Electronic Journal of Polish Agricultural Universities (EJPAU) founded by all Polish Agriculture Universities presents original papers and review articles relevant to all aspects of agricultural sciences. It is target for persons working both in science and industry,regulatory agencies or teaching in agricultural sector. Covered by IFIS Publishing (Food Science and Technology Abstracts), ELSEVIER Science - Food Science and Technology Program, CAS USA (Chemical Abstracts), CABI Publishing UK and ALPSP (Association of Learned and Professional Society Publisher - full membership). Presented in the Master List of Thomson ISI.
Volume 7
Issue 2
Available Online: http://www.ejpau.media.pl/volume7/issue2/biology/art-05.html


Dariusz Piesik



Field research was conducted to determine insects occurring on Rumex confertus Willd. The experiments were carried out in 1997, 1998, 1999 and additionally in 2001 from April to late September. The field trials were located in the natural habitat of R. confertus on meadows near Vistula river; in Bydgoszcz (53013'N, 18015'E) and Toruń (5302'N, 18061'E) vicinities. Mossy sorrel was injured by the following pests in order of feeding impact: Mamestra dissimilis Knoch., Rhinoncus pericarpius L., Phyllobius virideaeris Laich., and Phyllobius maculicornis Germ. The losses of R. confertus biomass were recorded throughout the whole growing season until the plants desiccating. Two generations of M. dissimilis in both locations were recorded. In case of R. pericarpius and Phyllobius spp. one generation was observed.

Key words: biological control, Rumex confertus Willd., mossy sorrel, insects, Mamestra dissimilis Knoch., Rhinoncus pericarpius L., Phyllobius spp..


R. confertus (mossy sorrel) is a widely adapted plant and one of the most dangerous weed in the world due to its reproductive potential expansion resulting from abundant seed production [4]. R. confertus occurs in new stands in Poland every year. As sorrel contains high amounts of oxalic acid when consumed in large quantities the lethal poisoning of animals can occur.

The chemical control of populations is difficult to maintain due to the rich root system that support rapid re-growth. After applying herbicides the green parts of the plant die, but shortly, new leaves emerge [18, 19]. Besides, unjustified chemical treatments can induce the breakdown of plant’s resistance [2, 9, 15].

Considering this dilemma biological control offers a potential solution in some regions for some pests [11, 22]. R. confertus is an example of the plant that is difficult to control by chemical methods and biological control might be a promising option to reduce its stands. Such insects as Mamestra spp. (Lepidoptera: Noctuidae) and Rhinoncus spp. (Coleoptera: Curculionidae) can play an important role in this approach [21].

The aim of this study was to evaluate the seasonal abundance and number of generations of M. dissimilis, R. pericarpius, Phyllobius spp. on R. confertus.


The experiments were carried out in 1997, 1998, 1999 and additionally in 2001 from April to late September. The field trials were located in the natural habitat of R. confertus on the marshy meadows near Vistula river; in Bydgoszcz (53013'N, 18015'E) and Toruń (5302'N, 18061'E) vicinities. Those places were chosen due to their location. R. confertus plants spread along the Vistula as well as the other rivers. Sampling was continued over whole growing season at 7 and 10 day intervals in Bydgoszcz and Toruń, respectively. In Bydgoszcz the study area covered 2,000 m2 with about 270 R. confertus growing plants. In Toruń the observations were performed in an area of 3,750 m2 with 320 mossy sorrel plants. Those areas showed significant diversification of many grass plants. The laboratory study was conducted at Dep. of Entomology, University of Technology and Agricultu re in Bydgoszcz.

In the beginning of 1997, 1998, 1999 and 2001 R. confertus was monitored and selected for the study. Whole rosette plants were used for the observation. Twenty-five randomly chosen plants in 4 replicates were observed and labeled for farther measurement. The insects sampling was performed throughout the growing season from spring to fall. Each time 25 sweeps (in 4 replicates) were made with a sweep net, which resulted in 25 compared plants. The collected insects were put in plastic bags and used for laboratory studies or killed with few droplets of CHCL3. Regular weekly (Bydgoszcz vicinity), and 10-day intervals (Toruń vicinity) observations allowed to determine insects feeding regularly on R. confertus plants and those that fed accidentally. Over the whole growing season observations were carried out on the biology, number of generations throughout the growing season and the occurrence of the species causing injuries on R. confertus. The sampling included al so larvae for the insect’s identification or rearing.

The analysis of variance means were separated using LSD Tukey’s test.


Bydgoszcz vicinity study.

M. dissimilis (Lepidoptera: Noctuidaea) is a moth with wingspan from 35 to 40 mm. Thorax, head and forewings are brownish, and hind wings brighter at a front wings.

Photo 1. Mamestra dissimilis Knoch. (photo by Dariusz Piesik)

The feeding of caterpillars on R. confertus decreased the assimilation leaves area. M. dissimilis adults were active at night but sampling was performed during a day. Consequently, the seasonal abundance (Fig. 1) shows only the changes in the density of the caterpillars.

Fig. 1. Seasonal abundance of M. dissimilis caterpillars in Bydgoszcz vicinity

There were two generations within the growing season. The development of the first generation was recorded in June. In 1997, the population was less numerous compared to the following years. The second generation of the moth was less abundant. The caterpillars occurred after mid-July and stayed on plants until the beginning of September. The largest number of individuals was recorded in 1999. It might mean that adjustment of the insects to environmental conditions has occurred and the sorrel plants have become an attractive source of food.

R. pericarpius (Coleoptera: Curculionidae) was another species in relation to R. confertus. Data show that R. pericarpius colonized the sorrel plants. The length of adult insect is from 2 to 2.5 mm. The body is covered with scales, with white lines along the prothorax, and visible distinctive white spot.

Photo 2. Rhinoncus pericarpius L. (photo by Dariusz Piesik)

The R. pericarpius occurrence was similar in 1998 and 1999 (Fig. 2) and was less numerous in 1997 and 2001.

Fig. 2. Seasonal abundance of R. pericarpius adults in Bydgoszcz vicinity

Insects occurred on plants for two months. After copulation, beetles laid eggs, however, no larvae were found after hatching. Probably, they fed in soil and their density was low. The lack of a second peak in numbers suggested that beetles did not emerge for feeding after metamorphosis, but stayed in soil until the next growing season.

Also other two species of Curculionidae were recorded; P. virideaeris and P. maculicornis. The first species is generally a little smaller with length 4.0-5.0 mm. The antennae and legs are red-yellowish. P. maculicornis is 6.0 mm long and its legs are also reddish, but they darker near the tibia tip. They occurred in May and the first peak of their abundance was recorded in mid-May (Fig. 3). They fed mostly on the young plants of R. confertus. Mossy sorrel development was not restricted due to the injuries caused by larvae. They developed on roots but other plant species.

Fig. 3. Occurrence of Phyllobius spp. adults in Bydgoszcz vicinity

The overwintering and the summer generation of adults were the most abundant in 1997 (5 and 11 individuals on 25 examined plants, respectively). In 1998, 1999 and 2001 were less favorable for the leaf weevil’s development. The summer generation colonized the plant at the end of July and the beginning of August. After feeding, the insects dropped to the soil for overwintering.

Toruń vicinity study.

In Toruń vicinity, the first generation of moths developed after overwintering of M. dissimilis pupae. Dark white eggs were laid in mass of 30-40. The emerging larvae fed holes in these leaves and reminded aggregately, caused large injuries. The seasonal abundance of caterpillars was similar to those in Bydgoszcz. The larval development of the generations occurred in June in 1998 and June and July in 1999 and 2001 (Fig. 4).

Fig. 4. Seasonal abundance of M. dissimilis caterpillars in Toruń vicinity

There were few caterpillars recorded in the first year of observations, while in 1999 and 2001 their number was larger. The second generation’s development took place at the end of July and first ten days of September. In 1999, there were more caterpillars counted.

Fig. 5. Seasonal abundance of R. pericarpius adults in Toruń vicinity

R. pericarpius left its overwintering site in first ten days of May (Fig. 5) and was observed on the plant until mid-June in 1998 and a little longer in 1999 and 2001. At the beginning of May six adults were captured in 1999. At the same time in 1998 two less individuals were observed.

Fig. 6. Occurrence of Phyllobius spp. adults in Toruń vicinity

The population of Phyllobius leaf weevils in Toruń increased in 1999 (Fig. 6). At the beginning of June four adults were caught while in 1998 only two individuals were captured. The summer generation developed from July to August in both years and their numbers were higher in 1999 and 2001. To compare to Bydgoszcz vicinity leaf weevils occurred later.

Over twice more caterpillars of M. dissimilis were captured in Bydgoszcz vicinity to compare to Toruń (Table 1).

Table 1. Total number of captured insects



Mamestra dissimilis

Rhinoncus pericarpius

Phyllobius spp.

Mamestra dissimilis

Rhinoncus pericarpius

Phyllobius spp.




































LSD Tukey a = 0.05







Similar tendency was observed for Phyllobius spp. Also, over twice more individuals were gathered. In case of R. pericarpius no significant differences between two locations were observed. In 1999 in Bydgoszcz vicinity the highest number of M. dissimilis and R. pericarpius were observed; 74,5 and 20,8 respectively. Beetles of Phyllobius spp. were the most abundant in 1997. In Toruń the highest number of individuals for all investigated insects were recorded in 1998.


Historically, biological control has been considered an environmentally safe approach to pest control. Biological control has been the most successful control strategy against invaders and is currently the curative control measure of choice against environmental weeds, owing to its effectiveness, low cost and relatively high environmental safety [6].

Increased trade, changes in agricultural practices, and greater efforts in environmental protection may lead to an increased demand for biological control introductions [7]. In biological control, exotic natural enemies often are introduced from one place to another to effect pest suppression. This is based on the premise that discovering, importing and colonizing natural enemies that occur where an insect is not considered a pest will bring it under control in the country of introduction [8].

The positive benefit–cost ratios for many projects indicate the effectiveness of classical biological control, and in some cases, indicate high economic viability. Despite benefit–cost ratios have become increasingly important in describing the success and potential of the biological control method [16]. Control options, including mechanical removal or herbicide applying for some weeds are limited [17].

Biological agents of mossy sorrel can play an important role in controlling sorrel density. Larvae and adults feeding of individual species caused significant injuries. The moths from Mamestra spp. impacted the vegetative parts of the R. confertus plant. According to some researchers the decrease of blade surface caused by Mamestra larva feeding significantly reduced the photosynthesis processes [1, 3, 14]. On the sorrel plants, also Phyllobius spp. were recorded. The adults attacked leaves, buds and pedicles, while the larvae fed on roots. Lerenius and Janson [12], Maceljski and Igrc [13], as well as Rougon et al. [20] have described feeding of adults and larvae of Phyllobius spp. on sorrel, indicating those insects as interesting for biological control.

Some other weevils have the potential for biological control. During the 1960s and 1970s, two species of weevils, Rhinocyllus conicus Froelich and Trichosirocalus horridus (Panzer), were imported into the United States and Canada as classical biological control agents of musk thistle [10]. Larvae of T. horridus feed in the plant crown, which often results in the production of multiple flower stems. R. conicus may attack flower heads. Larval feeding in the receptacle causes the abortion of developing ovules, as well as the destruction of young achenes [10]. As a result, the production of high quality seed may be reduced by as much as 78%. Also the Asian weevil Rhinoncomimus latipes Korotyaev, may be considered as potential biological control agent of Polygonum perfoliatum L. [5].


  1. Mossy sorrel (R. confertus), a weed of the polygonum family (Polygonaceae), was injured by following pests in order of feeding impact: M. dissimilis, R. pericarpius, P. virideaeris and P. maculicornis. The feeding was noted over the whole growing season.

  2. There were two generations of M. dissimilis; one of Phyllobius spp. and one of R. pericarpius in both locations.

  3. The results show some possibilities to utilize those insects as a biological control agents to reduce R. confertus population.


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Dariusz Piesik
Department of Applied Entomology
University of Technology and Agriculture
20 Kordeckiego St., 85–225 Bydgoszcz
tel. +48 52 3749361
e-mail: piesik@atr.bydgoszcz.pl

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