Impacts on Reticulitermes flavipes (Infraorder Isoptera: Rhinotermitidae) by Chlorantraniliprole Applied to Soil Surrounding Established Tunnels.

Soil-applied liquid termiticides are the most common control measure for subterranean termites. Characteristics unique to insecticidal chemistries such as repellency, toxicity, and time between contact and mortality, influence the interaction of termites with treated soil and overall treatment success. Two different treated-tunnel bioassays were used to evaluate the behavioral impacts and mortality of termites from treatment with chlorantraniliprole (the active ingredient in Altriset® termiticide) to existing, mature tunnels. Termites that were provided constant access to a 10-cm-long mature tunnel within soil treated with 5 or 50 ppm chlorantraniliprole were not repelled by the treatment and began exhibiting slower, uncoordinated movement, and cessation of tunneling and feeding in as little as 1 h after access. Termites provided access for 7, 14, or 21 d to previously constructed tunnels recently treated with 50 ppm chlorantraniliprole exhibited complete or near complete mortality by 28 d. The second bioassay design resembled a more typical field situation with a 40-cm-long mature tunnel and termites allowed access for a maximum of 5 min. Termites collected after just 5 min of access to the previously constructed tunnels recently treated with 50 ppm chlorantraniliprole exhibited similar symptomology within an hour followed by complete mortality at 18 d after exposure. These test designs simulate what occurs in the soil around an infested structure at the time of treatment. Results from these evaluations suggest that termites readily crawl through chlorantraniliprole-treated mature tunnels, rapidly lose ability to feed, and acquire a lethal dose from brief exposures.

Termite colony ontogeny: supplemental data in the long-term assessment of reproductive lifespan, female neotenic production and colony size in Reticulitermes flavipes (Isoptera: Rhinotermitidae).

Reticulitermes flavipes (Kollar) colonies established by field-collected alates were reared in the laboratory for 11 years. Weights of members of each caste and full-colony censuses were performed regularly; the most recent 2003-2004 data are reported. Colonies averaged 11623.5 +/- 910 individuals, and with the exception of primary queens from one genetic lineage, mean weights for all castes had increased since 2001. Female replacement reproductives, or neotenics, developed to replace dead queens in clusters of either few, large individuals or many, small individuals. Regardless of cluster size, female neotenics comprised more reproductive biomass per colony than primary queens. The number and size of female neotenics was independent of colony size or time elapsed since a founding queen's death.

Termite colony ontogeny: a long-term assessment of reproductive lifespan, caste ratios and colony size in Reticulitermes flavipes (Isoptera: Rhinotermitidae).

Thirty Reticulitermes flavipes (Kollar) colonies established by alates collected from two separate field sites were raised in the laboratory for eight years. Twenty-one of the colonies were founded by alates from one field source and nine from another, providing demographic data from two unrelated parental lineages. Colony totals ranged from 3620 to 11641 individuals, with no significant difference in size between lineages. Soldier caste proportion of the colony total and mean wet weights for workers, soldiers and kings were significantly different between the two lineages. This suggests that at least a portion of the variability observed in caste ratios and body size may be heritable. One founding reproductive had died in five of the colonies (17%); none lost both parents. The queenless colonies contained exclusively female replacement reproductives (neotenics); the kingless colony contained a female-skewed mixture of male and female neotenics. All the nests that lost a founding parent contained significantly more pre-alate nymphs than the nests with both a king and a queen. Comparisons with published reports of ontogenetic patterns in other termites and social insects are discussed.

Effects of sublethal exposure to imidacloprid on subsequent behavior of subterranean termite Reticulitermes virginicus (Isoptera: Rhinotermitidae).

Experiments were conducted to determine whether subterranean termites, Reticuliternes virginicus (Banks), previously exposed to sublethal doses of imidacloprid (Premise), and allowed to recover for 1 wk, demonstrated behavioral aversion to a subsequent exposure. Worker termites experiencing a previous sublethal but debilitating exposure to imidacloprid-treated sand (either 10 or 100 ppm for 4 h) showed no apparent aversion to a second encounter with imidacloprid-treated sand under conditions of this experiment. If these laboratory results hold in the field and termites traveling through a zone of soil treated with imidacloprid are impaired but subsequently recover, they will be just as likely as their naive nestmates to reenter the treated area if their travels take them through the nonrepellent application a second time. Our results also indicate that a sublethal exposure to imidacloprid can affect termite tunneling behavior. Many worker termites that received an initial 4-h exposure to 100 ppm imidacloprid-treated sand died, but those that survived tunneled significantly less than did their naive nestmates, as did some termites exposed to 10 ppm imidacloprid.

Phylogenetic relationship among termite families based on DNA sequence of mitochondrial 16S ribosomal RNA gene.

Termites (Order Isoptera: Class Insecta), are comprised of a complex assemblage of species, with considerable variation in life history, morphology, social behaviour, caste development and ecology. At present, isoptera is divided into seven families, fourteen subfamilies, approximately 270 genera and over 2000 species. Phylogenetic hypotheses currently available for termite families and genera are based on a limited number of morphological characters and lack rigorous cladistic analysis. In this paper we report on phylogenetic relationships among ten termite genera of five families based on a DNA sequence analysis of a portion of the mitochondrial 16S rRNA gene. Parsimony and distance analysis of DNA sequences supported the existing hypothesis that Mastotermitidae is the basal lineage among extant termites. Kalotermitidae was not found to be a sister taxon of Mastotermitidae as existing hypotheses suggest, but was most closely related to Rhinotermitidae and Termitidae. Representatives of Termopsidae were more basal relative to those of Kalotermitidae. The utility of 16S rRNA nucleotide sequence analysis for inferring phylogenetic relationships among termite families, subfamilies and genera is discussed.

Hydrocarbons ofNasutitermes acajutlae and comparison of methodologies for sampling cuticular hydrocarbons of caribbean termites for taxonomic and ecological studies.

Using data from the arboreal nestingNasutitermes acajutlae (Holmgren), we propose standard collection and extraction methodology for characterization of cuticular hydrocarbons of termites under field conditions in the tropics. Specifically, we evaluated: (1) the effect of the duration and the number of extractions; (2) the effect of drying termites before extraction; (3) the effect of sample size; (4) the effect of solvents (ethanol versus hexane) on cuticular hydrocarbon profiles. Olefins comprise ca. 70% of the cuticular hydrocarbons ofN. acajutlae. Hydrocarbons consist of two distinct groups: early-eluting components, primarilyn-alkanes and methyl-branched alkanes, and late-eluting compounds, which consist almost exclusively of unsaturated components with one to six double bonds. Soldiers have more early-eluting compounds than workers or alates. Nests from the same island had qualitatively similar, but quantitatively dissimilar hydrocarbon mixtures. Brief extractions of 300 live workers in 10 ml of hexane for only 20 sec produced a hydrocarbon mixture equivalent to a 10-min extraction. Long-term extraction of 300 workers in hexane for two years resulted in different mixtures of hydrocarbons. Drying workers tended to enhance extraction of the less abundant unsaturated compounds such as C41.4 and C41.5. A single extraction of a minimum of 100 workers (live or dried), with hexane for 20 sec to 10 min is best; these extraction regimes resulted in mixtures of hydrocarbons that are quantitatively very similar. For quantitative comparisons, extracts from dried samples should not be compared to those from live samples. Storage in ethanol caused numerous unidentified, nonhydrocarbon compounds to be extracted either from the cuticle or from internal tissues.

Ancestral transfer of symbionts between cockroaches and termites: an alternative hypothesis.

Closely related cellulolytic protozoa reside in the hindguts of extant woodroaches (Cryptocercidae) and termites (Isoptera). The evolutionary origin of these symbiotic relationships in the two lineages is uncertain. Transfer of protozoa between ancestors of modern Cryptocercus and termites remains a valid alternative theory to the established hypothesis of symbiont inheritance from a common ancestor. Nalepa's (Proc. R. Soc. Lond. B 246, 185 (1991] concerns regarding the protozoan transfer hypothesis focus on the biology of modern species, and neglect to consider the evolutionary framework of an ancestral dynamic postulated to occur among Palaeozoic insects. Legitimacy of the symbiont transfer theory removes the constraint of interpreting presence of cellulolytic protozoa as a synapomorphy between Cryptocercidae and Isoptera, with potential impact on objective resolution of dictyopteran phylogeny.

A case for ancestral transfer of symbionts between cockroaches and termites.

Living species of the cockroach family Cryptocercidae have intestinal symbionts that are congeneric with some of the gut protozoa found in Isoptera. Presence of such closely related symbionts in cryptocercids and in termites has been frequently interpreted as a uniquely derived homologous character shared between the two xylophagous groups. This may not be the most parsimonious interpretation. Cryptocercus nymphs placed into Zootermopsis (dampwood termite) colonies were killed and eaten by the termites. Termites placed into a Cryptocercus nest box were also fully consumed. Modern Cryptocercus punctulatus and Zootermopsis are often found in the same decaying logs in the Pacific Northwest of the U.S.A., and it is likely that their ancestors also cohabited in at least a portion of their ranges. By occasionally killing and consuming an intruder from the other group, gut protozoa could have been acquired and exchanged between termites and Cryptocercus or their ancestors, under natural conditions and before the life histories of the protozoa became specialized within the host orders. Implications for assessing the phylogeny of the two dictyopteroid groups are also discussed.

Surface hydrocarbon components of two species ofNasutitermes from Trinidad.

Colonies ofNasutitermes costalis (Holmgren) andN. ephratae (Holmgren) were collected from five locations in Trinidad. Cuticular hydrocarbons were characterized by gas chromatography-electron impact mass spectrometry and quantified by capillary gas chromatography. Sixteen major components were identified; all but one component (12, 16-dimethyltriacontane) were common to both species. The methyl-branched hydrocarbons were predominant inN. costalis, while the majority of the hydrocarbon components inN. ephratae weren-alkanes. One hydrocarbon (11,15-dimethylheptacosane) was found in abundance in samples ofN. ephratae from Trinidad but was not previously reported from collections of this species in Panama. In addition to the morphology of the soldiers and alates and the architecture of the arboreal nests,N. costalis andN. ephratae from Trinidad can easily be separated by chromatograms of the hydrocarbons.N. costalis has an enormous 13,17-dimethylhentriacontane peak (mean = 42.4% of total hydrocarbon). InN. ephratae this peak is much smaller and the 12,16-dimethyltriacontane peak is completely missing.N. costalis from Trinidad andN. corniger from Panama appear to have cuticular hydrocarbon profiles that are more similar to one another than are those ofN. ephratae from Trinidad and Panama.

Chemical composition and efficacy of cephalic gland secretion ofArmitermes chagresi (Isoptera: Termitidae).

Soldiers of the neotropical humivorous termiteArmitermes chagresi have large ice-tong-like mandibles for mechanical defense and a moderate length nasus from which cephalic gland defensive secretions are discharged. Soldiers do not eject secretion, but ooze droplets which are held at the nasus tip by hairs. The chemical secretion is composed of C22-C26 macrocyclic lactones, including C24 and C26 and α- and ß-hydroxylated lactones, with C24 macrolides predominating. The cephalic gland secretion has no pheromonal properties and does not induce alarm or attraction in soldiers or workers. Upon application, the secretion repels and is irritating to ants, but does not appear to act as an antihealant. The defensive behavior and chemistry ofA. chagresi is discussed in light of termite ecology and evolution.