Plant Size-dependent Escaping Behavior of Gregarious Nymphs of the Desert Locust, Schistocerca gregaria
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Plant Size-dependent Escaping Behavior of Gregarious Nymphs of the Desert Locust, Schistocerca gregaria Koutaro Ould Maeno & Cyril Piou & Sidi Ould Ely & Mohamed Abdallahi Ould Babah & Benjamin Pélissié & Sid’Ahmed Ould Mohamed & Mohamed EL Hacen Jaavar & Mohamed Etheimine & Satoshi Nakamura
Revised: 13 December 2012 / Accepted: 20 January 2013 / Published online: 31 January 2013 # Springer Science+Business Media New York 2013
Abstract The present study involves the tracking of marching bands of more than 300,000 gregarious nymphs of the desert locust, Schistocerca gregaria, to examine shelter plant preference and how species and size of shelter plants and nymphal group sizes jointly influence the escaping behavior of 4th- and 5th-instar gregarious nymphs. Field observations are conducted during daytime and night-time in the Sahara Desert in Mauritania. Three dominant plant species have been identified at the survey site: Hyoscyamus muticus, Panicum turgidum, and Nucularia perrini. The smallest mean plant size among the three plant species is H. muticus. Gregarious nymphs perch on all the three plant species irrespective of time, and form various sizes of groups ranging from 10,000 nymphs. Groups of gregarious locusts perching on the plants show either escaping or sheltering behavior in response to an approaching observer. Percentages of nymphal groups showing escaping behavior for H. muticus, P. turgidum and N. perrini are 96.4, 47.6 and 19.5 %, respectively. Defensive behavior is not affected by nymphal group size but by species and size of shelter plants. Nymphal groups tend to show escaping behavior when their perching plants are relatively small. No groups escape from their perching plants during night. These results might indicate that gregarious nymphs do not have a strong shelter plant preference and change their defensive behavior depending on species and size of sheltering plants and light conditions. K. O. Maeno (*) : S. Ould Ely : M. A. O. Babah : S. Ould Mohamed : M. E. H. Jaavar : M. Etheimine The Mauritanian Desert Locust Centre: Centre National de Lutte Antiacridienne (CNLA), Bp: 665, Nouakchott, Mauritania e-mail: [email protected] S. Nakamura Japan International Research Center for Agricultural Sciences (JIRCAS), Ohwash 1-1, Tsukuba, Ibaraki 305-8686, Japan C. Piou : B. Pélissié CIRAD, UPR Bioagresseurs analyse et maîtrise du risque, 34398 Montpellier, France
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J Insect Behav (2013) 26:623–633
Keywords Anti-predator strategy . escaping behavior . density-dependent phase polyphenism . gregarious locusts . Schistocerca gregaria
Introduction Defensive strategies in animals are one of the major traits determining survival rates of creatures prone to predation. Avoiding capture is the primary mode of defence for prey insects that cannot hide themselves from their natural enemies. To escape quickly from approaching predators, locusts and grasshoppers have developed various defensive ways such as jumping, flight and sheltering behavior (Uvarov 1977; Whiteman 1990). Although escaping action ma
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