Population ecology and movement of the American cockroach (Dictyoptera: Blattidae) in sewers

Efficacy and toxicity of cockroach gel bait (imidacloprid 2.5% and fipronil 0.05%) against American cockroach infestation in sewer system

Background

The American cockroach, Periplaneta americana, is the most prevalent domiciliary and invasive urban pest in the sewer and waste water system. It poses a substantial threat to human public health and home allergens. This study was conducted at Universiti Sains Malaysia main campus to highlight and provide information on the control and management of American cockroach infestations in sewage systems by comparing the efficiency of fipronil 0.05% gel bait with imidacloprid 2.5% gel bait. A total number of adult and nymph stages of trapped American cockroaches was recorded using glass jar traps at eight sampling sites. Gel baits were placed beneath the lids of each manhole shaft along the inner wall perimeter.

Results

The use of fipronil and imidacloprid gel baits in the sewer system resulted in a significant difference (P = 0.013). Imidacloprid 2.5% gel bait, compared to fipronil 0.05% gel bait, is the most effective treatment technique for reducing American cockroaches' population in sewer systems, with a high reduction percentage mean for both adult (91.17%) and nymph (85.50%) stages.

Conclusion

As a conclusion, imidacloprid gel bait can effectively control cockroaches in sewer systems up to eight weeks.

Potential value and chemical characterization of gut microbiota derived nitrogen containing metabolites in feces from Periplaneta americana (L.) at different growth stages

The American cockroach, Periplaneta americana (L.), is able to highly survive in various complicated environments around the globe, and often considered as a pest. In contrast, billions of P. americana have been massively reared in China and extensively used as a medicinal insect, due to its function for preventing and treating ulceration and heart failure. Considering the possibility that microbiota-derived metabolites could be an effective source to identify promising candidate drugs, we attempted to establish a rapid method for simultaneous determination of gut microbiota metabolites from medicinal insects. In this study, network pharmacology approach and ultra-performance liquid chromatography (UPLC) technique were employed to reveal the potential pharmacological activity and dynamics variation of nitrogen-containing metabolites (NCMs) originated from the gut microbiota of breeding P. americana at different growth stages. A metabolites-targets-diseases network showed that NCMs are likely to treat diseases such as ulceration and cancer. The analysis of NCMs' content with the growth pattern of P. americana indicated that the content of NCMs declined with P. americana aging. Both principal component analysis and orthogonal partial least squares discriminant analysis suggested that 8-hydroxy-2-quinolinecarboxylic acid and 8-hydroxy-3,4-dihydro-2(1H)-quinolinone are the potential differential metabolic markers for discriminating between nymphs and adults of P. americana. Moreover, the developed UPLC method showed an excellent linearity (R² > 0.999), repeatability (RSD < 2.6%), intra- and inter-day precisions (RSD < 2.2%), and recovery (95.5%–99.0%). Collectively, the study provides a valuable strategy for analyzing gut microbiota metabolites from insects and demonstrates the prospects for discovering novel drug candidates from the feces of P. americana.

Control of Cockroaches (Blattaria) in Sewers: A Practical Approach Systematic Review

Periplaneta americana (L.) (Blattaria: Blattidae), the American cockroach, is the most important invasive urban pest of sewer environments colonizing there with high significance of human public health and household allergens need to be controlled. Therefore this practical approach systematic review perform internationally to highlight and provide a detailed P. americana control in sewers. Of the 474 papers, 129 papers were selected to become this practical approach systematic review study of cockroach control in sewers. To control the American cockroaches, many studies have been conducted in various fields describing from an angle. The results were classified and discussed in getting cockroaches from sewers into buildings and their elimination, insecticide susceptibility, application of dust, bait and Inesfly paint insecticide formulations, biocontrol, and futuristic action categories. A recommending manner to achieve a successful P. americana cockroach control in sewers is using a combination of Integrated Pest Management (IPM) strategies resulted in significant reductions of cockroach infestations and asthma health outcomes. Use of P. americana breeding thelytoky, push-pull strategies and an automated sewer robot, and integrating health into the future buildings may be new approaches of P. americana control strategies.

Cockroach Oothecal Parasitoid, Evania appendigaster (Hymenoptera: Evaniidae) Exhibits Oviposition Preference Towards Oothecal Age Most Vulnerable to Host Cannibalism

Many female parasitoid wasps optimize host selection to balance the benefits of high-quality hosts and the costs of predator- or hyperparasitoid-induced mortality risks to maximize their fitness. Cannibalism exists in many insect species and affects survival of parasitoid larvae developing in or on parasitized hosts. However, little is known about how parasitoid wasps resolve the fitness consequence of host cannibalism-induced mortality risk during host selection. We examined the effect of oothecal age on cannibalism in the American cockroach Periplaneta americana (L.) (Dictyoptera: Blattidae) and its effect on host age selection and fitness of its oothecal parasitoid Evania appendigaster (L.) (Hymenoptera: Evaniidae). P. americana differentially cannibalized 1-d-old (30‒60%) versus 10- to 40-d-old oothecae (<9%). However, parasitoid females did not avoid but still preferred to parasitize 1-d-old (45%) over 10- to 40-d-old oothecae (1.6‒20%). The parasitism rate was greater and the handling time was shorter on 1-d-old compared to older oothecae. For parasitoid progeny emerging from different-aged oothecae, regression analysis showed that development time increased and body size (measured as hind tibia length) and longevity decreased with oothecal age. These results demonstrate that reduced parasitoid progeny survival due to host cannibalism did not change the parasitoid's oviposition preference for newly laid oothecae, and that E. appendigaster females traded progeny survival for fitness gains for themselves and their progeny.

Influences of Temperature and Ootheca Age on the Life History of the Cockroach Ootheca Parasitoid Aprostocetus hagenowii (Hymenoptera: Eulophidae)

The influences of ootheca age and temperature on the life history of Aprostocetus hagenowii (Ratzeburg) (Hymenoptera: Eulophidae), a gregarious ootheca parasitoid of the American cockroach Periplaneta americana (L.) (Dictyoptera: Blattidae), were evaluated. Oothecae were incubated at 20, 25, and 30 °C to produce oothecae aged 1-60, 1-40, and 1-30 d old, respectively. Fitness traits (development time, percentage emergence, number of progeny, percentage female progeny, and female body size) of A. hagenowii developing in these different-aged oothecae were determined. For oothecae incubated at 20, 25, and 30 °C, parasitoids successfully developed in oothecae aged up to 50, 30, and 20 d old, which represent 72.9%, 65.9%, and 61.9% of the total embryonic development time of P. americana, respectively, without any changes in their fitness traits. When A. hagenowii from oothecae kept at constant temperatures (20, 25, 30, 32, and 35 °C) were compared, the immature development time (71.0-34.0 d) and adult life span decreased with increasing temperature. No parasitoid emerged at 35 °C. The lower, upper, and optimal temperature-dependent developmental thresholds were 9.5, 34.2, and 31.1 °C, respectively. Thermal constant for total immature development was 666.7 degree-days. Temperature did not affect lifetime realized fecundity and number of oothecae parasitized by females but did influence parasitism activities over time. Sugar-fed females sustained longer periods of high parasitism rates (≥70%) at 20-30 °C (15-30 d) than at 32-35 °C (1-5 d). These results are useful for determining the ootheca age and temperature range optimal for parasitoid rearing and for estimating the effectiveness of biological control by the wasps.

The Core Gut Microbiome of the American Cockroach, Periplaneta americana, Is Stable and Resilient to Dietary Shifts

The omnivorous cockroach Periplaneta americana hosts a diverse hindgut microbiota encompassing hundreds of microbial species. In this study, we used 16S rRNA gene sequencing to examine the effect of diet on the composition of the P. americana hindgut microbial community. Results show that the hindgut microbiota of P. americana exhibit a highly stable core microbial community with low variance in compositions between individuals and minimal community change in response to dietary shifts. This core hindgut microbiome is shared between laboratory-hosted and wild-caught individuals, although wild-caught specimens exhibited a higher diversity of low-abundance microbes that were lost following extended cultivation under laboratory conditions. This taxonomic stability strongly contrasts with observations of the gut microbiota of mammals, which have been shown to be highly responsive to dietary change. A comparison of P. americana hindgut samples with human fecal samples indicated that the cockroach hindgut community exhibited higher alpha diversity but a substantially lower beta diversity than the human gut microbiome. This suggests that cockroaches have evolved unique mechanisms for establishing and maintaining a diverse and stable core microbiome.

IMPORTANCE

The gut microbiome plays an important role in the overall health of its host. A healthy gut microbiota typically assists with defense against pathogens and the digestion and absorption of nutrients from food, while dysbiosis of the gut microbiota has been associated with reduced health. In this study, we examined the composition and stability of the gut microbiota from the omnivorous cockroach Periplaneta americana. We found that P. americana hosts a diverse core gut microbiome that remains stable after drastic long-term changes in diet. While other insects, notably ant and bee species, have evolved mechanisms for maintaining a stable association with specific gut microbiota, these insects typically host low-diversity gut microbiomes and consume specialized diets. In contrast, P. americana hosts a gut microbiota that is highly species rich and consumes a diverse solid diet, suggesting that cockroaches have evolved unique mechanisms for developing and maintaining a stable gut microbiota.

Water balance profiles, humidity preference and survival of two sympatric cockroach egg parasitoids Evania appendigaster and Aprostocetus hagenowii (Hymenoptera: Evaniidae; Eulophidae)

The impact of desiccation on habitat selection, foraging and survival has been characterized for many insects. However, limited information is available for parasitic wasps. In this study, water balance, relative humidity (RH) preference, and effect of humidity on survival of solitary Evania appendigaster (L.) (Hymenoptera: Evaniidae) and gregarious Aprostocetus hagenowii (Ratzeburg) (Hymenoptera: Eulophidae) were examined. These species are both oothecal parasitoids of the American cockroach Periplaneta americana (L.) (Dictyoptera: Blattidae). E. appendigaster had significantly higher cuticular permeability (CP) and a lower surface area to volume ratio but a similar percentage of total body water content compared to A. hagenowii. No differences in these attributes were found between sexes of each parasitoid species. The percentage of total body water loss rates among E. appendigaster males and females and A. hagenowii females were similar but significantly lower than that of A. hagenowii males. All parasitoids except E. appendigaster males exhibited reduced survival times as the RH of their enclosure decreased from 87% to 38%, but this phenomenon did not occur when parasitoids were given a sugar solution. In environmental chambers with a 44-87% RH gradient, both sexes of E. appendigaster resided significantly more often in the 87% RH chamber than in the 44% RH chamber. For A. hagenowii, females preferred both the driest and the wettest chambers and males preferred the driest ones. These results demonstrate the water balance profile and its relationship to life history traits and differential responses to RH in these competing parasitoid wasps, suggesting the role of physiological and behavioral adaptations in shaping their ecological niche.