Comparative Study on Pseudaulacaspis Pentagona Resistance of Four Different Cultivars of Kiwifruit

Background:Kiwifruit is a common and popular fruit around the world. However, white peach scale (Pseudaulacaspis pentagona) [Targioni-Tozzetti], a scale insect with a wide range of hosts, seriously affects the yield and quality of kiwifruit. To investigate the differences in resistance of different kiwifruit cultivars to Pseudaulacaspis pentagona, cellular structure and gene expression assays were used to explain the mechanism. Results:In this study, based on the stability of the rate of injury fruit, we selected four cultivars from fifty kiwifruits for in-depth study, including “LC-04285”, “CF-3”, “DA-7B” and “Hayward”. By analyzing the differences in the anatomical structure of the canes of these cultivars, we found that the resistant cultivar "LC-04285" had thicker cuticle, denser epidermis and cortex. The real-time quantitative PCR data indicated that the expression levels of genes related to cuticle synthesis and formation of epidermis and cortex are also higher in “LC-04285”. Jasmonic acid (JA) is an important hormone involved in plant defense against many insect pests. In this study, we found that the expression levels of JA receptor COI1 were higher in “LC-04285”. However, the expression levels of AcJAZs, which played negative role in JA signaling, were higher in susceptible cultivar “Hayward”. Besides, the expression levels of AcICS, AcPAL4, AcPAL5, and AcNPRs, which were involved in salicylic acid (SA) synthesis and SA response, were also higher in “LC-04285”. Conclusions:Our results revealed the mechanism of kiwifruit resistance to P. pentagona at the molecular and cellular levels. This study provided useful guidance for breeding insect-resistant kiwifruit in future.

Evaluation of Entomopathogenic Bacteria Against Pseudaulacaspis pentagona (Targioni-Tozzetti) (Hemiptera: Diaspididae)

Pseudaulacaspis pentagona (Targioni-Tozzetti) (Hemiptera: Diaspidae) which has a wide host range, is an important pest causing losses in yield. The insecticides are used for control against this pest but insecticidal control is difficult as scales protect themselves very effectively with hard, waxy armor. Also, the negative effects of the chemicals used in the control against benefical insects and with the increasing awareness on environmental issues, alternative methods were sought. Therefore, this study was performed to develop an alternative and effective control method for this pest by using biocontrol bacteria Bacillus pumilus (TV-67C), Brevibacillus brevis (CP-1) and Bacillus megaterium (TV-91C) under controlled conditions. The death adult number of the pest was recorded and mortality rate was calculated. All of the tested bacterial strains showed mortality rates from 41.68% to 89.04% against the white peach scale under controlled conditions. Consequently, our results indicated that especially B. pumilus strain TV-67C and B. brevis strain CP-1 can be used as biocontrol agents of P. pentagona.

The Potential Global Distribution of the White Peach Scale Pseudaulacaspis pentagona (Targioni Tozzetti) under Climate Change

The white peach scale Pseudaulacaspis pentagona (Hemiptera: Diaspididae) is a pest that causes significant damage to more than 221 genera of host plants in more than 112 countries. P. pentagona primarily feeds on mulberry, peach, and tea, and this leads to the loosening of the epidermis of trees, which damages nutrient and water transportation in the branches, leading to branch death. P. pentagona is native to China and Japan, and has become an invasive species all over the world. However, the potential distribution of P. pentagona remains unclear. In this study, a potential distribution map of P. pentagona was developed using current and future climate information using MaxEnt. The model indicates that Asia, Europe, South America and North America are a highly suitable habitat range for this species. The MaxEnt models for the potential distribution of P. pentagona for the 2050s and 2070s suggest that in the case of no significant increase or even decrease in the highly suitable area, the suitable area increased significantly on any future climatic scenarios. The predicted area gain in the suitable habitat is 2.82 × 107 km2, including more of Asia, such as China, Japan, and Mongolia, and also including India, Vietnam, Romania, Ukraine, Poland, Hungary, Austria, The Czech Republic, Italy, and Germany in Europe, which shows an increase of 24.5% over the current habitat on RCP8.5 emission scenarios for the 2070s. With the warming of the climate, significant expansions are predicted in the suitable area, especially in Europe and East Asia. Under RCP8.5 for the 2050s, the model-predicted that the area of suitable habitat in China and the Korean Peninsula gains an increase of 18.8% over the current suitable habitat area. Under other climate scenarios, RCP8.5-2070s, the suitable areas were the largest, compared to projection for the current climate scenario (ca. 24.1% increase) which increased to 7.89 × 106 km2. In Europe, under RCP8.5 for the 2070s, the highly suitable areas were the largest, compared to the projection for the current climate scenario (ca. 46.2% increase), which increased to 8.64 × 105 km2, the area of suitable habitat suitability increased to 4.99 × 106 km2 (29.2% increase of the current condition). Potential increases or decreases in distribution ranges were modeled under future climatic scenarios. This study suggests that the most important factor that influenced current distribution of this pest was temperature, and BIO3 (isothermality) was the most important factor that contributed to 48.6% of the potential distribution map. Given the rapid spread of P. pentagona and the serious risk this species poses to local ecosystems, warning modelling and practical strategies to prevent the establishment and expansion of this species should be sought. This distribution map will help governments to identify areas that are suitable for current and future infestations, and to optimize pest management strategies.

Biodiversity and population fluctuations of parasitoids of the white peach scale, Pseudaulacaspis pentagona (Targioni-Tozzetti) (Hemiptera: Diaspididae), in kiwifruit orchards in Northern Iran

Summary The white peach scale, Pseudaulacaspis pentagona Targioni-Tozzetti (Hemiptera: Diaspididae), is one of the most important and destructive polyphagous pests of the Rosaceae family trees. Population fluctuations and biodiversity of the hymenopteran parasitoid species associated with the pest were studied in six kiwi orchards in Iran, during one-year period. Parasitoid species abundance, species diversity indices and evenness indices were calculated. Most of the parasitoid species were dominant or eudominant. Based on the alpha diversity indices, the Najarkola region had high diversity and the Kharatkola region had low diversity. The Paeendasteh region (based on Simpson’s Diversity on Camargo evenness indices) and the Samnakola region (based on the modified Nee, and on Smith and Wilson evenness indices) were less uniform. Among the recorded parasitoids, Encarsia berlesei Howard (Hymenoptera: Aphelinidae), followed by Aphytis proclia Walker (Hymenoptera: Aphelinidae), had the highest population in all orchards.

Flight of White Peach Scale, Pseudαulαcαspis pentαgonα, Males and Time of Crawler Appearance in Northern Greece

The seasonal Wight of white peach scale (WPS), Pseudaulacaspis pentagona Targioni-Tozzetti, males was studied during 1989, 1990 and 1991 in a peach orchard of Central Macedonia in Northern Greece by sex pheromone trapping. Three periods of male flight activity (mid-May to late June, mid-July to late August and early September to early November) were recorded annually. These flights correlated with three periods of crawler emergence (late June to early August, second ten days of August to third ten days of September, and mid-April to early May late May to early June of the next year). The first two periods of crawler activity came approximately 33 and 27 days after the beginning of the two first periods of male flight, respectively, while the crawlers corresponding to the third male flight emerged approximately 15 days after the deposition of the first spring eggs.

A geographical study on Pseudaulacaspis pentagona and its parasitoids in Hungarian highway margins using pheromone traps and molecular markers

A study has been conducted to monitor geographical spread of the white peach scale Pseudaulacaspis pentagona (Targioni Tozzetti) (Hemiptera: Diaspididae) (WPS) and its parasitoid populations in 32 stops of the Hungarian highways (M0. M1, M3, M5 and M7) using pheromone traps during 2009 and 2010. In addition to the data collected in the current study, previous data were used to investigate the population trend of this pest from 2007 to 2010. The number of males recorded in traps placed on highways was much lower than in the sites close to urban areas (M0). Our data support results of previous studies which suggest the spreading of white peach scale by vehicles (“transport vector”). The significant decrease in the WPS male catches from 2007 to 2010 might indicate the lowering of the population levels of this pest in the area of the study. Eight hymenopterous parasitoid species were captured in pheromone traps. Coccophagus sp. was the predominate species in pheromone traps of WPS in M7, how-ever they may be associated with another coccid species. The identity of scale males and some parasitoids was proved by molecular markers.