Ladybird Beetles (Coleoptera: Coccinellidae)

Abstract

Insects belonging to family Coccinellidae are commonly known as ladybird beetles. Most of them are predaceous and polyphagous insects. Their prey range is classified as essential, alternative or rejected. Ladybirds feeding on essential prey survive better as larvae and are more fecund as adults. Those feeding on alternative prey can only survive, but they neither grow nor reproduce. Rejected prey species are unpalatable due to their aposematic colouration and presence of certain allelochemicals, and are rejected even after their encounter. Ladybirds accept some prey species, which are non-toxic and inadequate, and worsen their life-history parameters. Such prey species are considered as ‘problematic prey’. Numerous factors may affect the prey preferences of ladybirds, like: (1) prey quality; (2) prey quantity; (3) morphology, mobility and defence of prey; (4) learning ability, memory, morphological characters and previous feeding experience of predator; (5) environmental parameters (temperature and photoperiod); and (6) genetic factors. While ladybirds locate their prey by extensive search, they switch over to intensive search once the feeding of prey is initiated. If no further prey species are captured, the predators gradually change their prey search mode from intensive to extensive search again. During both extensive and intensive searches, ladybirds sense environmental and inner cues that orientate them towards their prey. In addition, both abiotic (temperature, humidity and light intensity) and biotic (prey, other predators and their interactions) factors affect the searching behaviour of ladybirds by modifying their rate of movement. Thus, for the successful biocontrol programmes, all such factors that affect the prey-predator relationships in ladybirds need to be fully explored prior to the selection of ladybirds for mass multiplication in laboratories. © 2023 selection and editorial matter, Omkar; individual chapters, the contributors.