Effects of storage at low-temperature of various heteropteran host eggs on the egg parasitoid, <Emphasis Type="Italic">Trissolcus semistriatus</Emphasis>

Various heteropteran host eggs stored under two low-temperatures were tested in the laboratory for their usability in the production of sunn pest egg parasitoid, Trissolcus semistriatus. Parasitism, adult emergence rate and development time were assesed on stored and fresh eggs of Eurygaster integriceps, Dolycoris baccarum, Graphosoma lineatum and Eurydema ornatum. Masses of fresh host eggs in microcentrifuge tubes were maintained at +6 °C and −20 °C. Every 30 days, 50 eggs of host species were exposed to parasitism by T. semistriatus. The host eggs stored at 6 °C remained viable to parasitism by T. semistriatus up to 2 months, while those of stored at −20 °C were parasitized at high rates up to 4 months, alhough succesful parasitism rates decrease with time. However, it was indicated that both fresh or stored E. ornatum eggs were not preferred to parasitism by the parasitoid. A longer development time from egg to adult was observed in stored eggs under two tested storage techniques when compared with fresh eggs.     

Development,consumption rates and reproductive biology of <Emphasis Type="Italic">Orius albidipennis</Emphasis> reared on various prey

The predatory bug Orius albidipennis (Reuter) (Hemiptera: Anthocoridae) has tremendous potential as a biological control agent, especially in its native range around the Mediterranean Basin and East Africa. The need to exploit native biological control agents is growing in importance as concerns over the introduction of non-native species continue to increase. However, little is known of the effects of different prey on development and reproduction of O. albidipennis compared with other species of Orius. Therefore, we compared the development, survival, reproductive biology, and prey consumption of O. albidipennis when fed eggs of Ephestia kuehniella Zeller, Tetranychus urticae Koch, and Trialeurodes vaporariorum (Westwood), and larvae of Gynaikothrips ficorum (Marchal), under laboratory of 26 ± 1°C, 60 ± 10% RH and 16L:8D photoperiod. Individuals were reared from the neonate stage until death on one of the four prey types. The type of prey had profound effects on all measured performance traits. The highest survival rate was recorded for nymphs that were fed on E. kuehniella eggs, while the lowest survival rate was observed for those fed on T. vaporariorum eggs. The shortest nymphal period was recorded for nymphs fed on E. kuehniella eggs, while the longest was measured for those fed on T. urticae eggs. During the nymphal period, O. albidipennis consumed significantly more eggs of T. urticae than other prey types, whereas the lowest number of consumed prey were eggs of E. kuehniella. Adult females and males consumed significantly more T. urticae eggs than other types of prey. However, Orius albidipennis females showed the highest fecundity when fed on E. kuehniella eggs, and the lowest when fed on T. vaporariorum eggs. Adult females and males that fed on G. ficorum larvae had significantly longer life spans compared with those fed other prey. Because of their relatively rapid development and high fecundity, O. albidipennis fed E. kuehniella eggs had a significantly higher net reproductive rate (R_o) and intrinsic rate of increase (r _m ) than O. albidipennis fed other prey types. Overall, eggs of E. kuehniella were the most suitable diet for nymphs and adults of O. albidipennis. Although less suitable, O. albidipennis could survive and reproduce on the other prey types, which is a favourable attribute in biological control agents. These results on the effect of different prey types on development and reproduction of O. albidipennis will also contribute to the development of mass rearing programs for biological control agents in developing countries, such as Egypt.     

Interspecific nesting in marine fishes: spawning of the spinynose sculpin, <Emphasis Type="Italic">Asemichthys taylori</Emphasis>, on the eggs of the buffalo sculpin, <Emphasis Type="Italic">Enophrys bison</Emphasis>

Subtidal spawning of the cottid fish Enophrys bison occurs in southern British Columbia, where in the field a smaller subtidal cottid, Asemichthys taylori, exclusively utilizes E. bison nests by overlaying its own eggs on top of the E. bison eggs. In the laboratory, spawning of A. taylori in the absence of E. bison nests was observed to occur adjacent to eggs of another sculpin, Icelinus borealis, but no spawning of A. taylori was observed in the field in association with nests of any fish other than E. bison. The E. bison male guards the composite cluster of egg masses, and the A. taylori eggs hatch faster than the earlier laid E. bison eggs. Enophrys bison embryonic development appears retarded by overlying A. taylori eggs so the spawning by A. taylori on E. bison egg masses is a form of nesting parasitism, a behavior previously unknown among marine fishes. This study is the first report of interspecific nesting for marine fishes.     

Developmental stage of failed eggs in the red-legged partridge <Emphasis Type="Italic">Alectoris rufa</Emphasis>

Understanding whether egg failure occurs more frequently during laying or during incubation is important for determining the most vulnerable period of the egg phase in bird species with long laying and incubation periods. However, most studies compare nest failure during the egg stage and the hatchling stage. In this study we examined whether egg failure was higher during the laying period and early development than during the final stages of development in a population of red-legged partridge (Alectoris rufa) from northeast Spain. We collected 216 abandoned eggs in the field. Only 12% (n = 26) of the eggs were sufficiently intact to enable direct assessment of developmental stage, showing that 81% of 26 eggs were lost during early stages. The majority of eggs were depredated (n = 154, 71%), as evidenced by an opening hole. To take advantage of information contained in these eggs, we propose a simple method to assess their developmental stage by measuring the size of the opening of their hole. Based on this method, we estimated that the proportion of eggs lost during early stages ranged from 72 to 83%. We validated this result of a high percentage of egg failure during early developmental stages with a larger experimental sample. Nest losses in the partridge are higher during the laying period or early development. This result is important in that the direction of conservation efforts and their seasonal application should be adjusted to account for the most important factors affecting egg failure.     

<Emphasis Type="Italic">Wolbachia</Emphasis> Replication and Host Cell Division in <Emphasis Type="Italic">Aedes albopictus</Emphasis>

Wolbachia pipientis is an obligate intracellular endosymbiont of a range of arthropod species. The microbe is best known for its manipulations of host reproduction that include inducing cytoplasmic incompatibility, parthenogenesis, feminization, and male-killing. Like other vertically transmitted intracellular symbionts, Wolbachias replication rate must not outpace that of its host cells if it is to remain benign. The mosquito Aedes albopictus is naturally infected both singly and doubly with different strains of Wolbachia pipientis. During diapause in mosquito eggs, no host cell division is believed to occur. Further development is triggered only by subsequent exposure of the egg to water. This study uses diapause in Wolbachia-infected Aedes albopictus eggs to determine whether symbiont replication slows or stops when host cell division ceases or whether it continues at a low but constant rate. We have shown that Wolbachia densities in eggs are greatest during embryonation and then decline throughout diapause, suggesting that Wolbachia replication is dependent on host cell replication.     

Water exchange of flexible-shelled eggs and its effect on hatchling traits in the Chinese skink,<Emphasis Type="Italic"> Eumeces chinensis</Emphasis>

Flexible-shelled eggs of the Chinese skink (Eumeces chinensis) were used to determine the routes of water exchange with the environment and the effects of water exchange on hatchling traits. Eggs were incubated under three different hydric conditions at 28 °C. One group (ground eggs) was half-buried in incubation substrate. The second group (upper eggs) rested on the ground eggs but did not contact the substrate directly, and the third group was placed on a plastic platform above the substrate. Ground and upper eggs increased in mass and hatched successfully, while all eggs resting on the plastic platform lost mass and died within a week. Hence, E. chinensis eggs cannot sustain water balance through exchange of water vapor in air alone, but can absorb water from the substrate and other eggs and develop well. Water gained by upper eggs was only 20% of that absorbed by ground eggs, but hatchlings from the two treatments did not differ in morphology or locomotor performance. Therefore, the degree of water exchange of E. chinesis eggs has little effect on embryonic development and hatchling traits. The insensitivity of the eggs to variations in water exchange may be an adaptation against extreme hydric conditions in a species that deposits its eggs close to the soil surface.Communicated by I.D. Hume     

Biochemical adaptation for dormancy in subitaneous and dormant eggs of <Emphasis Type="Italic">Daphnia magna</Emphasis>

Daphnia can reproduce through subitaneous and dormant eggs. The production of dormant eggs is induced by stimuli associated with deteriorating growth conditions, and enable Daphnia populations to survive temporarily harsh environmental conditions. Dormant eggs are expected to have developed special biochemical adaptations to bridge this long unfavourable period, but little comparative biochemical data are available for dormant and subitaneous eggs. We compared levels of the following molecules between subitaneous and dormant eggs: (a) triglycerides, which are the most abundant energy storage molecules in Daphnia, (b) glycerol, a cryoprotectant also involved in energy storage, and (c) the heat shock protein Hsp60, a molecular chaperone that may assist in maintaining protein structural integrity and inhibiting cell metabolism during diapause. Unexpectedly, no difference in triglycerides content between egg types was found. As expected, dormant eggs contained more glycerol and relatively more Hsp60 than subitaneous eggs. The biochemical composition of dormant eggs can therefore be seen as an adaptation to the harsh environmental conditions these eggs encounter. Guest editor: Piet Spaak Cladocera: Proceedings of the 7th International Symposium on Cladocera     

Effect of Temperature on Development and Fecundity of the Predaceous Plant Bug <Emphasis Type="Italic">Deraeocoris brevis</Emphasis> Reared on <Emphasis Type="Italic">Ephestia kuehniella</Emphasis> Eggs

Temperature-dependent development and oviposition component models were developed for Deraeocoris brevis (Uhler) (Hemiptera: Miridae). Egg development times decreased with increasing temperature and ranged from 35.8 d at 15 °C to 6.7 d at 32 °C. Total development times of nymphs reared on frozen Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae) eggs decreased from an estimated 55.6 d at 15 °C to 9.2 d at 32 °C and 10.0 d at 34.6 °C. By fitting linear models to the data the lower developmental threshold temperatures for eggs, small nymphs (1st to 3rd instar), large nymphs (4th to 5th instar), and all nymphs combined were calculated as 10.5, 12.5, 11.8, and 11.9 °C, respectively. The thermal constants were 144.1, 90.3, 95.0, and 190.8 degree-days for each of the above stages. The non-linear model was based on a Gaussian equation, which fit the relationship between development rate and temperature well for all stages. The Weibull function provided a good fit for the distribution of development times of each stage. Adult longevity decreased with increasing temperature and ranged from 52.9 d at 21.7 to 16.8 d at 32.0 °C. D. brevis had a maximum fecundity of 471 eggs per female at 24 °C, which declined to 191 eggs per female at 32 °C. Also, three temperature-dependent components for an oviposition model of D. brevis were developed including models for total fecundity, age-specific cumulative oviposition rate, and age-specific survival rate.     

Expression of metabolic enzyme genes and heat-shock protein genes during embryonic development in diapause and non-diapause egg of multivoltine silkworm <Emphasis Type="Italic">Bombyx mori</Emphasis>

The expression of metabolic enzyme genes and heat-shock protein genes (Hsp) during early embryogenesis in diapause and non-diapause eggs of the silkworm Bombyx mori was quantified by semi-quantitative RT-PCR. The trehalase gene (Tre) was expressed in non-diapause eggs up-to nine days, while in diapause eggs was not up regulated. The glycogen phosphorylase gene (GPase) was expressed in non-diapause eggs, whereas in diapause eggs a high level was observed in early stage, but down regulated in later stage. The phosphofructokinase gene (PFK) and sorbitol dehyrogenase-2 gene (SDH-2) expression was fluctuated in non-diapause eggs, whereas in diapause eggs these were expressed only at early stage and not observed in later stage. The glucose-6-phosphate dehydrogenase gene (G6P-DH) in non-diapause eggs was highly expressed during the differentiation phase and decreased in the organogenesis phase. In contrast to this, expression in diapause eggs was of low level during differentiation phase and of high level observed in the organogenesis phase. In the tissues, PFK and SDH-2 were selectively expressed in cuticle and midgut, whereas Tre expression was high in midgut and ovary of larvae incubated at 15°C. The Hsp (20.4, 20.8, 40, 70, and 90) were expressed in both diapause and non-diapause eggs. Their expression was, however, selective in tissues with Hsp20.4 in midgut and ovary, Hsp40 in head, Hsp70 in cuticle and Hsp90 in ovary and head in high amounts at 15°C. These results suggest that the metabolic enzyme genes studied except Hsp play a major role during embryogenesis of diapause and non-diapause silkworm.     

<Emphasis Type="Italic">Catenaria anguillulae</Emphasis> Sorokin: a Natural Biocontrol Agent of <Emphasis Type="Italic">Meloidogyne graminicola</Emphasis> Causing Root Knot Disease of Rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.)

Summary Catenaria anguillulae parasitized and killed the eggs and second stage juveniles (J₂) of Meloidogyne graminicola under natural conditions. The percentage of infection in eggs was higher than J₂ of M.␣graminicola, which ranged between 0–50.3% and 0–18.9% in 2004 and 0–46.6% and 0–21.7% in 2005, respectively. The higher parasitism of eggs and J₂ was recorded from those fields in which plants were severely infected with M. graminicola. The degree of parasitism of eggs and J₂ by C. anguillulae varied with severity of root knot disease. The fields with a higher root gall index recorded a higher percentage of infection in eggs and J₂ of M. graminicola. In general, old galls when teased and incubated, recorded higher parasitism of eggs and juveniles than young galls.     

<Emphasis Type="Italic">Fopius arisanus</Emphasis> oviposition in four <Emphasis Type="Italic">Anastrepha</Emphasis> fruit fly species of economic importance in Mexico

We studied the oviposition performance of Fopius arisanus (Sonan) (Hymenoptera: Braconidae) attacking eggs of four fruit flies of the genus Anastrepha Schiner (Diptera: Tephritidae) under laboratory conditions. The complete process of oviposition on an individual egg of Anastrepha ludens (Loew) lasts in average 85.4 ± 2.9 s, including a tremor (25.8 ± 1.03 s) observed in the middle of this process related to the egg’s descent. The average parasitism of A. ludens egg was 60.9 ± 7.5%, with only 1.2% of superparasitized eggs. During individual acts of oviposition, we noted that F. arisanus possesses a highly flexible ovipositor that curves easily as it searches for additional suitable eggs, which may be of particular benefit when a female finds large clutches of eggs. The individual oviposition of F. arisanus in host fruits attacked by Anastrepha spp. varies with the egg clutch size of each fruit fly species: A. serpentina laid the biggest egg clutches (21.3 ± 1.4), followed by A. ludens (14.2 ± 0.9), and A. striata (1.0 ± 0.0) (=A. obliqua). The time spent by F. arisanus in individual ovipositions was parallel to these findings, reinforcing the idea that F. arisanus attacks several eggs in each individual insertion of its ovipositor. Neither formal oviposition acts, nor adult emergences of F. arisanus were registered in A. obliqua. We discuss the potential of F. arisanus as natural enemy of fruit flies of the genus Anastrepha, and explore the eventual developing of its mass rearing. Handling Editor: Torsten Meiners.     

Chemotactic responses and parasitism of Trichogramma pretiosum after successive generations in Spodoptera frugiperda

Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) is an important parasitoid of lepidopteran pests. Its parasitism success is related to its foraging behavior, mediated by kairomones from its hosts. We aimed to evaluate the chemotactic responses and parasitism of T. pretiosum from Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae) eggs as well as the parasitoid maintained for three generations in Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) eggs. Chemotactic responses of T. pretiosum from both hosts were evaluated in a dual choice olfactometer. Females were submitted to a choice between washed vs. unwashed eggs of E. kuehniella or S. frugiperda, as well as to unwashed eggs of both hosts. Egg extracts of both hosts were also contrasted with hexane and with each other. Parasitism of T. pretiosum exposed to eggs of the two species was also evaluated. Females from E. kuehniella were more attracted to odors from eggs of this host whenever it was present. Third generation parasitoids from S. frugiperda eggs were more attracted to eggs and egg extract of S. frugiperda than to those from E. kuehniella. The highest number of parasitized eggs and emerged parasitoids in S. frugiperda was observed in parasitoids coming from the third generation in this host. Therefore, imaginal conditioning could be an alternative to be considered for T. pretiosum learning before releasing, possibly optimizing its search and parasitism process in S. frugiperda eggs.     

Life history response of <Emphasis Type="Italic">Daphnia galeata</Emphasis> to heterogeneous conditions within a reservoir as determined in a cross-designed laboratory experiment

Growth and reproduction were studied in the laboratory in a cross-designed experimental set-up in four Daphnia galeata subpopulations collected from different locations (with respect to water characteristics) in a reservoir (epilimnion, metalimnion and hypolimnion in the deepest part of the reservoir near the dam and epilimnion of the upstream part of the reservoir) and in a laboratory clone of the same species. The results of two-way ANOVA revealed significant effects of the two parameters manipulated – source of water used for cultures and Daphnia subpopulation – on the life history characteristics of growth and reproduction. The water from the upstream part of the reservoir was the most favourable culture medium for all characteristics of the Daphnia groups studied (the largest primiparae, clutches and eggs, the shortest postembryonic development time and filtering setae). The poorest performances were recorded in the downstream, epilimnetic and metalimnetic waters. The primiparae in the hypolimnetic water were smaller but had relatively larger clutches of smaller eggs and slightly longer postembryonic development times. The Daphnia subpopulation originating from the hypolimnion had the smallest primiparae, the largest clutches, the smallest eggs and the shortest postembryonic development, whereas the opposite was found in animals from the epilmnion. These differences in ecologically relevant traits were supported by analysis of the quasi-neutral genetic markers that indicated significant site-dependent differences in clonal structure between the subpopulations. There was no consistent trend to higher within-group variance in the life history traits in the genetically heterogeneous subpopulations from the reservoir compared to the laboratory clone.     

Biology and host specificity of <Emphasis Type="Italic">Gonatocerus deleoni</Emphasis> (Hymenoptera: Mymaridae), a potential biocontrol agent of <Emphasis Type="Italic">Homalodisca vitripennis</Emphasis> (Hemiptera: Cicadellidae) in California,USA

The host-specificity and biological traits of Gonatocerus deleoni Triapitsyn, Logarzo & Virla (Hymenoptera: Mymaridae), a potential candidate for biological control of the glassy-winged sharpshooter (GWSS), Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae), were determined under laboratory conditions. G. deleoni is a solitary egg parasitoid native to Argentina, originally reared from sentinel eggs of Tapajosa rubromarginata (Signoret) (Cicadellidae). With GWSS as a fictitious host, G. deleoni’s average development time from oviposition to adult emergence was 18.8 ± 1.4 days, with males developing faster than females (18.0 ± 1.3 days, males; 19.0 ± 1.3 days, females). The average parasitism rate on 1–8-day-old eggs was 45.7% but this was significantly affected by the age of the egg, ranging from 1.4% to 69.9% (egg ages 8 and 3, respectively). The average sex ratio was 0.34 (percent males) and sex ratio was not significantly affected by egg age. G. deleoni was able to develop in eggs of GWSS and Homalodisca liturata Ball (both in the tribe Proconiini), but was unable to develop on eggs of Graphocephala atropunctata (Signoret) (different tribe, same subfamily) or Erythroneura elegantula Osborn (different subfamily).     

Biology of <Emphasis Type="Italic">Eretmocerus sudanensis</Emphasis> n. sp. Zolnerowich and Rose,parasitoid of <Emphasis Type="Italic">Bemisia tabaci</Emphasis> Gennadius

Eretmocerus sudanensis = E. nr. emirates was released in 1992 into South Florida from Sudan to control Bemisia tabaci. It has since become the dominant Eretmocerus species in southwest Florida. Specimens were recovered at the Southwest Florida Research and Education Center in Collier County from a population of B. tabaci on collard Brassica oleracea, and the parasitoid described as new species, though as yet unpublished. Here we report results of studies conducted to evaluate the biology of this parasitoid of B. tabaci biotype B under laboratory controlled conditions (26°C ± 0.5, 13 h light, 62% ± 6 HR). No preoviposition period was observed for E. sudanensis. Females lived an average of 13.2 days and in this time deposited an average of 161 eggs at a mean oviposition rate of 13 eggs per day. The total compared favorably with published values for E. melanoscutus (123 eggs) and was similar to E. mundus (171 eggs). E. sudanensis showed the same tendencies of preference and suitability for the intermediate host stages (2nd and 3rd) as reported for these same 2 species. However, parameters such as development time from egg to adult (16 days) and net reproductive rate (Ro = 91.3 eggs/female) were shorter and greater, respectively, compared to published results for either E. melanoscutus or E. mundus under similar conditions. Such differences in demographic parameters could indicate a significantly greater reproductive potential for E. sudanensis.     

Distribution of Japanese temperate bass, <Emphasis Type="Italic">Lateolabrax japonicus</Emphasis>, eggs and pelagic larvae in Ariake Bay

We collected eggs and larvae of the Japanese temperate bass, Lateolabrax japonicus, and present horizontal and temporal changes of distribution relative to development and growth during the species pelagic life history in Ariake Bay. Sampling was conducted from the inner to central region (11 sampling stations) of Ariake Bay using a plankton net (80 cm diameter, 0.5-mm mesh) from November 2000 to February 2001. Both eggs and larvae were collected most abundantly in mid-December. The CPUE of eggs in the surface layer was higher than the middle layer, which is in contrast to that at the larval stage. Most eggs were collected around the central and western regions of the bay. The distribution of eggs shifted vertically to the middle layer with development. Yolk-sac larvae were collected in the central region of the bay, and preflexion and flexion larvae were more abundantly collected in the inner region of the bay. The body length of larvae around the inner bay was larger than in the central region. The pelagic life history can be summarized as follows: eggs are distributed around the central region of the bay and eggs and larvae expand their distribution to the inner and shallower waters with growth. We conclude that the shift of vertical distribution in pelagic stages and the hydrographic features of the middle layer form one of the mechanisms enabling the inshore migration of L. japonicus.     

Description of the larva of <Emphasis Type="Italic">Curteria</Emphasis> Southcott, 1961 (Acari,Parasitengona, Erythraeidae) with notes on biology and life cycle

The larvae of Curteria episcopalis (C.L. Koch, 1837) and Curteria southcotti Gabryś, 1992, are described based on specimens reared in the laboratory. Pedroerythraeus Haitlinger, 2004 is considered a junior synonym of Curteria. Data on habitat specificity and phenology of the species as well as on development of eggs into larvae are given.     

Aspects of the reproductive biology of two archer fishes <Emphasis Type="Italic">Toxotes chatareus</Emphasis>, (Hamilton 1822) and <Emphasis Type="Italic">Toxotes jaculatrix</Emphasis> (Pallas 1767)

Various aspects of the reproductive biology of two archer fishes Toxotes chatareus and Toxotes jaculatrix were studied to describe gonad development, spawning season, sex ratio, and fecundity. Spawning season was assessed using monthly changes in gonadosomatic index (GSI) and histological inspection of the gonads. Both species exhibit two modes of oocytes; a mode of small primary growth oocytes and a single mode that increases with size as oocytes sequester vitellogenin and undergo maturation, showing the synchronous oocyte development typical of total spawners. Based on GSI values and advanced stages of oocyte maturity, T. chatareus and T. jaculatrix, females appear to spawn from November to December. The average fecundity of female T. chatareus was 55 000 ± 5538 eggs, and T. jaculatrix was 50 000 ± 3440 eggs; fecundity ranged from 20 000 to 150 000 eggs for both species, with relative fecundities of 600 to 1100 eggs/g body weight, and a mean value of 800 ± 32 for T. chatareus; relative fecundity ranged from 500 to 1100 with a mean value of 700 ± 23 for T. jaculatrix. Sex ratio, defined as the proportion of males to females, was 2.2 and 2.5 in T. chatareus and T. jaculatrix, respectively. The apparent abundance of males in samples could be due to females being positioned lower in the water column and therefore being sampled less frequently. Our results indicate that in both species, spawning occurs between the months of November and December during the monsoon season, which provides the mangrove coastal waters inhabited by these species with an abundance of food resources and additional floodplain nursery habitat for larvae and juveniles.     

Effect of pollen,natural prey and factitious prey on the development of <Emphasis Type="Italic">Iphiseius degenerans</Emphasis>

The predatory mite Iphiseius degenerans (Berlese) is commercially available as a biological control agent of thrips and spider mites in greenhouse crops. Developmental duration and immature survival of I. degeneransreared on nine types of food (almond pollen, apple pollen, castor bean pollen, plum pollen, sweet pepper pollen, Tetranychus urticaeKoch, Frankliniella occidentalis(Pergande), Ephestia kuehniella Zeller eggs and Artemia franciscana Kellogg cysts) and on three substrates (Multicel, sweet pepper leaf, and bean leaf) were determined in the laboratory. All experiments were carried out at 25 °C. On Multicel, mean developmental times on pollen ranged from 6.0 to 7.1 days, with the lowest value recorded on almond pollen and the highest on sweet pepper pollen. When reared on castor bean pollen significantly longer developmental times were obtained on a sweet pepper leaf compared to a bean leaf or Multicel. Developmental duration when offered T. urticaeon Multicel ranged between 6.1 and 6.9 days, on a bean leaf development was completed in 8.0 days. The longest developmental times on Multicel were recorded on Ephestia eggs (7.0 days) and on decapsulated Artemia cysts (7.5 days). No development beyond the protonymphal stage occurred in the absence of food or when encapsulated Artemia cysts or thrips larvae were offered on Multicel. On a sweet pepper leaf and a bean leaf, respectively 6.7 and 10.0% of the eggs reached adulthood when thrips larvae were provided as food; developmental times recorded here, were 9.0 and 8.3 days. Overall, immature mortality occurred mainly in the protonymphal stage and ranged from 0.0 to 36.7%. In conclusion, I. degenerans is able to feed on a variety of natural and unnatural foods, but thrips larvae and sweet pepper pollen are unfavourable food for immature development. This could compromise the establishment of this biological control agent when used against thrips in sweet pepper crops.