Invasive alien species have environmental, economic and social impacts, disproportionally threatening livelihood and food security of smallholder farmers in low- and medium-income countries. Fall armyworm (FAW) (Spodoptera frugiperda), an invasive insect pest from the Americas, causes considerable losses on maize to smallholder farmers in Africa since 2016. The increased use of pesticides to control FAW in Africa raises concerns for health and environmental risks resulting in a growing interest in research on biological control options for smallholder farmers. In order to evaluate the occurrence of local natural enemies attacking FAW, we collected on a weekly basis FAW eggs and larvae during a maize crop cycle in the rainy season of 2018–2019 at four locations in the Lusaka and Central provinces in Zambia. A total of 4373 larvae and 162 egg masses were collected. For each location and date of collection, crop stage, the number of plants checked and amount of damage were recorded to analyse which factors best explain the occurrence of the natural enemy species on maize. Overall parasitism rates from local natural enemies at each location varied between 8.45% and 33.11%. We identified 12 different egg-larval, larval and larval-pupal parasitoid species. Location, maize growth stage, pest density and larval stage significantly affected parasitoid species occurrence. Our findings indicate that there is potential for increasing local populations of natural enemies of FAW through conservation biological control programmes and develop safe and practical control methods for smallholder farmers.

International audienceIn parasitoids, the size of the adult is influenced by the size and quality of the host in which it develops. Body size is generally positively correlated with several adult fitness proxies (fecundity, longevity, and mating capacity). The initial resources available to an individual can influence gamete production (sperm and oocytes), and the number and quality of gametes produced directly influence the expected fitness of both males and females. Gamete production in relation to adult body size was quantified in Trichogramma euproctidis (Girault) (Hymenoptera: Trichogrammatidae), a short-lived egg parasitoid of lepidopteran species. To avoid host quality variation, male and female parasitoids of different body sizes were produced using superparasitism by allowing mated and virgin female parasitoids to oviposit on Trichoplusia ni Hu¨bner (Lepidoptera: Noctuidae) eggs. Seminal vesicles and ovaries of their offspring were dissected to count oocytes and to measure sperm length and oocytes volume. Tibia length was also measured to estimate body size. The number of oocytes, volume of oocytes, maternal investment index [= (number of oocytes * mean volume of oocytes) ⁄ 10 000] and sperm length were all significantly positively correlated to body size. These results show that initial resources acquired during larval stage induce phenotypic plasticity in gamete production in both male and female T. euproctidis. Whereas number of sperm and oocytes can influence the fitness of males and females through increased mating capacity and fecundity, variation in gamete size (sperm length and oocyte volume) could also affect the fitness of an individual through sperm and larval competition

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This manual aims to make information resources and technical advice available in order to support the deployment of biopesticides, which include microbials (e.g. bacteria, algae, protozoa, viruses and fungi), macrobials (e.g. predatory insects, parasitoids and beneficial nematodes), botanicals, and semiochemicals. It is intended to be a one-stop shop to address the information needs of the key groups who are responsible for selecting, sourcing and using biopesticides in the tobacco production system. These groups represent the target audiences, all of whom have challenges they must address and varying information needs (i.e. selecting biopesticides, sourcing biopesticides and training for field technicians and farmers on how to use biopesticides).

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