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.

     

Female teneral mating in a monandrous species

Schultesia nitor is a gregarious species living in Cacicus and Psarocolius ssp. pouch-like nests. Due to gregariousness, opportunities for multiple copulations in both sexes are not supposed to be restricted. Females produce only one brood during their life and die within a few days following the birth of their nymphs, but this unique brood could be the result of either single or multiple mating events (i.e., monandry vs. polyandry). In this study, we first determined the age of sexual receptivity of both males and females. Larval development in this species is shorter in males than in females and thus, this species is protandric. Males were not able to copulate the day after emergence. Contrary to males, teneral females (i.e., females achieving their imaginal molt but not yet fully sclerotised and colored) were attractive and were able to mate with males. In the second experiment, we tested the existence of multiple matings in both sexes. Our results showed that females were monandrous whereas males were polygynous. Since we had observed that females were monoandrous, we expected them to be choosy and we determined their ability to discriminate between virgin and nonvirgin males. When given the choice, females preferred virgin males and overall, they were more successful at mating than experienced ones. Our results suggest that monandry may be primarily driven by the female's short life-span fecundity. The occurrence of teneral mating in this species calls into question the existence of a male strategy for monopolizing females, and as well as the implication of female choice. Although further work is required, this species provides an interesting model for understanding sexual conflicts.     

Catecholamines and related o-diphenols in cockroach hemolymph and cuticle during sclerotization and melanization: comparative studies on the order Dictyoptera

Summary Catecholamines and related o-diphenols extracted from the cuticle and hemolymph of adult cockroaches during sclerotization and pigmentation of the cuticle were analyzed by reverse phase HPLC with electrochemical detection. At ecdysis, dopamine (DA) oconjugates predominated in the hemolymph of Periplaneta americana, P. australasiae, P. fuliginosa, P. brunnea, and Blatta orientalis (Blattidae); Blattella germanica (Blattellidae); and Gromphadorhina portentosa and Blaberus craniifer (Blaberidae). n-Acetyldopamine (NADA) conjugates were second in abundance in these species, but were major in the hemolymph of the other blaberoid species, Leucophaea maderae and Nauphoeta cinerea. After ecdysis NADA became the major hemolymph catecholamine in all species as DA decreased rapidly. n--Alanyldopamine (NBAD) concentrations in the hemolymph remained low in all species, although NBAD and its metabolite, n--alanylnorepinephrine (NBANE), were generally the major catecholamines in tanning cuticle. Catechol (1,2-dihydroxybenzene) occurred mainly as a conjugate(s) at high levels in the hemolymph of nymphs and adults of all blattid species. Only trace amounts were detected in B. germanica and Cryptocercus punctulatus (Cryptocercidae), and none was found in any of the blaberoid species. High concentrations of NBANE and NBAD accumulated in tanning cuticle of B. germanica, G. portentosa, and all blattid species, whereas NADA and DA predominated in cuticle from the other blaberoid species, particularly L. maderae and N. cinerea. However, cockroaches as a group appear to utilize both the n-acetyl and n--alanyl catecholamines for stabilization of the exoskeleton. The Blattidae differed most from the other families in having considerably higher concentrations of catecholamines in hemolymph and cuticle, as well as the large amounts of catechol conjugates in the hemolymph.Abbreviations AMD -methlydopa - DA dopamine - DOBA 3,4-dihydroxybenzoic acid - DOPA 3,4-dihydroxyphenylalanine - DOPAC 3,4-dihydroxyphenylacetic acid - DOPET 3,4-dibydroxyphenylethanol - DOPKET 3,4-dihydroxyphenylketoethanol - HPLC high performance liquid chromatography - NADA n-acetyldopamine - NANE n-acetylnorepinephrine - NBAD n--alanyldopamine - NBANE n--alanylnorepinephrine - NE notepinephrine Contribution No. 90-88-J from the Kansas Agricultural Experiment Station, Kansas State University, Manhattan, KS. Cooperative investigation between the KAES and the ARS, USDA. K.J. Kramer is a research chemist and Adjunct Professor at the U.S. Grain Marketing Research Laboratory and Kansas State University, respectively. Address reprint requests to T.L. Hopkins     

Central projections of campaniform sensilla on the cerci of crickets and cockroaches

Summary Campaniform sensilla associated with filiform hairs comprise an important receptor type of the multimodal sensory system of the cerci of crickets and cockroaches. Their axon projections were investigated using iontophoretic cobalt injection into single sensilla.In crickets (Gryllus bimaculatus, Acheta domestica), six different types of cereal campaniform sensilla projections can be distinguished on the basis of their axonal arborizations and terminations. Typically, a proportion of cereal campaniform sensilla, associated with long filiform hairs, give rise to axons that ascend as through fibres from the terminal ganglion to reach the sixth abdominal ganglion. Cereal campaniform sensilla associated with clavate hairs have projections restricted to the terminal ganglion alone.Whereas in crickets axons of cercal campaniform sensilla invade only certain segmental neuropils in the terminal ganglion, in cockroaches (Periplaneta americana) axons from cercal campaniform sensilla branch in every segmental neuropil. A proportion of cereal campaniform sensilla in this species also gives rise to through fibres to the fifth abdominal ganglion.We discuss morphological and functional interpretations of differences between crickets and cockroaches and consider the significance of this type of receptor in the context of previous studies of the cercal system.     

Social versus individual behaviour: a comparative approach to thermal behaviour of the honeybee (Apis mellifera L.) and the American cockroach (Periplaneta americana L.)

To study the relationship between the individual and social thermoregulatory behaviour, we used honeybee workers and American cockroaches. Single insects or groups of 10-20 individuals were placed in a temperature gradient chamber, and their thermal preference was recorded for 48 h under natural summer photoperiod. Single bees showed diurnal changes in selected ambient temperature, which culminated at 14:00 reaching 34+/-2 degrees C, and then slowly decreased, reaching a nocturnal minimum of 28+/-2 degrees C at 04:00. In contrast, the zenith of temperature selected by groups of bees (31+/-1 degrees C) was reached at 04:00 and the nadir (29+/-2 degrees C) was recorded at 14:00. Groups of bees clustered together during the night time, and dispersed during intense day time activity. Such changes were absent in groups of cockroaches. Cockroaches selected an ambient temperature of 30+/-1 degrees C both during day and night. In conclusion, there is a striking analogy in the diurnal thermal behaviour between a colony of bees and mammals. During their nychthemeral rest phase, both of them select higher temperatures than during the activity phase and, simultaneously, they reduce their overall surface area of heat loss to conserve metabolic heat. Therefore, the colony behaves as a homeothermic superorganism. In contrast, a single bee, isolated from the colony, utilizes a heterothermic strategy to save energy for a morning warm up.     

四种蜚蠊的呼吸信号特征比较

在20℃下,利用CO₂红外分析仪采集了美洲大蠊Periplaneta americana、褐斑大蠊P.brunnea、澳洲大蠊P.australasiae和德国小蠊Blattella germanica的呼吸信号。结果表明,它们均具有典型的不连续气体交换循环（discontinuous gas exchange cycle, DGC）呼吸模式,且一个DGC可分为爆发间期和爆发期2个阶段。4种蜚蠊雄性成虫DGC的特征各异：美洲大蠊完成一个DGC周期平均约需24.55 min,明显长于褐斑大蠊(11.67 min)和澳洲大蠊(10.75 min),德国小蠊周期最短,仅为4.41 min;对于爆发间期历时在整个DGC历时所占的比例,美洲大蠊最大,平均为57％,德国小蠊次之,为48％,褐斑大蠊和澳洲大蠊比较接近,分别为37％和36％。德国小蠊单位体重的CO₂平均释放速率最大,而另外3种蜚蠊的差异不明显。4种蜚蠊爆发期CO₂释放体积均随DGC历时增加而增加,美洲大蠊和德国小蠊单位体重的CO₂平均释放率随DGC历时增加而减少,在褐斑大蠊和澳洲大蠊中它们关系不明显。美洲大蠊、褐斑大蠊和澳洲大蠊CO₂平均释放率和爆发期CO₂释放体积与体重呈正相关,在德国小蠊中关系不明显;4种蜚蠊DGC各阶段历时和DGC频率与它们体重的关系均不明显。     

Susceptibility of cockroaches (Gromphadorhina portentosa,Nauphoeta cinerea and Blaptica dubia) exposed to entomopathogenic nematodes

Cockroaches are major pests, vectors of pathogenic bacteria and induce allergies. Current control methods use chemical pesticides, but they can be ineffective and costly and there are reports of resistance in the field; hence new control methods are needed. There are conflicting reports about the susceptibility of cockroaches to entomopathogenic nematodes (EPNs); so we investigated if EPNs could kill several diverse cockroach species, including the Madagascan hissing roach (Gromphadorhina portentosa), the Lobster roach (Nauphoeta cinerea) and Blaptica dubia. Female adult cockroaches were exposed to either commercial products containing Steinernema kraussei or a combination of Heterorhabditis spp. and Steinernema spp. at 50 and 150 nematodes per cm² for 21 days. We also monitored feeding and the numbers of infective juveniles that were produced from each cockroach corpse. We found that S. kraussei were harmless to all cockroach species (at both doses) but when exposed to a mixture of Heterorhabditis spp. and Steinernema spp. B. dubia died after 6 days and its feeding was strongly inhibited. We also found that the mixture of Heterorhabditis spp. and Steinernema spp. could proliferate in the cadavers of B. dubia whilst S. kraussei could only reproduce in G. portentosa and B. dubia but not N. cinerea. In conclusion, S. kraussei was harmless to all three cockroach species but B. dubia was killed when exposed to Heterorhabditis spp. and Steinernema spp., highlighting the differences in the host range of EPNs.     

五种蜚蠊的生物学特性和综合治理

介绍了分布广泛和危害严重的室内 5种常见蜚蠊 ,德国小蠊、美洲大蠊、黑胸大蠊、澳洲大蠊和褐斑大蠊的生物学特性和行为习性以及德国小蠊为何能成为室内优势种的原因。蜚蠊的综合治理系统包括 :检查和调查、环境治理、非化学防治、杀虫剂防治、昆虫信息化合物和昆虫生长调节剂的防治和其它防治方法。对残留和非残留杀虫剂和剂型的基本概念和应用做了解释 ,并分别介绍了对每种蜚蠊的具体治理措施。     

Are cockroaches reliable bioindicators of persistent organic pollutant contamination of indoor environments?

We measured the concentrations of selected persistent organic pollutants (POPs) such as parent and halogenated polycyclic aromatic hydrocarbons (PAHs and HPAHs) and polybrominated diphenyl ethers (PBDEs) in indoor dust (ID) and indoor cockroach samples collected from Shenzhen, South China. Biota-dust accumulation factors (BDAFs) were computed and utilized to quantify targeted pollutant bioaccumulation in ID and cockroaches. Generally, halogenated compounds have higher BDAFs when compared to non-halogenated compounds. There are significant differences (p < 0.05) between the BDAFs of non-halogenated POPs (PAHs) and halogenated POPs (HPAHs and PBDEs). Correlation analysis of target pollutants’ levels in ID and cockroaches were also conducted. The correlation coefficients for PAHs are less than 0.2 (p > 0.5) suggesting no significant relationship exists for PAHs between ID and cockroaches. In contrast, significant correlations exist for halogenated POPs (HPAH and PBDE) between ID and cockroaches (correlation coefficients >0.94, p < 0.0001). Based on this, the potential of cockroaches to be used as reliable bioindicators of POPs contamination of indoor environments was preliminarily evaluated. Our results indicate that indoor cockroaches may be useful bioindicator of indoor pollution for HPAHs and PBDEs contaminations.     

Evaluation of antimicrobial activity of bacterial symbionts isolated from wild field cockroach Blattella vaga from Saudi Arabia

Drug-resistant pathogens form the main threat to global health during the current century. Annually, a lot of patients die in hospitals due to infection with one or more drug-resistant bacteria especially Staphylococcus aureus (MRSA). In the absence of new effective antimicrobial drugs, the number of deaths said to be increased. Searching for new antibiotics in our backyard form a part of scientist strategies to solve such serious health problem. Insects consider one of such interesting sources of the new era of antimicrobial drugs. Cockroaches as an example can live and adapt in a polluted area for a long time, so through this work field cockroach, Blattella vaga was collected from two semi-wild areas around Riyadh, Saudi Arabia for isolation of gut bacteria searching for new antimicrobial agents. Three species of bacteria were identified from field cockroach gut: Bacillus licheniformis, Bacillus subtilis, and Kocuria rosea. The three species were isolated, purified, and tested for their antimicrobial activity against four drug-resistant pathogens (three bacteria: Salmonella enterica (ATCC25566), Staphylococcus aureus (MRSA) (Clinical strain), and Streptococcus mutans (RCMB 017(1) ATCC ® 25175™) and one fungus: Candida albicans (RCMB005003(1) ATCC® 10231™)). The results show no antimicrobial activity of Bacillus subtilis and very good activity Bacillus licheniformis and Kocuria rosea. Bacillus licheniformis gives very effective activity against Candida albicans while Kocuria rosea is effective against MRSA and Streptococcus mutans. None of the gut isolated bacteria show any activity against Salmonella enterica. Such results revealed that the metabolites of these bacteria could be used as substitutes to the already used antibiotics to overcome the problem of multidrug-resistant human pathogens.