Search

Abstract: The effects of Immunocytophyte, a derivative of ethyl arachydonate (arachidonic acid ethyl ester), on the numbers of the twospotted spider mite and the predatory gall midge Feltiella luboviaewere studied on cucumber plants in a greenhouse. No considerable impact of Immunocytophyte on the herbivore and its predator was observed. The role of the acariphage in intraspecific interactions in the tritrophic system “cucumber plant—spider mite—predatory gall midge” was assessed, since these interactions influence the effectiveness of Immunocytophyte in regulating the growth and development of plants. Irrespective of Immunocytophyte application, F. luboviaeeffectively reduced the abundance of spider mites and, consequently, the level of pest damage to cucumber plants. The influence of Immunocytophyte on the formation and growth of lateral shoots depended on the damage level. The stimulating effect of Immunocytophyte on cucumber plant morphogenesis was recorded at damage levels that did not exceed 25% of the leaf surface due to the predator’s activity.

Relations between the predatory species were studied in the tritrophic system “plant—spider mite Tetranychus urticae—predatory mite Phytoseiulus persimilis+ predatory gall midge Feltiella luboviae” on Ginga F1 and Muromsky 36 cucumber cultivars, differing in their resistance to the phytophage. It was shown that the formation and functioning of the consortium were largely influenced by the resistance properties of the cucumber cultivars and the bioecological features of the consorts. The acariphages most effectively suppressed the pest at the initial stage of consortium formation, when their first generation was active. The efficiency of the predatory midge F. luboviaeon the susceptible cucumber cultivar was lower in the presence of the predatory mite Ph. persimilis. The resistant cultivar not only compensated for the negative effect of one predator (Ph. persimilis) on the oviposition behavior of the other predator (F. luboviae), but also increased the efficiency of combined use of the acariphages as compared to their separate application.

Two species of predatory gall midges of the genus Feltielladevelop in the colonies of the spider mite Tetranychus urticaeKoch (Acarina, Trombidiformes: Tetranychidae) in the vicinity of St. Petersburg. A new species Feltiella luboviaesp. n.is described, and the diagnoses of the genus Feltiellaand the widespread species F. acarisuga(Vallot), which was found in the northwest of Russia for the first time, are supplemented. Feltiella luboviaesp. n. differs from the closely related F. acarisugaand F. acarivora(Zehntner) in a number of morphological, morphometric, biological, and molecular genetic characteristics. The male genitalia of F. luboviaesp. n. have the following characters: basal protrusions angular, bare, aedeagus narrow, hypoproct swollen laterally, cerci cordiform, flagellomeres with pyriform distal node and whorls of long circumfilar sensorial loops, 2nd segment of hind tarsus 6.0–8.2 times as long as 1st and much longer than 3rd–5th tarsomeres combined. The embryonic development of F. luboviaesp. n. lasts 3.9 ± 0.12 days, the larval development lasts 9.3 ± 0.11 days, the pupal development lasts 5.9 ± 0.14 days, and the adult life span is 3.6 ± 0.13 days. The larvae and pupae of F. luboviaesp. n. develop faster than those of F. acarisuga. The COI nucleotide sequence of F. luboviaesp. n. had a 89% match with that of F. acarisugaand a 91% match with that of F. acarivora. The diagnosis of the genus Feltiellais supplemented by morphometric indices. Data on the rearing conditions for the laboratory population of F. luboviaesp. n. and evaluation of its effectiveness in protected ground as compared to F. acarisugaare given.