@article{holbrook_bachmann_schal_2000, title={Effects of ovariectomy and mating on the activity of the corpora allata in adult female Blattella germanica (L.) (Dictyoptera : Blattellidae)}, volume={25}, ISSN={["0307-6962"]}, DOI={10.1046/j.1365-3032.2000.00161.x}, abstractNote={Summary}, number={1}, journal={PHYSIOLOGICAL ENTOMOLOGY}, author={Holbrook, GL and Bachmann, JAS and Schal, C}, year={2000}, month={Mar}, pages={27–34} }
 @article{holbrook_armstrong_bachmann_deasy_schal_2000, title={Role of feeding in the reproductive 'group effect' in females of the German cockroach Blattella germanica (L.)}, volume={46}, ISSN={["1879-1611"]}, DOI={10.1016/S0022-1910(99)00201-2}, abstractNote={We have found that whether a female German cockroach, Blattella germanica (L.), is kept alone or in the presence of another female has a major impact on how fast it reproduces and how much it eats. By the sixth day of adulthood, females paired since adult eclosion had substantially larger oöcytes than did females isolated during the same time, and females paired with intact females, or with ones rendered incapable of feeding, consumed more rat chow in the first six days of adulthood than did isolated females. The stimulatory effect of pairing on reproduction was, however, partially independent of feeding because the oöcytes of solitary and paired females differed in size on day 6 even when they were given, and had consumed, the same amount of food. This result was confirmed with analysis of covariance using the total food intake of a female as the covariate in the analysis. A female's social condition probably influenced the development of its oöcytes by affecting the quantity of juvenile hormone synthesized by its corpora allata. The corpora allata of paired females produced more hormone than did those of isolated ones, even when all females had consumed an equivalent amount of food. Moreover, females treated with a juvenile hormone analog, fenoxycarb, reproduced more quickly than identically reared and fed control females, showing that juvenile hormone could influence reproduction independently of feeding. We conclude that both group rearing and food intake accelerate oöcyte development by diminishing the brain's inhibition on the synthesis of juvenile hormone.}, number={6}, journal={JOURNAL OF INSECT PHYSIOLOGY}, author={Holbrook, GL and Armstrong, E and Bachmann, JAS and Deasy, BM and Schal, C}, year={2000}, month={Jun}, pages={941–949} }
 @article{young_bachmann_schal_1999, title={Food intake in Blattella germanica (L.) nymphs affects hydrocarbon synthesis and its allocation in adults between epicuticle and reproduction}, volume={41}, ISSN={["0739-4462"]}, DOI={10.1002/(SICI)1520-6327(1999)41:4<214::AID-ARCH5>3.0.CO;2-7}, abstractNote={The causal relationship between food intake and hydrocarbon synthesis was examined in vivo and in vitro. Fed Blattella germanica (L.) nymphs synthesized hydrocarbons in a stage-specific manner, with high rates occurring in the first 6 days of a 13-day last stadium, in relation to feeding. A similar pattern was exhibited in vitro by sternites and tergites from fed nymphs. In contrast, starved nymphs synthesized hydrocarbons at normal rates for the first 2 days, but then synthesis declined and ceased by day 6. Their abdominal sternites and tergites displayed a similar biosynthetic pattern in vitro, showing that starved tissues lost the capacity to synthesize hydrocarbons, even when provided appropriate nutrients. Synthesis resumed within 2 days of being fed on day 6, reaching a maximum rate 6 days later. Some hydrocarbon appeared on the nymphal cuticle, but almost 4-fold more hydrocarbon was internal in hemolymph lipophorin, fat body, and the developing imaginal cuticle. Because most hydrocarbon synthesized in nymphs provisions the adult, and synthesis is related to food intake, we examined trade-offs in allocations in food-limited insects. Nymphs provided with insufficient quantities of food allocated normal amounts of hydrocarbons to the nymphal epicuticle, but molted into smaller adults with significantly less internal hydrocarbons. These cockroaches directed nearly normal amounts of hydrocarbons to their epicuticle, oocytes, and oothecae, at the cost of internal hydrocarbon reserves for repair and subsequent gonotrophic cycles. Hydrocarbons, thus, appear to serve an important cross-stadial resource and the object of competition among several nymphal and adult tissues. Arch. Copyright 1999 Wiley-Liss, Inc.}, number={4}, journal={ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY}, author={Young, HP and Bachmann, JAS and Schal, C}, year={1999}, pages={214–224} }
 @article{young_bachmann_sevala_schal_1999, title={Site of synthesis, tissue distribution, and lipophorin transport of hydrocarbons in Blattella germanica (L.) nymphs}, volume={45}, ISSN={["1879-1611"]}, DOI={10.1016/S0022-1910(98)00128-0}, abstractNote={The site of hydrocarbon (HC) synthesis and the amount of HC in various tissues were investigated in relation to developmental stage in the last larval stadium of the German cockroach, Blattella germanica. Abdominal integument linearly incorporated [1-(14)C]propionate into HC for at least 6h in vitro, whereas other body parts synthesized little or no HC. The third through sixth abdominal sternites and tergites were the principal sites of synthesis. High rates of HC synthesis resulted in a fivefold increase in internal HC during the last stadium. We examined the distribution of HC in the hemolymph, fat body, and the developing imaginal cuticle. Hemolymph HC titer was relatively constant at approximately 8&mgr;g/&mgr;l. However, as hemolymph volume increased from 5 to 11&mgr;l in the first 4days of the last stadium, HC content increased and then remained stable the remainder of the stadium. Lipophorin, immunoprecipitated with adult lipophorin polyclonal antibodies, was the only HC carrier protein in nymphal hemolymph and its HC profile was identical to that of hemolymph and similar to that of the epicuticle. The concentration and total amount of hemolymph lipophorin increased until 3days before adult eclosion and declined immediately after ecdysis. The HC content of non-biosynthetic integument (legs, pronotum) doubled during formation of the imaginal cuticle, as did the HC content of sternites, which synthesize HC. HC content of fat body, however, increased threefold during the same period, suggesting that the fat body serves as a storage site for HC during cuticle formation. We conclude that in the last stadium HC is synthesized by abdominal oenocytes, loaded onto hemolymph lipophorin, and transported to fat body and both nymphal and imaginal cuticle. Hydrocarbons associate with the imaginal integument several days before eclosion.}, number={4}, journal={JOURNAL OF INSECT PHYSIOLOGY}, author={Young, HP and Bachmann, JAS and Sevala, V and Schal, C}, year={1999}, month={Apr}, pages={305–315} }
 @article{sites of synthesis and transport pathways of insect hydrocarbons: cuticle and ovary as target tissues_1998, volume={38}, number={2}, journal={American Zoologist}, year={1998}, month={Apr}, pages={382–393} }
 @article{sevala_bachmann_schal_1997, title={Lipophorin: A hemolymph juvenile hormone binding protein in the German cockroach, Blattella germanica}, volume={27}, ISSN={["0965-1748"]}, DOI={10.1016/S0965-1748(97)00042-8}, abstractNote={We examined the binding of [3H](10R) juvenile hormone (JH) III to lipophorin that was purified from the hemolymph of Blattella germanica. Binding was found to be specific, saturable and with high affinity to JH III. Using Scatchard analysis, the equilibrium dissociation constant (Kd) and total binding capacity (Bmax) were estimated to be 9.75±0.64 nM and 0.241±0.02 nmol/mg protein, respectively. Competitive displacement studies with racemic JH III, JH I, cuticular hydrocarbon, contact sex pheromone, and the JH analogs pyriproxyfen, fenoxycarb, and hydroprene showed that only JH III readily displaced [3H](10R)JH III from the binding site. However, hydroprene competed for the JH III binding site more effectively than the other two JH analogs. Photoaffinity labelling using the JH III analog [3H]epoxyfarnesyl diazoacetate demonstrated that the JH binding site was on apolipophorin-I, the large subunit of the lipophorin complex.}, number={7}, journal={INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY}, author={Sevala, VL and Bachmann, JAS and Schal, C}, year={1997}, month={Jul}, pages={663–670} }
 @article{schal_holbrook_bachmann_sevala_1997, title={Reproductive biology of the German cockroach, Blattella germanica: Juvenile hormone as a pleiotropic master regulator}, volume={35}, ISSN={["0739-4462"]}, DOI={10.1002/(SICI)1520-6327(1997)35:4<405::AID-ARCH5>3.0.CO;2-Q}, abstractNote={Juvenile hormone (JH) exerts major pleiotropic effects on cockroach development and reproduction. The production of JH by the corpora allata (CA) in the adult female German cockroach, Blattella germanica, is dependent upon and modulated by both internal and environmental stimuli. Mating, intake of highquality food, social interactions, and the presence of vitellogenic ovaries facilitate JH synthesis. Conversely, starvation, deficient diets, enforced virginity, isolation, and a pre- or post-vitellogenic ovary cause the CA to produce less JH. Sensory stimulation of the genital vestibulum by the ootheca also inhibits the CA via signals that ascend the ventral nerve cord. All these stimulatory and inhibitory signals are integrated by the brain, and a preponderance of favorable signals results in a graded lifting of brain inhibition, permitting the synthesis and release of JH. The effects of inhibitory signals on JH biosynthesis can be lifted experimentally by severing nervous connections between the brain and the CA. Such an operation accelerates activation of the CA. Besides controlling gonadal maturation in females, JH concurrently regulates the production of sexual signals, including both attractant- and courtship-eliciting pheromones, and the behavioral expression of calling (pheromone release) and sexual receptivity. Although JH is required for the expression of copulatory readiness in female B. germanica, it appears that signals associated with copulation (spermatophore, sperm, accessory secretions) can inhibit this behavioral state even when titers of JH are permissive for receptivity. These observations suggest that JH might regulate sexual receptivity in females indirectly through}, number={4}, journal={ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY}, author={Schal, C and Holbrook, GL and Bachmann, JAS and Sevala, VL}, year={1997}, pages={405–426} }