School of Mathematical and Physical Sciences, University of Newcastle, Callaghan, Australia.
School of Agriculture, Food and Wine, University of Adelaide, Adelaide, Australia.
PLoS Comput Biol. 2021 Jul 7;17(7):e1008353. doi: 10.1371/journal.pcbi.1008353. eCollection 2021 Jul.
Locusts are short horned grasshoppers that exhibit two behaviour types depending on their local population density. These are: solitarious, where they will actively avoid other locusts, and gregarious where they will seek them out. It is in this gregarious state that locusts can form massive and destructive flying swarms or plagues. However, these swarms are usually preceded by the aggregation of juvenile wingless locust nymphs. In this paper we attempt to understand how the distribution of food resources affect the group formation process. We do this by introducing a multi-population partial differential equation model that includes non-local locust interactions, local locust and food interactions, and gregarisation. Our results suggest that, food acts to increase the maximum density of locust groups, lowers the percentage of the population that needs to be gregarious for group formation, and decreases both the required density of locusts and time for group formation around an optimal food width. Finally, by looking at foraging efficiency within the numerical experiments we find that there exists a foraging advantage to being gregarious.
蝗虫是短角蚱蜢，根据其当地种群密度表现出两种行为类型。这些是：独居的，它们会主动避开其他蝗虫，以及群居的，它们会寻找它们。正是在这种群居状态下，蝗虫才能形成大规模和破坏性的飞行群或蝗灾。然而，这些群通常是由未成年无翅蝗虫若虫的聚集引起的。在本文中，我们试图了解食物资源的分布如何影响群体形成过程。我们通过引入一个多群体偏微分方程模型来实现这一点，该模型包括非局部蝗虫相互作用、局部蝗虫和食物相互作用以及群居化。我们的结果表明，食物会增加蝗虫群体的最大密度，降低群体形成所需的群居个体百分比，并降低蝗虫的密度和形成群体所需的时间，以达到最佳食物宽度。最后，通过在数值实验中观察觅食效率，我们发现群居具有觅食优势。
