Rearing of Phenacoccus manihoti
P. manihoti larvae obtained from cassava plantation. Then the larvae infested cassava plants were grown in a plastic cup (height 16 cm, diameter 10 cm) in laboratory conditions.
1. Long larva stage P. ramburi: from the rearing of predators taken 20 samples of P. ramburi, to determine the long period of 1st instar, 2nd instar, and 3rd instar of larvae.
2. Prey preferences of 3rd instar of larvae P. ramburi, at the stage of instar P. Manihoti.: At this treatment using 3rd instar of larvae P. ramburi and enter into a petri dish and then treated with the mealybug 1st instar to adults each 50 prey. Treatment conducted on 10 replicates. Observations were made by looking at the number of each instar P. manihoti remaining at 3, 6, 12, and 24 hours after the release of predators. Before treatment, predators were fasted for about 12 hours. Then calculated the degree of selection (preference index) for prey with the formula: Li = ri – pi, Li prey selection index, ri = proportion of prey eaten by predators, and pi = proportion of prey available. Maximum preference occurs when ri = 1 and pi = 0, and maximum rejection occurs if ri = 0, and pi = 1. If the value of Li positive and approaching the maximum value of the preference, and if the value of L is negative, avoidance (rejection) to the maximum. Data analysis using SPSS Version 16.0. Then proceed with ANOVA, Duncan's multiple range test at the 5% level.
3. Predation potential of each level stadia larvae of P. ramburi on P. manihoti.: