The management of the cutworm, Agrotis segetum (Denis & Schiffermüller) (Lepidoptera: Noctuidae), is challenging since the larvae spend most of their life cycle hiding underneath weeds or in the soil. Crop producers often report poor efficacy of chemical control, necessitating the development of alternative control strategies. Although many species of parasitoids and entomopathogenic nematodes (EPNs), have been reported from around the world where this pest occurs, no comprehensive list of these species exists, and little is known about their occurrence and impact as biological control agents in South Africa. A literature search yielded 75 parasitoid species, and six EPN species that parasitise A. segetum eggs and larvae. To assess the levels of parasitism in South Africa, cutworm populations were sampled from 14 different geographical regions, reared in a laboratory and monitored for parasitism and other mortality factors. The overall parasitism level recorded in this study was high (43.6%), with Macrocentrus collaris (Spinola) (Hymenoptera: Braconidae) being the most common (39.2%) parasitoid species, followed by Gonia bimaculata Wiedemann (Diptera: Tachinidae) (3.2%) and Periscepsia carbonaria (Panzer) (Diptera: Tachinidae) (1.2%). Entomopathogenic viruses were responsible for 26.1% of larval mortalities, while EPNs (Mermithidae) and entomopathogenic fungi caused 15.7% and 3.2% of mortalities, respectively. The incidence of parasitism, particularly by M. collaris, suggest that parasitoids could play a role in the suppression of A. segetum populations.

Limited adoption of integrated pest management approaches including biological control is associated with lack of knowledge, experience and technical support. One of the main reasons for lack of success of biological control of arthropod pests is cited as the poor involvement of farming communities and extension in dissemination of information. This study considers changes in farmers’ knowledge, attitudes and practices towards biological control of the invasive pest papaya mealybug (Paracoccus marginatus) following initial releases of the parasitic wasp, Acerophagus papayae in the coastal counties of Kilifi, Kwale, and Mombasa in Kenya. Interviews were conducted with farmers across two years: (i) in 2021, prior to release of A. papayae, and (ii) in 2022, following initial releases of A. papayae. A comparison is made between 141 farmer responses across survey years complemented by information from three focus group discussions. Results highlight a 12% increase in awareness of biological control across survey years and a positive change in perception of biological control attributes such as effectiveness and improved crop productivity. Men were more likely to perceive biocontrol as effective, safe and affordable than women. Using a Difference-in-Difference analysis, on average treatment farms achieved approximately 196 kg greater harvest than the control farms and the control farms lost a greater amount of income (94 USD) than the treatment farms across the survey years. The findings from this study highlight the need for continued awareness-raising and gender responsive farmer education on the use and benefits of biological control, and how to reduce the use of chemical pesticide.

Chnootriba hirta (Thunberg) feeds on the foliage of several native Solanum species in South Africa, with occasional associations with introduced congeners. In comparing the beetle’s performance and preferences across three exotic and one native Solanum species, this study produced an unusual result. During adult and larval no-choice tests, the exotic Solanum americanum Miller proved the most suitable host plant, followed by the native S. dasyphyllum Schumacher and Thonning, with the exotic cultivated S. lycopersicum Linnaeus (tomato) proving marginally suitable. In contrast, the exotic S. viarum Dunal, an invasive weed in the southern USA, did not support feeding and development. During adult choice tests, C. hirta did not discriminate between S. americanum and S. dasyphyllum, but avoided S. lycopersicum. These differences in host-plant suitability may relate, in part, to the presence of glandular leaf trichomes, renowned anti-herbivore defences, on S. viarum and S. lycopersicum, but not on S. americanum or S. dasyphyllum. Since C. hirta, a broadly oligophagous herbivore within the native Solanum insect community, cannot exploit S. viarum, the plant may well expand its range in South Africa due to an escape from insect herbivory.

In this study we assessed how an invasive tree (Acacia mearnsii) and an ecologically equivalent native species (Virgilia divaricata) interact with their insect pests and fungal pathogens in sympatric populations along forest edges in the Cape Floristic region of South Africa. We determined how insect herbivore abundance and fungal disease development differ between the two species across a moisture gradient and whether observed differences can be explained by moisture availability and/or plant nutrient levels. The two host plants had similar foliar nutrient content, but measurements of δ12C / δ13C isotope ratios in leaves indicated that only the native plant experienced drought stress at drier sites. The degree of disease development after tree wounding was similar for both species and was not correlated with soil moisture content in either species. As predicted by the biotic release hypothesis, herbivore numbers were significantly higher on the native plant. Herbivore numbers on A. mearnsii were unaffected by moisture availability, but herbivore numbers on V. divaricata increased at drier sites. Consequently, under conditions of increased drought, V. divaricata may experience higher levels of drought stress than the invasive A. mearnsii and may suffer from increased insect herbivory, rendering it a weaker competitor. Herbivore abundance and disease development were significantly influenced by plant nutrient content for A. mearnsii, but not for V. divaricata. Relatively nutrient-poor A. mearnsii trees experienced higher herbivore loads but slower disease development than nutrient-rich trees. Therefore, the susceptibility of A. mearnsii seems to be determined by plant nutrient levels, a factor that varies independently from water availability.

Mosquitoes substantially impact human and animal health as vectors of disease and consequently take a heavy toll on the economy. In order to effectively investigate the evolutionary history of vectors of disease and understand their associated biological tendencies, it is vital to correctly identify and classify the relevant species. Since phylogenetic studies on South African species are currently markedly underrepresented in the literature, the current study aimed to investigate the placement of South African Anopheles Meigen mosquito species within the genus’ extensive taxonomic framework based on the cytochrome oxidase subunit 1 (COI), internal transcribed spacer 2 (ITS2) and 28S ribosomal DNA sequences. Maximum likelihood and Bayesian phylogenetic analyses were performed for each of the COI, ITS2 and 28S DNA datasets, as well as a concatenated analysis for all three DNA regions combined. Upon examination, several phylogenetic findings were corroborated by analyses based on multiple DNA regions. These findings supported the non-monophyly of several taxa relevant to the region (subgenus Anopheles, Laticorn Section, and the Funestus Group) and may indicate the non-monophyly of several South African species [An. coustani Laveran, An. tenebrosus Dönitz, An. parensis Gillies, An. funestus Giles and An. longipalpis C (Theobald) (Type C) (Koekemoer et al. 2009)]. The results reveal numerous challenges within the current systematic framework of the genus Anopheles and provide a novel focus on the phylogeny of South African taxa.

Udzungwana bispinosa, gen. et sp. n. is described from Tanzania and placed in a new corthyline subtribe Udzungwanina, subtribus n. Although this new subtribe lacks a single diagnostic character, the combination of characters makes it unique both within Corthylini and among other tribes. The new taxon is associated with dead hanging lianas in a tropical rain forest.

Exotic crop production negatively affects native biodiversity and alters ecosystem functions and services. Cultivation of indigenous crops can mediate some biodiversity impacts, as these are often less intensively managed than exotic crops and they provide familiar niches for native organisms. Protea (Proteaceae), a floricultural crop with high economic value and ecological significance, is harvested within both natural and cultivated systems in South Africa. A multitude of organisms are intimately involved in Protea ecology, but many are also pests and pose significant phytosanitary risks. Here we evaluated the impact of Protea cultivation on the diversity of mites associated with inflorescences, infructescences, and the rhizosphere in the Greater Cape Floristic Region biodiversity hotspot of South Africa. Natural sites harboured higher mite diversity than cultivated sites, although this was only significant for those mites associated with the rhizosphere or when Protea crops were intensively managed. Mite community assemblage composition differed between different management types, localities, and niches. Management actions had little effect on mite assemblage composition in inflorescences and infructescences, likely due to continuous long-distance colonisation from natural areas via pollinators. In contrast, mite assemblages associated with the rhizosphere were highly impacted in all cultivated sites. These results indicate that indigenous crops can sustain substantial above-ground native mite biodiversity, but ecologically important soil assemblages may be severely impacted. Current field-based management strategies are not effective in controlling mite assemblages within Protea inflorescences, posing significant phytosanitary risks.

In the Eastern Cape, natural landscapes that are adjacent to rivers and the sea are threatened by illegal sand mining, which occurs without prior assessment of biodiversity. Sand mining activities lead to the reduction of vegetation cover and plant species richness. Generally, species richness of arthropods correlates positively with plant species richness. Thus, it is important to test the effect of sand mining on arthropod diversity. In this study we compared species richness, abundance, Shannon-Wiener diversity and composition of ants, beetles and spiders between sand-mined areas and the surrounding grassland. Arthropods were collected using pitfall traps in eight plots in the sand-mined area and eight plots in the surrounding grassland. The sand-mined area and the grassland supported similar species richness and abundance of arthropods. However, significantly greater diversity was in the surrounding grassland than the sand-mined area. Furthermore, species composition of arthropods between the two areas was significantly different. Additionally, there were 13 morphospecies that were indicators of the sand-mined area, and ten morphospecies that were indicators of the surrounding grassland, while there were no shared indicator species between the two study areas. As such, disturbance-tolerant species that prefer open habitats may have replaced specialist arthropods. Given that our study showed that illegal sand mining changes species composition and reduce the diversity of arthropods, sand mining should be restricted to designated areas to reduce the impact of mining on arthropods and improve conservation.

Temperature and relative humidity are key factors affecting the physiological and behavioural responses of natural enemies, including Trichogramma parasitoids frequently employed as biological control agents. Here, the effect of three temperatures (25, 30 and 35 °C) and relative humidity levels (10, 75 and 100%) on the fitness of two Trichogramma cacoeciae (Marchal) strains (Tunisian/Italian) were evaluated. Results indicated that temperature and relative humidity influenced all life-history parameters of parasitoids. Parasitism of the G0 generation by the Tunisian strain was higher compared to that of the Italian strain at 30 °C (10% RH) (22.33 ± 5.94 and 16.46 ± 6.45, respectively, for the Tunisian and Italian strain) and 35 °C (75% RH) (16.26 ± 5.11 and 11.33 ± 5.81, respectively, for the Tunisian and Italian strain). Furthermore, the parasitism rate is better in the G1 compared to the G0 generation only for the Italian strain at 25–30 °C and at 10, 75 and 100% RH. Emergence was significantly decreased for both strains at 35 °C regardless of the relative humidity level. For the G1 generation, no parasitism and emergence were shown by the Italian strain at 35 °C for all tested relative humidities. Our data indicate the Tunisian strain is adapted to higher temperatures. The implications of these results to improve the biological control of lepidopteran pests are discussed.

Heterorhabditis bacteriophora is an entomopathogenic nematode (EPN), and together with its mutualistic bacteria, is a highly effective insect biocontrol agent. The preferred method for large-scale production involves in vitro liquid culture, whereby the nematode and bacteria are cultivated in an artificial medium that replicates the haemocoel conditions found within the insect host. Although the mass-culturing method for H. bacteriophora has proven successful in other countries, it has still to be implemented as a local commercial product in South Africa, despite its considerable potential for pest control. Several factors impact on the success of an in vitro liquid culture, including the bacterial inoculum density and the ingredients used in the culture media. Thus, this study aimed to develop an in vitro liquid culture protocol for a local isolate of H. bacteriophora. Switching from soy powder to egg yolk powder significantly increased the yield of infective juveniles (IJ) during culture, despite there being no differences in IJ recovery between days 2 to 4 after nematode inoculum. Furthermore, the bacterial inoculum density exerts a significant influence on recovery and yield, with the use of a 2% (v/v) inoculum concentration showing the most favourable results. Bacterial cell density is crucial for IJ recovery, as it provides the food signal that activates the IJ. The success obtained with this liquid culture technique for H. bacteriophora paves the way for the optimisation of various additional liquid culture parameters, including nutrients levels, oxygen concentrations and cost-effective ingredients.