Agriculture, Vol. 20 No. 1, 2014.
Other
PEAR SHOOT SAWFLY (JANUS COMPRESSUS FABRICIUS) – LIFE CYCLE AND BIOLOGICAL AND MORPHOLOGICAL CHARACTERISTIC
Tihomir Validžić
orcid.org/0000-0001-9396-4789
; Ministry of Agriculture, Department of Agriculture Inspection, Zagreb, Croatia
Abstract
The aim of the thesis was to investigate life cycle, biological and morphological characteristics of pear shoot sawfly (Janus compressus Fabricius, Hymenoptera Cephidae), furthermore to identify natural enemies in order to protect pear from this pest. The trial was conducted in the period of three years: 2010, 2011 and 2012 in pear orchards at five localities. Monitoring of adult sawfly was done by yellow sticky traps. Laboratory research was done at the Faculty of Agriculture, Department of Plant Protection, Section of Entomology and Nematology. In this study, pear shoot sawfly in Eastern Slavonia occurred in the period of four weeks, starting from the third decade of April with the peak population at the beginning of the May. Adults flight is the most intensive during warm and sunny days, when temperatures are above 14°C. Adult sawflies are characterized by elongated body and antennae, usually 7-12 mm long and sexual dimorphism is present. Pest is univoltine. Basic colour of adult sawfly is black. Antennae are moniliform and consist of 20 (male) - 22 (female) segments. Females have red or dark red colored abdomen, while males have yellow or orange one. Eggs are cylindrically shaped, 0.8-1.0 mm long. Female lays approximately 30 eggs. Embryonic development of pear shoot sawfly eggs lasts from 11 to 14 days. Larvae are 8-10 mm long, white or pale yellow. Larvae molt three times. Pear shoot sawfly larvae were parasitized by insects from Hymenoptera order, from five identified and one unidentified genera. Level of parasitism by genera is as follows: Eurytoma sp. (Hymenoptera: Eurytomidae) – 9.83%, Tetrastichus sp. (Hymenoptera: Eulophidae) – 2.01%, Eupelmus sp. (Hymenoptera: Eupelmidae) – 1.66%, Pteromalus sp. (Hymenoptera: Pteromalidae) – 0.55%, Ichneumonida sp. (Hymenoptera: Pimplinae) – 0.35% and unidentified genera – 0.62%. Plant parasitic species Metopoplax origani (Hemiptera: Lygaeidae) was found in 1.80% of analyzed shoots. Larvae were also parasitized by three genera of entomopathogenic fungi. Insect parasites and birds caused 43.6% of larval mortality, while 4.22% larval mortality was caused by entomopathogenic fungi. This research proved 10-12 days earlier appearance of adult sawfly in climatic conditions of Eastern Slavonia, contrary to other authors findings. Each female damages on the average 30 young pear shoots. Adults sawfly become inactive when average daily temperatures are lower than 10°C and during rainy and windy days. Natural enemies (parasitic wasps and entomopathogenic fungi) significantly affect larvae mortality while temperatures below 2°C (frost) are important factor for adult sawfly mortality.
Keywords
pear shoot sawfly; Janus compressus F.; life cycle; biological and morphological characteristic; insect parasitism; mortality
Hrčak ID:
123395
URI
Publication date:
18.6.2014.
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