Histological Findings in Captive Madagascar Hissing Cockroaches (Gromphadorhina portentosa) and a Literature Review

Abstract

Madagascar hissing cockroaches (MHC, Gromphadorhina portentosa) are members of the Blaberidae (giant cockroaches) family of the Insecta class. They are native to the African island of Madagascar where they live within leaf litter on the rainforest floor. Due to their large size, relative tameness, and general easy keeping, they have become popular in classrooms, zoological collections, museums, research laboratories, and as private exotic pets; however, descriptions of diseases of MHC in the literature are rare. The objective of this study is to describe and characterize postmortem histological findings in 18 captive MHC from a single zoological collection. In this retrospective study, 18 (4 females and 14 males) adult MHC necropsies were submitted to Northwest ZooPath between 2016 and 2020 for evaluation. The main organs with histological lesions were chitinous gut (foregut and/or hindgut; n = 17), tracheae ( n = 15), fat body ( n = 14), ventriculus (midgut) ( n = 13), body wall ( n = 12), Malpighian tubules ( n = 12), and hemolymphatic sinuses ( n = 12). All animals had inflammatory lesions affecting various organs. Inflammatory lesions typically consisted of aggregates of hemocytes with variable amounts of melanization and/or encapsulation. Bacterial, fungal, and parasitic infections were common and variably associated with hemocytic inflammation. Many of these organisms may represent symbiotic organisms of the MHC that cause opportunistic infections. This study contributes to the current knowledge of pathological findings and disease response of MHC and reviews diseases reported in multiple cockroach species.

Assessing the Welfare of Captive Group-Housed Cockroaches, Gromphadorhina oblongonota

“…G. oblongonota (Figures 1 and 2), also known as the wide-horned hisser, are one of the largest cockroach species in the world, measuring between 5 cm and 10 cm (adult), and are found in southern Madagascar. They are flightless and produce a hissing sound by expelling air through modified spiracles [34][35][36].…”

“…Animals 2023, 13,3351 4 of 20 10 cm (adult), and are found in southern Madagascar. They are flightless and produce a hissing sound by expelling air through modified spiracles [34][35][36]. The group is all-male to prevent overpopulation and is supplemented with males removed from a breeding population used at the zoo for feeding-in.…”

“…'Activity level' simply looked at the percentage of individuals that showed signs of activity during the observation period: 9.30 a.m.-4.30 p.m. We considered activity during the day an indicator of reduced welfare due to the impact on circadian rhythm [42] and the evidence that sleep deprivation in cockroaches and other invertebrates impacts memory formation [43] and can lead to increased metabolic rate, with severe sleep deprivation resulting in death [44]. 'Food intake' was removed, as the amount and type of items fed were too variable to determine accurate changes in the quantity consumed (there was always a large amount remaining when fed again), plus, as food was available 24/7 and G. oblongonota are nocturnal [36,45,46], they were rarely seen feeding. Psychological (Table 2): The psychological parameter measured three factors: abnormal behaviour, response to guest presence and social interaction.…”

“…In addition to the results from this study supporting use of the AWAG for welfare assessments of groups, they will also feed directly into husbandry and enclosure changes for this group of G. oblongonota. These changes will include a larger enclosure, focussing on floor space rather than height as G. oblongonota are primarily terrestrial [36,65,66]. A greater floor area will also allow for gradients in temperature, humidity and light, providing choice and control over how the environment is used [1,39,53].…”