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.
The biology of
Swirski et Amitai and
Zaher et El-Borolossy was studied using
(Nalepa and Trouessart) active stages as food source. For
, development was faster than in
, 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
were fed on active stages of the peach silver mite. A diet of
provided the highest female longevity and mean total fecundity, which resulted in the highest net reproductive rate (Ro = 35.568) for
. The highest intrinsic rate of increase (r
= 0.244), finite rate of increase (λ = 1.2766) and shortest generation time (T = 13.784) were recorded for
. The sex ratio of the progeny was strongly female biased (female/total = 0.72, 0.68) when active stages of
were provided for
(Hughes) (Acari: Phytoseiidae) has been reported from Africa, Asia and Europe, often in association with
Koch (Acari: Tetranychidae), one of the most important pests of strawberry, cucumber and eggplant in different parts of the world.
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
. In the laboratory, we compared the developmental times, survival and oviposition rates of the predatory mite feeding on the primary food
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
are adequate food sources for generalist mite survival and development.
was able to sustain oviposition when fed on the fungus
, so it was proved to be an alternative food, conversely the predator failed to oviposit when fed on
, hence, both fungi can be consider as supplementary food for the predator. The fungus
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.
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.
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.
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.
Juvenile survival and development in
(Athias Henriot) and
Ribaga feeding on con- and heterospecific phytoseiid immatures were studied in the laboratory at 28±1 °C and 70±5% RH and 16 h photoperiod. Larvae of all phytoseiids studied do not feed at all to reach the subsequent life stage. The majority (approximately 90%) of
protonymphs cannibalizing larvae died before reaching the deutonymphal stage. Only two individuals completed juvenile development.All
protonymphs failed to reach the subsequent stage and reach the adulthood when offered interspecificaly prey. Cannibalizing immature individuals of
were able to reach adulthood. The mean developmental times of cannibalizing
and when feeding on
larvae were similar and significantly shorter than that the former fed on larvae of
led to a significantly longer developmental period than the former fed interspecifically. Protonymphs and deutonymphs of
ate nearly twice more of
larvae than when fed con- or heterospecifically prey. The present study indicates that
showed from a very low tendency to feed on conspecific prey to nontendency to feed heterospecific prey. Results show also that phytoseiid immatures are suitable prey for developing stages of some polyphagous phytoseiids. Since all 3 phytoseiids inhabiting fig trees, their immatures can be regarded as potential prey for competitive phytoseiids (
) in time of food scarcity (eriophyid mites).
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.
Life history and reproductive parameters of the predatory mite
(Athias-Henriot) were studied, to evaluate its potential as a predator of
(hufnagel) eggs as an alternative food substance in the laboratory. Total developmental time of the immature stages was the shortest on eggs of
, and the longest on eggs of
. Fecundity was highest on eggs of
(19.8 eggs/female, 1.25 eggs/female/day and 18.22 eggs/female, 1.27 eggs/female/day) and lowest on
eggs (9.0 eggs/female, 0.90 eggs/female/day). A diet of
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
. A diet of
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
Under experimental conditions, the fecundity of
increased with greater availability of prey
, 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.