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The biology of Typhlodromips swirskii (Athias-Henriot), Typhlodromus negevi Swirski et Amitai and Amblyseius denmarki Zaher et El-Borolossy was studied using Aculus fockeui (Nalepa and Trouessart) active stages as food source. For T. swirskii , development was faster than in A. denmarki and T. negevi . In A. denmarki , the oviposition period was longer and reproduction was higher than in both predacious mites. A total of 49.4, 43.0 and 32.3 eggs per female, respectively, were obtained when A. denmarki, T. swirskii and T. negevi were fed on active stages of the peach silver mite. A diet of A. fockeui provided the highest female longevity and mean total fecundity, which resulted in the highest net reproductive rate (Ro = 35.568) for A. denmarki . The highest intrinsic rate of increase (r m = 0.244), finite rate of increase (λ = 1.2766) and shortest generation time (T = 13.784) were recorded for T. swirskii . The sex ratio of the progeny was strongly female biased (female/total = 0.72, 0.68) when active stages of A. fockeui were provided for A. denmarki and T. swirskii .
Agistemus exsertus Gonzalez (Acari: Stigmaeidae) has been reported from Africa, Asia and Europe. In Egypt, it was noted to be associated with Tetranychus urticae Koch (Acari: Tetranychidae), one of the most important pest of fruit trees, vegetables and field crops. In this study, we test the hypothesis that factitious prey such as eggs of the greater wax moth, Galleria mellonella L. (Lepidoptera: Pyralidae) could be a suitable food source for the predatory mite A. exsertus. In the laboratory, we compared the developmental times, survival and life table parameters of the predatory mite A. exsertus feeding on the natural prey (T. urticae eggs) or the factitious prey (eggs of G. mellonella) as primary / alternative or supplementary food at 30 °C, 70–75% RH and photoperiod of 16: 8 (L: D) hours.Total developmental time of A. exsertus females was faster on eggs of G. mellonella than eggs of T. urticae. A total of 131.5 and 97.9 eggs per female, respectively, were obtained when A. exsertus was fed on eggs of above factitious and natural prey. Life table parameters were estimated as net reproductive rate (Ro) 92.30 and 57.291, intrinsic rate of increase (rm) 0.2384 and 0.2084 days−1, finite rate of increase (λ) 1.2692 and 1.2318, mean generation time (T) 18.98 and 19.41 days and doubling time (DT) 1.26 and 1.44 days when the predator fed on eggs of G. mellonella and T. urticae.Thus, it is concluded that A. exsertus can be considered as a valuable addition to the existing biological control for the pyralid insect, G. mellonella and also the predator can gain equally benefits from predation on factitious and natural prey.
Laboratory studies were conducted on the acceptability of pollen grains of Ricinus communis (L.) and Helianthus annuus L. to Amblyseius zaheri Yousef and El-Borolossy, Euseius yousefi Zaher and El-Borolossy, Amblyseius lindquisti Schuster and Pritchard, Typhlodromus balanites El-Badry, Typhlodromus sennarensis El-Badry and Amblyseius cabonus (Schicha) as indicated by effect on development, survival, oviposition and life table parameters. A. zaheri and E. yousefi had a shorter developmental period on both pollen grains than A. lindquisti. Development was not completed in case of T. balanites, T. sennarensis and A. cabonus. A. zaheri and E. yousefi showed the highest oviposition rate when fed R. communis compared to H. annuus. A. lindquisti failed to lay any eggs when fed on both pollen grains. On both predator species, a diet of R. communis provided the shortest generation time (T) relatively, greatest female longevity and mean total fecundity (f) which resulted in the highest net reproductive rate (Ro) value (41.46 and 43.28 expected females per female), intrinsic rate of increase (rm = 0.279 and 0.258) and finite rate of increase (er m = 1.322 and 1.294 per day) for A. zaheri and E. yousefi respectively.
Neoseiulus barkeri (Hughes) (Acari: Phytoseiidae) has been reported from Africa, Asia and Europe, often in association with Tetranychus urticae Koch (Acari: Tetranychidae), one of the most important pests of strawberry, cucumber and eggplant in different parts of the world. Neoseiulus barkeri is often observed for a limited time on plants in the absence of prey, feeding on alternative and supplementary foods and reaching high population levels. In this study, we test the hypothesis that various fungi (recorded in association with the host plant) could be suitable food source for the predatory mite N. barkeri . In the laboratory, we compared the developmental times, survival and oviposition rates of the predatory mite feeding on the primary food (T. urticae) or mycelium and spores of Aspergillus niger, Alternaria solani, Penicillium digitatum and Penicillium italicum as alternative or supplementary food. Results indicated that the fungi, A. niger, A. solani and P. digitatum are adequate food sources for generalist mite survival and development. Neoseiulus barkeri was able to sustain oviposition when fed on the fungus A. niger , so it was proved to be an alternative food, conversely the predator failed to oviposit when fed on P. digitatum and A. solani , hence, both fungi can be consider as supplementary food for the predator. The fungus P. italicum is proved to be inadequate food, since most of protonymphs failed to complete its development and reach adult female. The objective of this study was to evaluate the feeding preference and the effect of food items (pest mite or fungi) commonly present on strawberry, cucumber and pepper in fields or greenhouses.
The biology of Agistemus exsertus Gonzalez was studied using two different insect eggs, Ephestia kuehniella Zeller and Parlatoria zizyphus (Lucas) as the food source. The development was faster and reproduction was higher when A. exsertus fed on eggs of E. kuehniella. A total of 97.78 and 75.27 eggs per female were obtained when eggs of E. kuehniella and P. zizyphus were provided respectively. A diet of E. kuehniella (eggs) provided the greatest female longevity and mean total fecundity which resulted in the higher net reproductive rate (Ro) value (61.25), intrinsic rate of natural increase (rm = 0.196) and finite rate of increase (rm = 1.22) per day for A. exsertus. A diet of P. zizyphus (eggs) resulted in close values of T = 21.70; rm = 0.174; e r m = 1.19. The sex rate of the progeny was strongly female biased (female/total = 0.72 and 0.66) when both eggs of E. kuehniella and P. zizyphus were provided.
Influence of various prey stages of the pest Tetranychus urticae Koch on survival, development, and reproduction as well as the life table parameters of the predacious mite Neoseiulus barkeri (Hughes) was studied under laboratory conditions. Neoseiulus barkeri females lived shorter (36.31 days versus 45.00), had a higher total fecundity (64.81 eggs female−1 versus 53.81 eggs female−1) and a higher daily fecundity rate (2.76 eggs female−1 day−1 versus 1.78 eggs female−1 day−1), and exhibited a higher intrinsic rate of increase (0.339 individuals female−1 day−1 versus 0.226 individuals female−1 day−1) and shorter generation time (11.60 days versus 15.70 days), at 28–30 °C, 70–75% RH under continuous fluorescent light, when reared on a diet of larvae rather than a diet on mixed nymph stages of T. urticae on raspberry leaf disks. The sex ratio of the progeny was strongly female biased recorded when female of N. barkeri fed on larvae and nymphs of T. urticae. The adult female of N. barkeri consumed daily an average of 25.0 larvae versus 82.0 eggs (24–48-h old) of T. urticae during its life cycle, while it was increased to 48.6 larvae versus 80.5 eggs (24–48-h old) daily during the adult stage. Neoseiulus barkeri failed to develop beyond the protonymphal stage when the predator offered eggs (0–24-h old) of T. urticae as food. Larvae of T. urticae proved to be the most favorable stage of T. urticae for N. barkeri, while the eggs (24–48-h old) were the least.
Life history and reproductive parameters of the predatory mite Euseius scutalis (Athias-Henriot) were studied, to evaluate its potential as a predator of Spodoptera littoralis Boisduval, Spodoptera exigua (Hubner) and Agrotis ipsilon (hufnagel) eggs as an alternative food substance in the laboratory. Total developmental time of the immature stages was the shortest on eggs of S. littoralis , and the longest on eggs of A. ipsilon . Fecundity was highest on eggs of S. littoralis and S. exigua (19.8 eggs/female, 1.25 eggs/female/day and 18.22 eggs/female, 1.27 eggs/female/day) and lowest on A. epsilon eggs (9.0 eggs/female, 0.90 eggs/female/day). A diet of S. littoralis eggs showed a relatively higher values of the net reproductive rate (Ro = 10.945), intrinsic rate of increase (rm = 0.14644) and finite rate of increase (λ = 1.1577 per day) than eggs of S. exigua and A. ipsilon . A diet of A. ipsilon eggs resulted shortest female longevity and lowest total fecundity which resulted in the lowest net reproductive rate (Ro = 5.40), intrinsic rate of increase (rm = 0.10078) and finite rate of increase (λ = 1.106) per day for E. scutalis .
Juvenile survival, predation and development in Typhlodromips swirskii (Athias-Henriot), Euseius scutalis (Athias-Henriot) and Typhlodromus athiasae Porath and Swirski feeding on con- and heterospecific phytoseiid immatures were investigated in the laboratory at 32 ± 2 °C and 70 ± 5% RH. Larvae of all phytoseiid studied do not feed at all to reach the subsequent life stage. More than 90% of T. swirskii and E. scutalis protonymphs preying on larvae of both heterospecific larvae reached the adult stage. The majority (approximately 98%) of T. athiasae protonymphs feeding on larvae of T. swirskii died before reaching the deutonymphal stage, while when preying on E. scutalis , all individuals reached to adulthood. The mean developmental time of T. swirskii from protonymphal stage to adulthood was 2.4 days when feeding on T athiasae and 2.2 days when feeding on E. scutalis . When protonymphs of E. scutalis feeding on larvae of T. swirskii or T. athiasae , completed juvenile development (mean developmental time 2.9 and 2.5 days, respectively).When protonymphs of T. swirskii and T. athiasae held without food, all survived approximately 3 to 4 days and then died before reaching to deutonymphal stage. Unfed immatures of E. scutalis lived longer than the corresponding stages of T. athiasae and T. swirskii (approximately 5 to 7 days). Immatures of T. swirskii and E. scutalis exhibited higher predation rates than T. athiasae when fed on heterospecific prey. Cannibalizing immatures of all 3 phytoseiid species were able to reach adulthood. The present study indicates that phytoseiid immatures are suitable prey for developing stages of polyphagous phytoseiids. Since E. scutalis, T. athiasae and T. swirskii inhabiting the same plant species, their immatures can be regarded as potential prey for competitive phytoseiids in times of food scarcity.
Under experimental conditions, the fecundity of Typhlodromus athiasae increased with greater availability of prey (Tetranychus urticae) , but declined after reaching a level of 16 prey per day. The number of prey killed per egg produced and the number of prey killed per day during the reproductive period increased with prey availability. The total number of reproductive days increased initially, but leveled off at higher levels of prey density. As the prey density was increased, there was a shift in sex ratio towards an increased proportion of females. Age of mated females has an influence also on fecundity and sex ratio; old females produced fewer eggs compared with young females under constant condition of abundant prey.
Cannibalism and intraguild predation of immature stages and adult females of the stigmaeid mite, Agistemus exsertus Gonzalez were studied under laboratory conditions. Agistemus exsertus successfully developed and reproduced on con- and heterospecific eggs. Feeding on the natural prey Tetranychus urticae Koch eggs enhanced the development of A. exsertus, resulted in the shortest mean generation time and was the most commensurate food for the oviposition of the predator, as exhibited by the highest predation rate, fecundity and net reproductive rate. Preying interspecifically on eggs of Typhlodromus negevi Swirski and Amitai and the natural prey T. urticae produced higher intrinsic rates of increase and finite rates of increase for the predator in comparison to feed on conspecific eggs. Preying intraspecifically gave the lowest predation rate, fecundity, net reproductive rate and negative value of intrinsic rates of increase.When the predator confined without prey, no eggs was laid by the predator.This difference in the predator response to feed intra and interspecific predation should be considered to enhance the role of the predator in biological control programs.
