Argentine ants, Linepithema humile (Mayr) (Hymenoptera: Formicidae), are a significant pest in various agricultural systems around the world, and are often associated with outbreaks of phloem‐feeding hemipteran insects. Previous research has evaluated a number of active ingredients and management approaches for controlling Argentine ant populations in agricultural systems, but various regulatory and economic issues have limited the development of effective management tools. Current chemical controls rely on residual sprays or toxic baits, each one posing unique disadvantages that limit their usefulness and efficacy. This study evaluated the potential of water‐storing crystals to effectively deliver liquid baits to Argentine ants. The efficacy of bait crystals containing 0.007% thiamethoxam was first evaluated in laboratory colonies. In addition, field studies were performed in a commercial plum orchard to determine the efficacy of the bait crystals. Protein marking was used within the orchard to examine the distribution of the bait in Argentine ant populations when delivered via water‐storing crystals. Results of laboratory tests showed that water‐storing crystals containing 0.007% thiamethoxam are highly attractive and effective against Argentine ants and require ca. 3–5 days to kill all castes and life stages. Results of the protein‐marking study demonstrated that the percentage of ants carrying protein‐labeled sugar water decreases sharply with increasing distance from the bait station. Bait movement was limited to within 17 m of the bait dispenser. Furthermore, bait efficacy tests in the field showed that Argentine ants can be effectively controlled using liquid thiamethoxam baits deployed via water‐storing crystals. The bait was highly effective and ant densities throughout the baited plots declined by 94 ± 2% within 14 days. The results of this study demonstrate that (1) thiamethoxam is highly effective for Argentine ant control in fruit orchards when used in low concentrations (0.007%), and (2) water‐storing crystals are an effective tool for delivering liquid baits to Argentine ants in agricultural settings.

BackgroundThe Argentine ant, Linepithema humile, is a widespread invasive ant species that has successfully established in nearly all continents across the globe. Argentine ants are characterised by a social structure known as unicoloniality, where territorial boundaries between nests are absent and intraspecific aggression is rare. This is particularly pronounced in introduced populations and results in the formation of large and spatially expansive supercolonies. Although it is amongst the most well studied of invasive ants, very little work has been done on this ant in South Africa. In this first study, we investigate the population structure of Argentine ants in South Africa. We use behavioural (aggression tests) and chemical (CHC) approaches to investigate the population structure of Argentine ants within the Western Cape, identify the number of supercolonies and infer number of introductions.ResultsBoth the aggression assays and chemical data revealed that the Western Cape Argentine ant population can be divided into two behaviourally and chemically distinct supercolonies. Intraspecific aggression was evident between the two supercolonies of Argentine ants with ants able to discriminate among conspecific non-nestmates. This discrimination is linked to the divergence in cuticular hydrocarbon profiles of ants originating from the two supercolonies.ConclusionsThe presence of these two distinct supercolonies is suggestive of at least two independent introductions of this ant within the Western Cape. Moreover, the pattern of colonisation observed in this study, with the two colonies interspersed, is in agreement with global patterns of Argentine ant invasions. Our findings are of interest because recent studies show that Argentine ants from South Africa are different from those identified in other introduced ranges and therefore provide an opportunity to further understand factors that determine the distributional and spread patterns of Argentine ant supercolonies.

Moringa oleifera (moringa) trees excel mainly in tropical and sub-tropical regions and are known to thrive in a wide range of soil types. The recent rise in moringa production in various agro-ecological zones of South Africa could be attributed to its multiple benefits, including nutritional and medicinal properties. Since its introduction as a cultivated crop, there has been a growing interest from farmers, researchers and government on various aspects of the tree such as its morphology, chemistry, growing conditions, production, processing and utilisation. We reviewed the work done on moringa within the South African context in terms of production, growing conditions and cultivation practices. The involvement of government departments on moringa-oriented activities and its consumption as food were also reviewed. In addition, gaps were outlined on its utilisation that need to be addressed, and recommendations provided on what could be done to ensure successful production of moringa in South Africa.

Invasive ants threaten biodiversity, ecosystem services and agricultural systems. This study evaluated a prey‐baiting approach for managing Argentine ants in natural habitat invaded by Argentine ants. Blackmound termites (Amitermes hastatus) were topically exposed to fipronil and presented to Argentine ants (Linepithema humile). In laboratory assays, L. humile colonies were offered fipronil‐treated termites within experimental arenas. The termites were readily consumed, and results demonstrate that a single termite topically treated with 590 ng fipronil is capable of killing at least 500 L. humile workers in 4 days. Field studies were conducted in natural areas invaded by L. humile. Fipronil‐treated termites scattered within experimental plots provided rapid control of L. humile and ant densities throughout the treated plots declined by 98 ± 5% within 21 days. Results demonstrate that the prey‐baiting approach is highly effective against L. humile and may offer an effective alternative to traditional bait treatments. Furthermore, prey‐baiting offers environmental benefits by delivering substantially less toxicant to the environment relative to current control methods which rely on commercial bait formulations and may offer greater target specificity.

Invasive species typically establish in areas outside their natural distribution through accidental introduction and accidental release or escape. Some species are introduced legally for economic and social benefits such as recreational hunting, the pet trade and research through established permitting processes driven by appropriate laws and regulations. The aim of this study was to determine whether there is a trend in demand for regulated alien taxa based on permit requests and to ascertain the activities for which permits requested in order to infer the drivers of alien taxa demand in South Africa. We examined the Department of Environmental Affairs (DEA) species permitting application database records from October 2015 to February 2018. From the total of 1,390 permit applications during this period, 79.2% of the permits were issued for various economic and social activities associated with the following species: Red lechwe (Kobus leche leche, Gray), fallow deer (Dama dama Linnaeus), Grass carp (Ctenopharyngodon idella Valenciennes), Nile tilapia (Oreochromis niloticus Linnaeus) and rose‐ring parakeet (Psittacula krameri Scopoli). Our results suggest that economic activities such as hunting and sport fishing are driving the demand for some regulated species. We suggest reinforced monitoring and inspection for permit compliance for species sought to minimise potential escape.