Laboratory studies revealed that the acarid mite, Tyrophagus casei Oudemans is an adequate diet for development and reproduction of the stigmaeid mite, Agistemus exsertus Gonzalez. A combination of pollen grains of castor bean Ricinus comrnunis L. and T. casei is a sufficient plant-animal diet for the development and reproduction of the phytoseiid mite, Amblyseius gossipi Elbadry. When the later predator was restricted to such animal prey it developed to the adult stage, but females failed to lay eggs. KEY-WORDS :Agistemus exsertus, Amblyseius gossipi, Tyrophagus casei, Mass rearing, Diet, Reproduction.The interest in predaceous mites and their manipulation for biological control has expanded greatly. Development of programs to control mite pests by mass release of phytoseiids has received much attention (Gould, 1980 ;van Lenteren et al., 1980 ; Woets & van Lenteten, 1981). In Egypt, previous studies showed that Amblyseius gossipi Elbadry is the most common phytoseiid mite on several crops and could adequately control some mite pests (Rasmy & Elbanhawy, 1975 ;Rasmy et al., 1982). It was also reported that the stigmaeid mite, Agistemus exsertus Gonzalez is a useful predator on several crops in that area (Hafez et aL, 1983).Studies of Wafa et al. (1969) and Rasmy (1975) showed that both predaceous mites could be reared on pollen. It is noteworthy that Sehliesske (1981) mass-reared the phytoseiid mites Amblyseius cucumeris Oudemans and A. mackenziei Schuster & Pritchard on grain mites. These studies were undertaken therefore to develop more convenient methods to mass-rear these predaceous mites and to find an adequate alternate prey to aid in establishment of the released predator using the acarid mite, Tyrophagus casei Oudemans as a diet. To claim such relationships between, these predators and T. casei, laboratory studies were conducted to determine the reproductive rates on the prey. MATERIALS AND METHODSThe acarid mite, T. casei was mass-reared on slices of parmesan cheese kept in plastic containers under conditions of 12~ and 80 % RH in an incubator. The cheese slices served for about 3 months in the rearing units, then they were replaced with new ones. To collect T.
The predacious mite Typhlodromus pelargonicus EI-Badry preyed on the different developmental stages of the two spotted spider mite Tetranychus urticae Koch. The development was quickest and the number of prey consumed was highest when individuals were maintained on eggs compared with nymphs or adult female stages. The predator was able to develop and reproduce on the eriophyid mite Eriophyes dioscoridis. Soliman & Abou-Awad, nymphs of the tobacco whitefly Bemisia tabaci (Genn.) and pollen grains of Phoenix dactylifera and Ricinus communis. The average number of eggs/~/day was 1.4, 0.7, 1.2 and 0.9 on eriophyid, whitefly, Ph. dactylifera and R. communis respectively. KEY-WORDS :Phytoseiidae, predacious mite, Typhlodromus pelargonicus, Tetranychus urticae, cucumber.In Egypt, cucumber plants, either cultivated in the open field or in plastic tunnels suffer from infestations by several pests such as the 2 spotted spider mite (TSSM) Tetranychus urticae Koch, the tobacco whitefly Bemisia tabaci (Genn.) and several aphids. After virtually being effective, insecticides like dicofol have become less popular. This was due to residue contamination, phytoxicity and resistance in TSSM strains.The introduction of the predacious mite Phytoseiulus persimilis A.H. has been effective against TSSM, particularly in greenhouses (Parr & Hussey, 1969 ;Gould et al., 1969). In contrast to T. pelargonicus, Ph. persimilis is a specific predator on TSSM and suffer 100 % mortality in its absence. Also it is very sensitive to change in temperature or relative humidity with optima being 24-27 oC and 70-90 % R.H. respectively (unpublished data). In plastic tunnels with no temperature regulation and in some parts of Egypt, temperatures may exceed 40 ~ during the growing season and relative humidity fall below 40 % where it is impossible for Ph. persimilis to survive (unpublished data). So, a survey of native predacious mites on cucumber plants was carded out to identify species able to survive on a wide range of host prey. The first dominant species associated with TSSM was Typhlodromus pelargonicus EI-Badry. The present work studies biological aspects, feeding preference and capacities of this species.
When females of the predacious mite Phytoseius finitimus Ribaga ingested dicofol and avermectin with the prey Eriophyes dioscoridis Soliman & Abou‐Awad, the egg production sharply decreased after 120 h in the former, while continued at a lower rate in the later respectively. Dicofol was moderately toxic when ingested, although, avermectin caused mortality increased by increasing the time of exposure to treated prey. Few immatures reached maturity when fed on treated prey with dicofol, contrasting better development and less immature mortality on avermectin treated prey. Zusammenfassung Untersuchungen über die Überlebensrate, Reproduktion und Entwicklung der räuberischen Milbe, Phytoseius finitimus (Acari, Phytoseiidae) nach Fütterung mit Dicofol‐ und Avermectin‐behandelten Beutetieren Bei weiblichen Raubmilben von Phytoseius finitimus, die über die Beutetiere (Eriophyes dioscoridis) Dicofol und Avermectin aufnahmen, konnte man beim ersten Präparat eine deutliche Abnahme der Eiproduktion ab 120stündiger Fraßzeit feststellen. Beim zweiten Präparat blieb die Eiproduktion auch bei längerer Fraßzeit erhalten, allerdings auf niedrigerem Niveau. Während bei zunehmender Fütterungszeit mit Avermectin‐behandelten Beutetieren die Wirkung auf die Raubmilbe anstieg, zeigte Dicofol diesbezüglich unterschiedliche Wirkungen. Wenige Tiere erreichten das erwachsene Stadium, wenn sie während ihrer Entwicklung mit Dicofol‐behandelten Beutetieren gefüttert wurden, dagegen zeigte sich bei Avermectin eine vergleichsweise bessere Entwicklung und geringere Mortalität während der Entwicklung.
Ecological studies on the citrus rust mite P. oleivorus infesting citrus orchards at the northern coast of the Mediterranean Sea in the U.A.R. and its management were carried out for two years. Population behaviour of the pest was influenced by the prevailing climatic conditions and host preference, while the rôle of the predacious mites was not considerable there. One acaricide application was sufficient to suppress the mite outbreak below the economic level for the entire year if it was applid when mite population started to increase. Zusammenfassung Zur Ökologie und Bekämpfung der Citrusmilbe Phyllocoptruta oleivorus (Ashm.) Es wurden 2jährige Untersuchungen über die Ökologie und Bekämpfung von P, oleivorus, einem Schädling der Zitrus‐Kulturen, in den nördlichen Küstengebieten des Mittelmeeres der U.A.R. durchgeführt. Die Populationsdichte wurde hauptsächlich von den klimatischen Bedingungen sowie dem Wirtsangebot bestimmt, während die Rolle räuberischer Milben nicht erheblich war. Es genügt eine Behandlung im Jahr mit Insektiziden, um die Milbe in einer wirtschaftlich vertretbaren Dichte zu halten, sofern die Anwendung mit dem Beginn der Massenvermehrung des Schädlings zusammenfällt.
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