Galeruca pomonae

Galeruca pomonae

Galeruca pomonae is a beetle of the family of leaf beetles. The species is represented in Europe by three subspecies in Central Europe it is represented by the nominate pomonae Galeruca pomonae. The family relationships are unclear, therefore, we speak of the " Galeruca pomonae complex". Synonyms for Galeruca pomonae are Galeruca cretica, Adimonia erratica and Chrysomela rustica. The genus Galeruca is represented in Europe with five sub- genera and 31 species. The most familiar type is the tansy leaf beetle.

The genus name is from the Latin Galeruca Galea, " helmet, shield " and erucic " caterpillar " derived and refers to the caterpillar-like beetle larva. The species name pomonae ( pomōnae ) refers to the goddess Pomona.

Characteristics of the beetle

The color variable beetles can have different shades of brown or partially or completely black. It reaches a length of seven to twelve millimeters. The body outline is rounded to teardrop-shaped with the narrowest point at the anterior margin of the head and the greatest width behind the middle of the elytra. The strongly curved insect can be easily confused with several similar species.

The head is tilted forward. The sensors are turned in on the front between the leading edge of the eye and at the base of each approximated ( Fig. 1). They have about half the body length. Third and fourth antennal segment are approximately equal in length. The eyes are round and relatively small.

The very uneven and coarsely punctured prothorax is viewed from above, trapezoidal and lateral margins edged. The front edge is almost straight. The front corners of the pronotum are less rounded than in Galeruca tanaceti. Behind the front corners of the pronotum is deeply indented (Fig. 2 and 1) so that the side edge appears in a sphere. This is the best discriminating ability towards Galeruca interrupta ( comparative picture below links).

The elytra are coarsely punctured and distinctly ribbed. They are very sparsely covered with fine hair. The side edge is offset trough-shaped, flattened the channel narrowing near Galeruca pomonae at the shoulder ( Fig. 4). The elytra are rounded together at the end.

The belly is fine yellow hairs (Fig. 5). All rails are dotted raspelartig. The tarsi appear quadrinominal ( kryptopentamer ).

Larva

The black larvae are reminiscent of butterfly caterpillars. When breeding with the wild card as food plant five larval stages were observed. The larvae measured in the third stage of 4.39 mm with a tolerance of 0.53 mm. The fourth stage lasted between six and eight days and the larvae length averaged 6.09 mm plus minus 0.59 millimeters. In the fifth stage, the larvae were 7.63 mm long, with a tolerance of 0.89 mm. The 5th stage lasted 14 to 17 days. The dolls extent from 6.72 to 8.32 millimeter. The adults hatched after an average of 3.5 days ( the larvae were taken in the early stage of nature, therefore missing more information ).

Biology

The data on the biology of the species are not uniform. The occurrence is in Central Europe on dry warm locations ( slopes with southern exposure, sand pits, kurzrasige Heath and pastures, sunny forest edges ) limited. In Russia, the species was found at sea level and was present there in the wetter trough-like depressions of the steppe. In Turkey, the localities were from 300 to 1100 meters altitude.

The species lives in the grass layer on a lot of various herbaceous plants ( knapweed, scabious, thistles, leontodon, phlox, sage, yarrow, oregano, shepherd's purse, card, ...). Despite these polyphagia is examined whether Galeruca pomonae can be used in the biological control of carding. In these studies showed that in alternative offer of five different crops in a Turkish population only carding were chosen as a food source. It is possible that the populations differ in the choice behavior of the food plants.

Some species of the genus Galeruca hold a summer rest, during which they hide themselves in deeper cooler and moister soil layers. In the northwestern part of the distribution area a summer rest of the adult bees in July and August has been demonstrated that reproduction occurs in late summer and autumn. In France, a female of Galeruca was pomonae in August ten inches deep found buried in the ground. In Ukraine, over-winter as an egg the way.

In the rearing of Turkish populations in southern France with the Wild Teasel packages brown marbled eggs on the inner edge of the pots were found with the food plant or the eggs deposited on or between soil particles. The first larval stage was observed in April, the slip of the imagos was held in June, live specimens in the laboratory were found to August. The females mated prior to oviposition several times. The larvae ate on the leaf blade at the tip of the leaf rosettes of the host plant. To bore holes to necrosis formed. With the appropriate density whole floor areas are defoliated. It has been observed with respect to the ruling in the leaf rosettes high moisture tolerance of the larvae.

Dissemination

The species is widespread in most of Europe, but is missing in the North. To the east the area of ​​distribution continues to Central Asia. The beetle was introduced to North America. The beetle is absent in the Iberian Peninsula and the British Isles, as well as in Slovenia, Croatia, Bosnia - Herzegovina, Albania, Macedonia and Greece.