Effect of cannibalism phenomenon on some biological aspects and predation efficiency on Tetranychus urticae Koch of the ladybird beetle, Coccinella undecimpunctata Linnaeus

Abstract

The coccinellid predator, Coccinella undecimpunctata (L.) is one of the most important insect predator, which plays an important role in regulation of too many insect pests in Egypt and worldwide. Cannibalism phenomenon is a well-known behavioral feature in this predator, as the larvae and adults prey upon each other. The consumption capacity of this predator on Tetranychus urticae Koch, as well the eggs, first and second larval instars of the this coccinellid was evaluated. The adults and 4 th larval instar and adults of C. undecimpunctata devoured more prey compared to those devoured by 1 st , 2 and 3 rd larval instars. The fourth larval instar of the coccinellid fed upon an average of 96.7 ± 1.2 eggs and 12.0 ± 0.7 larvae of first larvae instar of the same species in Petri dish, in the absence of the spider mite (nonchoice feeding). In the presence of the mite and eggs of C. undecimpunctata, the fourth larval instar fed upon 2.2 ± 0.8 eggs and consumed only 1.0 ± 0.5 larvae in 1 st larval instar of C. undecimpunctata (choice feeding), and consumed and consumed 126.0 ± 1.0 individual of spider mite in the absence of other prey (non-choice feeding). The adult of the coccinellid fed upon 10.52 ± 0.9 eggs and 5.09 ± 0.5 1 st larval instars, in the absence of the mite, but fed upon 1.08 ± 0.15 eggs in the presence of the spider mite and C. undecimpunctata eggs in the same dich. Also, the coccinellid adult fed upon 0.19 ± 0.21 first larval instars in the presence of C. undecimpunctata larval and mites found in the same Petri dish. The adults of C. undecimpunctata consumed 45.83 ± 1.17 individual of the spider mite in the absence of eggs and larvae of C. undecimpunctata. Data of cannibalism and predatory efficiency show that eggs and 1 st larval instars of C. undecimpunctata are more devoured by C. undecimpunctata adults comparing to 4 th larval inster and larvae of the coccinellid. The two-spotted spider mite is the preferred to all stage of the coccinellid. Results show that scarcity of the prey is one the main reason to cannibalism phenomenon, but it is a conspecific behavior of all coccinellids to keep all species.