Abstract
Simple SummaryAnagyrus vladimiri has been widely employed as a biological control agent (BCA) against the vine mealybugs Planococcus ficus but the knowledge about its employment against other mealybug species is limited. In this study, we investigated the potential efficacy of A. vladimiri for Pseudococcus comstocki management, considering the increasing threat represented by this mealybug pest in Mediterranean vineyards and fruit orchards. No-choice and two-choice tests were conducted to quantify parasitoid behavior against P. ficus and P. comstocki. Our results pointed out that A. vladimiri successfully parasitized both pests, showing no host preference between the two species. Our observations highlight that this parasitoid can be successfully deployed as BCA against P. comstocki populations.The Comstock mealybug, Pseudococcus comstocki (Hemiptera: Pseudococcidae) is a primary pest of orchards in the North and Northwest of China. This pest appeared recently in Europe, including Italy, where it is infesting mainly vineyards as well as apple and pear orchards. The present study investigated the efficacy of Anagyrus vladimiri, a known biological control agent (BCA) of Planococcus ficus, on P. comstocki to evaluate a potential use for the management of this new pest. No-choice tests were conducted to quantify the parasitoid behavior against P. ficus and P. comstocki. The parasitoid successfully parasitized both species (parasitization rate: 51% and 67% on P. comstocki and P. ficus, respectively). The A. vladimiri developmental time (19.67 ± 1.12 vs. 19.70 ± 1.07 days), sex ratio (1.16 ± 1.12 vs. 1.58 ± 1.07) and hind tibia length of the progeny showed no differences when P. comstocki and P. ficus, respectively, were exploited as hosts. Two-choice tests, conducted by providing the parasitoid with a mixed population of P. ficus and P. comstocki, showed no host preference for either of the two mealybug species (23 vs. 27 first choices on P. comstocki and P. ficus, respectively). The parasitization rate (61.5% and 64.5% in P. comstocki and P. ficus, respectively) did not differ between the two hosts. Overall, our study adds basic knowledge on parasitoid behavior and host preferences and confirms the use of this economically important encyrtid species as an effective BCA against the invasive Comstock mealybug.
Highlights
The Comstock mealybug, Pseudococcus comstocki (Kuwana) (Hemiptera: Pseudococcidae), is widely recognized as an important insect pest of fruit trees, especially pear trees, in many fruit-producing regions of the world, with special reference to North and Northwest China [1]
In no-choice tests, when A. vladimiri encountered a potential host, it started antennal tapping on the mealybug body to accept or reject the host (Figure 1)
Comparing latency (χ2 = 0.86, d.f. = 1, p = 0.35), host dragging (χ2 = 0.0085, d.f. = 1, p = 0.92) and superparasitization (χ2 = 3.15, d.f. = 1, p = 0.076), the results showed no significant differences between P. comstocki and P. ficus (Figure 5)
Summary
The Comstock mealybug, Pseudococcus comstocki (Kuwana) (Hemiptera: Pseudococcidae), is widely recognized as an important insect pest of fruit trees, especially pear trees, in many fruit-producing regions of the world, with special reference to North and Northwest China [1]. Its importance as an emerging pest of fruit, vineyard and ornamental crops in European countries, including Italy, is increasing [2,3] Several studies have been conducted to increase the knowledge about the biology of this mealybug pest, looking for effective control strategies [5,6]. Jeon et al [8] investigated the incorporation of temperature in the development of forecasting models for timing insecticide applications against P. comstocki
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