Sprayed barriers of diflubenzuron for control of the migratory locust (Locusta migratoria capito (Sauss.)) [Orthoptera: Acrididae] in Madagascar: short-term impact on relative abundance of terrestrial non-target invertebrates
1996; Elsevier BV; Volume: 15; Issue: 6 Linguagem: Inglês
10.1016/0261-2194(96)00029-4
ISSN1873-6904
Autores Tópico(s)Biological Control of Invasive Species
ResumoAbstract Relative abundance of terrestrial, non-target invertebrates in savannah grassland was monitored following large-scale field trials using the insect growth regulator (IGR) diflubenzuron applied as barrier treatments for control of the migratory locust in Madagascar. Identical sampling techniques were employed to monitor invertebrates at two different trial sites, separated by about 300 km; one treated with IGR barriers over an area of 20 km 2 in 1993 and the second, treated similarly over an area of 5 km 2 in 1994. Data were collected for more than 300 species from over 120 families and 17 orders. Faunal composition of sweep net catches was similar at the order and family level for the two areas, but quite different at the species level. The majority of invertebrates sampled either occurred in numbers too small to be evaluated statistically or showed no evidence of effects even within spray barriers over a 3 month period following spraying. However, depending on timing of spraying, relative abundance of both caterpillars [Lepidoptera] and non-target grasshoppers [Acrididae] declined within spray barriers following treatment and remained low for several months. Adverse impacts on spiders [Araneae] (particularly Salticidae), crickets [Orthoptera; Gryllidae] and bugs [Heteroptera] could not be discounted. Inter-barrier spaces, 500 m wide, acted as true refugia, with no evidence of effects of spraying on fauna within the middle 300 m of these areas. Diflubenzuron barriers appear to be relatively safe to non-target fauna in the short term, by comparison with other methods of locust control. However, with barriers spaced at 500–600 m, the severe decline in abundance of caterpillars and of non-target grasshoppers within spray barriers cannot be dismissed as ecologically insignificant for the treated area as a whole and further monitoring of these insects should accompany future diflubenzuron barrier use. The technique seems likely to be environmentally acceptable, but this can only be confirmed after evaluation of longer-term impacts.
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