Agistemus Exsertus Research Articles

Enhancing the Biological Control of Mite Species Infesting Olive Trees through Application of Predatory Mite Agistemus exsertus Gonzalez (Acari: Stigmaeidae) and Eco-Friendly Natural Compounds.

Olive (Olea europaea L.) is a subtropical tree cultivated in arid, dry and temperate regions. Olive orchards in Al-Jouf of Saudi Arabia are the largest worldwide and currently face harmful pest infestation. The present study aimed at evaluating the efficiency of the predatory mite Agistemus exsertus Gonzalez (Acari: Stigmaeidae) and the exogenously applied melatonin (MT), glycine betaine (GB) and 5-aminolevulinic acid (ALA) as eco-friendly approaches for enhancing the biological control of four mite species (Tegolophus hassani, Oxycenus niloticus, Aceria olivi and Tetranychus urticae) infesting olive trees in Al-Jouf under laboratory and field conditions. Field experiment was conducted on 6-year-old Manzanillo olive trees grown in a private orchard farm in Al-Jouf during two seasons, 2020 and 2021. Results revealed that A. exsertus developed successfully from egg to adult. The females of T. hassani, O. niloticus, A. olivi, and T. urticae required 7.36, 8.89, 9.98 and 8.38 days, respectively, to develop from egg to adult at 28°C and 65 ± 5% relative humidity. O. niloticus was the most preferred prey of A. exsertus. The net reproductive rate (R0 ) was 42.1, 38.7, 34.6 and 36.8 females/female/generation, the intrinsic rate of increase (rm ) was 0.27, 0.26, 0.23 and 0.20 females/female/day, and the mean generation time (T) was 16.2, 17.1, 18.6 and 17.2 days when a predator consumed T. hassani, O. niloticus, A. olivi and T. urticae, respectively. The adult female consumed daily about 114 O. niloticus, 105 A. olivi, 95 T. hassani and 15.2 T. urticae individuals, respectively. A. exsertus proved to be an effective biocontrol agent against mites infesting olive trees. In addition, the exogenous application of 1 mM MT, 15 mM GB and 25 mg/L ALA, alone or in combination, caused significant mortality for the four mites. Application of these natural compounds, alone or in combination, also significantly enhanced the growth, relative water content, relative chlorophyll, content of flavonoid and nutrients, antioxidant enzymes activities, stress-related genes expression and fruit yield and quality of the infested olive trees compared to non-treated infested trees. This study is the first that demonstrates the efficiency of these eco-friendly approaches for controlling mites infesting olive trees, and could be used as a replacement for the harmful chemical acaricides.

Susceptibility of soybean varieties for mites associated with some biological aspects

Populations of Tetranychus urticae Koch (Acari: Tetranychidae), and its predatory mite, Agistemus exsertus Gonzalez (Acari: Stigmaeidae), were determined on four soybean varieties during 2016 season, as well as study of some biological aspects for both species was done. The obtained results revealed that Giza 35 variety was the most susceptible variety with significant difference between the mean numbers of T. urticae compared with other varieties. The mean of infestation was 11.89 individuals/25cm2 of leaves, while the mean number of T. urticae was 7.11 and 3.54 individuals/25cm2 of leaves for Giza 111 and Giza 82 without significant difference. Giza 22 recorded the lowest mean number of T. urticae 1.53 individuals/25cm2. The population dynamics of T. urticae cleared that infestation increased gradually from mid-June reach its maximum at the end of July then decreased gradually at the beginning of August reach its minimum number at the beginning of September before the harvest time. As for A. exsertus, data showed that the mean number of A. exsertus was the highest on Giza 35 (2.46 individuals/25cm2) followed by Giza 22 (2.13 individuals/25cm2), but Giza 82 and Giza 111 mean numbers were 1.99, and 1.91 individuals/25cm2. Life cycle of Tetranychid males was the shortest when reared on Giza 35with significant difference with other varieties. As for females, the shortest life cycle was when reared on Giza 35 with significant difference with Giza 22, which recorded the longest life cycle for males and females respectively.

Species Composition and Diversity of Mites Inhabiting Pomegranate Orchards at Assiut, Upper Egypt

Mites play an important role in the biological cycle of nature, as well as in the agricultural cycles of plants. They are considered to be very important for most plants, especially fruit orchards, which case both, qualitative and quantitative losses, they also cause different types of allergenic reactions among the fruit handles and farmers. A comprehensive survey of mites inhabiting pomegranate orchards at Assiut and its suburbs was conducted in the work herein. During the current work, colonies of the pomegranate false spider mite, Tenuipalpus punicae Pritchard & Baker and the mango spider mite, Oligonychus mangiferus (Rahman & Sapra) were recorded on pomegranate trees at Assiut governorate. The relative abundance of both mite species and their natural enemies was conducted. Based on previous studies, about 24 mite species in nine families were recorded in Egypt. In order to determine species composition of phytophagous and predacious mites on pomegranate trees, samples were taken from leaves, buds and fruits during 2018/2019 and 2019/2020 seasons. The citrus brown mite, Eutetranychus orientalis (Klein); T. punicae and the broad mite, Polyphagotarsonemus latus (Banks) seemed to be the most common phytophagous mites on pomegranate trees. On the other side, several predatory mite species were also recorded in the present work. Of these, Amblyseius swirskii Athias-Henriot; Euseius scutalis (Athias-Henriot); Typhlodromus (Typhlodromus) pyri Scheuten; Neoseiulus barkeri Hughes (Phytoseiidae), and Agistemus exsertus Gonzalez (Stigmaeidae), all were recorded in large numbers, especially on pomegranate leaves of all varieties. While Cheletogenes ornatus (Canestrini & Fanzago) and Cheletomimus bakeri (Ehara) (Cheyletidae) were recorded mostly on leaves and fruits. Quantifying the occurrence of various predacious mite species on pomegranate trees, may be of great importance to reduce the number of phytophagous ones. In separated subsequent studies, the efficacy of these predatory mites can be estimated as one of the biological control agents.

Susceptibility of Soybean Varieties to Mites Associated with Some Biological Aspects

Populations of Tetranychus urticae Koch (Acari: Tetranychidae), and its predatory mite, Agistemus exsertus Gonzalez (Acari: Stigmaeidae), were determined on four soybean varieties, namely, Giza 22, 35, 82 and 111, during the 2016 season, and in addition some biological aspects of both species were studied. The results obtained revealed that Giza 35 variety was the most susceptible variety with significant difference between the mean numbers of T. urticae compared with other varieties. The mean rate of infestation was 11.89 individuals/25 cm2 of leaves, while the mean number of T. urticae was 7.11 and 3.54 individuals/25 cm2 of leaves for Giza 111 and Giza 82 without significant difference. Giza 22 recorded the lowest mean number of T. urticae, 1.53 individuals/25 cm2. The population dynamics of T. urticae showed that infestation increased gradually from mid-June reach its maximum at the end of July, and then decreased gradually at the beginning of August, reaching its minimum number at the beginning of September before harvest time. As for A. exsertus, data showed that the mean number of A. exsertus was the highest on Giza 35 (2.46 individuals/25 cm2) followed by Giza 22 (2.13 individuals/25 cm2), but Giza 82 and Giza 111 mean numbers were 1.99, and 1.91 individuals/25 cm2. Life cycle of tetranychid males was the shortest when reared on Giza 35 with significant difference with other varieties. As for females the shortest life cycle was when reared on Giza 35 with significant difference with Giza 22 which recorded the longest life cycle for males and females, respectively.

Occurrence and Population Dynamics of Mites Associated with Citrus Trees at Menoufia Governorate

Population dynamics and species composition of phytophagous and predatory mites in citrus orchards were determined from January to December 2016 at Shenofa locality, Shebin El-Kom, Menoufia governorate, Egypt. The survey revealed the occurrence of phytophagous mites as: Panonychus citri (McGregor), Eutetranychus orientalis (Klein) (Tetranychidae); Phyllocoptruta oleivora (Ashmed) (Eriophyidae); Brevipalpus californicus (Banks) (Tenuipalpidae) and Tydeus californicus (Banks) (Tydeidae), representing the most common phytophagous species found in citrus orchards. In addition, two predatory mite species of two families were recorded as: Amblyseius swirskii Athias-Henriot (Phytoseiidae) and Agistemus exsertus Gonzalez (Stigmaeidae) were found to be the most abundant predatory species inhabiting citrus leaves. The population fluctuation of phytophagous and predacious mites on studied citrus varieties was varied according to citrus varieties and sampling dates reaching its highest peak, in most cases, during September. Navel orange recorded the highest numbers of P. oleivora in comparison with other varieties of citrus (290.31 indiv. /10 leaves), while the highest number of P. citri and B. californicus were 85.63 and 45.3 indiv. /10 leaves on Balady orange. The obtained result indicated that the maximum and minimum temperature and relative humidity expressed as an insignificantly positive during 2016 season on the population of P. oleivora, E. orientalis, B. californicus, T. californicus, A. swirskii and A. exertus, but highly significance difference was obtained between population of P. citri only. Finally, it could be concluded that winter months are suitable for applying different biological control agents including predatory mites where pests are lowest in numbers and the optimum environmental factors are present as well.

POPULATION FLUCTUATIONS OF CERTAIN MITES ASSOCIATED WITH SOYBEAN AND COTTON PLANTS IN RELATION TO CLIMATIC FACTORS AND LEAF PHYTOCHEMICAL CONTENTS

population fluctuations of certain mites associated with soybean and cotton plants were investigated during seasons, 2012 and 2013 at Sharkia Governorate, as well as its relation with some prevailing climatic factors. In soybean plants, the population of phytophagous mite, Tetranychus urticae Koch was recorded in high number in 2nd season than the 1st one, whereby represented by 272.83 and 202.69 individuals, respectively. While, the predacious mite, Phytoseiulus macropilis (Banks) recorded in high number in 1st season than the 2nd season were aggregated 37.72 and 25.91 individuals, respectively; on soybean plants. The population of T. urticae was higher in 1st year than the 2nd year (394.92 and 367.65 individuals, respectively; while the predacious mites were high in the 2nd year than that obtained in the 1st one on cotton plants. These results revealed that there is negative significant relation between the predacious mite species and the phytophagous mite species on soybean and cotton plants. The population of the spider mite T. urticae was significantly related to the leaf contents of protein and phosphorous, while there was no significance between the predator (P. macropilis) with leaf phytochemical contents of soybean during two seasons 2012/13. The population of the spider mite and leaf phytochemical contents of cotton during season 2013 revealed that there is highly significant correlation between the pest mite T. urticae with protein, carbohydrate, total sugar and reducing sugar, while there was no significance between the pest and non-reducing sugar. The population revealed that there is no significant correlation between the predator Typhlodromus californicus withprotein, carbohydrate, reducing sugar and non-reducing sugar. The correlation coefficient was significant between the predator Agistemus exsertus and carbohydrate, total sugar and reducing sugar, they also recorded a highly significant correlation between the predator and protein; while there was no significance difference between the two predators (A. swiriskii & E. scutalis) with phytochemical contents

Effect of Different Temperatures on Some Biological Aspects of the Predaceous Mite, Agistemus exsertus Gonzalez

Life cycle of A. exsertus female differed according to temperature degree; the shortest period was at 30 °C, 8.23 days, while the longest at 20°C, 12.02 days. The developmental rate ranged from 68.14% at 20 °C to 73.04% at 30 °C for female. Survival female's immatures %was also affected with temperature being 73.45, 80.24 and 83.61% at 20, 25 and 30 °C, respectively. The total amount of consumed preys/predator different developmental stages and sex increased with increased temperature from 20 to 30 °C. The total average number of T. urticae fed by predator immatures was 17.23, 14.76 and 10.71 preys at 30. 25 and 20 °C. Also, female predator consumed greater number of prey individuals at high temperature, 78.34 preys at 30 °C, decreased to 65.25 preys at 25 °C but the rate of consumption was less at low temperature 50.00 preys at 20°C. The effect of temperature on life table parameters was determined. Net reproductive rate (Ro) differed according to temperature as this value increased with temperature increase. Thus, these values averaged 11.21, 15.04 and 21.57 times for 20, 25 and 30 oc. The intrinsic rate of increase (rm) was 0.10, 0.13 and 0.15 individuals/female/day for the above same order. The mean generation time (T) decreased when the temperature increased.

Effects of starvation and humidity on the development and survival of <em>Amblyseius swirskii</em>, <em>Agistemus exsertus</em> and <em>Amblyseius eharai</em>

The ability of predatory mites to endure starvation or low humidity is very important for them to maintain their populations in unfavorable environments. The effects of starvation and humidity on the development and survival of Amblyseius (Typhlodromips) swirskii, Amblyseius eharai and Agistemus exsertus were studied in the laboratory. The results showed that most eggs of A. eharai and A. exsertus could not hatch at relative humidities (RH) lower than 60%. Only A. swirskii larvae could develop into protonymph stage without prey at 60–100%RH among three species. When the prey was absent, protonymphs or gravid females of A. swirskii survived significantly longer than those of A. eharai at 60–100%RH, respectively. Furthermore, at lower humidities (60–70%RH) similar case was observed in the virgin female stage. In addition, nymphs and females of the two phytoseiid mites survived significantly longer than those of A. exsertus at 60–100%RH. It indicated that A. swirskii might be a stronger competitor relative to A. eharai or A. exsertus under starvation and low humidity conditions.

Mites Inhibiting Guava Trees and Their Dynamics in Relation to Weather Factors and Plant Phenology

Surveying mites associated with guava trees (Psidium guajava L.) at Qalyoubia governrate, Egypt indicated the occurrence of main five ones (i.e. the eriophyid, Tegolophus guavae (Boczek), the tenuipalpid, Brevipalpus phoenicis (Ceijskes), the tetranychid, Tetranychus urticae Koch, the phytoseiid, Amblyseius swirskii A.-H. and the stigmaeid, Agistemus exsertus (Gonzalez)). Other six species were present in low numbers. The population dynamics of the main ones in relation to weather factors and guava plant phenology were discussed. Populations of T. urticae peaked in mid-Jun, and Oct. as 183.56 and 172.94 motile stages/leaf, respectively. B. phoenicis was observed at high population level in Jun. and Jul. on fruits and leaves, respectively. T. urticae population peaked in Jun. T. guavae preferred the east side of the tree. Significant relation occurred between mite's populations and temperature increases; while the relation with relative humidity was not significant. The dynamics of the phytophagous mites' population densities (as second trophic level) seemed to follow the plant phenology (specially the leaves). That of the predacious mites seemed to follow their prey dynamics with lag of time. T. guavae population was more significant on upper tree level than middle followed by lower one. Younger leaves and lower surface were preferred to this mite than older ones and upper surface.

Cannibalism and intraguild predation of the predatory mite,Agistemus exsertusGonzalez (Acari: Stigmaeidae)

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.

Predation, oviposition and longevity of the predacious mite, Agistemus exsertus Gonzalez at different prey densities of Tetranychus urticae Koch (Acari: Stigmaeidae, Tetranychidae)

The relation between some biological aspects of the predatory mite, Agistemus exsertus Gonzalez and nymph densities of Tetranychus urticae Koch was studied in the laboratory. Predation and oviposition of A. exsertus showed Holling's Type II functional and numerical responses to changes in prey density. The total predation by A. exsertus females initially averaged 79.42 nymphs/female at 2 prey nymphs/day, significantly increased to a maximum average of 208.92 nymphs/female at 10 nymphs/day and gradually decreased to 90.92 nymphs/female at 30 prey items/day. Similarly, the predator significantly deposited total averages of 14.75, 76.42 and 34.33 eggs/female at 2, 10 and 30 nymph densities/day, respectively. The preoviposition and oviposition periods as well as longevity of A. exsertus significantly shortened with increasing prey densities.

Effect of cannibalism on predation, oviposition and longevity of the predacious mite, Agistemus exsertus Gonzalez (Acari: Stigmaeidae)

Cannibalism (intraspecific predation) on conspecific eggs was investigated in the predatory stigmaeid mite, Agistemus exsertus Gonzalez in the absence of eggs of Tetranychus urticae Koch (no-choice tests) and presence of three densities of prey eggs simultaneously (choice tests) in the laboratory. Data show that cannibalism occurs in immatures and adult females of the predator, which successfully developed and reproduced on conspecific eggs as an alternative prey in the absence of prey eggs. In no-choice tests, cannibalism rate on conspecific eggs by A. exsertus stages was significantly lower than the predation rate on T. urticae eggs. The predatory mite exhibited a marked decline in oviposition rate when preyed on conspecific eggs compared with feeding on prey eggs. The developmental duration and longevity of A. exsertus females were significantly longer 1.9 and 1.7 times, respectively, when fed on conspecific eggs than feeding on T. urticae eggs. The propensity of the predator towards cannibalism depends on the prey density, when T. urticae eggs and conspecific eggs are present simultaneously. Provision of increased densities of prey eggs significantly decreased cannibalism and predation by A. exsertus stages, which fed generally less on conspecific eggs than on T. urticae eggs in choice tests. The oviposition rate of the predator increased significantly, as the egg density of the prey increased. The developmental period and longevity of A. exsertus females showed significantly gradual shortness with increasing egg density of the prey.

Natural and factitious prey for rearing the predacious miteAgistemus exsertusGonzales (Acari: Stigmaeidae)

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.

Phytophagous and predaceous mites associated with vegetable crops from Riyadh, Saudi Arabia

This study was conducted to investigate phytophagous and predatory mites associated with vegetable plants in Riyadh, Saudi Arabia. Eight phytophagous and 10 predacious mites were collected from 14 species of vegetable crops covering five major production localities. Out of these 18 mite species, 13 species are new to the mite fauna of Saudi Arabia. In addition, the two species, Tenuipalpus punicae and Agistemus exsertus, are reported for the first time on vegetable crops in Saudi Arabia. For each mite species found, notes on host plant association and occurrence period are given. An illustrated key for the identification of the 18 mite species reported in this study is provided and this can be used to improve the IPM programs by applying the local natural predatory mites in controlling mite pests in Saudi Arabia.

Temperature influence on biology, thermal requirement and life table of the predatory mites Agistemus exsertus Gonzalez and Phytoseius plumifer (Can. & Fanz.) reared on Tetranychus urticae Koch

The effect of temperature on the biology, thermal requirement and life table of Agistemus exsertus Gonzalez and Phytoseius plumifer (Can. & Fanz.) feeding on immatures of Tetranychus urticae Koch, was determined at four temperature degrees, i.e. 20, 25, 30 and 35°C. The total developmental durations of either predatory mite correlated negatively with increasing temperature. Minimum developmental thresholds (T o) of egg, larva, protonymph, deutonymph stages and life cycle of A. exsertus females averaged 0.95, 9.25, 7.80, 1.03 and 5.29 respectively, while those of P. plumifer females were 6.83, 9.35, 15.39, 15.40 and 13.22. On the other hand, A. exsertus and P. plumifer female required 416.66 and 126.58 DD, respectively, to reach adulthood. A. exsertus and P. plumifer net reproductive rate (R 0) averaged 16.13 and 8.23 then increased to 29.67 and 13.67 then sharply declined reaching 12.10 and 7.93 when the predator was kept at 20, 25 and 35°C, respectively. r m values of A. exsertus reached 0.06, 0.11, 0.12 and 0.13 reared at 20, 25, 30 and 35°C, respectively, while those of P. plumifer averaged 0.04, 0.11, 0.12 and 0.16. The doubling time (DT) of A. exsertus was 10.98, 6.10, 5.82 and 5.25, while that of P. plumifer averaged 15.93, 6.18, 5.70 and 4.35 at 20, 25, 30 and 35°C, respectively. Also, gross reproductive rate (GRR) of A. exsertus was 22.05, 51.70, 29.01 and 22.18, while that of P. plumifer averaged 12.67, 18.20, 18.40 and 11.82 at the same temperatures. The finite rate of increase in e rm values of either predator increased positively with increasing temperature degree.

Influence of plant leaf surface on the development, reproduction and life table parameters of the predacious mite, Agistemus exsertus Gonzalez (Acari: Stigmaeidae)

The influence of leaf surfaces of different host plants on the biology and life table parameters of the predacious mite, Agistemus exsertus Gonzalez was studied in the laboratory. A. exsertus successfully developed and reproduced on all tested plant leaves. Smooth, glabrous pear leaves accelerated the development of A. exsertus and showed the shortest mean generation time. Slightly rough, slightly hairy leaves of mulberry and acalypha were the most suitable surface for oviposition of the predator. These leaves exhibited the highest fecundity and net reproductive rate. On the other hand, leaves of rough, pubescent apple and scabrous, bristly lantana were the least suitable surface for oviposition of A. exsertus. They showed the lowest fecundity and net reproductive rate. Acalypha leaves exhibited the highest intrinsic rate of increase for the predator, whereas lantana leaves showed the lowest value. This difference in the predator response to leaf surfaces of host plants should be considered to enhance the role of the predator in biological control programs.

Species composition and seasonal changes of spider mite density on a leguminous plant Pueraria lobata

Populations of spider mites were sampled from kudzu vine Pueraria lobata (Willd.) from 1997 to 1999 at two study sites in Ibaraki, central Japan. Of the five spider mite species sampled, Tetranychus pueraricola Ehara and Gotoh was the most abundant (accounting for 75.6–96.9% of mites) in each of the three years. The next most abundant species were T. ludeni Zacher (0.8–19.0%), T. parakanzawai Ehara (1.1–9.7%) and T. piercei McGregor (3.1%), but their density and species richness varied from year to year and from site to site. The populations peaked in June and/or September–October. Predators associated with spider mite populations were phytoseiid mites such as Amblyseius tsugawai Ehara, Phytoseius nipponicus Ehara and Neoseiulus womersleyi (Schicha), Scolothrips takahashii Priesner, Oligota spp., Feltiella spp. and stigmaeid mites such as Agistemus exsertus Gonzalez and A. terminalis (Quayle), which were well synchronized with spider mite density. Overwintered females began to appear and oviposit on some herbaceous weeds growing at the study sites in early April. Spider mites appeared on kudzu vine leaves in early May just after flushing. Most colonies (defined as areas surrounded with silky spider mite threads) had only one species but a small percentage had two or three species.

Agistemus exsertus Gonzalez (Acari: Stigmaeidae) as a predator of two scale insects of the family Diaspididae (Homoptera: Diaspididae)

The predacious mite Agistemus exsertus Gonzalez completed its life-span when fed on eggs and crawlers of the Florida red scale Chrysomphalus ficus Ashmead and the white date scale Parlatoria blanchardi (Targioni). The development was faster when individuals were maintained on eggs and crawlers of C. ficus, compared with both stages of P. blanchardi. The average number of eggs/female/day was 2.5 and 1.1 on eggs and crawlers of C. ficus, respectively. Eggs and crawlers of P. blanchardi were an unsuitable food for egg laying for A. exsertus. Life table parameters showed that A. exsertus preferred eggs of C. ficus to the crawlers as prey. The population of the predator feeding on eggs and crawlers of Florida red scale multiplied 45 and 7 times in a generation time of 23 and 20.5 days, respectively. Under these conditions, the intrinsic rate of increase (r m) was (0.17 and 0.098) individuals/female/day on eggs and crawlers of C. ficus, while the finite rate of increase (λ) was (1.18 and 1.11) on both stages of C. ficus.

Relationships between Phytoseiid Eggs, Developmental Success and Reproduction in Agistemus exsertus (Acari: Stigmaeidae)

The biology of Agistemus exsertus Gonzalez was studied to determine the suitability of different phytoseiid eggs as prey. The development was faster and reproduction was higher when A. exsertus fed on eggs of Amblyseius lindquisti Schuster and Pritchard, Neoseiulus cucumeris (Oudemans) and Amblyseius zaheri Yousef and El borolossy (6.57 days and 111.5 eggs; 6.71 days and 110.1 eggs and 6.93 days and 101.0 eggs) than that of Euseius scutalis Athias-Henriot, Neoseiulus barkeri (Hughes) and Amblyseius swiriskii Athias-Henriot (8.6 days and 63.1 eggs; 7.29 days and 52.0 eggs and 7.87 days and 37.7 eggs), respectively. A. exsertus consumed daily more N. barkeri and A. zaheri eggs (4.63 and 3.85) than other phytoseiid eggs, respectively. Deits of A. lindquisti, N. cucumeris and E. scutalis (eggs) provided the greatest female longevity and the least was in case of N. barkeri.

Effects of Diet on the Biology and Life Tables of the Predacious Mite Agistemus exsertus (Acari: Stigmaeidae)

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.