Effect of photoperiod on slow and fast developing individuals in aphidophagous ladybirds, Menochilus sexmaculatus and Propylea dissecta (Coleoptera: Coccinellidae)

Abstract

The effects of environmental parameters on insect development have been studied extensively. But the reasons for 2 differential developmental rates within same cohort under varying environmental factors have not been explored. For the purpose, in this study the existence and stability of slow and fast development under 5 photoperiods (i.e., 8L: 16D, 10L : 14D, 12L : 12D, 14L : 10D and 16L : 8D; light and dark hours per day) and its effect on body mass and reproductive attributes in 2 aphidophagous ladybirds, Menochilus sexmaculatus (Fabricius) and Propylea dissecta (Mulsant) was examined on Aphis craccivora Koch at 27 ± 1 °C temperature. A clear bimodal (2 peaks, where the first peak represented the fast developing and the 2nd peak slow developing individuals) pattern of distribution at each photoperiod was found. The proportion of slow and fast developing individuals in a cohort differed with photoperiods. The slow developing individuals were more in numbers at 8L : 16D, in equal numbers at 14L : 10D and in less numbers at 16L: 8D, indicating that the variation in emergence was owing to exogenous cues influenced differential rates of mortality. Slow developing individuals had female biased sex ratio, higher longevity and lower body mass than fast developing individuals. Fast developing females laid higher numbers of eggs with higher egg viability than slow developing females. Study of such variations in development at different photoperiods is helpful to understand its role in the development of insects particularly ladybirds and permits the selection of fast developing bioagents for their use in biocontrol of pest species.

Evolution of slow and fast development in predatory ladybirds

“…), which differs from the ‘bimodal’ distributions reported by Mishra and Omkar () and Singh et al. (, ) for Menochilus sexmaculata and Propylea dissecta . Close examination of their results reveal that the sample sizes they used were a fifth to half the sample size used here, and more worrying is that the distributions recorded by Singh et al.…”

“…The frequency distribution of the duration of development of larvae of A. bipunctata, all reared under similar conditions, is unimodal ( fig. 1), which differs from the 'bimodal' distributions reported by Mishra and Omkar (2012) and Singh et al (2014Singh et al ( , 2015 for Menochilus sexmaculata and Propylea dissecta. Close examination of their results reveal that the sample sizes they used were a fifth to half the sample size used here, and more worrying is that the distributions recorded by Singh et al (2014) for these two species differ from those previously recorded by these authors for the same species under the same conditions.…”

Slow and fast development in two aphidophagous ladybirds on scarce and abundant prey supply

“…Two predaceous ladybirds, M. sexmaculatus and P. dissecta, were selected for the study owing to their: (a) local abundance, (b) wide prey range, (c) fast development, (d) high reproduction and (e) previous studies on related aspects (Mishra & Omkar, 2012;Singh et al, 2014Singh et al, , 2016.…”

“…Bimodal (two peaks i.e., slow and fast) distribution has been reported not only in intraspecific body size (Gouws et al, 2011) but also in the developmental rates (Mishra & Omkar, 2012;Singh et al, 2014Singh et al, , 2016. The bimodal distribution and the proportion of slow:fast emergence has been found to shift in M. sexmaculatus and P. dissecta, with change in abiotic conditions like temperature and photoperiod (Singh et al, 2014(Singh et al, , 2016. The ratio of slow and fast developing individuals also differs with the biotic conditions, such as prey; poor prey species favoured the emergence of more slow developing individuals and vice versa (Singh et al, unpublished data).…”

Predator‐prey interactions in selected slow and fast developing females of a ladybird,Propylea dissecta

“…Ladybirds are potential biocontrol agents of a number of insect prey (Hodek et al, ), and intraspecific variation is common in developmental rates (Dixon, ; Hodek et al, ) and morphological traits (e.g., Mckinnon and Pierotti, ; Pech‐May et al, ). Recent studies in ladybirds have indicated the presence of slow and fast developers in a cohort (Mishra and Omkar, ; Singh et al, , ; Pandey et al, ) and potential environmen­tal as well as genetic control of this variation (Stern, ). Phenotypic plasticity for developmental rate in the ladybird, Hippodamia convergens (Guérin‐Méneville) has been successfully exploited to select for faster developing individuals (Rodriguez‐Saona and Miller, ).…”