Don't kill your allies : The impact of chemical and biological locust and grasshopper control on birds

Abstract

Changing views on avian predation after widespread introduction of chemical locust control Elliott (1962) mentioned more than one hundred bird species of 34 families as locust predators in Eastern Africa. Husain & Bhalla (1931) did the same for the Indian subcontinent and came up with 35 species, while more than 200 bird species were found to prey on grasshoppers in the USA (Metcalf 1980). An updated survey of published accounts and other relevant sources conducted by Table 21) revealed that at least 537 bird species of 61 families are currently known to prey upon locusts and grasshoppers in Africa. Several bird families in Africa, such as the Coraciidae and Laniidae, appear to be specialised acridivores. A wide range of acridid species is recorded as food for Ciconiidae, Glareolidae and Corvidae. Individual bird species which can be associated with a diverse acridid diet are e.g. Black Kites Milvus migrans and Pied Crows Corvus alba, but also White Storks and Abdim's Storks Ciconia abdimii, Lesser Kestrels Falco naumanni and Montagu's Harriers Circus pygargus. Based on extensive field work in Niger, Petersen et al. (2008) and Falk et al. (2006) found that pre-migratory movements of Abdim's Storks are in synchrony with the seasonal movements of Senegalese Grasshoppers.Most published accounts on predation of acridids in Africa since the Second World War are of birds present during major outbreaks of locusts. It is therefore not surprising that several authors concluded that the efficacy of (avian) predators in dealing with swarms during upsurges or plagues was rather limited (Dean 1964, Stower & Greathead 1969. The magnitude of such locust swarms (adults) or of hopper bands (nymphal stages), however, was of an extremely massive nature, as visually described by Meinertzhagen (1959): "The hoppers were at Middelburg (Cape) and so numerous that trains were held up owing to squashed bodies greasing the lines so that engine wheels would not bite the rails…".Given the unpredictable nature of locust outbreaks, grasshoppers, in particular the species surviving the dry season as diapausing adults, are a much more reliable food source for (migratory) birds wintering in the Sahel than migratory locusts. However, it was not until recently that this concept found its advocates (Mullié et al. 1995, Jensen et al. 2006. The importance of Ornithacris cavroisi as a major prey species during the dry season in the Sahel has meanwhile been described for Swallow-tailed Kites Chelictinia riocourii

Itinerant lifestyle and congregation of lesser kestrels in West Africa

“…And (3) kestrels might use larger prey species at the last staging sites compared to the previous sites (e.g. grasshoppers species such as Ornithacris cavroisi or the larger desert locusts Schistocerca gregaria females, Mullié, 2021), requiring more time on the wing (more time flying vs. perch hunting smaller prey at first sites).…”

Sustainable Plant Pest Management Through Optimization and Minimization

“…The overwhelming majority of global biodiversity is insects with up to 1% of the one million described species being pests. Environmental pollution by agricultural chemicals, such as pesticides and fertilizers, are one of the major drivers for the decline of insect fauna worldwide, including pollinators, natural enemies and decomposers [14] .…”