Density dependence and noise determine the long‐term dynamics of two species of lady beetle (Coleoptera: Coccinellidae: Epilachninae) in the Indonesian tropics

Abstract

1. The long-term dynamics of two beetles ( Epilachna vigintioctopunctata and Epilachna enneasticta ) from Indonesia are analysed using descriptive time-series statistics and mechanistic time-series models.2. Statistical analysis of the time series reveals that the dynamics of E. vigintioctopunctata are underpinned by a second order density-dependent [AR(2)] process, which is consistent between sites. Similarly, the dynamics of E. enneasticta are also described by a second order density-dependent [AR(2)] process. The predicted dynamics from these statistical models are stable dynamics.3. Mechanistic models of the density dependence predict that in the absence of noise the dynamics of the populations should also be stable. Inclusion of the stochasticity in the models of density dependence allows a more accurate description of the population dynamics of each species to be determined.4. Correlation analyses reveal that the fluctuations between species are a function of both the density dependence and the environmental conditions experienced by each species. Under low environmental variance it is predicted that the dynamics could be synchronised but under high variance in environmental noise, the dynamics may not be synchronised and species respond idiosyncratically to the environment.5. The study highlights the value of long-term population dynamic time series for exploring the structure of population regulation and fluctuations in insect populations. Entomology, 32, 28-37 y ¼ a 0 1 a 1 Á x h1 t 1 a 2 Á x h2 t21 30 Michael B. Bonsall, Nusyirwan Hasan and Koji Nakamura

Stability of native and exotic lady beetle populations in a diverse landscape

“…The same is true for tropical lady beetle species (Coccinellidae; Bonsall et al. ) and for fish species in a diverse community (Henderson and Magurran ). Often species with similar life histories, living in the same habitat, and exposed to the same environmental variation, nevertheless exhibit species‐specific levels of population variability (Lamb et al.…”

“…Nevertheless, long-term studies of groups of aphid species (Aphididae), with similar life histories and living in the same habitat, show that the degree and types of density dependence vary among species, and density dependence explains more of the variation in annual abundance than environmental variability (Alyokhin et al 2005, Davis et al 2014. The same is true for tropical lady beetle species (Coccinellidae; Bonsall et al 2007) and for fish species in a diverse community (Henderson and Magurran 2014). Often species with similar life histories, living in the same habitat, and exposed to the same environmental variation, nevertheless exhibit species-specific levels of population variability (Lamb et al 2011, Galloway and Lamb 2014, Lamb and Galloway 2016, Lamb and Boivin 2017a.…”

Warming at the population level: Effects on age structure, density, and generation cycles

“…Although generation cycles are less well known than the famous multigeneration cycles exhibited by some animals, they are nonetheless important in many field systems, and arguably more important in economic terms. Populations of a wide variety of tropical insect species including many important pests exhibit generation cycles (Azerefegne, Solbreck, & Ives, ; Bigger, ; Bonsall, Hasan, & Nakamura, ; Godfray & Hassell, ; Hickel, Hickel, Souza, Vilela, & Miramontes, ; Nakamura, Hasant, Abbas, Godfray, & Bonsall, ; Wall, Howard, & Bindu, ; Yamanaka, Nelson, Uchimura, & Bjørnstad, ), as do a number of economically important fish species, including sockeye salmon, Oncorhynchus nerka (Guill, Drossel, Just, & Carmack, ), vendace Coregonus albula (Huusko & Hyvärinen, ; Marjomäki, Urpanen, & Karjalainen, ), and possibly bluefin tuna Thunnus thynnus (Ravier & Fromentin, ). Daphnia populations are also known to exhibit generation cycles in both the laboratory and the field (McCauley & Murdoch, ).…”

The effects of colonization, extinction and competition on co‐existence in metacommunities

“…To minimize the negative log‐likelihoods for the stochastic implementation of the set of continuous‐time competition models (Table 1), we used a simplex algorithm (Nelder & Mead 1965; Press et al . 1992) incorporating a numerical integration routine (Bonsall & Hastings 2004; Bonsall & Hassell 2005; Bonsall & Benmayor 2005; Bonsall, Hasan & Nakamura 2007). This optimization method is relatively robust at finding the minima and maxima of functions (Press et al .…”