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Genetically marked insecticide-susceptible strains of the German cockroach, Blattella germanica (L.), were crossed to the Seasons-resistant strain to examine the inheritance and linkage of resistance to cypermethrin, fenvalerate, permethrin, and phenothrin. Tests on the F1 progeny from reciprocal crosses indicated that resistance to these pyrethroids is not sex linked and is incompletely recessive in each case. Backcrosses to the Seasons strain resulted in a 1:1:1:1 ratio with the black-body marker from linkage group IV. F2 crosses, involving the orange-body marker from linkage group VI, produced a 9:3:3:1 ratio. These results fit the hypothesis that resistance to each insecticide is inherited as a monofactorial, autosomal, incompletely recessive trait not linked to Bl or or . The data do not allow a distinction between whether 1 gene controls resistance to all 4 insecticides, or whether as many as 4 similarly acting genes are responsible. Other data are discussed that support the latter possibility.

Methods for detecting resistance to chlorpyrifos and cypermethrin in the German cockroach, Blattella germanica (L.), were evaluated. Results from the tarsal-contact method (jar test) are greatly influenced by the amount of insecticide used. In tests with high levels of insecticide, little or no resistance was detected. By using less insecticide, the existence of resistance was revealed. Recognition of this fact allows discrepencies between the lethal dose, lethal concentration, and lethal time methods to be largely resolved. These findings indicate that caution must be exercised in the use of the jar test to avoid misinterpretation of the results.

A simulated crack and crevice method of exposure to insecticides was developed to ascertain the relationship between mortality produced by field-application rates and resistance ratios obtained by the time-mortality method. Nymphal German cockroaches, Blattella germanica (L.), from strains of widely varying resistance backgrounds were tested with chlorpyrifos, acephate, cyfluthrin, and cypermethrin. I observed an inverse relationship between resistance ratios and 72-h crack and crevice mortality in all 4 cases. Gene frequency estimates paralleled resistance ratios for cyfluthrin and cypermethrin. I concluded that time mortality resistance ratios provide a good indication of the level of resistance in a given strain, and that resistance ratios >3.0 signal potential control failures in the field.

Crosses were made between the Asian cockroach, Blattella asahinai Mizukubo, and resistant strains of the German cockroach, B. germanica (L.), to assess the transfer of pyrethroid resistance to the progeny and to study the inheritance mechanism(s) involved. It was shown that the strain of Asian cockroaches studied was susceptible to four pyrethroids. F 1 progeny were essentially susceptible to the same compounds. Tests with F 2 progeny and those from backcrosses to the resistant parent indicated that the data for each pyrethroid fit an hypothesis of simple, autosomal, nearly completely recessive inheritance. The results are discussed from the standpoint of the impact of the Asian genome on the inheritance mechanism(s)

Twelve field-collected populations of German cockroaches, Blattella germanica (L.), were examined for resistance to dietary abamectin at 40 ppm. Half of these populations had significantly increased resistance ratios compared with the VPI-susceptible strain, but the highest value was only 2.4. Feeding inhibition was variable but nevertheless pronounced in all 12 strains. Feeding-choice tests with two strains revealed that each strain consumed treated and untreated food about equally. Mortality was reduced in both strains. Cross-resistance from cyclodiene resistance was not found. Low-level selections with abamectin did not result in increased resistance. Whereas resistance to abamectin does not appear to be a problem at present, two potential resistance mechanisms were identified and are discussed briefly.

The effects of three synergists on the level of resistance to eight pyrethroids were examined in field-collected populations of the German cockroach, Blattella germanica (L.). Resistance to allethrin was not affected by piperonyl butoxide (PBO), (2-(2-ethylhexyl)-3a,4,7,7a-tetrahydro-4,7-methano-1H-isoindole-1,3(2H)- dione (MGK 264), or S,S,S-tributyl phosphorotrithioate (DEF). Resistance to pyrethrins also was not affected by these synergists in the same or similar strains but was negated almost completely by them in strains resistant only to pyrethrins. Resistance to permethrin, cypermethrin, and cyfluthrin largely was negated by these synergists. Results were variable with esfenvalerate, fenvalerate, and especially phenothrin. For example, with phenothrin the synergists were partially effective against some strains but were totally ineffective against others. The results appear to be unrelated to the chemistry of the pyrethroids studied. I report evidence that indicates the possible presence of several independent resistance mechanisms. My results suggest that these synergists generally will not combat pyrethroid resistance in this species, although they are highly effective in some cases.

Bendiocarb resistance was assessed genetically in the German cockroach, Blattella germanica (L.), by conventional crossing experiments. It is inherited as a simple, autosomal, incompletely recessive, Mendelian trait. Manipulation of the test procedure clearly identified the resistant homozygote. thus allowing gene frequency estimates to be made using the Hardy-Weinburg equilibrium expression. Gene frequnecies were estimated for 18 field-collected populations at two time intervals. In the initial tests, gene frequencies varied from 0.99 to 0.15. Significant decreases in gene frequency occurred in four populations over time; significant increases were observed in two others. Comparisons were made between gene frequency estimates of the level of resistance and conventional resistance ratios. I concluded that resistance ratios do not provide an adequate evaluation of the status of resistance. The results are discussed from the standpoints of their effect on resistance management and the effect of extended periods of laboratory culture on the assessment of resistance.

The response of a susceptible and two pyrethroid-resistant field strains of the German cockroach, Blattella germanica, to four emulsifiable concentrates (ECs)--Tempo (cyfluthrin), Demon (cypermethrin), Dursban (chlorpyrifos) LO, and XRM 5184 (chlorpyrifos)--was investigated. Application rates were 0.4, 0.1, 0.5, and 0.5%, respectively. Susceptible cockroaches avoided dried formulations of the pyrethroids Tempo and Demon, but resistant cockroaches did not; avoidance was greater with Demon than with Tempo. Filter papers freshly impregnated (wet) with Demon and Tempo flushed susceptible cockroaches (Demon greater than Tempo). Resistant cockroaches were flushed only by Demon, but less so than susceptible strain cockroaches. No mortality occurred in experiments with the pyrethroids. Dried formulations of Dursban LO and XRM 5184 had little, if any, repellency to nymphs of either the susceptible or resistant strains. Initially (1-3 h), most cockroaches settled on treated papers. Subsequent movement off treated papers was a step in the process leading to knockdown. At 24 h, mortality of susceptible cockroaches was 100% in the experiment with Dursban LO and 95% in the experiment with XRM 5184. Highest mortality in a resistant strain (40%) was in the contact experiment with Dursban LO. In contact repellency and flushing experiments, mortality was higher with Dursban LO than with XRM 5184. Neither chlorpyrifos formulation flushed cockroaches effectively. Mortality in flushing experiments was less than in the contact repellency experiments.

Late instar German cockroach male and female nymphs were exposed continuously for two weeks to surfaces treated with fenoxycarb, diflubenzuron, and pyriproxyfen, singly and in combination. Concentrations were determined that eliminated or nearly eliminated reproduction in matings with untreated mates, either through mortality, effects on reproduction, or a combination of mortality and ‘sterility' (no hatch). The major effect of fenoxycarb, pyriproxyfen, and pyriproxyfen plus fenoxycarb was on reproduction. The major effect of diflubenzuron was mortality. No hatch occurred in matings of females that were exposed to low concentrations of pyriproxyfen and fenoxycarb (2 ng/cm² and 6 ng/cm², respectively); sterility was incomplete when females were exposed to 600 ng/cm² of diflubenzuron. Mortality and sterility acted together to eliminate productive matings (matings that produced nymphs) when relatively high concentrations of diflubenzuron were combined with one or both of the other insect growth regulators (IGRs). In the triple combination, very small amounts of fenoxycarb and pyriproxyfen (total 1.1 ng/cm²) combined with 200 ng/cm² of diflubenzuron eliminated productive matings of treated females, but similar results with treated males were found only at higher concentrations of each IGR.

Selection experiments with a pyrethrins-susceptible and a pyrethrins-resistant strain of German cockroaches, Blattella germanica (L.), were conducted for 17 generations with either permethrin or fenvalerate as the selecting agent. Large nymphs were left on treated glass surfaces for extended periods of time each generation. Mortality was assessed at 24 h. The level of resistance was determined periodically by time-mortality testing. The VPI-susceptible strain served as the basis for comparison. The pyrethrins-susceptible strain developed resistance to pyrethrins early in the selection process; this strain ultimately became resistant to allethrin, phenothrin, permethrin, fenvalerate, cyfluthrin, and cypermethrin. Fenvalerate caused faster development of resistance than did permethrin. The pyrethrins-resistant strain, selected with fenvalerate, quickly became resistant to allethrin, permethrin, phenothrin, and fenvalerate. Ultimately, it developed resistance to all nine pyrethroids tested.

Late-instar German cockroaches, Blattella germanica (L.), were used to evaluate the relative effects of single treatments and combinations of three insect growth regulators (IGRs): pyriproxyfen, fenoxycarb, and diflubenzuron. Groups of 15 males or 15 females were held for 2 wk on food treated with varying amounts of IGRs. After removal, newly mature adults were placed with untreated adults of the opposite sex. Mortality, adult phenotype (normal wings, divergent wings, curly wings, and nymphoids), and reproduction were assessed. Mortality occurred largely in the nymphal stage except when all three IGRs were combined. Neither the average number of nymphs per egg case nor hatch of egg cases from phenotypically normal cockroaches (normal wings, occasional darkening of the body) was affected in single treatments or in combinations of two IGRs, but nymphal numbers were reduced when the three IGRs were combined. Hatch from matings of insects with divergent wings varied. At low concentrations (3-10 ppm), hatch was generally normal; at high concentrations, most mating tests were unproductive. Mating tests of cockroaches with curly wings were almost always unproductive. When males with curly wings were mated, females dropped either unfertilized egg cases (no mating) or partially fertilized egg cases. Curly-wing females either dropped unfertilized egg cases or failed to form egg cases because of deleterious effects on ovarian development. Nymphoids did not mate. Diflubenzuron at 100 ppm had no effect other than causing the appearance of a few insects with divergent wings. Effects on phenotype and reproduction began at 3 ppm of both pyriproxyfen and fenoxycarb and at a comparable concentration in the combination of pyriproxyfen + fenoxycarb (1 ppm each). Female sterility was complete at 100 ppm of pyriproxyfen and fenoxycarb. When pyriproxyfen or fenoxycarb was combined with equal amounts of diflubenzuron, the number of productive matings was not reduced at 6 ppm (3 ppm per each IGR). At 20 ppm (10 ppm per each IGR), a reduction in productive matings coincided with the appearance of curly wings. Complete female sterility occurred only at 600 ppm (300 ppm per IGR). The most severe effects occurred in the experiment with equal amounts of pyriproxyfen, fenoxycarb, and diflubenzuron. In addition to reduced hatch from normal phenotypes, this experiment caused complete male sterility (300 ppm; 100 ppm of each IGR). Female sterility was complete at greater than or equal to 90 ppm (30 ppm of each IGR).

The toxicity of synergism of and resistance to insecticides in four strains of German cockroach, Blattella germanica (L.), were investigated. Toxicity of nine insecticides by topical application to the susceptible strain varied greater than 2,000-fold, with deltamethrin (LD50 = 0.004 micrograms per cockroach) and malathion (LD50 = 8.4 micrograms per cockroach) being the most and least toxic, respectively. Resistance to pyrethrins (9.5-fold) in the Kenly strain was unaffected by the synergists piperonyl butoxide (PBO) or S,S,S-tributylphosphorotrithioate (DEF), suggesting that the metabolism is not involved in this case. Malathion resistance in the Rutgers strain was suppressible with PBO, implicating oxidative metabolism as a resistance mechanism. The Ectiban-R strain was resistant to all the pyrethroids tested, and cypermethrin resistance was not suppressible with PBO or DEF. These findings support results of previous studies that indicated this train has a kdr-like mechanism. Bendiocarb resistance in both the Kenly and Rutgers strains was partially suppressed by either PBO or DEF, suggesting that oxidative and hydrolytic metabolism are involved in the resistance. Trends between the effects of the synergists on the susceptible versus resistant strains are discussed.

1. 1. Female Parcoblalta fulvescens feed selectively on diets differing in nutrient content when given a choice during the reproductive cycle. 2. 2. Diets high in carbohydrate and protein content are preferred early in the cycle, while a cellulose-containing diet is readily consumed toward the end of the cycle. 3. 3. The total diet consumed by females given a choice contained about 16% protein, and they did not excrete uric acid while on this diet. 4. 4. Females on diets high in carbohydrate or cellulose required longer to complete the reproductive cycle than females on high-protein diet or those given a dietary choice. 5. 5. Nitrogen-stressed females will consume urate-containing fecal pellets, but only if they have utilizable carbohydrate in their diet.

A genetically marked insecticide-susceptible strain of the German cockroach, Blattella germanica (L.), has been developed by incorporating the orange-body trait into a stock containing the genomes of 2 of the most susceptible strains available. The new stock retained its susceptibility as indicated by tarsal contact tests with 12 insecticides. The integrity of the stock can be ensured by removing any wild type body color contaminants. This stock is well suited to become the standard-susceptible strain for the German cockroach and is available upon request.

Pyrethrins resistance was assessed genetically in the German cockroach, Blattella germanica (L.), by conventional crossing experiments. It is inherited as a simple, autosomal, incompletely dominant, trait. By manipulating the test procedure, the susceptible homozygote was clearly identified, allowing gene frequency estimates to be made using the Hardy-Weinburg equilibrium expression. Gene frequencies were estimated for four susceptible and 16 resistant field-collected populations. Values ranged from 0.10 to 0.18 for the susceptible strains, and from 0.34 to > 0.90 for the resistant strains. Changes in gene frequency over time for several resistant strains were not significant. The results are discussed from the standpoints of their effects on cockroach control and the stability of pyrethrins resistance even during extended periods with no selection pressure.

The level of resistance to seven pyrethroids was followed in a laboratory-selected population of Blattella germanica (L.) for 15 generations, during which time it was not exposed to any insecticide. As estimated by LT50 resistance ratios (RRs), resistance declined in a stepwise manner to preselection levels with all of the pyrethroids except pyrethrins. I also compared the levels of resistance as indicated by RRs and by gene frequency (GF) estimates. Results showed that GF estimates provide a more precise indication of the changes in resistance that occur over time than do RRs alone, especially when combined with RR and end-point mortality data. I discuss my results from the standpoints of the number of genetic mechanisms involved in pyrethroid resistance in this insect, and what the declines in resistance mean for future cockroach control.

Ten field-collected strains of the German cockroach, Blattella germanica (L.), with varying levels of pyrethroid resistance were tested for possible cross-resistance to abamectin administered as a bait. The time-mortality method was used for comparison of response with a known susceptible strain in 10-d feeding experiments. Essentially no resistance to abamectin was found. Extensive feeding inhibition occurred after a few days, but the amount of abamectin consumed varied substantially from strain to strain. Abamectin may have considerable potential as a cockroach bait insecticide.

Several patterns of uric acid voiding exist among various cockroach species. The impact of dietary nitrogen levels on these patterns has now been examined. Blattella germanica, Supella longipalpa, and Latiblattella inornata do not void uric acid even when maintained on diets containing 10.6% nitrogen for up to 30 days. Two species of Nahublattella void some uric acid on that diet, but high mortality was observed by 15 days. Parcoblatta fulvescens voids increasing amounts of uric acid as formed pellets when dietary nitrogen is increased, and suffers no untoward effects. The partitioning of injected 14C-purine (hypoxanthine) by Parcoblatta was shown to occur first by conversion to 14C-uric acid. Thereafter, 14C is found in evolved 14CO2, feces, egg cases, and whole body. The partitioning of 14C is influenced by the level of dietary nitrogen available. On a nitrogen-restricted diet, larger amounts of 14CO2 are evolved but little 14C occurs in the feces. When nitrogen is abundant, reduced amounts of 14CO2 are evolved and more 14C is voided with the feces. 14C-containing compounds, including 14C-uric acid, are incorporated into egg cases. Radiolabel remaining in the injected insects at the end of the experiment was also influenced by the dietary regime. These results are discussed in relation to the flow of uric acid through Parcoblatta and its utilization by this insect.

The Title of this paper refers not to the Entomological Society of America, but rather to society in general as it currently exists in this country. Unfortunately, some entomologists share this almost hysterical fear of chemicals implied by the title.

1. 1. Crude extracts of concentrations of endosymbionts from newly formed cockroach oothecae have been assayed anaerobically and aerobically for enzyme activity related to the degradation of uric acid. 2. 2. The extracts exhibited uric acid-dependent oxidation of both methyl viologen and NADH 2 when strictly anaerobic conditions were maintained throughout the extraction and assay procedures. 3. 3. Under aerobic conditions, extracts from egg endosymbionts and cockroach fat body catalyzed the xanthine-dependent reduction of NAD + . 4. 4. The enzyme activity exhibited is strikingly similar to that of xanthine dehydrogenase. 5. 5. The significance of these results is discussed in relation to uric acid storage in the cockroach fat body.

Food and water consumption by adult female German cockroaches has been examined in relation to the reproductive cycle. Daily consumption was recorded for individual insects and was related to certain landmark events in each of four egg-case production cycles. It was shown that peaks of feeding and drinking occur during the egg maturation period, but are abruptly terminated at the appearance of each egg case. During the period when females carry the egg case, they feed and drink sparingly. The possible role played by feeding and especially drinking in the regulation of reproduction in this important pest species is discussed. RESUME Consommation d'eau et d'aliments pendant le cycle reproductif des femelles de Blattella germanica L'examen de la consommation d'eau et d'aliments par les femelles adultes de Blattella germanica a ete lie au cycle reproductif. La consommation individuelle quotidienne des insectes a ete reliee a certains evenements marquants dans chacun de quatre cycles de production d'ootheque. Les pics d'alimentation et d'absorption se produisaient pendant la periode de maturation des oeufs, mais disparaissaient brutalement a l'apparition de chaque ootheque. Pendant la periode ou les femelles portent les ootheques, elles s'alimentent et s'abreuvent parcimonieusement. Le role eventuel joue par l'alimentation et particulierement l'absorption dans la regulation de la reproduction de cet important insecte nuisible est examine.

1. 1. Young adult American cockroaches ( Periplaneta americana L.) were allowed to accumulate nitrogen stores by maintenance on a highly positive nitrogen balance diet. Upon removal to one of three negative nitrogen balance diets, dietary nitrogen intake, body nitrogen uptake, body uric acid content and nitrogen elimination were monitored. 2. 2. Changes in body nitrogen, uric acid nitrogen and body weight were observed when cockroaches were placed on negative nitrogen balance regimes. The rate of uric acid mobilization was related to the amount of carbohydrate and nitrogen present in the diet. Insects maintained on dextrin for 17 weeks mobilized urate stores most rapidly. 3. 3. Females mobilized urate stores more rapidly than males. Oothecal production accounted for a considerable portion of the nitrogen lost. Comparisons of the nitrogen balance values suggest that a portion of the uric acid nitrogen is utilized during egg production and may be incorporated into the ootheca. 4. 4. The mobilization of urate stores may involve the mycetocyte symbionts as well as the metabolic processes of the insect. Mobilization and utilization of nitrogen contained in stored urates is briefly discussed.

Metaphase I cells from heterozygotes in eight reciprocal chromosome translocation stocks of Blattella germanica (L.) have been examined and counted. The data show that three stocks have random disjunction (adjacent and alternate orientations are equally frequent), but the cell types adjacent-1, alternate-1, adjacent-2, and alternate-2 are present in a ratio of 2∶1∶1∶2. Four stocks with directed disjunction have similar patterns, except for a heavy preponderance of alternate-2 cells. This difference is reflected in the finding that 60–65% of all cells in these interchanges are type II cells (alternate-2 plus adjacent-2), and the individual percentages agree closely with the percent directed disjunction in each case. One inter-change with directed disjunction is distinctly different in that the frequencies of both alternate-1 and alternate-2 cells are elevated and contribute to directed disjunction. It has also been demonstrated with two stocks that changes in disjunction frequencies can be brought about by genetic manipulation. These observations provide a better understanding of the differences between random and directed disjunction.

1. 1. Uric acid has been positively identified in the Malpighian tubules of three urate-voiding cockroach species—Parcoblatta fulvescens (S. and Z.), Shawella couloniana (S.) and Simploce hospes (P.). 2. 2. In secreting tubules, uric acid occurs in the lumen of the middle and proximal regions and occasionally in the distal tips. 3. 3. Urates are present in the tubule lumen as small spherules which form an opaque white slurry. 4. 4. Urates are discharged into the hindgut in sufficient quantities to obscure the presence of food residues in urate-containing fecal pellets. 5. 5. Birefringent materials occur in vacuoles within the tubule cells, which may indicate vesicular transport of urate.

1. 1. Five additional cockroach species were shown to void uric acid to the exterior bringing the total to nine out of 49 species examined. All nine belong to the subfamily Blattellinae. 2. 2. Uric acid content in whole excreta from six species of Parcoblatta varied from 5.7 to 11.2%, while that in the white, formed-pellets varied from 25.4 to 36.1%. 3. 3. Young Parcoblattait nymphs void little uric acid during the first month of life, but subsequently expel it at adult rates. 4. 4. Fat body from 35 species of cockroaches has a consistent general cytological pattern involving three cell types. 5. 5. Fat body from all species examined contains uric acid within urate cells. 6. 6. Several possible strategies for urate utilization by cockroaches are discussed.

By use of a recessive-genetic marker, it has been shown that adult female German cockroaches, Blattella germanica (L.), can be successfully inseminated by more than one male. Reinsemination was demonstrated to occur rarely between the first mating and production of the first egg case, while about 20% of the females examined remated between egg cases. The total impact of second matings on the offspring produced was small because of remating infrequency and the prevalence of incomplete sperm precedence in those that were reinseminated. RESUME DETERMINATION GENETIQUE DE LA FREQUENCE DES INSEMINATIONS ET DE LA COMPETITION ENTRE SPERMATOZOIDES CHEZ BLATTELLA GERMANICA Le marquage par un gene recessif a permis de montrer que les femelles de Blattella germanica peuvent etre inseminees avec succes par plus d'un mâle. La seconde insemination a rarement lieu entre la premiere copulation et la production de la premiere ootheque, tandis que 20% des femelles examinees recopulent entre la production des differentes ootheques. L'impact global des secondes copulations sur la descendance est faible parce que, d'une part, la frequence des nouvelles copulations est limitee. et que, d'autre part, les spermatozoides de la premiere copulation incomplete des femelles reinseminees sont avantages.

Newly emerged adult female Parcoblatta fulvescens (Saussure & Zehntner) mate ca. 10 days after emergence and produce their first ootheca 5 days later. All matings occurred between 0230 and 0700 hours and lasted an average of 100 ± 40 (±SEM) min. Subsequently, females of this species and P. pennsylvanica (DeGeer) produce an ootheca about every 8 days. They feed extensively during the period from oothecal deposition to appearance of the next ootheca. This is necessary to support sustained reproduction because each ootheca equals 15–20% of female body weight. Oothecae of five Parcoblatta species have been compared in size and number of egg compartments. P. pennsylvanica from Texas has been shown to undergo two complete generations per year in the laboratory.

Patterns of urate storage have been examined in young nymphs of the American cockroach in relation to dietary levels of nitrogen. On a standard dog food diet, stored urates gradually increase with age in a manner which roughly parallels weight gain. Excessive urate storage occurs when dietary nitrogen levels are high, while urate stores are depleted in insects on a nitrogen deficient diet. Excretion of urates was not detected under any conditions examined. ZUSAMMENFASSUNG HARNSAURESPEICHERUNG BEI JUNGLARVEN DER AMERIKANISCHEN SCHABE An Junglarven der Amerikanischen Schabe wurde die Art der Uratspeicherung in Abhangigkeit vom Stickstoffgehalt der Nahrung untersucht. Auf einer Standard-Hundefutterdiat nimmt das eingelagerte Urat allmahlich mit dem Alter zu und zwar ungefahr parallel mit dem Gewicht. Ubermassig viel Urat wird eingelagert bei hohem Stickstoffgehalt der Nahrung. Dagegen werden die Uratvorrate abgebaut bei stickstoffarmer Nahrung. Eine Ausscheidung von Urat wurde unter keiner der berucksichtigten Versuchsbedingungen festgestellt.

o 1. Nitrogen and cation excretion/storage in 23 cockroach species representing 11 subfamilies have been examined. Measurements of externally excreted ammonia nitrogen, uric acid nitrogen, total nitrogen, potassium and sodium were made. Values of total body nitrogen, body urate nitrogen, and body potassium and sodium are also reported. 2. A significant correlation was found between body nitrogen and body uric acid nitrogen. Certain species contained very high levels of uric acid/urates representing as much as 72% of their total body nitrogen. Contrarily, other species were found to contain low levels of uric acid/urates, representing as little as 3% of their body nitrogen. 3. A less significant correlation was found between internal nitrogen storage and external nitrogen excretion. Certain species can be classified as uricotelic, since as much as 62% of their total fecal nitrogen may be excreted as uric acid-nitrogen. Other species can be designated as ammonotelic, since they may excrete as much as 70% of their total fecal nitrogen as ammonia nitrogen. 4. Increased body nitrogen retention may be correlated with increases in body potassium and/or sodium. The internal storage of nitrogen as uric acid appears to involve the formation of potassium and/or sodium urate salts.

Two new reciprocal translocations in the German cockroach have been analyzed. They were identified cytologically to be T(3;12) and T(7;12). Linkage studies showed that groups XI, IX, and IV are on chromosomes 12, 3, and 7, respectively, and clearly demonstrated sex differences in recombination. Each of these chromosomes have distinctive morphological features that facilitate their identification, and permit breakpoint and centromere localization. A sex difference in fecundity is associated with T(7;12), but not T(3;12). About 40 percent mortality occurred when T(3;12) males or females and T(7;12) females were outcrossed. Outcrossing T(7;12) males produced the expected 50 percent mortality. Cell counts at metaphase I revealed that T(3;12) males exhibit directed segregation, while T(7;12) males do not. Tests for homozygosity indicated that the T(7;12) homozygote is viable. A map of chromosome 12 is presented showing the tentative placement of linkage group XI with respect to interchange breakpoints and chromosome morphology. The results are discussed in relation to possible sex differences in chiasma localization.

1. 1. Adult female Parcobtatta pennsylvanica and P. fulvescens exhibit pronounced feeding and drinking cycles during their 8-day reproductive cycle. 2. 2. Food and/or water deprivation at oothecal deposition markedly inhibited basal oocyte development. 3. 3. The voiding of urate-containing fecal pellets by P. fulvescens is also cyclic, and peaked 1 day after peak feeding. It occurred only in females on high-nitrogen diets. 4. 4. Females on a graded series of nitrogen diets did not show a progressive increase in the level of body urate on the higher nitrogen diets, suggesting that urate excretion plays a role in regulating the level of internal urates.

A pilot experiment in genetic control of the German cockroach was conducted aboard a small vessel based at Norfolk, Virginia. It utilized “sterile” ♂ ♂ (double translocation heterozygotes) whose sterility effects were due to embryonic lethality plus complete entrapment of any remaining viable embryos within the egg case. Initial infestations were reduced by insecticides prior to male release. Three releases of unmated ♂ ♂ were made at monthly intervals. Infested harborages, located in the course of insecticide application, were used as release sites. The experiment was terminated after 4 1/2 months. The results showed that released ♂ ♂ joined groups near release sites and that they competed well against wild type ♂ ♂. Apparently neither they nor ♀ ♀ ♀ ♀ with which they mated moved far from these sites. Sterility effects differed in respect to specific sites and general areas. Population growth was retarded markedly in the galley, the area of heaviest initial infestation. Terminal infestation was heaviest in the mess deck, although the highest sterility among ♀ ♀ ♀ ♀ occurred at/near the mess-deck release site (only one mess deck-infested site was found prior to initation of the experiment). It is suggested that a slight increase in the number released would have suppressed/eliminated groups inhabiting galley harborages, but that site selection was the major problem in the mess deck. Analyses of nymphal age classes and mating types among ♀ ♀ ♀ ♀ led to a hypothesis that insecticide-induced dispersal of nymphs resulted in the infestation of many new mess-deck harborages. Population growth was unchecked at these sites because they were too far removed from the sterile male release sites. RESUME Le lâcher de males steriles dans des populations naturelles de Blattella germanica Une experience pilote dans la lutte genetique contre Blattella germanica L. a ete realisee sur un petit navire encre a Norfolk, Virginie. La lethalite embryonnaire des mâles steriles utilises (heterozygotes a double translocation) etait associee au piegeage des quelques embryons viables dans les ootheques. Les pullulations initiales avaient ete reduites par des insecticides avant le lâcher des mâles. Des mâles vierges ont ete lâches a trois reprises a un mois d'intervalle. Les abris contamines, localises au cours des traitements insecticides, ont ete utilises comme lieux de lâcher. L'experience s'est achevee au bout de quatre mois et demi. Les resultats montrent que les mâles introduits rejoignent les autres blattes pres des lieux de liberation et qu'ils ne sont pas defavorises dans leur competition avec les autres mâles. Ni eux, ni les femelles avec lesquelles ils se sont accouples, ne s'eloignent apparemment de ces emplacements. Les effets de sterilisation varient en fonction des sites specifiques et des zones plus vastes. La croissance de la population est significativement retardee dans la cuisine, zone ou l'infestation initiale etait la plus elevee. L'infestation finale la plus importante est dans le pont du mess, bien que la sterilite des femelles la plus elevee s'observe a (ou pres) du lieu de liberation au pont du mess (seulement un lieu d'infestation avait ete observe sur le pont du mess avant le debut de l'experience). On pense qu'une legere augmentation de l'effectif libere aurait supprime (ou elimine) les groupes occupant des abris dans la cuisine, mais que la selection des sites etait le principal probleme pour le pont du mess. L'analyse des classes d'âges des larves et des categories de femelles accouplees laisse supposer que la dispersion des larves provoquee par l'insecticide a entraine la contamination de beaucoup de nouveaux abris dans le pont du mess. La croissance de la population n'a pas ete contenue dans ces sites parce qu'ils etaient trop eloignes des lieux de lâcher des mâles steriles.

Newly emerged adult female German cockroaches, Blattella germanica (L.) (Dictyoptera: Blattellidae) fed avermectin B1 at concentrations of 6.5 ppm and higher in the food exhibited high mortality at 10 days. Survivors of these dosages failed to reproduce. Lower dosages produced some mortality and inhibited mating and reproduction. Those individuals that did reproduce had normal-sized oothecae and the percent hatch was normal. The higher concentrations produced a marked inhibition of feeding which appeared to be related to toxicity rather than to unpalatability or repellency. When nymphs were fed avermectin B1 for short periods, higher dosages were required to produce mortality. Young nymphs were the most susceptible. Feeding inhibition also occurred in these short-term studies, but the survivors reproduced normally as did the progeny from the females fed avermectin continuously. The possible use of avermectin B1 in baits for cockroach control is discussed. RESUME Effets de la consommation d'avermectine B1 sur la mortalite et la reproduction de Blattella germanica (Dictyoptera: Blattellidae) Alimentees peu apres la mue imaginale avec une nourriture contenant 6,5 ppm ou plus d'avermectine B1, des femelles de B. germanica L. ont presente une forte mortalite a 10 jours; les survivantes ne se sont pas reproduites. Des doses plus faibles ont provoque quelque mortalite et quelque inhibition des accouplements et de la reproduction; les individus qui se sont reproduits avaient des ootheques de taille normale et le taux d'eclosion etait correct. Les concentrations plus elevees ont provoque une nette inhibition de l'alimentation, qui semblait etre plus due a la toxicite qu'a la repulsion ou au gout. Quand des larves âgees ont ete alimentees avec de l'avermectine B1 pendant de breves periodes, des doses plus elevees etaient necessaires pour provoquer la mortalite. Les jeunes larves etaient les plus sensibles. Une inhibition de l'alimentation apparut dans ces etudes a court terme, mais les survivants se reproduisirent normalement, comme le firent les descendants des femelles alimentees continuellement avec de l'avermectine. La discussion porte sur l'utilisation eventuelle de l'avermectine B1 dans des appâts pour lutter contre les blattes.

1. 1. Thirty one additional cockroach species have been examined with respect to external voiding of uric acid. Eight of them, belonging to the subfamily Plectopterinae, void formed-urate pellets sparingly. 2. 2. Two species of Ischnoptera void urates admixed with feces at the rate of 2% by weight. 3. 3. The leaf mantid voids urates admixed with feces at the rate of about 20% by weight. 4. 4. The ability of adult female Parcoblatta fulvescens to avoid urate pellets can be altered by varying dietary nitrogen levels. 5. 5. The importance of these results to understanding the various nitrogen strategies found among cockroaches is discussed.

Kynurenine formamidase is widely distributed in the tissues of the American cockroach, Periplaneta americana, but is highest in activity in the fat body. Enzyme from this tissue is found in the soluble fraction of the cell, has no sharp pH optimum, and exhibits an apparent K m value of 1.43 × 10 −3 M. Sodium bisulphite is a strong inhibitor of the reaction, and has the characteristics of an uncompetitive inhibitor. Formamidase from pearl and lavender eye color mutant stocks has a tissue distribution pattern and activity characteristics essentially identical to those of wild type. Possible biochemical lesions for these mutant stocks are suggested.

Forty-five field-collected strains of German cockroaches, Blattella germanica were tested for resistance to 12 different insecticides by the time-mortality response method in comparison with a known susceptible strain. Only low to moderate resistance to diazinon, chlorpyrifos, and acephate was detected. Resistance to malathion was widespread; about half of the strains tested showed high resistance. High resistance to the carbamates propoxur and bendiocarb also occurred. High resistance was uncommon with propoxur, but about 35 strains were highly resistant to bendiocarb. High resistance to pyrethrins was observed in about of the strains tested. Resistance to the pyrethroids allethrin, permethrin, phenothrin, fenvalerate, and cyfluthrin was detected in some of the strains examined. All of the strains tested were susceptible to one or more of the insecticides used. These results indicate that, although resistance is a serious problem in this species, satisfactory control should be possible by selection of an appropriate insecticide.

The effects of food and water deprivation on survival and reproduction of adult female German cockroaches were examined. Females, maintained under constant conditions, were deprived of food or water following adult maturation, mating, during the oothecal incubation period, and after first oothecal hatch. It was found that both food and water deprivations caused increased mortality, delays in the reproductive cycle and decreased oothecal hatch. The relative importance of food vs. water deprivation on reproduction is discussed along with possible reproductive strategies for this species. RESUME Action du jeune et de la suppression d'eau sur la reproduction de femelles de Blattella germanica L. Les femelles, maintenues en conditions constantes, ont ete privees d'aliments et d'eau apres la maturite imaginale, l'accouplement, pendant la periode d'incubation et apres l'eclosion de la premiere ootheque. On a observe une mortalite accrue, un retard dans le cycle de reproduction et une diminution des eclosions de l'ootheque. L'importance relative de l'alimentation par rapport au jeune hydrique sur la reproduction est discutee en relation avec les strategies reproductives possibles de cette espece.

NAD-and NADP-linked isocitrate dehydrogenases (ICDH) have been identified in fly and cockroach thoracic muscle mitochondria. The NAD-linked enzymes from both species have been partially purified from mitochondrial acetone powders. The fly enzyme has been studied in detail. This enzyme is very stable and can be stored in 30 per cent saturated ammonium sulphate containing 20 mM phosphate buffer at pH 7.0 for 3 weeks at room temperature without loss of activity. Mg++ and Mn++ stimulate activity optimally at concentrations equivalent to substrate concentration. ADP stimulates activity optimally at 2 mM in conjunction with NAD+ (4mM), isocitrate (6 mM), and Mg++ (6 mM). Other properties of the enzyme are also described, and a discussion is included.

The toxic effects of 8 carbamate insecticides have been compared in susceptible and carbaryl-resistant strains of Blattella germanica (L.). Baygon® ( o -isopropoxyphenyl methylcarbamate) and UC-10854 ( m -isopropylphenyl methylcarbamate) effectively killed cockroaches of both strains with a topical method of application. Dimetilan and Isolan® (l-isopropyl-3-methyl-5-pyrazolyl dimethyl-carbamate) were less toxic, and there was little resistance to these materials in the carbaryl-resistant cockroaches. Susceptible cockroaches were killed effectively by UC-21149 (2-methyl-2-(methylthio)propionaldehyde O -(methylcarbamoyl)oxime) and Matacil® (4-(dimethylamino)-m-lolyl methylcarbamate), but there was evidence of cross resistance to these compounds in the resistant strain. Cross resistance to MC-A-600 (benzo[b]thien-4-yl methyl carbamate) occurred in carbaryl-resistant cockroaches when a topical method of application was used. There was no apparent cross resistance to this material when a dipping technique was employed for testing. Carbaryl was ineffective in killing cockroaches of either strain by the topical method; as expected, significant levels of resistance were demonstrated in the resistant strain with a dipping technique.

Mitochondria isolated from cockroach thoracic muscles have been used to demonstrate that the rate of oxidation of several Krebs-cycle intermediates is under the control of adenosine diphosphate concentration. Respiratory-control indices as high as 25 have been achieved with both pyruvate and glutamate. Contrarily, the rate of oxidation of α-glycerol phosphate is influenced by adenosine diphosphate concentration to only a minor degree, but is markedly inhibited by accumulation of the oxidation product. When the ratio [reactant]/[product] is approx. 3, oxidation of α-glycerol phosphate becomes very low. These findings are used to propose a theory which may satisfactorily explain the problem of respiratory control in insect muscles.

A preliminary survey of mitotic and meiotic cells from 12 cockroach species was made. Cells were obtained from embryonic and testicular tissues and were prepared by the squash technique. Haploid and diploid numbers were either established or confirmed for each species. Diploid numbers ranged from 20 in Supella to 74 in Blaberus , with numbers of 24 and 28 being common to several species. Chromosome size appeared to vary inversely with chromosome number. The XO sex determination mechanism was confirmed, and the X chromosome was identified in at least 2 species. Observations on centromere location and on certain unusual chromosome situations are also presented.

Three distinct inorganic pyrophosphatases with different pH optima have been isolated from thoracic muscle mitochondria of the American cockroach. Purification was achieved by sonication, differential centrifugation, ammonium sulphate fractionation, and column chromatography on Sephadex, DEAE † cellulose, and CM cellulose. Each of the enzymes required magnesium for maximal activation but the optimum magnesium to substrate ratio varied. The Michaelis constants were 1·2×10 −3 , 2×10 −3 , and 1·6×10 −3 M for the acid, neutral, and alkaline pyrophosphatase, respectively. All three of the enzymes split inorganic phosphate from polyphosphate and GTP to some degree. In addition, the enzymes were inhibited by NaF, DNP, NaCN, and to a lesser extent by certain purine and pyrimidine nucleotides. Divalent metal ions also inhibited the reactions presumably by competing with available magnesium ions.