The effect of different wavelengths of light, white (control; broad spectrum), blue (ca. 475 nm), yellow (ca. 570 nm) and red (ca. 650 nm), at constant intensity (195 ± 5 lux) on developmental time, reproductive and non-reproductive periods, fecundity, egg viability, prey consumption and fitness of two aphidophagous ladybirds, Cheilomenes sexmaculata and Propylea dissecta were studied. Both ladybird species consumed most aphids, developed fastest and reproduced best when kept under white light, followed by yellow, blue and red light. Fitness of both the ladybirds was highest under white and lowest under red light. There were positive correlations between prey consumption and developmental rate, and prey consumption and fecundity.

In the Parthenium beetle, Zygogramma bicolorata Pallister (Coleoptera: Chrysomelidae), variation in body size exists between and within the sexes. The females are larger than the males. Darwin (1874) proposed the fecundity advantage hypothesis, i.e. large sized female produce more progeny, with subsequent studies supporting as well as refuting the hypothesis. Thus, in order to evaluate whether this hypothesis stands in Z. bicolorata we performed experiments to investigate the role of body size in influencing: (i) assortative mating, (ii) reproductive attributes, and (iii) growth, development and survival of offspring. It is the first attempt in this beetle. We found that size influenced assortative mating, reproductive output and offspring fitness. Larger males and females were preferred as mates over smaller ones. The pairs having larger adults as mates had higher fecundity while the egg viability was influenced by the male size only. The offspring of larger parents had fast development and higher survival indicating thereby possible better nutrient allotment by the female and supply of accessory gland proteins by the male in addition to better quality of genes.

Mating and reproduction not only provide benefits but can also incur substantial costs. An increasing number of recent studies have indicated that mate searching, mating, and ejaculate production requires large amount of energy which can result in high cost to males. Here, we examine the effect of number of matings of males and mating duration on mating and reproductive success in Menochilus sexmaculatus (Coleoptera: Coccinellidae) by subjecting them to 3 consecutive matings of 30, 60, 90 min, and complete mating (a) with no interval and (b) with interval of 24 hr between the matings. The results reveal a reduction in reproductive performance for both the setup and reduction is more when mating is consecutive without gap. This shows that between subsequent matings males require time to recuperate the sperm/ejaculate. As a male engages in a greater number of matings, the time it takes to begin mating when paired with a female increases and the overall duration of mating decreases. However, frequent mating attempts made by males result in reduction in their body weight. Thus, in this ladybird beetle mating and related physiological process consume lots of energy and the body weight of males tend to decrease which further modifies their reproductive performance. The study helps us to identify the cost of mating from male's perspective and indicates that males need to rejuvenate between the matings.

In view of global environmental change, ecological factors especially temperature, affect development of the poikilotherms like insects. Since ladybirds are at risk of injury under mass‐rearing conditions, their ability to regenerate injured limbs is highly crucial for their survival. Therefore, the effect of limb regeneration in relation to temperature forms the basis of the present study. The immature stages of insects, being more vulnerable to the surrounding temperature, were considered to study the effect of the prior thermal experience of larvae on regeneration. We exposed the early larval stages of the ladybird beetle, Cheilomenes sexmaculata, to different temperature conditions pre‐ and postamputation. Exposure of immature stages to extreme temperatures did not affect the ability to regenerate and regeneration occurred at given temperature conditions. However, the regenerated legs were smaller in size across given temperatures as compared to unamputated legs. Body weights in amputated treatments showed no difference and remained unchanged across temperatures when compared to unamputated treatments. Postamputation developmental duration, equivalent to recovery time postlimb amputation, was found to be affected by larval thermal conditions. Recovery was faster in larval treatments exposed to higher temperatures. Thus, larval thermal conditions though did not affect the ability to regenerate lost limbs directly, it does modulate the time taken to regenerate.

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