Imported Willow Leaf Beetle Research Articles

Odorant binding protein 18 increases the pathogen resistance of the imported willow leaf beetle, Plagiodera versicolora.

Insect odorant-binding proteins (OBPs) are a class of small molecular weight soluble proteins. In the past few years, OBPs had been found to work as carriers of ligands and play a crucial role in olfaction and various other physiological processes, like immunity. A subset of insect OBPs had been found to be expressed differently and play a function in immunity of fungal infection. However, there are few studies on the role of OBPs in immunity of bacterial infection. To identify the immune-related OBPs of Plagiodera versicolora after infected by Pseudomonas aeruginosa, we determined the mortality of P. versicolora to P. aeruginosa and selected the time point of 50% mortality of larvae to collect samples for RNA-seq. RNAi technology was used to investigate the function of immune-related OBPs after P. aeruginosa infection. RNA-seq data shows that PverOBP18 gene significantly up-regulated by 1.8-fold and further RT-qPCR affirmed its expression. Developmental expression profile showed that the expression of PverOBP18 was highest in the pupae, followed by the female adults, and lower in the 1st-3rd larvae and male adults with lowest in eggs. Tissue expression profiling showed that PverOBP18 was dominantly expressed in the epidermis. RNAi knockdown of PverOBP18 significantly reduced the expression of bacterial recognition receptor gene PGRP and antibacterial peptide gene Attacin and reduced the resistance of P. versicolora to P. aeruginosa infection. Our results indicated that PverOBP18 gene increased the pathogen resistance of P. versicolora by cooperating with the immune genes and provided valuable insights into using OBPs as targets to design novel strategies for management of P. versicolora.

Laboratory effects of three biocontrol agents against imported willow leaf beetle, 2023

Laboratory effects of three biocontrol agents against imported willow leaf beetle, 2023

Contribution to the knowledge of development and harmfulness of imported willow leaf beetle (Plagiodera versicolora) (Coleoptera, Chrysomelidae)

The paper deals with the occurrence, development and harmfulness of imported willow leaf beetle (Plagiodera versicolora Laich.) in riparian and accompanying stands of the Svratka and Svitava rivers in the region of Brno. Salix fragilis L. and S. × rubens Schr. are the most damaged species there. Imagoes leave wintering places usually at the beginning of May. During about a 60-day period, they damage ca. 23.3 cm<sup>2</sup> leaves of S. fragilis and lay 250 to 730 (on average 539) eggs. The whole egg-laying consists of 16 to 48 (on average 35.5) groups with 6 to 26 (on average 15.2) eggs. The fecundity of females hatched in the laboratory is minimally twice lower. Larvae hatch after 5 to 8 (in the laboratory after 4.3) days and damage about 282 mm<sup>2</sup> leaves. The development from laying eggs until hatching imagoes of the <br />1<sup>st</sup> generation takes about 21 (in the laboratory about 15) days. Imagoes of the 1<sup>st</sup> generation occur on trees from the end of May to mid-August and die after completing their reproduction. Plagiodera versicolora creates 3 to 4 (in the laboratory 4 to 6) generations during a year. The small part of imagoes of the 2<sup>nd</sup> generation, predominant part (or all) imagoes of the 3<sup>rd</sup> generation and under conditions of a tetravoltine development all imagoes of the 4<sup>th</sup> generation enter a diapause. In the course of the growing season, the food consumption of imagoes and larvae decreases and fecundity of females markedly decreases. Schizonotus sieboldi (Ratz.), Medina melania (Meig.) and M. luctuosa (Meig.) rank among main enemies of Plagiodera versicolora.

Preference and performance of a willow-feeding leaf beetle: soil nutrient and flooding effects on host quality.

The distribution and abundance of herbivores on plants growing under different environmental conditions may depend upon preference and/or performance. Soil nutrients and water availability are key determinants of herbivore distribution, as both influence plant growth and tissue quality. However, the effects of water on plant quality may depend upon the availability of nutrients and vice versa. Surprisingly few studies have examined the interactions between the two. We investigated the effects of soil nutrient and water availability on (1) the growth and chemistry of the silky willow (Salix sericea Marshall), and (2) the preference and performance of the imported willow leaf beetle (Plagiodera versicolora Laichartig). We conducted two common garden experiments using a similar 2x2 fully factorial design with two levels of soil nutrients (low, high) and two levels of water availability (field capacity, flooded). In the first experiment (larval performance), larval development time and pupal weight were not influenced by nutrient or water availability to the plant. This occurred despite the fact that plants in the high nutrient treatments had higher protein concentration and lower foliar concentrations of the phenolic glycoside 2'-cinnamoylsalicortin. In the second experiment (adult preference), we caged four plants (one from each treatment) and released beetles into cages. We found that plant growth and leaf protein depended upon the interaction between nutrient and water availability. Plant growth was greatest in the high nutrient-field capacity treatment and leaf protein was greatest in the high nutrient-flooded treatment. In contrast, adults settled and oviposited preferentially on the high nutrient treatment under flooded conditions, but we found no evidence of interactions between nutrients and water on preference. Thus, at least under flooded conditions nutrients affect adult preference. We also found that foliar protein was correlated positively with adult oviposition preference and per capita egg production. Our results, then, suggest that soil nutrients can influence adult preference, and that adults choose high-quality hosts (high protein) that promote egg production.

Soil nutrients and water availability interact to influence willow growth and chemistry but not leaf beetle performance

AbstractWe investigated the effects of soil nutrient and water availability on the growth and chemistry of the silky willow (Salix sericea Marshall), and on the performance of the imported willow leaf beetle (Plagiodera versicolora Laichartig). Our major aims were to determine whether there are nutrient–water interactions on plant traits and whether this leads to parallel interactions for herbivore performance. We used a 2 × 3 fully factorial design, which consisted of high and low nutrient treatments crossed with dry, field capacity, and flooded water treatments. We found that nutrient additions increased plant growth, but only in field capacity and flooded conditions (nutrient–water interaction). Leaf nitrogen content also depended on the interaction between soil nutrients and water: nutrient addition resulted in a larger increase in foliar nitrogen in the field capacity treatment than in the flooded and dry treatments. Of the two phenolic glycosides measured, salicortin and 2′‐cinnamoylsalicortin, only one was affected by the treatments. 2′‐cinnamoylsalicortin concentration was lower in the high nutrient–dry treatment compared with the other treatments. In contrast to plant responses, there were no interactions found for larval or pupal weight or development time. Nutrient addition led to an increase in female pupal weight, and foliar N was positively correlated with female pupal weight and negatively correlated with female development time. In addition, leaf water was positively correlated with female development time. The lack of interactions for insect performance may stem from the small absolute differences in foliar nitrogen content associated with the interaction between the nutrients and water. Taken together, our results suggest that nutrient–water interactions influence plant traits that are potentially important for insect performance (leaf nitrogen and water), but these interactions do not produce parallel interactions in beetle performance.

Proteinase inhibitor II gene in transgenic poplar: Chemical and biological assays

Transgenic poplar lines were developed to investigate the role of a proteinase inhibitor in pest resistance of woody plants. Using an Agrobacterium binary vector system, the clone ‘Hansen’ ( Populus alba L. × P. grandidentata Michx.) was transformed with chimeric genes containing the coding region of potato proteinase inhibitor II ( PIN2) linked to either a bacterial nopaline synthase ( nos) or a cauliflower mosaic virus (35 S) promoter. All transferred DNA also contained a selectable marker in the form of a nos promoter linked to a neomycin phosphotransferase II ( NPT II) structural gene. The presence of the transferred PIN2 and NPT II sequences in poplar was confirmed for nine transgenic lines using polymerase chain reaction (PCR). Expression of PIN2 in leaves of transgenic poplar was demonstrated by enzyme-linked immunosorbent assays (ELISAs) and western blots. Two unique polypeptides from transgenic poplar, of ca 8 kDa and ca 12 kDa, indicate that PIN2 was translated appropriately. Resistance to the imported willow leaf beetle was tested in laboratory bioassays. The untransformed clone ‘Hansen’ and 11 transgenic lines were submitted to freshly hatched larvae to determine effects on pupal weight, larval development time and leaf area consumed. A significant difference from the untransformed clone in leaf area consumed was detected in one transgenic line, Tr665. Trends were indicated for several other transgenic lines for the other parameters.

Daytime mechanisms of reaggregation in imported willow leaf beetle, Plagiodera versicolora, larvae (Coleoptera: Chrysomelidae)

The roles that leaf quality, the presence of siblings, trails, vision and touch play in reaggregation by imported willow leaf beetle larvae were examined. Larvae responded positively to the presence of siblings, their secretions, and faeces while reaggregating. Larvae do not have to see or touch siblings in order for reaggregation to occur and leaf quality does not appear to be involved in reaggregation. There were differences in behaviour of 4- and 8-day-old larvae: 4-day-old larvae responded positively to the presence of siblings whereas 8-day-old larvae did not, and under natural conditions 4-day-old larvae are found in aggregations whereas 8-day-old larvae are solitary.

The effect of season and group size on survivorship and larval growth in Plagiodera versicolora

Abstract. The larvae of the multivoltine imported willow leaf beetle, Plagiodera versicolora (Laicharting), are found in larval aggregations during the first half of the larval stage. An experimental study was conducted to test for seasonal (brood) and group size effects on larval fitness. For each of the three broods, egg group sizes of1, 4, 8, 16, 24 and 32 were established in the field and monitored for the first 6 days post‐hatching. There was no effect of group size on larval weight, but there was a significant effect of group size on survival. Individuals from group size 16 had the highest survival, which coincides with the mean natural cluster size of 15.3 eggs. There were no significant interactions between brood and group size. The effect of larval weight on adult fitness was determined in the laboratory and the field. Larval weight was correlated with egg production in the laboratory but not in the field.

Response of the imported willow leaf beetle to Bacillus thuringiensis var. san diego on poplar and willow

Response of the imported willow leaf beetle to Bacillus thuringiensis var. san diego on poplar and willow

Control of Imported Willow Leaf Beetle on Willow, 1990

Abstract Control of imported willow leaf beetle larvae was evaluated by selecting the terminal 61 cm of a branch infested with larvae on each of 3 trees. Treatments were randomly assigned to the infested branches and replicated 3 times with each branch serving a single replication. Branches were sprayed until runoff using a 1 qt capacity, hand-held Polysprayer. Temperature at time of application was 24°C and wind velocity was less than 5 mph. Larval mortality counts were conducted prior to spraying (0 DAT) and at 2, 6, 9, and 16 DAT by counting the total number of live larvae (all instars) on the terminal 61 cm of each treated branch. Larvae that were shriveled, distorted, and lacked movement were considered dead. No attempt was made to evaluate for adult beetle control.

An Artificial Diet for Cottonwood and Imported Willow Leaf Beetles (Coleoptera: Chrysomelidae) and Comparative Performance on Poplar Foliage2

An artificial diet was developed for laboratory rearing of the cottonwood leaf beetle, Chrysomela scripta F., and the imported willow leaf beetle, Plagiodera versicolora (Laicharting). To reduce microbial contamination of the media, procedures were developed for separating egg masses and sterilizing egg surfaces. Cottonwood leaf beetle larvae reared from neonate to adult on this artificial diet had greater mortality, took longer to develop, and were smaller than larvae reared on fresh poplar foliage. Adult longevity was similar for both diet-and foliage-reared larvae. Survival and adult fresh weight of imported willow leaf beetle larvae reared on the artificial diet were similar to those of cohorts reared on fresh poplar foliage. However, individuals reared on artificial diet took longer to develop and produced shorter-lived adults than cohorts reared on foliage. Larvae of both species would not eat fresh foliage after being fed on the artificial diet. Adults of both species maintianed on the artificial diet laid few eggs but resumed normal oviposition when fed fresh foliage. This artificial diet proved useful for rearing larvae and maintaining adults during periods when fresh foliage was limited.

Efficacy of Summer Oil Spray on Thirteen Commonly Occurring Insect Pests

The limited investigations of the past have shown that, when applied at low concentrations to woody ornamentals in verdant condition, horticultural oil provides a safe and effective means of controlling a wide variety of arthropod pests. This report provides data showing that the superior oil product Sunspray 6E Plus is highly effective against the woolly larch adelgid, cottony maple scale, calico scale, golden oak scale, boxwood psyllid, honeylocust plant bug, sycamore lace bug, European pine sawfly, and the euonymus webworm. Poor to no effect is reported here against adults of the sycamore plant bug, adults and larvae of the imported willow leaf beetle, and Japanese beetle. Phytotoxicity data are also included.

Selection Within and between Kin Groups of the Imported Willow Leaf Beetle

Two opposing levels of selection determine the evolution of cannibalism in the imported willow leaf beetle, Plagiodera versicolora. Within kin groups, cannibals exhibit a developmental and survival advantage over non-cannibals. Between groups, individuals in groups with low rates of cannibalism enjoy a survival advantage owing to an increase in survival with larval group size. This effect of the cannibal on group survivorship is not a simple function of group size; rather, the effect of an individual's phenotype on the fitness of the other members of its kin group depends on the array of phenotypes in the group. Two factors determining the evolution of cannibalism vary in space and time: the relative strength of selection within and between groups; and the average degree of relatedness within groups, which determines the evolutionary outcome of selection. This sets up the possibility that the balance between selection for cannibalism within and between groups may vary in a complicated manner across the range of this species.

Plant stress and insect performance: cottonwood, ozone and a leaf beetle.

Leaf area consumption rates, development rates, survivorship, and fecundity of the imported willow leaf beetle (Plagiodera versicolora Laich) were examined on two clones of eastern cottonwood which were previously exposed to ozone or charcoal-filtered air. P. versicolora consumed more ozone treated foliage, but were more fecund when reared on charcoal-filtered air treated plants. Beetle development rates and survivorship were not significantly different on treated and control cottonwoods. We concluded that: 1) Ozone fumigation of cottonwood reduced foliage quality, and the reproductive success and overall performance of P. versicolora. 2) increased foliage consumption by beetles was probably a mechanism compensating for decreases in foliage quality. 3) Reductions in beetle fecundity were due to an initial reduction in oviposition rates. 4) Beetle feeding preference did not correlate with the suitability of foliage for beetle performance. These results are discussed in relation to the impact of air pollution on plant-insect interactions.

Acute Ozone Stress on Eastern Cottonwood (Populus deltoides Bartr.) and the Pest Potential of the Aphid, Chaitophorus populicola Thomas (Homoptera: Aphididae)

The effect of acute ozone exposure of eastern cottonwood ( Populus deltoides Bartr.) on the survivorship, reproduction, and development of the aphid Chaitophorus populicola Thomas (Homoptera: Aphididae) was investigated. Cottonwoods were exposed to 397 μ g/m3 (0.20 ppm) ozone or charcoal-filtered air and infested with aphids on leaf plastochron index 5, 40 h after fumigation. Aphid performance was not significantly different on plants exposed to ozone compared with charcoal-filtered air-treated control plants. These data do not support the notion that aphid performance will directly increase on air pollution-stressed plants. We also examined settling and feeding preference of aphids for cottonwood leaves of different developmental ages. Aphids significantly preferred leaf plastochron index 5 to all other leaf ages. These data support hypotheses relating aphid leaf preference to stages of leaf development. Reproduction of the cottonwood leaf rust fungus ( Melampsora medusae Thum.) and the imported willow leaf beetle ( Plagiodera versicolora Laicharting) are reduced on ozone-fumigated plants (reported elsewhere). If aphid populations are affected by competition with these cottonwood pests for leaf resources, then aphid pest potential may actually increase in areas characterized by episodic ozone concentrations because of ozone-induced decreases in populations of M. medusae and P. versicolora .

Spatial and Temporal Variation in Group Relatedness: Evidence from the Imported Willow Leaf Beetle

Spatial and Temporal Variation in Group Relatedness: Evidence from the Imported Willow Leaf Beetle

An Experimental Study of the Effect of Group Size on Larval Growth and Survivorship in the Imported Willow Leaf Beetle, Plagiodera versicolora (Coleoptera: Chrysomelidae)

The larvae of the imported willow leaf beetle, Plagiodera versicolora (Laicharting), feed in coordinated groups of full and half siblings during early development. When disturbed they exude an antipredator chemical, which may be more effective in groups. Two experimental studies were conducted to test for a group advantage. Groups of initial size 2–10 or 2–14 larvae were established and sampled from days 1 to 6 after hatching. The first study showed no effect of group size on survivorship nor on average leaf area consumed, but there was a significant effect of group size on larval growth. This suggested an increase in feeding efficiency with group size. In the second study the initial average rate of cannibalism for a group had a significant effect on subsequent individual growth rates, and survivorship increased with group size.

Life History of Natural Populations of the Imported Willow Leaf Beetle, Plagiodera versicolora (Coleoptera: Chrysomelidae)

Two populations of the imported willow leaf beetle, Plagiodera versicolora (Laicharting), in northern Illinois were studied during four spring seasons between 1979 and 1983. The life cycle includes an egg stage of 5–6 days, a larval stage of 14 days, a pupal stage of 4–5 days, and an adult stage lasting 3–4 weeks. Mean clutch size in the field ranged from 15 to 19 eggs for the four seasons; mean size of eclosing larval groups ranged from 8 to 13. Larvae remain aggregated during the first three stadia, and there is a positive effect of initial group size on larval survivorship

The suitability of damaged willow leaves as food for the leaf beetle, Phgiodera versicolora

Abstract. 1. The effect of previous damage on the suitability of willow (Mix bubylonicu and S.ulbu‘Tristis’) leaves as food for the imported willow leaf beetle, Plugiodera versicoloru Laich. (Coleoptera: Chrysomelidae), was evaluated by feeding adults and larvae leaves from damaged and undamaged branchlets.2. Females had lower fecundity when fed leaves from artificially damaged branchlets of S.ufba‘Tristis’. A similar result was obtained when beetles ate leaves from naturally damaged branchlets of S.babylonica.3. Feeding preference tests suggest that the reductions in leaf suitability were not due to adults avoiding damaged leaves as a food source.4. PZugiodera versicolora larvae required longer to develop and attained a lower adult weight when fed leaves from damaged branchlets.5. Changes in leaf suitability brought about by herbivore feeding may affect the seasonal abundance of P.versicoloru on its willow hosts.

The effect of multiple mating on genetic relatedness in larval aggregations of the imported willow leaf beetle (Plagiodera versicolora, Coleoptera: Chrysomelidae)

The effect of multiple mating on the average genetic relatedness within socially interacting sib groups was studied in the imported willow leaf beetle. Using an electrophoretically determined genetic marker, it was demonstrated that between 49 and 96% of wild caught females produce egg clutches expressing multiple sires. Following theoretical predictions of Wade (1982), this information was used to estimate the harmonic mean number of sires per family and then the average relatedness within families. Average relatedness was estimated to be 0.38. An alternate form of data analysis suggested by Pamilo and Crozier (1982) did not require any knowledge of paternity and resulted in a slightly higher estimate of relatedness, 0.44.