Background
This study was conducted to investigate host stage preference and demographic parameters of the parasitoid species, Leptomastix dactylopii Howard (Hymenoptera: Encyrtidae), the parasitoid of vine mealybug Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae), an important pest in vineyards in many countries.
Results
The results revealed that L. dactylopii was not able to develop on the 1st and 2nd nymphal instars of P. ficus and preferred female mealybugs as the host to the 3rd nymphal instar. Hind tibia length and head capsule width of both female and male parasitoids emerged from the mummies of mealybugs parasitized in the female stage were greater than the values of the parasitoids emerged from the mummies of mealybugs parasitized in the 3rd nymphal instar. Demographic parameters of the parasitoid were calculated with the use of development and reproduction data obtained from life table of L. dactylopii. The intrinsic rate of increase was determined as (r = 0.1527 d−1), finite rate of increase as (λ = 1.1650 d−1), net reproductive rate as (R0 = 46.0667 offspring), and mean generation time as (T0 = 25.0830 d).
Conclusions
It was concluded that L. dactylopii was able to develop, especially in the female and in the 3rd nymphal instar of P. ficus and could be used for biological control of the vine mealybug.
In this study, the effects of three different bacterial isolates added to the vase solution on the vase life were investigated. All three bacterial isolates significantly increased the vase life of gerbera cut flowers. While the vase life of the flowers in the control solution was 3 days, this period reached up to 11 days in the flowers kept in the vase containing bacteria. Daily water uptake decreased with increasing time in vase in all treatments. Although there were some differences between treatments in terms of daily water uptake, it has been determined that bacteria application does not have a significant effect on water uptake. The relative fresh weight decreased with increasing time in the vase. Bacteria applications slowed the rate of decrease in fresh weight. Bacillus cereus found to be more effective than other bacterial isolates in slowing fresh weight decrease.
Nephus includens Kirsch (Coleoptera: Coccinellidae) is one of the most important predators of the mealybug, Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae), which one of the important pests of vineyards. In this study, the consumption capacity and preference of N. includens for the mealybug’s stages, were investigated. The experiments were carried out in a climate-controlled cabinet at 25 ± 1°C, 60 ± 10% R.H and 16:8 hrs (light: dark). The egg stage of the mealybug was the stage most consumed by all of the larval stages and the adult of N. includens. Also, the consumption level by the predator decreased with the progression in the development stage of the mealybug. It was also determined that the level of consumption by the predator increased with the progression of its larval stages, and that the highest consumption was by the adult stage of the predator on all mealybug stages, except the egg. The first nymphal stage of the mealybug was the stage most preferred by the 1st, 2nd and 3rd larval stages and the adult stage of the predator, whereas the egg stage was most prefered by the 4th larval stage of the predator.
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