these organisms could easily alter stand dynamics and impact wood utilization strategies. A series of American Wood Protection Association Standard E1-09 “choice tests” were carried out to determine the feeding preference of Reticulitermes flavipes Kollar (Isoptera: Rhinotermitidae) for blue-stained sapwood and sapwood impregnated with various bark beetle pheromones. Reticulitermes flavipes exhibited a feeding preference for both air-dried and kiln-dried blue-stained sapwood, unstained sapwood treated with frontalin, and air-dried blue-stained sapwood treated with a 0.02% solution of both frontalin and endo-brevicomin. The implications of these results are far reaching, with particular relevance to forest health, ecology, and utilization.     

Escape Behavior of the Formosan Subterranean Termite (Isoptera: Rhinotermitidae) in Response to Disturbance

Disturbances to monitors and baits have often been noted as a confounding factor for the success of termite baiting systems. We studied escape behavior of Coptotermes formosanus Shiraki to a food source disturbance in the laboratory. Four peripheral chambers connected to the central food chamber through tubes served as escape routes from which escape patterns, escape and return times and differences in soldier and worker responses were recorded. We used two sand conditions: moist and dry to test whether favorable versus unfavorable conditions change escape behavior. The post disturbance responses were video recorded for 1 h. C. formosanus quickly escaped from the central chamber when disturbed. The time taken to reach the maximum number of termites that escaped ranged from 20 s to 210 s followed by a gradual return to the disturbed chamber. The majority of the escapees returned to the disturbed area within a few minutes after evacuation in both dry and wet sand conditions. A significantly higher percentage of termites escaped in wet sand arenas (43%) than in the dry sand arenas (31%). Our experiments demonstrate that C. formosanus is highly unlikely to abandon bait stations for extensive periods of time as a result of mechanical disturbances regardless of habitat quality.     

Queue Size Determines the Width of Tunnels in the Formosan Subterranean Termite (Isoptera: Rhinotermitidae)

We present a model of tunnel excavation by termites that requires no pheromone labeling of soil or work sites, but instead relies on tactile interactions and individuals who actively orient their movement. Potential termite excavators moved from the tunnel origin towards the distal end of the tunnel and formed a queue behind those termites at the digging face. Delayed termites excavated soil laterally from the tunnel wall at a position governed by their position in the queue of termites. By examining excavation under artificially induced conditions of longer and shorter queues of termites at the tunnel end, we showed that tunnel width increased with increased queue size and the rate of lateral excavation in a process we termed “digging pressure.”     

Subterranean termites (Isoptera: Rhinotermitidae): Exploitation of equivalent food resources with different forms of placement

Abstract Coptotermes gestroi and Heterotermes tenuis have been described as important urban pests in Brazil. The establishment of control technologies using baits that consider the social behavior of termites requires a better knowledge of their foraging behavior. Thus, this study analyzed the feeding behavior of these species with three different forms of food placement: food on the surface of a substrate and food either partially or completely buried in the substrate. Experimental arenas were composed of a central chamber connected to three food chambers. Each central chamber contained 550 foragers of C. gestroi or 517 foragers of H. tenuis. Blocks of Pinus elliottii were placed in the different food chambers. After 28 days, the consumption of each wood block and the percentage of foraging individuals recruited for food chambers were verified in relation to the total survival rate obtained for each one of the 20 replicates. Results showed that completely buried food was most consumed for H. tenuis and presented a higher recruitment rate of workers and soldiers for both species. Although the consumption had non‐significant differences for C. gestroi, these termites exhibited a tendency to prefer completely buried food. In these conditions, it can be concluded that the forms of food placement used in the present research influenced the recruitment of individuals for both species. Data also suggests that when the foraging subterranean termites find food resources in the tunneling substrate, they tend to concentrate their efforts on it, a behavior regime that reduces exposure to external environment.     

Trail Communication During Foraging and Recruitment in the Subterranean Termite Reticulitermes santonensis De Feytaud (Isoptera, Rhinotermitidae)

The search for food in the French subterranean termite Reticulitermes santonensis De Feytaud is organized in part by chemical trails laid with the secretion of their abdominal sternal gland. Trail-laying and -following behavior of R. santonensis was investigated in bioassays. During foraging for food termites walk slowly (on average, 2.3 mm/s) and lay a dotted trail by dabbing the abdomen at intervals on the ground. When food is discovered they return at a quick pace (on average, 8.9 mm/s) to the nest, laying a trail for recruiting nestmates to the food source. While laying this recruitment trail the workers drag the abdomen continuously on the ground. The recruitment trail is highly attractive: it is followed within a few seconds, by more nestmates, and at a quicker pace (on average, 6.4 mm/s) than foraging trails (on average, 2.9 mm/s). The difference between foraging and recruitment trails in R. santonensis could be attributed to different quantities of trail pheromone. A caste-specific difference in trail pheromone thresholds, with workers of R. santonensis being more sensitive to trails than soldiers, was also documented: soldiers respond only to trails with a high concentration of trail pheromone.     

Distribution of Formosan subterranean termite (Isoptera: Rhinotermitidae) in Mississippi

An extensive monitoring and survey program in Mississippi was conducted from 2000 to 2004 to investigate the distribution of the Formosan subterranean termite, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae). Seventy-two towns from 22 counties in southern Mississippi were monitored with a total of 3914 traps that catch alates during the swarming season. In addition, 259 licensed pest management professionals in Mississippi were surveyed to determine the locations of termite infestations treated. The alates of C. formosanus were recovered in 12 counties with light traps, and termite infestations were documented in an additional 13 from data collected in the termite survey. Infestations of C. formosanus have been documented in urban, urban cluster, rural, and forested areas of Mississippi. However, the distribution in mean total capture of alates for 4 yr differed significantly among the four ecological areas with the highest percentage in forested areas (31%) and the lowest percentage in urban cluster areas (17%). Most of the infestations of C. formosanus were geographically distributed along the coastal areas of southern Mississippi from Gulfport to Pascagoula. The greatest total number of alates captured in light traps was documented in Pearl River County. Mass swarming of C. formosanus occurred primarily in May or June, depending on weather conditions. The number of documented counties with the evidence of large and widely dispersed swarms of C. formosanus in different ecological areas, and the increase in total annual alate captures from 2000 to 2003, suggest that this invasive termite species is now firmly established in Mississippi.     

Hermetically sealed baits for subterranean termites (Isoptera: Rhinotermitidae)

Cellulose baits containing 0.5% hexaflumuron were hermetically sealed in a closed cell polyethylene sheet envelope and placed in soil to test their durability and efficacy against field colonies of the Formosan subterranean termite, Coptotermes formosanus Shiraki, or the eastern subterranean termite, Reticulitermes flavipes (Kollar). The closed cell polyethylene sheet was readily tunneled through by termites, yet it was impervious to water and protected the cellulose baits and hexaflumuron from the environment. Only in a few incidents did the polyethylene envelope become infiltrated by plant roots, resulting in water intrusion and apparent degradation of cellulose baits. After consuming one to three sealed baits, three colonies each of both termite species were eliminated. The sealed baits may be placed in soil for months or years without the need of monitoring, and they are readily penetrated and fed upon by termites when they are present. Application of baits hermetically sealed in a protective sheet may save labor costs by bypassing the monitoring phase, circumvent the station avoidance by some termite species, and enable the use of baiting technologies in large areas such as agricultural fields in which the manual monitoring is impractical.     

Distribution and genetic variation of Reticulitermes (Isoptera: Rhinotermitidae) in Portugal

The genus Reticulitermes has a Holartic distribution and is widely represented in southern Europe. It is established in Portugal, across the full range of ambient environmental conditions, using different types of wood resources, as available, and nesting ubiquitously in many types of soil. Sequencing of part of the mtDNA COII gene revealed that all the specimens sampled on a north-south transect of the country were Reticulitermes grassei (considered synonymous with R. lucifugus grassei). Nevertheless, an association between the genetic and the geographical distances of sampled specimens was shown, leading to the conclusion that discrete termite populations have differentiated in situ. The geographic component of the genetic polymorphism should be the subject for further research.     

Ethnic Differences in Physiological Responses to Fear Conditioned Stimuli

The idea that emotional expression varies with ethnicity is based largely on questionnaires and behavioral observations rather than physiological measures. We therefore compared the skin conductance responses (SCR) of Hispanic (Puerto Rican) and White non-Hispanic subjects in a fear conditioning and fear extinction task. Subjects were recruited from two sites: San Juan, Puerto Rico (PR), and Boston, Massachusetts (MA), using identical methods. A total of 78 healthy subjects (39 from PR, 39 from MA) were divided by sex and matched for age and educational level. Females from the two sites did not differ in their SCRs during any experimental phase of fear conditioning (habituation, conditioning, or extinction). In contrast, PR males responded significantly to the conditioned stimulus than MA males or PR females. Subtracting ethnic differences observed during the habituation phase (prior to conditioning) eliminated differences from subsequent phases, suggesting that PR males are elevated in their response to novelty rather than fear learning. Our findings suggest that, in addition to sex differences, there are ethnic differences in physiological responses to novel stimuli at least in males, which could be relevant for the assessment and treatment of anxiety disorders.     

Genetic relationship between Coptotermes gestroi and Coptotermes vastator (Isoptera: Rhinotermitidae)

The phylogenetic relationship of Coptotermes gestroi (Wasmann) and Coptotermes vastator Light (Isoptera: Rhinotermitidae) was determined using DNA sequence comparisons of mitochondrial genes. Partial sequences of the ribosomal RNA small subunit 12S, ribosomal RNA large subunit 16S, and mitochondrial COII were obtained from nine populations of C. gestroi from South East Asia (Malaysia, Singapore, Thailand, and Indonesia) and four populations of C. vastator from the Philippines and Hawaii. In addition, four populations of Coptotermes formosanus Shiraki and Globitermes sulphureus (Haviland) were used as the outgroups. Consensus sequences were obtained and aligned. C. vastator and C. gestroi are synonymous, based on high sequence homology across the 12S, 16S, and COII genes. The interspecific pairwise sequence divergence, based on Kimura 2-parameter model between C. gestroi and C. vastator, varied only up to 0.80%. Morphometric measurements of 16 characteristics revealed numerous overlaps between the examined individuals of both species. Based on the molecular phylogenetics and morphometric data, it is proposed that C. vastator is a junior synonym of C. gestroi.     

Septate Gregarines From Reticulitermes Flavipes and Reticulitermes Virginicus (Isoptera: Rhinotermitidae)

ABSTRACT. The gregarine parasites of Reticulitermes virginicus and Reticulitermes flavipes begin their development as trophozoites attached to the midgut epithelium by a small button-shaped epimerite. the epimerite is lost when the parasite becomes free-living in the gut lumen as a solitary gamont. Syzygy is late and was not observed. When full-grown, gamonts enter the hemocoel and fuse in pairs to form large gametocysts that are attached to the midgut of the termite by a duct. Thousands of sporocysts are formed within the original gametocyst. the mature sporocysts are released into the lumen of the midgut through the connecting duct. They are then passed out with the feces. These gregarines are believed to be identical to Gregarina termitis Leidy which was described from a single gamont and later erroneously placed in the genus Hirmocystis by Henry.     

Responses of Coptotermes formosanus and Reticulitermes flavipes (Isoptera: Rhinotermitidae) to three types of wood rot fungi cultured on different substrates

This study examined the responses of two termite species, the Formosan subterranean termite, Coptotermes formosanus Shiraki, and the eastern subterranean termite, Reticulitermes flavipes (Kollar), to three types of wood decay fungi: a brown rot fungus, Gloeophyllum trabeum (Persoon: Fries) Murrill; a white rot fungus, Phanerochaete chrysosporium Burdsall; and a litter rot fungus, Marasmiellus troyanus (Murrill) Singer. We also examined the responses of termites to these three types of fungi grown on different substrates. For all three fungal species, both termite species showed a strong preference for fungus-infected sawdust over uninfected sawdust. In choice tests, both termite species preferred sawdust infected with either M. troyanus or P. chrysosporium over G. trabeum. However, termites did not show any preference for fungus-infected potato dextrose agar over uninfected potato dextrose agar. Tunneling activity of C. formosanus was greater in sand treated with methanol extracts of fungus-infected sawdust than in sand treated with extracts of uninfected sawdust. Because chemicals in the fungal extracts caused termites to tunnel further into treated sand than untreated sand, these chemicals could potentially be used to direct termite foraging toward bait stations in the field.