白蚁防治技术

白蚁是破坏性很强的社会性昆虫。文章从白蚁的探测和监测、物理防治、化学防治、生物源物质防治和白蚁信息素的利用技术5个方面综述白蚁防治技术的最新研究进展。同时展望白蚁未来的研究领域。     

Regulation of juvenile hormone titers by soldiers in the Formosan subterranean termite, Coptotermes formosanus

In field collections of the Formosan subterranean termite Coptotermes formosanus, soldiers averaged less than 10%. The proportion of soldiers increased to about 25% or higher when termites were kept in the laboratory, as did the juvenile hormone III (JH III) titers for both workers and soldiers. In laboratory experiments with a proportion of soldiers 25% or higher, very few new pre-soldiers were formed and the JH titer in existing soldiers remained constant. On the contrary, workers from groups containing less than 25% soldiers formed more pre-soldiers. In such cases, both workers and soldiers showed higher JH titers. Newly formed soldiers also had higher JH titers than older soldiers. It is speculated that populations containing higher soldier proportions inhibit further soldier differentiation, eventually holding the JH titers under the threshold or suppressing the activity of corpora allata resulting in lower JH titers in workers.     

Screening of genes expressed in developing mandibles during soldier differentiation in the termite Hodotermopsis sjostedti

We investigated the morphological changes accompanying soldier differentiation in the damp-wood termite Hodotermopsis sjostedti. Genes expressed in the developing mandibles, which undergo the most remarkable morphological changes during soldier differentiation, were screened using fluorescent differential display. Database searches for sequence similarities were conducted and the relative expression levels were then quantified by real-time polymerase chain reaction. Among the identified candidate genes, 12 genes were upregulated during soldier differentiation. These included genes for cuticle proteins, nucleic acid binding proteins, ribosomal proteins and actin-binding protein, which were inferred to be involved in caste-specific morphogenesis in termites.     

Juvenile hormone III titers and regulation of soldier caste in coptotermes formosanus (Isoptera: Rhinotermitidae)

Juvenile hormone (JH) is an important growth hormone in insects that has also been implicated in caste determination in termites. Gas chromatography-mass spectrometry was used to establish that the JH in the Formosan subterranean termite, Coptotermes formosanus Shiraki, is JH III. JH III titers were measured in workers, pre-soldiers, and soldiers from samples collected from the field. The average titers of JH III in workers and soldiers were about 13 and 25 pg mg(-1), respectively. However, pre-soldiers contained a significantly higher amount, 596 pg mg(-1). As expected, treatment of workers with a JH-analogue, methoprene, triggered rapid formation of pre-soldiers. However, these pre-soldiers had a very low JH III titer (62 pg mg(-1)). It appears that the application of JHA, while inducing pre-soldier formation, does not increase the endogenous JH III titer. The titer, however, increased as the pre-soldiers aged and before transforming into soldiers.     

Early development of locomotor behavior in vervet monkeys

The locomotor development of three vervet infants across approximately the first 2 months of life is described. Fairly normal-looking walking movements (as compared to adults) were seen in all the animals by approximately 1 month of age and galloping was observed by 2 months. Early locomotor footfall patterns were often aberrant and bounding-type gaits were sometimes exhibited. Most of the symmetrical gaits observed were classifiable as lateral sequence. Across the 2-month period the animals showed decreased three- and four-foot support and improvements in joint angular displacement patterns. From their earliest locomotor movements the infants showed significant linear relationship between both cycle duration and swing and stance durations of the limbs. We suggest that locomotor control mechanisms are probably fairly mature at birth but that weight support and postural control problems explain the initial locomotor difficulties exhibited by these infants.     

Queen-specific volatile in a higher termite Nasutitermes takasagoensis (Isoptera: Termitidae)

In social insect colonies, queen-produced pheromones have important functions in social regulation. These substances influence the behavior and physiology of colony members. A queen-produced volatile that inhibits differentiation of new neotenic reproductives was recently identified in the lower termite Reticulitermes speratus. However, there are no known queen-specific volatiles of this type in any other termite species. Here, we report volatile compounds emitted by live queens of the higher termite Nasutitermes takasagoensis. We used headspace gas chromatography mass spectroscopy (HS GC-MS) to analyze volatiles emitted by live primary queens, workers, soldiers, alates, and eggs collected in a Japanese subtropical forest. Among 14 detected compounds, 7 were soldier-specific, 1 was alate-specific, 1 was egg-specific, and 1 was queen-specific. The queen-specific volatile was phenylethanol, which is different than the compound identified in R. speratus. The identification of this queen-specific volatile is the first step in determining its functions in higher termite social regulation. Comparisons of queen pheromone substances regulating caste differentiation among various termite taxa will contribute to a better understanding of the evolution of social systems in termites.     

Emergence rhythms and protandry in relation to daily patterns of locomotor activity inTrichogramma species

Summary In insect parasitoids, the mating structure of the population depends on the emergence pattern of adults and on their behaviour after emergence. In order to study some aspects of these characteristics in four species of egg parasitoid of the genusTrichogramma, laboratory experiments using automatic video analysis are performed. Adult emergence is concentrated in the morning, with an earlier time for males. The variability of the time of emergence is under genetic control. The relationships between the emergence pattern and the locomotor activity are considered by measuring individually: first, the delay between the emergence and the first locomotion which is significantly greater in females than in males and, second, the activity of newly emerged males, which is maximum at the time of the emergence of females. The locomotor activity is influenced by mating; mated females are much more active than virgin ones, mated males are less active than virgin ones. The adaptive values of the rhythmicity of emergence and of protandry are discussed together with their relationship with the patterns of locomotor activity. The results are also considered with respect to mating strategies in insect parasitoids; they actually support the hypothesis of mating occurring principally among individuals native to the same host patch inTrichogramma species.     

Temporal polyethism in incipient colonies of the primitive termiteZootermopsis angusticollis: A single multiage caste

Division of labor was studied in incipient colonies of the dampwood termite Zootermopsis angusticollisby recording repertoire size, behavior frequencies, and time budgets of larvae. Behavioral repertoire size increased with age: first- and secondinstar larvae were mainly inactive, whereas larvae of the third through seventh instars performed 64–100% of all tasks. The increase in repertoire size from the second to the third instar was abrupt; repertoire size and composition remained more or less constant for older instars. No correlation between age (instars III–VII) and tasks was identified, suggesting that colony labor is performed by a single functional caste that spans the third to the seventh instar without any age-based division of labor. Small colony size, low oviposition rate, simple nest architecture, a lack of spatial association of tasks, and the potential for attaining reproductive status appear to be associated with the lack of age-related behavioral specialization in Z. angusticollis.In effect, the absence of temporal polyethism in this species is likely a consequence of its nesting habits and physiological and developmental constraints.     

Biparental care in incipient colonies of the dampwood termiteZootermopsis angusticollis Hagen (Isoptera: Termopsidae)

Parental care and division of labor in male and female primary reproductives in incipient colonies of the dampwood termite Zootermopsis angusticolliswere studied by recording repertory sizes, behavior frequencies, time budgets, and transition probabilities of acts. Repertory sizes for males and females were identical, and behaviors were performed at similar frequencies. Time budget data also suggested equal participation in parental care by both sexes. Transition probability analysis suggested that males and females did not organize their behavior in roles. We therefore found no indication of sex-based division of labor during colony foundation and the incipient stages of colony growth. The lack of behavioral specialization may be due to the fact that acts might be related and/or have more than one function, and different tasks are not spatially associated. Our observations are consistent with the hypothesis that monogamous mating systems in termites involve mate assistance.     

On the origin of termite workers: weighing up the phylogenetic evidence

Resolving the phylogenetic history of a 'true' worker caste in termites is essential to our understanding of termite eusocial evolution. Whether this caste is ancient and monophyletic or derived and polyphyletic will have a tremendous impact on our interpretation of termite eusocial history and remains an outstanding question in termite biology. Recent work has begun to re-examine this question in light of new phylogenetic information, but new questions have now arisen about how best to model character state changes in termite caste systems. In the present paper, we compare the models of Grandcolas and D'Haese [J. Evol. Biol. 15 (2002) 885] and Thompson et al. [J. Evol Biol. 13 (2000) 8691 and attempt to make explicit how these proposals differ with respect to the number of, and homology between, character states. We highlight the support each model has for the two principal, but competing, evolutionary hypotheses outlined above.