Abstract
The reproductive and demographic attributes of the aphidophagous ladybird, Hippodamia variegata (Goeze) (Coleoptera: Coccinellidae), when fed on the aphid species, Aphis craccivora (Koch), reared on four host plants, viz. Dolichos lablab L., Vigna unguiculata L. Walp, Cajanus cajan (L.) Millsp., and Ranunculus sceleratus L., were investigated in the laboratory to find host suitability for the production of the ladybird. Results indicated that there was a significant effect of host plant on both reproductive and demographic parameters of the predator. The host plant suitability was in the rank order D. lablab = V. unguiculata > C. cajan > R. sceleratus. This ladybird started reproducing very early and laid a high number of eggs for a longer period of time when the adults were fed on aphids raised on D. lablab and V. unguiculata. Both the fecundity and percent egg hatching increased significantly in the case of the abovementioned two host plants. Similar host plant effects were found on demographic parameters of H. variegata, with significantly high values of net reproductive rate (rm), short generation (Tc), and doubling times (D.T.) on D. lablab and V. unguiculata. Age-specific fecundity of H. variegata at all host plant treatments was triangular in function with an initial increase in ovipositional rate with age, followed by attainment of peak and gradual decline till egg laying ceases. These peaks were higher on the host plant treatments, D. lablab and V. unguiculata. Sub-optimal values of both reproductive and demographic parameters were found on the host plant, R. sceleratus. Thus, it could be concluded that both D. lablab and V. unguiculata were the suitable host plants to raise aphid, A. craccivora, for the augmentative rearing of the ladybird, H. variegata.
Highlights
Predaceous coccinellids, popularly known as ladybirds (Coleoptera: Coccinellidae), are important biocontrol agents of numerous crop pests, viz. aphids, mealybugs, whiteflies, thrips, and other tiny soft-bodied insects (Dixon 2000 and Hodek et al 2012)
These were sexed and paired in Petri dishes (2.0 cm height × 9.0 cm diameter) in four sets provided daily with a sufficient quantity of A. craccivora infested on (i) D. lablab, (ii) V. unguiculata, (iii) C. cajan, and (iv) R. sceleratus
The data for normality, using the Kolmogorov–Smirnoff test, and homogeneity of variance, using Bartlett’s test via statistical software, SAS version 9.0, were tested, as well were the data of pre-oviposition and oviposition periods, daily oviposition, fecundity, and percent egg viability of H. variegata, when fed on A. craccivora raised on four host plants, to one-way ANOVA, using SAS, version 9.0
Summary
Predaceous coccinellids, popularly known as ladybirds (Coleoptera: Coccinellidae), are important biocontrol agents of numerous crop pests, viz. aphids, mealybugs, whiteflies, thrips, and other tiny soft-bodied insects (Dixon 2000 and Hodek et al 2012). Aphids, mealybugs, whiteflies, thrips, and other tiny soft-bodied insects (Dixon 2000 and Hodek et al 2012). Their augmentative rearing in the laboratory depends largely on the prey food and the abiotic factors (Omkar and Pervez 2016). Hodek and Evans (2012) expanded the classical idea of Pervez et al Egyptian Journal of Biological Pest Control (2018) 28:91 and Eastop 2000). A. craccivora is a major pest of Indian bean, [Lablab purpureus (L.) Sweet = Dolichos lablab L.], cowpea, Vigna unguiculata L. Walp (Karungi et al 2000), and pigeon pea [Cajanus cajan (L.) Millsp.]. It infests poison buttercup, Ranunculus sceleratus L. It infests poison buttercup, Ranunculus sceleratus L. (Pervez and Kumar 2017)
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