Mealybug (Hemiptera: Pseudococcidae) Species Associated with Cacao Mild Mosaic Virus and Evidence of Virus Acquisition

Theobroma cacao is affected by viruses on every continent where the crop is cultivated, with the most well-known ones belonging to the Badnavirus genus. One of these, cacao mild mosaic virus (CaMMV), is present in the Americas, and is transmitted by several species of Pseudococcidae (mealybugs). To determine which species are associated with virus-affected cacao plants in North America, and to assess their potential as vectors, mealybugs (n = 166) were collected from infected trees in Florida, and identified using COI, ITS2, and 28S markers. The species present were Pseudococcus jackbeardsleyi (38%; n = 63), Maconellicoccus hirsutus (34.3%; n = 57), Pseudococcus comstocki (15.7%; n = 26), and Ferrisia virgata (12%; n = 20). Virus acquisition was assessed by testing mealybug DNA (0.8 ng) using a nested PCR that amplified a 500 bp fragment of the movement protein–coat protein region of CaMMV. Virus sequences were obtained from 34.6 to 43.1% of the insects tested; however, acquisition did not differ among species, X2 (3, N = 166) = 0.56, p < 0.91. This study identified two new mealybug species, P. jackbeardsleyi and M. hirsutus, as potential vectors of CaMMV. This information is essential for understanding the infection cycle of CaMMV and developing effective management strategies.

Use of Sugar Dispensers to Disrupt Ant Attendance and Improve Biological Control of Mealybugs in Vineyard

Planococcus ficus (Signoret) and Pseudococcus comstocki (Kuwana) (Hemiptera: Pseudococcidae) are economically important pests occurring in vineyards, causing severe economic losses for growers and compromising bunch production. The partial effectiveness of insecticides used in controlling mealybug infestations as well as their high impact on the environment and on human health have led to the research of alternative and sustainable control methods, including biological control. Several natural enemies are reported to be effective against mealybugs, but their activity may be hindered by tending ants. These social insects are known to exhibit a mutualistic relationship with mealybugs, resulting in extremely aggressive behavior against beneficial insects. Consequently, this study explored a method to mitigate ant attendance by means of sugar dispensers in order to improve ecosystem services, as well as decrease mealybug infestation in vineyards. Field trials were carried out in four commercial vineyards of Northern Italy infested by mealybugs, in which Anagyrus vladimiri Triapitsyn (Hymenoptera: Encyrtidae) and Cryptolaemus montrouzieri Mulsant (Coleoptera: Coccinellidae) were released as biological control agents. Our results showed that sugar dispensers reduced ant activity and mealybug infestation, leading to a significant enhancement of ecosystem services. The technique showed a great potential in boosting biological control against mealybugs in field conditions, though the field application seemed to be labour intensive and needs to be replicated for a multi-year evaluation.

Old Parasitoids for New Mealybugs: Host Location Behavior and Parasitization Efficacy of Anagyrus vladimiri on Pseudococcus comstocki

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.

New data on the fauna of mealybugs (Hemiptera; Pseudococcidae) inhabiting subtropical plants in the Lankaran-Astara Region of Azerbaijan

Invasive insect species enter new environment mainly with their host plants and spread rapidly in new conditions due to the absence of natural entomophages that can effectively limit their numbers. Comprehensive studies of the invaders, including crop pest, are of great importance for agricultural practice. In this regard, we investigated mealybugs (Pseudococcidae) in the orchards of five subtropical species, viz. lemon (Citrus limon) mandarin (Citrus reticulate), orange (Citrus sinensis), persimmon (Diospyros kaki), and pomegranate (Punica granatum) in the Lankaran-Astara Region of Azerbaijan. The research was conducted in 2016‒2019 in various seasons. Three mealybug species were recorded from the area in question: Pseudococcus comstocki Kuwana 1902, Pseudococcus viburni Signoret 1875, Pseudococcus calceolariae (Maskell, 1879). An annotated list of species provides collecting localities, their geographical coordinates, dates of collection, and the number of individuals found. We obtained data on species distribution, biology, host plants and signs of infestation. Ps. viburni was registered in the fauna of Azerbaijan for the first time; a developement period of its larvae and imagoes is provided. The highest infestation of the vegetative organs was observed on the citrus plants: on average, 30 % of trees were damaged by Ps. comstocki, 27 % by Ps. viburni, and 21 % by Ps. calceolariae. Two mealybug species (Ps. comstocki, Ps. viburni) were found on the persimmon and only one species (Ps. comstocki) on the pomegranate. Ps. comstocki population density was the highest in the study area (3–5 larvae per 10 cm of branches, and 4–5 colonies per 100 leaves during flowering). All three species were found together on the stems and leaves of citrus crops; Ps. comstocki was observed on the fruits of mandarin and persimmon, and Ps. viburni was only on the persimmon. Based on the data obtained, the degree of harmfulness of the above species was determined: for Ps. comstocki – 3–5 larvae per 10 cm of branches, and 4–5 colonies per 100 leaves during flowering; for Ps. viburni – 2–3 larvae per 10 cm of branches, and 3–4 colonies per 100 leaves during flowering; and for Ps. calceolariae – 2–3 larvae per 10 cm of branches, and 2–3 colonies per 100 leaves during flowering.

Data on the scale insect (Hemiptera: Coccomorpha) fauna of Greece, with description of two new species

Surveys of the scale insect (Hemiptera: Coccomorpha) fauna of Greece were carried out in 2013 and 2014. Altogether 93 scale insect species were collected, belonging to 11 families. Thirty-eight species (41%) proved to be new to the Greek fauna, including two species new to science (Anophococcus hellenicus Kaydan & Szita sp. n. (Acanthococcidae) and Iberococcus attikus Szita & Fetykó sp. n. (Pseudococcidae)), and two introduced invasive species (Phenacoccus graminicola Leonardi and Pseudococcus comstocki (Kuwana), both Pseudococcidae). The rest of the species seem to be native to the Greek fauna. The total number of scale insect species recorded from Greece is increased to 253.