Models for estimation of population density of late instar nymphs and fledglings of the desert locust,<i>Schistocerca gregaria</i>(Forsk.)

Bashir, S. El; Inayatullah, C.; Ahmed, Atidzhe; Abdelrahman, H.E.

doi:10.1080/09670879309371842

Cited by 6 publications

(4 citation statements)

References 5 publications

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“…Existing attempts to predict the emergence of swarms based on time-series analyses of outbreaks have been largely unsuccessful (16)(17)(18). Ecologically based forecasting models for S. gregaria and other locust species show more promise (19)(20)(21)(22)(23)(24)(25)(26). These models have been based on the properties of populations not individuals.…”

Section: Discussionmentioning

confidence: 99%

Spatial scales of desert locust gregarization

Collett

Despland

Simpson

et al. 1998

Proc. Natl. Acad. Sci. U.S.A.

131

102

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Central to swarm formation in migratory locusts is a crowding-induced change from a ''solitarious'' to a ''gregarious'' phenotype. This change can occur within the lifetime of a single locust and accrues across generations. It represents an extreme example of phenotypic plasticity. We present computer simulations and a laboratory experiment that show how differences in resource distributions, conspicuous only at small spatial scales, can have significant effects on phase change at the population level; local spatial concentration of resource induces gregarization. Simulations also show that populations inhabiting a locally concentrated resource tend to change phase rapidly and synchronously in response to altered population densities. Our results show why information about the structure of resource at small spatial scales should become key components in monitoring and control strategies.The desert locust, Schistocerca gregaria, is one of the world's most notorious insect pests. Most of the time, it exists at low densities across sub-Saharan Africa and into India. At unpredictable intervals, plagues occur; swarms leave this recession zone and invade neighboring areas of Africa, Asia, and Europe. The crowding-induced phase transition between the ''solitarious'' and ''gregarious'' forms involves a suite of changes in behavior, morphometry, color, development, fecundity, and endocrine physiology (1-3). Gregarious individuals become more active and are attracted, instead of repelled, by other locusts. Most phase characters change between instars or accrue across generations through maternal inheritance (4-7), but a solitarious individual's behavior becomes gregarious after only 4 h of crowding and reverts to solitariousness after only 4 h of reisolation (4,5,8). The detailed time course of behavioral-phase change has been quantified only recently and has important implications for selecting the appropriate temporal and spatial scales required to understand locust swarming.An experimental study has shown that locusts confined in an experimental arena for 8 h are more gregarious if the arena contains a lower density of resource (e.g. food, perches, or favorable microclimatic sites; ref. 8). In the present study, we examine the effects of resource distribution and locust density on gregarization, while keeping the overall density of resource constant. MATERIALS AND METHODSFractal Dimension of Resource. Fractal surfaces used in the experiment and simulation were created on a 64 by 64 grid by using an algorithm with midpoint displacement (9). Food patches were located on the highest 20 points. The fractal dimension of the resulting distribution is then described by using a box-counting algorithm. The arena is divided into boxes of length r grid squares, and the number of boxes containing food patches is counted. This process is carried out four times with the origin of the boxes successively shifted diagonally across one grid square. By using the mean number of nonempty boxes N(r), the fractal dimension is calcula...

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Section: Discussionmentioning

confidence: 99%

Spatial scales of desert locust gregarization

Collett

Despland

Simpson

et al. 1998

Proc. Natl. Acad. Sci. U.S.A.

131

102

View full text Add to dashboard Cite

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“…The desert locust, Schistocerca gregaria (Forskål) (Orthoptera, Acrididae) is one of the most serious agricultural pests. During outbreaks, swarms may consist of millions of individuals (40–80 million locusts per km 2 ; e.g., Singh & Singh, 1977 ; Steedman, 1988 ; EL-Bashir et al, 1993 ), and the damage to crops can be enormous, as the locusts are able to consume hundreds of tons of vegetation per day ( Shaluf, 2007 ). Moreover, according to some estimates, 1/10 of the global human population is affected by this pest ( Latchininsky et al, 2011 ).…”

Section: Introductionmentioning

confidence: 99%

Precopulatory behavior and sexual conflict in the desert locust

Golov

Rillich

Harari

et al. 2018

PeerJ

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Studies of mating and reproductive behavior have contributed much to our understanding of various animals’ ecological success. The desert locust, Schistocerca gregaria, is an important agricultural pest. However, knowledge of locust courtship and precopulatory behavior is surprisingly limited. Here we provide a comprehensive study of the precopulatory behavior of both sexes of the desert locust in the gregarious phase, with particular emphasis on the conflict between the sexes. Detailed HD-video monitoring of courtship and mating of 20 locust pairs, in a controlled environment, enabled both qualitative and quantitative descriptions of the behavior. A comprehensive list of behavioral elements was used to generate an eight-step ethogram, from first encounter between the sexes to actual copulation. Further analyses included the probability of each element occurring, and a kinematic diagram based on a transitional matrix. Eleven novel behavioral elements are described in this study, and two potential points of conflict between the sexes are identified. Locust sexual interaction was characterized by the dominance of the males during the pre-mounting stage, and an overall stereotypic male courtship behavior. In contrast, females displayed no clear courtship-related behavior and an overall less organized behavioral sequence. Central elements in the sexual behavior of the females were low-amplitude hind-leg vibration, as well as rejecting males by jumping and kicking. Intricate reciprocal interactions between the sexes were evident mostly at the mounting stage. The reported findings contribute important insights to our knowledge of locust mating and reproductive behavior, and may assist in confronting this devastating agricultural pest.

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“…During outbreaks, swarms may consist in millions of individuals (40-80 million locusts ser km 2 ; e.g. Singh & Singh 1977;Steedman 1988;El Bashir et al 1993), and the damage to cross can be enormous, as the locusts are able to consume hundreds of tons of vegetation ser day (Shaluf 2007). Moreover, according to some estimates, 1/10 of the global human sosulation is affected by this sest (Latchininsky et al 2011).…”

Section: Introductionmentioning

confidence: 99%

Peer Review #1 of "Precopulatory behavior and sexual conflict in the desert locust (v0.1)"

Maeno¹

2018

View full text Add to dashboard Cite

Studies of mating and reproductive behavior have contributed much to our understanding of various animals' ecological success. The desert locust, Schistocerca gregaria, is an important agricultural pest. However, knowledge of locust courtship and precopulatory behavior is surprisingly limited. Here we provide a comprehensive study of the precopulatory behavior of both sexes of the desert locust in the gregarious phase, with particular emphasis on the conflict between the sexes. Detailed HD-video monitoring of courtship and mating of 20 locust pairs, in a controlled environment, enabled both qualitative and quantitative descriptions of the behavior. A comprehensive list of behavioral elements was used to generate an eight-step ethogram, depicting from first encounter between the sexes to actual copulation. Further analyses included the probability of each element occurring, and a kinematic diagram based on a transitional matrix. Eleven novel behavioral elements are described in this study, and two potential points of conflict between the sexes are identified. Locust sexual interaction was characterized by the dominance of the males during the pre-mounting stage, and an overall stereotypic male courtship behavior. In contrast, females displayed no clear courtship-related behavior and an overall less organized behavioral sequence. Central elements in the sexual behavior of the females were low-amplitude hind-leg vibration, as well as rejecting males by jumping and kicking. Intricate reciprocal interactions between the sexes were evident mostly at the mounting stage. The reported findings contribute important insights to our knowledge of locust mating and reproductive behavior, and may assist in confronting this devastating agricultural pest.

show abstract

Models for estimation of population density of late instar nymphs and fledglings of the desert locust,Schistocerca gregaria(Forsk.)

Cited by 6 publications

References 5 publications

Spatial scales of desert locust gregarization

Spatial scales of desert locust gregarization

Precopulatory behavior and sexual conflict in the desert locust

Peer Review #1 of "Precopulatory behavior and sexual conflict in the desert locust (v0.1)"

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