Apple saw wasp

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Apple saw wasp
Systematics
Class : Insects (Insecta)
Order : Hymenoptera (Hymenoptera)
Subordination : Plant Wasps (Symphyta)
Superfamily : Sawfly (Tenthredinoidea)
Family : Sawfly (Tenthredinidae)
Type : Apple saw wasp
Scientific name
Hoplocampa testudinea
( Klug , 1816)

The apple sawfly ( Haplocampa testudinea ) comes from the family of Real sawflies (Tenthredinidae). The caterpillar bores itself into young apple fruits , which is why it is considered a fruit pest.

description

The apple saw wasp is about 6–7.3 mm long. It has a shiny, compact body that is black on top and light brown to orange on the underside. The legs are yellowish-brown in color. The wings are translucent and streaked with dark brown veins. The apple saw wasp has short, nine-link thread-like antennae.

The caterpillar is white-yellow and has a dark brown head capsule. It has ten pairs of legs, which distinguishes it from the larvae of curlers , which only have eight pairs of legs. The caterpillar gives off a characteristic bug odor.

Way of life

The apple saw wasp is common all over Europe. It was first registered on the North American continent in 1939 and has since spread to the United States. The apple saw wasp lives in a stable manner. The flight of the apple saw wasp lasts from shortly before to shortly after the apple blossom. It is mainly active in the morning and noon on sunny days. The female starts laying eggs about one to two weeks after the start of the flight. To do this, it slits open the base of the apple blossom exactly below the sepals with the help of its sawing device at the rear end of the body and lays a single egg into the slit-shaped, approx. 2 mm long opening. A female lays between 10 and 20 eggs, which are preferably laid on the royal flower. A caterpillar hatches from the white, elongated and approx. 0.8 mm large egg after about 6 to 14 days. This first eats at the soft tissue of the egg-laying slot. Then it eats a spiral duct directly under the skin of the developing fruit before it bores up to the core. Here it gnaws at one or more apple pits, which inhibits the further development of the fruit. The first infected fruits are left by the caterpillar after about two weeks of eating, which then bores into a neighboring fruit, which is then eaten out inside. Infestation of another fruit is possible.

The larvae, which are fully grown after three to four weeks, leave the fruit and fall to the ground. Here they drill approx. 10-25 cm deep into the ground and spin themselves into a brownish cocoon in order to overwinter. They transform into nymphs (resting stage), which pupate in the following spring. Three to four weeks later, when the apple trees are in bloom, the next generation of wasps hatches. The larvae can survive in the ground for up to three years (so-called overhangs).

Damage

The apple fruits that are initially infected remain small and are darker in color than healthy fruits; they are noticeably hairy. Often they fall off prematurely as a result of the interrupted fruit development. If the hatched sawfly larva misses the core and the kernels are not damaged, the first infected fruit, on the other hand, can develop to maturity. As the fruit grows, the peel tears open over the miner's duct and the surface of the resulting wound corks. With the fully grown fruit, a spiral-shaped scar running around the fruit is visible in the apple skin, which usually starts from the calyx pit.

Second and third-infected fruits, on the other hand, are pierced by the larva and hollowed out inside. You are in the immediate vicinity of the fruit that was first infected. On the outside of these fruits there is an approx. 1.5 mm hole through which the larva pushes moist, smelly black droppings outwards. They fall off before harvest and do not show any scars on the surface.

Combat

The apple saw wasp can cause considerable damage in commercial fruit growing; a strong occurrence with corresponding yield losses has been observed especially since 1999. With strong to excessive fruit set, a slight infestation with saw wasps as a natural thinning of the surplus fruit is sometimes even desirable.

Control measures specifically directed against the apple sawfly are only necessary in years with a very strong infestation and in extreme infestation situations as well as with a low number of flowers. For a one-off use of pesticides to be successful, it must be applied shortly before the larvae hatch. In organic apple cultivation, quassia extract is used to combat the apple saw wasp .

The flight of the apple sawfly must be observed in order to estimate the intensity of the infestation and the correct time for treatment. Since saw wasps are flower visitors, the course of the flight can be monitored with the help of white traps . In order to be able to assess the course of the flight correctly, it should be noted that the traps must be attached before the early blooming apple varieties begin to bloom. As a damage threshold here 30-40 wasps will ever White case accepted.

Egg-laying and infestation control is difficult due to the egg-laying location of the apple sawfly, which is why the infestation intensity is usually estimated based on the previous year's infestation. Since the larvae can survive in the soil for up to three years, an assessment of the risk of infestation based on the previous year's infestation is very uncertain. The damage threshold depends primarily on the number of flowers and fruits. An infestation of 3 to 4% of the fruit tufts in May and June of the previous year is assumed to be the critical infestation rate of the apple sawfly.

Web links

Individual evidence

  1. ↑ H. Höhn and A. Stäubli: Saw wasps (Hoplocampes) on apple and plum trees. Leaflet 140. Federal Department of Economic Affairs FDEA - Agroscope Changins-Wädenswil Research Station ACW
  2. ↑ EL Taschenberg: Entomology for gardeners and gardening enthusiasts: or natural history of the insects, worms etc. which are harmful to horticulture, as well as their natural enemies, together with an indication of the protective means to be used against the former. Eduard Kummer publisher, Leipzig 1871, p. 157
  3. ↑ RW Weires: European Apple Sawfly - Haplocampa testudinea (Klug). Insect Identification Sheet No. 20 of the New York State Integrated Pest Management Program, 1991, accessed June 15, 2014
  4. ↑ John L. Capinera (Ed.): Encyclopedia of Entomology. Volume 2, Springer 2008, p. 250
  5. ↑ H. Höhn and A. Stäubli: Saw wasps (Hoplocampes) on apple and plum trees. Leaflet 140. Federal Department of Economic Affairs FDEA - Agroscope Changins-Wädenswil Research Station ACW
  6. ↑ Apple saw wasp on the homepage of the Competence Center Obstbau-Bodensee, accessed on June 14, 2014
  7. ↑ Maja Michel: Quassia use against the apple saw wasp (Hoplocampa testudinea) in organic farming in Mecklenburg-Western Pomerania. Lecture at the Mecklenburg-Western Pomerania Fruit Growing Day on February 22, 2011 in Güstrow-Bockhorst
  8. ↑ HF van Emden: Chapter 11.2.3. Family Tenthredinidae. In: Handbook of Agricultural Entomology. Wiley & Sons, 2013
  9. ↑ CPW Zebitz: Regulation of the apple saw wasp in organic fruit growing, final report on the research project no .: 03OE524 / 2, 2005, p. 19
  10. ↑ H. Höhn and A. Stäubli: Saw wasps (Hoplocampes) on apple and plum trees. Leaflet 140. Federal Department of Economic Affairs FDEA - Agroscope Changins-Wädenswil Research Station ACW
  11. ↑ Apple saw wasp on the homepage of the Competence Center Obstbau-Bodensee, accessed on June 14, 2014
  12. ↑ B. Graf et al .: Apple saw wasp: Follow now the “lean” years. In: Obst- und Weinbau 15, 1994, pp. 348-349
  13. ↑ Apple saw wasp on the homepage of the Competence Center Obstbau-Bodensee, accessed on June 14, 2014