It has been suggested that the discontinuous ventilation cycle (DVC) observed in many insects, including all ants described to date, is an adaptation to reduce respiratory water loss. To test this hypothesis, it is necessary to measure respiratory water loss as a percentage of total water loss and to estimate what sustained rates of water loss would be in the absence of spiracular control. We used two independent techniques to measure real-time water loss rates in female alates of Pogonomyrmex rugosus. The first measured water vapor emission and CO2 production simultaneously using dual-wavelength infrared absorbance analysis (DWIRAA). The second measured water loss gravimetrically. Real-time measurement allowed the separation of cuticular water loss rates (interburst) from water loss rates during the ventilation phase (burst) of the DVC. Cuticular permeability of P. rugosus female alates was only 27ng h−1 cm−2 Pa−1, one-third of that reported for workers of the same species and the lowest yet reported for ants. Partly because of this low cuticular permeability, respiratory water loss represented a greater percentage of overall water loss (13%) than has generally been reported for other insects. The DWIRAA and gravimetric techniques gave equivalent results. Peak rates of water loss during the burst phase were 2.8-fold higher than cuticular water loss rates alone (7.68mg g−1 h−1versus 2.77mg g−1 h−1 at 25°C). This is a conservative estimate of water loss rates in the absence of spiracular control. Contrary to findings in certain other insects that suggest a negligible role for respiratory water loss, we find that, in an insect that employs the DVC and has low cuticular permeability, overall water loss rates rise several-fold in the absence of direct spiracular control. Our findings lend strong support to the water conservation hypothesis for the role of the DVC. In at least some insects, respiratory water loss rates can reach magnitudes significant enough, relative to other routes of water loss, for strong selective pressure to act on them.

Understanding the contribution of outdoor-resting Anopheles mosquitoes to residual malaria transmission is important in terms of scaling up vector control towards malaria elimination in South Africa. The aim of this project was to assess the potential role of Anopheles parensis and other Anopheles species in residual malaria transmission, using sentinel surveillance sites in the uMkhanyakude District of northern KwaZulu-Natal Province. Monthly vector surveillance was conducted at the sentinel sites from January 2017 to May 2018. Outdoor-placed clay pot resting traps were used to collect male and female adult Anopheles mosquitoes. All Anopheles gambiae complex and Anopheles funestus group specimens collected were identified to species and all females were screened for Plasmodium falciparum circumsporozoite protein (CSP) by enzyme-linked immunosorbent assay (ELISA). Samples showing infectivity for P. falciparum were further verified by a nested PCR and subsequent DNA sequence analysis. From a sample of 491 anophelines, Anopheles arabiensis (n = 228) and An. parensis (n = 194) were the most abundant. Other species collected included Anopheles merus (n =11), Anopheles quadriannulatus (n = 10), Anopheles leesoni (n = 29), Anopheles rivulorum (n =18), and Anopheles vaneedeni (n =1). Of the 317 female specimens screened for P. falciparum CSP, one Anopheles arabiensis and one An. parensis showed positive by ELISA and Plasmodium nested PCR. For the An. parensis specimen, confirmation of its species identity was based on sequence analysis of the ITS2 region, and the presence of P. falciparum DNA was further confirmed by sequence analysis. Anopheles parensis is a potential vector of malaria in South Africa although its contribution to transmission is likely to be minimal at best owing to its strong zoophilic tendency. By contrast, An. arabiensis is a major vector that is primarily responsible for the bulk of residual malaria transmission in South Africa. As all recently collected sporozoite-positive Anopheles mosquitoes were found in outdoor-placed resting traps, it is necessary to introduce interventions that can be used to control outdoor-resting vector populations while maintaining the efficacy of South Africa’s indoor house spraying operations.

Termites are a good food source, being rich in proteins, fats, vitamins and many essential mineral nutrients, and thus provide food security for poor households. We report on a survey conducted in the Vhembe District Municipality of Limpopo Province, South Africa, to identify edible termite species and find out how they are harvested, prepared, graded, packaged and marketed. We also looked at the socio-economic factors of the harvesters, marketers and consumers. Using a structured questionnaire, 104 individuals were interviewed from 48 villages. Most of the harvesters were over the age of 60 years but termites are consumed by the whole family. The results of the survey revealed that only three termite species are consumed: soldiers of Macrotermes falciger (89.90%), M. natalensis (8.08%) and M. michaelseni (2.02%). The preferred method of preparation was frying (77.55% of the respondents). At least 80.77% of the respondents indicated that some religions have restrictions on termite consumption but no ethnic restrictions were reported. The income derived from selling termites was estimated to range from ZAR2040 to ZAR17 680 per annum between April 2015 and April 2016. The results of this study showed that edible termites contribute significantly to the livelihoods of many rural families and this indigenous knowledge should be passed on to younger generations. Research on the sustainability of termite harvesting is recommended. Significance: Termites are sources of food with high economic and social importance, and are easily accessible by the poor. Studies have been conducted on edible termites in many African countries, yet comparatively little is known about edible termites in South Africa. Preservation of indigenous knowledge used during harvesting and processing needs to be prioritised.

SUMMARY: The sealed subelytral cavity of many flightless beetle species is widely acknowledged to be an adaptation to water saving in arid-habitat species. However, this hypothesis relies on the acceptance of two largely untested assumptions: (i) that the movement of respiratory gases is unidirectional from anterior to posterior and (ii) that the coordinated action of the spiracles directs this flow. We tested these assumptions by simultaneously measuring CO2 and O2 exchange at the anterior mesothorax,independently of gas exchange in the posterior body, which included the subelytral cavity, of a large apterous beetle, Circellium bacchus. Flow-through respirometry revealed a marked discontinuous gas-exchange cycle(DGC) pattern from the anterior half of the body. Very little CO2was released from the posterior body, where the DGC was not apparent. Labelled air was shown to flow forwards from the posterior to the anterior body. Individual sampling from the mesothoracic spiracles revealed that the right mesothoracic spiracle, lying outside the elytral cavity, is the primary route for respiratory gas exchange in C. bacchus at rest. This discovery necessitates a reassessment of the currently assumed role of the subelytral cavity in water conservation and is, to our knowledge, the first demonstration of forward airflow associated with the unilateral use of a single thoracic spiracle for respiration in an insect.