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Alien invasive insect and mite species (AIS) represent a major challenge for agriculture, food production, and biodiversity in Africa. However, the lack of awareness and appreciation of AIS threats continues to hinder the development of appropriate policies and practices for their management in sub-Saharan Africa. The objectives of this review are to (1) provide a synthesis of current and future threats to food production and the economic impacts of AIS, (2) identify challenges to their management at national and regional levels, and (3) propose a strategy for a concerted pan-African response. The review identifies a total of 16 alien invasive insect and mite pests, affecting all categories of food crops, causing combined losses in excess of US$ 1 billion annually across Africa. Various models predict that AIS threats will continue to increase due to expansion of the geographic distribution and host range of existing invasions, thus threatening the already tenuous food situation on the continent. The review also reveals that only 16.7% of the countries have adequate border control procedures, while over 66.7% do not have comprehensive AIS management strategies. Therefore, we propose development of a pan-African strategy for effectively responding to AIS threats, and achieving the continental visions of free trade and collective food security. We recommend that biosecurity be considered as a food security intervention complementing yield improvement technologies, and implemented as a core element of national and regional strategies.

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A 3-year study was undertaken on and around a prominent South African mesa to determine its role for grasshoppers in a sea of grazed flatlands. The number of grasshopper species and individuals on the summit, slopes and flatlands varied significantly in relation to measured environmental variables. The summit, through inaccessibility to livestock grazing, was effectively a conservation refugium for one highly responsive grasshopper species, Orthochtha dasycnemis. There was no significant difference in species richness between years of sampling, although there were significant variations in grasshopper abundance between years. The difference in rainfall between years was significant and appeared to be the key factor influencing grasshopper population dynamics. This study clearly shows that a mesa can act as a conservation island and refugium supporting an insect assemblage that would be otherwise altered by heavy livestock grazing on the surrounding flatlands. This summit assemblage was strongly linked with those on the slopes, and is determined by low grazing intensity and associated soil and vegetation structure.

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