Diversity and abundance of lepidopteran stem borer natural enemies in natural and cultivated habitats in Botswana

Lepidopteran stem-borers in Africa are attacked by diverse natural enemies in natural and cultivated environments. Field surveys of stem-borer natural enemies and associated host plants were conducted during the austral summers of 2014/15 and 2015/16 on natural and cultivated habitats across Botswana to determine their diversity and relative abundance. In cultivated habitats, the most common parasitoids of larvae were Cotesia flavipes Cameron, C. sesamiae (Cameron), and of pupae, Pediobius furvus Gahan and Gambroides nimbipennis Seyrig. In natural habitats, the larval parasitoids Chelonus curvimaculatus Cameron and Goniozus indicus Ashmead were recorded, along with the pupal parasitoid, Dentichasmias busseolae Heinrich. Furthermore, the predatory ants Linepithema humile Mayr, Crematogaster peringueyi Emery and Aenictus species were recorded in both cultivated and natural habitats. The major cultivated plants hosting stem-borers and related natural enemies were maize, sorghum, sweet sorghum, and the major wild plants were Echinochloa pyramidalis, Typha latifolia, Schoenopkctus corymbosus and Cyperus dives. Chilo partellus Swinhoe and Sesamia spp. were the major hosts for parasitoids, with C. partellus predominating in cultivated habitats and Sesamia jansei Tams & Bowden in natural habitats. Larval parasitism ranged from 2.1 to 34.7% and 3.3 to 14.3% in cultivated and natural habitats respectively, whereas pupal parasitism ranged from 6.1 to 10.6% and 6.7 to 9.1%, respectively. Parasitoid percentage abundance ranged from 1.1 to 41.6% and 4.8 to 38.1% in cultivated and natural habitats respectively, with C. flavipes dominating in cultivated and C. curvimaculatus in natural habitats. Our results show that cultivated and natural environments in Botswana harbor a diverse natural enemy community worthy of conserving for stem-borer biological control

Horizon scanning to assess the bioclimatic potential for the alien species Spodoptera eridania

BACKGROUND: The southern armyworm (SAW) Spodoptera eridania (Stoll) (Lepidoptera: Noctuidae) is native to the tropical Americas where the pest can feed on more than 100 plant species. SAW was recently detected in West and Central Africa, feeding on various crops including cassava, cotton, amaranth and tomato. The current work was carried out to predict the potential spatial distribution of SAW and four of its co‐evolved parasitoids at a global scale using the maximum entropy (Maxent) algorithm. RESULTS: SAW may not be a huge problem outside its native range (the Americas) for the time being, but may compromise crop yields in specific hotspots in coming years. The analysis of its potential distribution anticipates that the pest might easily migrate east and south from Cameroon and Gabon. CONCLUSION: The models used generally demonstrate that all the parasitoids considered are good candidates for the biological control of SAW globally, except they will not be able to establish in specific climates. The current paper discusses the potential role of biological control using parasitoids as a crucial component of a durable climate‐smart integrated management of SAW to support decision making in Africa and in other regions of bioclimatic suitability. © 2021 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry

Low‐temperature tolerance in coprophagic beetle species (Coleoptera: Scarabaeidae): implications for ecological services

1. Low temperatures affect insect functioning and population dynamics. Although temperate species cope with low temperatures better than their tropical counterparts, increasing temperature variability due to climate change exposes tropical species to frequent cold stress. For keystone insect species providing important ecosystem services, low-temperature tolerances, and behavioural responses remain unknown, hampering predictions under climate change. 2. The present study examined low-temperature physiology [critical thermal minima (CTmin) and chill coma recovery time (CCRT)] of six dung beetle species across three activity times: diurnal Allogymnopleurus indigaceous (Reiche) and Euoniticellus intermedius (Reiche); crepuscular Onthophagus alexis (Klug) and Onthophagus gazella (Fabricius), and; nocturnal Copris elephenor (Klug) and Scarabaeus zambezianus (Peringuey). Further, ecological service delivery (dung removal) was examined between diurnal and nocturnal species across the temperature regimes. 3. Nocturnal species had significantly greater cold tolerance than both crepuscular and diurnal species, while CCRT was significantly shortest in diurnal than both crepuscular and nocturnal species. Dung ball production between diurnal and nocturnal species interacted with temperature, with diurnal species producing significantly fewer balls at low temperatures, while nocturnal beetles were not significantly affected. In turn, nocturnal species produced significantly larger balls than the diurnal species across temperatures. Effects of temperature regime shifts were intertwined with the foraging ecology of individual species. 4. Future research should quantify species' functional responses toward different amounts of dung masses as stressful temperatures increase. 5. Results are significant for determination of species thermal ranges and predicting costs of low-temperature stress through reduced ecological services under shifting thermal environments