The fall armyworm (FAW), Spodoptera frugiperda (Lepidoptera: Noctuidae) is a recent invasive pest species that has successfully established across sub-Saharan Africa where it continues to disrupt agriculture, particularly smallholder cereal production. Management of FAW in its native range in the Americas has led to the development of resistance to many commercial pesticides before its arrival in Africa. Pesticide use may therefore be ineffective for FAW control in Africa, so new and more sustainable approaches to pest management are required that can help reduce the impact of this exotic pest. Pesticidal plants provide an effective and established approach to pest management in African smallholder farming and recent research has shown that their use can be cost-beneficial and sustainable. In order to optimize the use of botanical extracts for FAW control, we initially screened ten commonly used plant species. In laboratory trials, contact toxicity and feeding bioassays showed differential effects. Some plant species had little to no effect when compared to untreated controls; thus, only the five most promising plant species were selected for more detailed study. In contact toxicity tests, the highest larval mortality was obtained from Nicotiana tabacum (66%) and Lippia javanica (66%). Similarly, in a feeding bioassay L. javanica (62%) and N. tabacum (60%) exhibited high larval mortality at the highest concentration evaluated (10% w/v). Feeding deterrence was evaluated using glass-fibre discs treated with plant extracts, which showed that Cymbopogon citratus (36%) and Azadirachta indica (20%) were the most potent feeding deterrents among the pesticidal plants evaluated. In a screenhouse experiment where living maize plants infested with fall armyworm larvae were treated with plant extracts, N. tabacum and L. javanica were the most potent species at reducing foliar damage compared to the untreated control whilst the synthetic pesticide chlorpyrifos was the most effective in reducing fall armyworm foliar damage. Further field trial evaluation is recommended, particularly involving smallholder maize fields to assess effectiveness across a range of contexts.

Hermetic storage methods are effective at protecting grain against insect pests. Biotic and abiotic factors influence oxygen depletion during hermetic storage. We investigated the dual effects of temperature and initial pest infestation level on oxygen depletion during airtight storage. Glass jars filled with cowpea grain were infested (25 or 50 adult cowpea bruchids), then hermetically sealed and stored at 20, 30, or 40 °C for 30 days. Oxygen depletion, relative humidity, and temperature were monitored. Germination, grain moisture content, grain damage and weight loss, and adult emergence were assessed. Oxygen depletion varied by temperature and insect infestation level. However, 30 °C was the optimum temperature for oxygen depletion (reaching 5% or less in 10 days) regardless of insect infestation level. No changes were observed in germination and grain moisture content, minimal grain damage, or weight loss (<1%). Only at 20 °C were adult insects able to survive after 30 days and emerged 45 days post-treatment under normoxia. Therefore, hermetic storage containers should remain closed for more than 30 days to minimize re-infestation of grain in areas where average ambient temperatures rarely exceed 23 °C. Further research is needed to assess the effect of low temperatures on oxygen depletion and insect survival in hermetic storage beyond 30 days.

The natural occurrence of entomopathogenic fungal endophytes in sugarcane (Saccharum officinarum) and in soil samples from sugarcane fields was evaluated in Chikwawa District, southern Malawi. Fungi from soil were isolated by baiting using Galleria mellonella larva. Fungal endophytes were isolated from surface-sterilized plant tissue sections. Forty-seven isolates resembled the genus Beauveria, 9 isolates were Metarhizium, and 20 isolates were Isaria. There was no significant difference in the number and type of fungal isolates collected from soil and from plant tissue. There was, however, a significant difference in the part of the plant where fungal species were isolated, which fungal species were isolated, and the number of fungal species isolated at each location. Phylogenetic analysis of 47 Beauveria isolates based on DNA sequencing of the Bloc intergenic region indicated that these isolates all belonged to B. bassiana and aligned with sequences of B. bassiana isolates of African and Neotropical origin. The Malawian B. bassiana isolates formed a distinct clade. No larvae died from infestation by multiple fungi. To the best of our knowledge, this is the first report of B. bassiana and Isaria spp. occurring naturally as endophytes in sugarcane. Further, it is the first report of B. bassiana, Isaria spp., and Metarhizium spp. in the soil of sugarcane fields in Africa.

A new species and a new genus of Rhachiberothidae, Rhachiella malawica gen. nov., spec. nov., are described from Malawi. The new species is characterized by a flat vertex, a long penisfilum in the male, and by a bifurcate pseudohypocauda in the female. This combination of characters requires the description of a new genus, which is the sister taxon of Mucroberotha Tjeder, 1959. This is the first record of Rhachiberothidae in Malawi. The distributions of all 14 species of Rhachiberothidae so far known are shown in three maps.