Invasive and indigenous armoured scales (Sternorrhyncha: diaspididae) in urban lanscapes of Ukraine

The results of long-term survey of аrumored scales (Sternorrhyncha: Diaspididae) that was provided in urban landscapes in Forest- Steppe and Steppeе zones of Ukraine are presented. The species composition of alien armored scales consists of 24 species from 19 genera. 10 species were found in open field whereas 14 species were registered in green house. The most distributed were A. nerii, D. boisduvalii та D. bromeliae. The vast majority of species found in survey belong to polyphagous and represent alien species. Due to climate change, in summer there has been a shift of sub tropically originated armor scales( Aspidiotus nerii, Diaspis boisduvalii and D. bromeliae) from greenhouses to open field host plants. The coconut scale Pinnaspis buxi Bouch was recorder for the first time in this study. The features of the invasive armored scales adaptation in light of the of their development is discussed. Analysis of some important aspects of the development of morphological features of armored scales and other soft scales species of under the influence of abiotic factors indicated that the evolution of this group of insects occurred not only by adaptation but also by avoiding environmental influences. The evolution of environmental avoidance has taken place in all families of Coccoidea. The formation of the shield is seen not only as a way to avoid the influence of the environment, but as the transition of these insects to another level of evolution − the transformation of the environment to their needs.

Life history and population dynamics of Aspidiotus nerii (Bouche, 1833), Homoptera: Diaspididae, Saissetia oleae (Olivier, 1751), Homoptera: Lecanidae and Pollinia pollini (Costa, 1857), Homoptera: Asterolecanidae on olive trees in the Blida Region (Algeria)

The work consists of a study on the level of infestation of the 3 species of olive-infused mealybugs at the two stations (Soumaa and Guerrouaou) in the Blida région, with particular attention to the évolution of Pollinia pollini (Asterolecanidae), Octaspidiotus nerii (Diaspididae) and Saissetia oleae (Lecanidae). Unlike the Soumaa station, there is a large infestation in the Guerrouaou station by the three (most abundant) species with a high rate. The life cycle monitoring and the bio-ecology of these three pests were carried out through periodic population counts on the leaves and twigs of the tree from 08 August 2016 to 29 May 2017 in the wilaya of Blida. It appears that the study of the biology of P.pollini evolves in 2 annual generations (the first is the spring generation; the second is through the summer. The larval stage remains the most abandoned compared to other developmental stages. The South orientation seems the most affectionate by P.pollini. We can conclude that O .nerii has two generations « spring and automne » depending on climatic factors. The East and West exposure represent the places most sought after by this scale where we found a relative abundance between larvae and adult females. S. oleae develops only one generation per year (automnal génération). Females are the most abundant in Soumaa station and larvae in Guerrouaou station. The eastern orientation and the automne season are the most favourable for the development of the mealybug.

Abundance, seasonality and parasitism of Diaspididae (Hemiptera) on olive trees

Olive culture is a recent activity in Rio Grande do Sul, Brazil with little information on its scale insects. Abundance and seasonality of armored scale insects (Hemiptera, Diaspididae) and their parasitism was evaluated in olive orchard, Olea europaea L., cultivar Arbequina, in Caçapava do Sul (30°30′43″ S, 53°29′27″ W), RS, Brazil. Samples were monthly collected from April 2012 to March 2013. At each occasion 20 trees were drawn and, from each quadrant of their canopies (northern, southern, eastern and western) two branches (20 - 30 cm - length and contained at least 20 leaves) were randomly removed, respectively from the inner part and the outer part of the canopy. We found five species of Diaspididae, Aonidiella aurantii (Maskell), Hemiberlesia cyanophylli (Signoret), Acutaspis paulista (Hempel), Aspidiotus nerii Bouché and Melanaspis obscura (Comstock). It was not found an unique pattern of abundance, indicating that these species respond differently to temperature variations between seasons. The armored scale insects were evenly distributed among quadrants. Only H. cyanophylli showed differences in abundance between the inner and outer branches. We registered parasitism in all Diaspididae species; the total parasitism rate was 9.78%.

Developmental duration and predation rate of the coccidophagous coccinellid Rhyzobius lophanthae (Blaisdell) (Coleoptera: Coccinellidae) on Aspidiotus nerii Bouche

The consumption rate, survival, and developmental duration of the coccidophagous coccinellid Rhyzobius lophanthae (Blaisdell) (Coleoptera: Coccinellidae), a predator of the armored scale insect, Aspidiotus nerii Bouche (Hemiptera: Diaspididae) were studied under laboratory conditions at two temperature regimes of 25 ± 1 and 30 ± 1°C, 50–65% RH, and 16L:8D. Developmental time (egg to adult) significantly decreased with increase in the temperature. It lasted 27.5 days at 25 ± 1°C and 21.3 days at 30 ± 1°C. The development threshold of R. lophanthae immature stages was 7.823°C, while the thermal constant was 472.379 degree-days. No mortality was recorded during the incubation period. The total mortality rate amongst the larval instars was with 3.33% at 25 ± 1°C and 6.77% at 30 ± 1°C. The sex ratio male to female was 1:1.06. The consumption rate significantly increased with increasing temperatures and within the larval instars. The four larval instar consumed 24.3 and 33.5 adults of A. nerii at 25 ± 1 and 30 ± 1°C, respectively. Overall, micro-climate temperature had a significant impact on the biological parameters of R. lophanthae.

Factors Influencing Insecticide Efficacy against Armored and Soft Scales

Scale insects (Hemiptera: Coccoidea) are among the most economically important pests of ornamental plants. Soft scales (Coccidae) are phloem-feeding insects that produce large amounts of honeydew. By contrast, armored scales (Diaspididae) feed on the contents of plant cells and produce a waxy test that covers their bodies. We studied two species of armored scales [pine needle scale (Chionaspis pinifoliae) and oleander scale (Aspidiotus nerii)] and two species of soft scales [calico scale (Eulecanium cerasorum) and striped pine scale (Toumeyella pini)] to compare efficacy of selected insecticides. In addition, we assessed how the duration of first instar emergence might influence insecticide efficacy. Several reduced-risk insecticides (chlorantraniliprole, pyriproxyfen, spiromesifen, and spirotetramat), horticulture oil, and two broad-spectrum insecticide standards (bifenthrin and dinotefuran) were evaluated. Efficacy of insecticides was consistent within each scale family. Bifenthrin and pyriproxyfen were the only insecticides that killed soft scale insects. By contrast, all insecticides killed armored scales when the crawler stage was the target of application. Armored and soft scales may differ in susceptibility to pesticides because of likely differences in the chemical composition of their integuments and covers. Finally, we found that the effectiveness of a single application of insecticide declined by >15% when the duration of the crawling juvenile period was increased from 1 to 4 weeks. Increases in duration of a scale crawling period decreased the efficacy of a pesticide application.

Efficacy of Horticultural Oil and Insecticidal Soap against Selected Armored and Soft Scales

Insecticidal soap and horticultural oil have the potential to kill individuals within populations of soft-bodied insect pests by suffocation. However, scientific literature is inconsistent about the efficacy of insecticidal soaps and petroleum-based oils against armored scale (Hemiptera: Diaspidae) and soft scale (Hemiptera: Coccidae). We examined the efficacy of horticultural oil and insecticidal soap against armored and soft scales at different developmental life stages. Studies were conducted in the laboratory and field with two species of armored scale [pine needle scale (Chionaspis pinifoliae) and oleander scale (Aspidiotus nerii)] and two species of soft scale [calico scale (Eulecanium cerasorium) and striped pine scale (Toumeylla pini)]. All insecticide applications were made at a rate of 2 gal per 100 gal water. Our laboratory results suggested that horticultural oil and insecticidal soap killed both calico scale (73% and 93%, respectively) and oleander scale (67% and 78%, respectively) when insecticides targeted 1-day-old scales. Scale insects built up tolerance to both materials over time after they settled. However, our field data indicated that horticultural oil had high control of settled armored scale [oleander scale (90%) and pine needle scale (83%)], but failed to control settled soft scale [stripe pine scale (5%)]. Insecticidal soap reduced armored scale [oleander scale (54%)]. Neither horticultural oil nor insecticidal soap significantly reduced populations of adult armored or soft scales compared with a control. Overall, horticultural oil killed a greater percentage of armored scales than soft scales, whereas insecticidal soap gave greater control against soft scales. We suggest that differences were driven by chemical properties of both insect integuments and insecticides. The waxy cover of an armored scale might reduce penetration of polar insecticidal soap whereas polar integument of a soft scale might impede infiltration of the lipophilic horticultural oil. Consequently, timing application to crawler stage is important for effective management of armored or soft scale with horticultural oils and insecticidal soaps.