Identification and characterization of 10 polymorphic microsatellite loci in the German cockroach,Blattella germanica

Primer sequences and initial characterization are presented for 10 microsatellite loci isolated from the German cockroach, Blattella germanica. In a sample of 30 individuals from a single population sample, all loci were polymorphic with two to 12 alleles segregating per locus and levels of observed heterozygosity ranging from 0.27 to 0.92. One locus showed a deficit of heterozygotes. Experimental conditions are described for polymerase chain reaction multiplexing, which enables the genotyping of eight loci in three electrophoretic runs consisting of one set of three and two sets of two markers. Seven primer sets cross‐amplify in the related Blattella asahinai.     

Endocrine effects of social stimuli on maturing queens of the dampwood termite Zootermopsis angusticollis

Abstract.  The reproductive physiology of social insects is often highly responsive to social stimuli from nestmates, but the mechanisms underlying this sensitivity are usually poorly understood. The effect of varied social conditions on the endocrinology and ovarian maturation in maturing female primary reproductives of the dampwood termite Zootermopsis angusticollis Hagen is studied to better understand their developmental responses to conspecifics. Newly dealate queens are paired with a reproductive male, with another maturing female, or are allowed to mature in isolation. Developmental responses are tracked by monitoring rates of juvenile hormone (JH) production by corpora allata in vitro , haemolymph ecdysteroids titres and ovarian development after 5, 10, 15 and 30 days of maturation. Significant declines in rates of JH production rates are observed by days 5, 10 and 30, respectively, for females paired with males, left to mature in isolation or paired with a female. Ecdysteroid titres increase by day 5 and stay elevated in females nesting with males. By contrast, for CA from females that are isolated or paired with another female, the titres decline and stay low until at least day 15, but increase significantly by day 30. These hormonal differences correspond to differential rates of physiological maturation, with more rapid ovarian development occurring in females paired with a male, than in those nesting alone or with another female. The results suggest that JH and ecdysteroids modulate the ovarian response of alates to stimuli from nestmates during this period of maturation, and that JH and ecdysteroid titres may be regulated independently during this period of development.     

Vertical community structure and resource utilization in neotropical forest cockroaches

ABSTRACT.

• 1 Patterns of vertical habitat use of ten species of cockroaches are examined. Three assemblages of cockroaches are recognized on the basis of morphology, foraging behaviour, foraging heights, and overlaps and breadths of vertical distributions.
• 2 Three apterous and brachypterous species occur near the ground and comprise one assemblage. They feed mainly on material in the leaf-litter.
• 3 Species that perch higher either migrate into the leaf-litter on a diel basis and feed on both leaf-litter and epiphyllic materials, or some are strictly arboreal and forage on algae, liverworts, lichens, spores, pollen and trichomes on the surfaces of leaves.
• 4 Trophic and behavioural correlations with perch height are described and the functions of perching are examined.
• 5 We conclude that studies of interactions among species are confounded by our lack of understanding of stage- and sex-specific interactions of coexisting species. A simplistic ‘species’approach to such interactions is inadequate because it does not recognize intraspecific variation.

     

Social influences on nymphal development in the cockroach, Diploptera punctata

Solitary male nymphs of the cockroach Diploptera punctata (Eschscholtz) (Blattaria: Blaberidae) took significantly longer to reach adulthood than males paired with either a male or female nymph or grouped with four other male nymphs since birth. When isolated throughout nymphal development, 15.8% of males passed through 3 stadia before adult eclosion, and the remainder went through 4 stadia. In contrast, 61.3% of paired males became adults in 3 stadia. Males need not, however, be isolated or paired for the entire nymphal period to express isolated or paired patterns of development. About 60% of males paired in just the first stadium or its initial 9 days became adults in 3 stadia, and only 20.4% of males isolated in the first stadium and the first 3 days of the second reached adulthood within 3 stadia. Although the first stadium was a critical period in which social condition determined the course of future development, analyses of covariance showed that isolated males gained less weight than paired ones, not only in the first stadium, but in the second as well. Moreover, the degree of growth of a male in the second stadium, measured as either weight gain or relative growth rate, did not depend on the male's social condition in the first stadium, because isolated second-instar males grew less than paired ones, even when both sets of insects had been paired in the first stadium. Female nymphal development, unlike that of males, was not greatly affected by social factors.     

Effects of temperature and light on calling in the tiger moth Holomelina lamae (Freeman) (Lepidoptera: Arctiidae)

ABSTRACT. In Holomelina lamae Freeman daily eclosion of adults is gated, with males emerging before females. By advancing the onset of photophase and by delaying the onset of scotophase, it was demonstrated that lights-on acts as the main phase-setting cue for calling. Few females call on the day they eclose. Calling is initiated c. 9 h after the onset of photophase in 2-day-old females, and shifts to earlier times in older females. The duration of calling also increases with age. That calling is controlled by an endogenous circadian clock is indicated by its persistence in continuous light (LL) and dark (DD). In LL calling is dampened rapidly, but a single scotophase re-entrains the rhythm. Decreases in temperature advance the onset of calling and the mean hour of calling, while increases in temperature delay both. However, the magnitudes of such phase-shifts depended upon hour of the photoperiod. Moreover, cooling and heating appears to exert both transient and long-term effects on the calling rhythm. An 8 h period at a reduced temperature in LL induces calling in females whose calling is dampened, and entrains the calling rhythm. Females maintained in DD from second instar larvae to the adult stage exhibit a circadian calling rhythm set by eclosion.     

Endocrine regulation of female contact sex pheromone production in the German cockroach, Blattella germanica

ABSTRACT The amount of the major component of the cuticular sex pheromone, 3, 11-dimethyl-2-nonacosanone, on individual female German cockroaches, Blattella germanica (L.), as a function of age was determined by gas-liquid-chromatographic analysis. Accumulation of phermone increased with age in both virgin and mated females. During the first gono-trophic cycle, the pheromone accumulated most rapidly when oocyte growth rates were maximal (days 5–10), and least rapidly while the female carried an ootheca (days 11–32). Pheromone accumulation was similar in virgin and mated females when the same physiological stages (determined by oocyte maturation) were considered. Inhibition of Juvenile Hormone release, through allatectomy, chemicals (precocene or fluoromevalonate), or through mechanical egg case implants, suppressed or delayed pheromone production and oocyte growth. The Juvenile Hormone analogue ZR512 induced allatectomized or head-ligated females and females with chemically or mechanically inhibited corpora allata to produce pheromone and enlarge their basal oocytes. Finally, ZR512 applied to intact females stimulated pheromone production in a dose-dependent manner.     

Responses of Amblyomma americanum and Dermacentor variabilis to odorants that attract haematophagous insects

Carbon dioxide (CO₂), 1‐octen‐3‐ol, acetone, ammonium hydroxide, L‐lactic‐acid, dimethyl trisulphide and isobutyric acid were tested as attractants for two tick species, Amblyomma americanum and Dermacentor variabilis (Acari: Ixodidae), in dose–response bioassays using Y‐tube olfactometers. Only CO₂, acetone, 1‐octen‐3‐ol and ammonium hydroxide elicited significant preferences from adult A. americanum, and only CO₂ was attractive to adult D. variabilis. Acetone, 1‐octen‐3‐ol and ammonium hydroxide were separately evaluated at three doses against CO₂ (from dry ice) at a field site supporting a natural population of A. americanum nymphs and adults. Carbon dioxide consistently attracted the highest number of host‐seeking ticks. However, for the first time, acetone, 1‐octen‐3‐ol and ammonium hydroxide were shown to attract high numbers of A. americanum. Further research is needed to determine the utility of these semiochemicals as attractants in tick surveillance and area‐wide management programmes.     

Effects of dextrin and cellulose on feeding and reproduction in female brown-banded cockroaches, Supella longipalpa

Abstract Food consumption and reproduction were compared through two gonotrophic cycles in female brown-banded cockroaches, Supella longipalpa (F.), fed a standard rat food diet which had been serially diluted with methyl cellulose, alpha cellulose or dextrin. Females did not increase daily intake to compensate for dilution, and reproductive rate was highly dependent upon the degree of dilution of the diet. With increasing dextrin concentrations, digestibility increased, but reproductive rate, size and mass of oothecae, and efficiency of food utilization progressively decreased.
On diets containing 75% rat food and 25% methyl cellulose, females consumed minimal amounts of food and 80% of the females did not mate or produce oothecae within 30 days. On identical diets containing 25% alpha cellulose, food digestibility decreased and females ate significantly more than females fed 25% methyl cellulose, but less than females fed rat food. Many (65%) females fed 25% alpha cellulose produced oothecae which were smaller and took longer to form than in control females fed on rat food. At concentrations higher than 50% of either methyl or alpha cellulose daily intake was further reduced and females died rapidly.     

Pheromone puff trajectory and upwind flight of male gypsy moths in a forest

ABSTRACT. Pheromone released from a point source beneath a forest canopy usually follows a non-linear trajectory as demonstrated by the paths of small, neutrally-buoyant, helium-filled balloons or puffs of smoke. Mark-recapture experiments show that few male gypsy moths ( Lymantria dispar L.) follow a pheromone plume over distances greater than 80 m even though they can easily detect pheromone at that distance as indicated by wingfanning assay. The directional consistency of successive puffs of pheromone appears more important than the linearity of their trajectories in enabling males to locate a pheromone source.     

Variability in Juvenile Hormone production by locust corpora allata kept in vitro for long periods

Abstract. Juvenile Hormone III (JH-III) production by corpora allata (CA) of sexually mature female locusts (Locusta migratoria migratorioides (R. & F.)) was maintained in vitro for up to 30 days in an agar-solidified medium. Hormone production was measured periodically with a short-term radiochemical assay. Low-activity CA increased their activity significantly after 24–48 h incubation in the long-term medium, but high-activity glands did not. Variations in activity were considerable among glands tested on the same day and among measurements from the same gland on different days. Farnesoic acid-stimulated rates of JH-III production were always higher than the basal rates, suggesting that the CA were not maximally activated. However, freshly excised low-activity CA, whose hormone production increased in the long-term conditions, showed similar farnesoic acid-stimulated rates of JH-III production to those of freshly excised high-activity glands, suggesting that at the time of excision of the corpora allata rate-limiting step(s) preceding farnesoic acid biosynthesis were inhibited or refractory to stimulation in vivo.