Effect of infection by Metarhizium anisopliae (Hypocreales: Clavicipitaceae) on the feeding and oviposition of the pea leafminer Liriomyza huidobrensis (Diptera: Agromyzidae) on different host plants

The effect of fungal infection by Metarhizium anisopliae on feeding and oviposition of adult Liriomyza huidobrensis was examined on three host plants, faba bean (Vicia faba), French bean (Phaseolus vuklgaris) and snow pea (Pisum sativum) in the laboratory. Flies were contaminated with dry conidia and allowed to feed and oviposit on the different host plants. Mortality in L. huidobrensis varied between 14% and 20% in the controls and between 77% and 100% in fungal treatments 120 h post-infection for the three host plants. L. huidobrensis made more punctures (47.3–52.6 cm^?2) in the control than in the fungal treatments (23.1–26.9 cm^?2) for the three host plants. The cumulative average number of punctures cm^?2/female by L. huidobrensis was higher in the controls than in fungal treatments from 72 h post-treatment in faba bean (12.2 vs. 8.2) and French bean (14.8 vs. 8.9), and from 48 h post-inoculation in snow pea (8.5 vs. 5.7). Female L. huidobrensis laid more eggs in the control (0.6–6.1) than in fungal treatments (0.2–1.5) across the host plants tested. The cumulative mean number of eggs cm^?2/female was significantly higher in the controls than in fungal treatments from 48 h post-treatment in faba bean (0.4 vs. 0.2) and French bean (0.1 vs. 0), and 96 h post-inoculation in snow pea (0.2 vs. 0.1). The host plant did not affect the average total number of punctures but had a significant effect on egg laying, with faba bean harboring greater number of eggs in both control and fungal treatments. A proper timeline application of the fungus before onset of feeding and oviposition peaks will be crucial in field suppression of the pest using M. anisopliae. In addition, a great consideration must be given to the target host plants prior to application of the fungus.     

Endophytic colonization of Vicia faba and Phaseolus vulgaris (Fabaceae) by fungal pathogens and their effects on the life-history parameters of Liriomyza huidobrensis (Diptera: Agromyzidae)

Ten fungal isolates belonging to the genera Beauveria (3), Hypocrea (1), Gibberella (1), Metarhizium (2), Trichoderma (1) and Fusarium (2) were evaluated in the laboratory to determine whether they could become endophytic in two pea leafminer (Liriomyza huidobrensis) host plants (Vicia faba and Phaseolus vulgaris), and to assess their possible negative effects on leafminers. Beauveria (ICIPE279), Hypocrea, Gibberella, Fusarium and Trichoderma isolates colonized roots, stems and leaves of both host plant species. Beauveria isolates G1LU3 and S4SU1 colonized roots, stems, and leaves of P. vulgaris but only the root and stem of V. faba. Isolates of Metarhizium failed to colonize the two host plants. The effects of endophytically colonized fungal pathogens on mortality, oviposition, emergence and longevity of L. huidobrensis were investigated after endophytic colonization of V. faba plants. All the fungal isolates that succeeded in colonizing the host plant were pathogenic to L. huidobrensis, causing 100 % mortality within 13.2 ± 0.7–15.0 ± 0.6 d. However, Hypocrea outperformed the other isolates (p < 0.0 001) in reducing longevity of the progeny (11.2 ± 1.0 vs. 17.8 ± 1.4 d in the control), the number of pupae (80.0 ± 6.7 vs. 387.0 ± 21.7 pupae in the control), and adult longevity (3.8 ± 1.0 vs. 9.9 ± 1.8 d in the control). Adult emergence was significantly reduced (p < 0.0 001) in Hypocrea (21.4 %) and Beauveria (38.0 %) treatments compared to the control (82.9 %).     

Ontogeny and reproductive biology of Diadegma semiclausum (Hym.: Ichneumonidae), a larval endoparasitoid of Diamondback Moth,Plutella xylostella (Lep.: Plutellidae)

In this article, the ontogeny and reproductive biology of Diadegma semiclausum (Hym.: Ichneumonidae), an important parasitoid of Plutella xylostella (Lep.: Plutellidae) are described in detail. We did dissect parasitized P. xylostella larvae in phosphate-buffered saline and determine the external morphology of its parasitoid at all developmental stages. The developmental duration of its immature stages, adult longevity, total oviposition period and fecundity of the parasitoid are determined at 24 ± 1 °C, 65  ±  5% R.H., and a photoperiod of 16:8 h L:D. The mean duration of egg and larval stages is 9.56 days and the prepupa and pupa stages last for 8.27 days. In average, female longevity is 1.31 times longer than that of males, and females lay 300 eggs in total. The peak of D. semiclausum oviposition is on the eighth day after mating. The egg loading pattern of D. semiclausum was investigated to determine the parasitoid ‘ovigeny index’ throughout the female's parasitoid lifetime. Initial egg load in immature females (<2 h age) is 1.45 per female and the mean lifetime potential fecundity (total immature and mature oocytes), at four interval ages, is 34. With an ovigeny index value of 0.038, D. semiclausum is considered moderately to strongly synovigenic. In the absence of the host, after 3 days, the number of eggs is decreased in D. semiclausum. Our results demonstrated that there is a negative relation between the ovigeny index and egg resorption in this parasitoid.     

Interactions between Phaedrotoma scabriventris Nixon (Hymenoptera: Braconidae) and Diglyphus isaea Walker (Hymenoptera: Eulophidae), parasitoids of Liriomyza huidobrensis (Blanchard) (Diptera: Agromyzidae)

Liriomyza leafminer flies represent a serious threat to horticultural production in East Africa. Total field parasitism rates recorded in Kenya are below 5%, with the indigenous ectoparasitoid Diglyphus isaea Walker being one of the key parasitoid species. The International Centre of Insect Physiology and Ecology (icipe), in collaboration with the International Potato Centre (CIP), imported into Kenya the endoparasitoid Phaedrotoma scabriventris Nixon to improve natural control of leafminers. The objective of this study was to investigate the interactions between D. isaea and P. scabriventris when used together for the biological control of Liriomyza species. These interactions were studied under laboratory conditions, using treatments that involved single, simultaneous and sequential releases of the different parasitoid species onto plants infested by L. huidobrensis larvae. While used separately, parasitism rates of D. isaea and P. scabriventris were 30.4 ± 10.9% and 63.6 ± 7.7% respectively. However, when used simultaneously, the total parasitism rate increased to 77.0 ± 5.3%. Although P. scabriventris had no effect on D. isaea, the presence of D. isaea reduced the specific parasitism rate of P. scabriventris. In addition, both parasitoids induced leafminer mortality through larval-feeding and stinging. However, feeding and stinging mortality induced by D. isaea (41.9 ± 9.1%) was significantly higher compared to P. scabriventris (11.9 ± 8.7). Similarly, pupal mortality due to feeding and stinging activity was 49.1 ± 6.5% and 21.6 ± 1.9% when exposed to D. isaea and P. scabriventris respectively. The implication for simultaneous use of both parasitoids in East Africa is discussed.     

Mass production of Diglyphus isaea (Hymenoptera: Eulophidae), a biological control agent of a Korean population of potato leaf miner Liriomyza huidobrensis (Blanchard) (Diptera: Agromyzidae)

The potato leaf miner, Liriomyza huidobrensis (Blanchard), is an important pest of potato throughout the world, including Korea. A method was developed for mass rearing the parasitoid Diglyphus isaea (Walker) using faba bean, Vicia faba L. (Fabaceae), as the host‐plant and L. huidobrensis as the insect host. Faba bean plants were planted in pots and maintained in a greenhouse for about 15 d. Pots were then exposed to adult leaf miners in oviposition cages for 4 h. Plants containing late second to early third instar larvae were exposed to adult D. isaea in parasitoid cages for 24 h. The leaf area per pot after 15 d was 597.9 cm², which produced 103.33 larvae per pot. The number of adult parasitoids emerging per pot was 72.5; about 41% of these were female. The daily cost of parasitoid production was USD20.95 per 1000 individual parasitoids. The methodology developed for D. isaea could be used to rear other ectoparasitoids such as Hemiptarsenus spp. and Pnigalio sp. with different insect hosts like L. trifolii. This is why this mass‐rearing information is important for securing test insect materials for ecological and biological study of Liriomyza species, and also for developing a biological control for Liriomyza species other than L. huidobrensis by mass production of associated natural enemies. We are facing rapid agro‐ecosystem changes including pest systems. Continuous monitoring of Liriomyza in solanaceous crops is needed.     

Efficacy of the parasitoid,Diaeretiella rapae (McIntosh) (Hymenoptera: Braconidae) against Myzus persicae (Sulzer) (Hemiptera: Aphididae) infesting rapeseed-mustard

Efficacy of Diaeretiella rapae (McIntosh) (Hymenoptera: Braconidae) was determined by studying its biological and behavioural attributes on the aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae). Total developmental duration of the parasitoid was longer in younger instars compared to that in older instars of aphid. Host age negatively affected the oviposition period and fecundity of the ovipositing parasitoid. Survival of the immatures was higher in older than the younger instars of the aphid. Sex ratio for the parasitoid was female-biased. Longevity of female parasitoid was higher while parasitizing aphid nymphs of younger age groups (1–2 days old) compared to that of older age groups (4–5 days old). Parasitoid showed a higher preference towards second instar of M. persicae both in choice and no-choice tests. Results on mutual interference revealed that per capita searching efficiency decreased from 0.91 to 0.07 as parasitoid densities increased from 1 to 8. Logistic regression exhibited a type II functional response for D. rapae. The estimated values of search-efficiency (a) and handling time (T_h) were 0.038 h⁻¹ and 1.59 h, respectively. The maximum parasitization rate was 15.08. This investigation suggests that D. rapae could be an effective candidate for augmentative biological control of M. persicae which infests several plant species of economic importance.     

Bionomics of Orasema simplex (Hymenoptera: Eucharitidae), a parasitoid of Solenopsis fire ants (Hymenoptera: Formicidae) in Argentina

Biological characteristics of the parasitoid Orasema simplex Heraty (Hymenoptera: Eucharitidae), a potential candidate for the biological control of fire ants in the United States were investigated. Female survivorship, fertility and oviposition preferences were studied in the laboratory. Naturally parasitized colonies were examined to determine offspring sex ratio, development success and time, and to artificially parasitize healthy ant colonies. In addition, field studies were carried out to establish natural oviposition substrates and adult activity patterns. Orasema simplex female survivorship was 3.6 ± 1.5 days. Newly emerged females contained 613.5 ± 114.0 mature eggs. The adult development success in natural parasitized colonies was 22.2% with a female-biased sex ratio (4:1). The time required from planidia to adult was 29.5 ± 5.4 days. In the field, adults were mostly found around the ant nests at midday. A broad range of plant species was observed as oviposition substrates. The transfer of planidia to healthy ant colonies was achieved but the development success was very low. Orasema simplex appears to have a limited potential as a fire ant biocontrol agent because of cosmetic damage to a wide variety of plants used for oviposition. However, further studies are necessary to evaluate the real damage exerted by oviposition punctures.     

Seasonal Occurrence of Henosepilachna vigintioctopunctata (F.) (Coleoptera: Coccinellidae) and Its Parasitoid on Ashwagandha in India

The outbreak of Henosepilachna vigintioctopunctata (F.) was noticed on a medicinal plant, Withania somnifera Dunal during 2004-05. The population level of the pest was reached its peak in August. The parasitoid Pediobius foveolatus caused 51.94%±12.20% parasitism. The pest completed its life cycle in 20.15±1.50 days on W. somnifera. The longevity of the male and female adults of the pest was 22.07±3.71 and 31.07±4.38 days, respectively. The gravid females of H. vigintioctopunctata laid an average of 287.64±33.38 eggs during their oviposition period of 10.40±2.80 days.     

A tritrophic analysis of host preference and performance in a polyphagous leafminer

The optimal oviposition theory predicts that oviposition preferences of phytophagous insects should correlate with host suitability for their offspring. As plant host suitability depends not only on its quality as food, but also on its provision of enemy‐free space, we examined the relationship between adult host preference and offspring performance for the leafminer Liriomyza huidobrensis (Blanchard) (Diptera: Agromyzidae) on various host plants, considering also the interaction with natural enemies. Preference and offspring performance were assessed through observational field data and laboratory experiments in central Argentina. Field data suggested a positive host preference – performance linkage, as the leafminer attained larger body size on the crops where it was more abundant. Laboratory trials supported these results: Vicia faba L. (Fabaceae) was the preferred host in the laboratory as well as in the field, performance of L. huidobrensis being also best on this host, with highest survival rates and shortest development time. The actively feeding larval stage showed the largest plant‐related effects. Higher overall parasitism rates were found on plants from which smaller leafminers were reared, reinforcing the preference–performance linkage. On the other hand, the main parasitoid Phaedrotoma scabriventris Nixon (Hymenoptera: Braconidae) reached larger body size, and caused higher mortality rates on crops where the leafminer was larger. Changes in abundance of particular parasitoid species could thus modify overall parasitism trends.     

Effect of temperature on development and reproduction of Neoseiulus barkeri (Acari: Phytoseiidae) fed on Aleuroglyphus ovatus

The effect of five constant temperatures (16, 20, 24, 28 and 32°C) on the development, survival and reproduction of Neoseiulus barkeri Hughes fed on Aleuroglyphus ovatus Toupeau (Acari: Acaridae) was examined in the laboratory at 85% relative humidity. Development time of different immature stages decreased with increasing temperature, total egg-to-adult development time varied from 5.0 ± 0.13 to 17.5 ± 0.29 days. The lower thermal threshold for development was 9.7 ± 2.48°C and the thermal constant from egg to adult was 111.1 ± 12.34 degree-days. Pre- and post-oviposition period and female longevity all shortened as temperature increased. The longest oviposition period was observed at 24°C with 20.4 ± 1.13 days. At 20, 24, 28 and 32°C, mated females laid on average 0.7 ± 0.08, 1.5 ± 0.04, 1.6 ± 0.11 and 1.5 ± 0.11 eggs per day, respectively, but no eggs were laid at 16°C. Both the maximum fecundity (30.9 eggs per female) and the highest intrinsic rate of increase (r _m = 0.166) were obtained at 28°C. The results of this study indicated that a mass rearing of N. barkeri with A. ovatus as prey is feasible at the appropriate temperature.     

Effects of Endophyte Colonization of Vicia faba (Fabaceae) Plants on the Life–History of Leafminer Parasitoids Phaedrotoma scabriventris (Hymenoptera: Braconidae) and Diglyphus isaea (Hymenoptera: Eulophidae)

Effects of the fungal endophytes Beauveria bassiana (isolates ICIPE 279, G1LU3, S4SU1) and Hypocrea lixii (isolate F3ST1) on the life-history of Phaedrotoma scabriventris and Diglyphus isaea, parasitoids of the pea leafminer Liriomyza huidobrensis, were studied in the laboratory. Parasitoids were allowed to parasitize 2^nd and 3^rd instar L. huidobrensis larvae reared on endophytically-inoculated faba bean, Vicia faba. In the control, parasitoids were reared on non-inoculated host plants. Parasitism, pupation, adult emergence and survival were recorded. No significant difference was observed between the control and the endophyte-inoculated plants in terms of parasitism rates of P. scabriventris (p = 0.68) and D. isaea (p = 0.45) and adult'' survival times (p = 0.06). The survival period of the F1 progeny of P. scabriventris was reduced (p<0.0001) in B. bassiana S4SU1 to 28 days as compared to more than 40 days for B. bassiana G1LU3, ICIPE 279 and H. lixii F3ST1. However, no significant difference (p = 0.54) was observed in the survival times of the F1 progeny of D. isaea. This study has demonstrated that together, endophytes and parasitoids have beneficial effects in L. huidobrensis population suppression.     

Ultrastructure of Microplitis croceipes (Cresson) (Braconidae : Hymenoptera) teratocytes

The developing embryo of the braconid, Microplitis croceipes (Braconidae : Hymenoptera), is encased in an extraembryonic serosal membrane. Hatching of the parasitoid within the larva of its habitual host, Hehothis virescens (Noctuidae : Lepidoptera), is initiated about 40 hr after oviposition when held at 25 ± 2°C. At this time, the monolayered serosal membrane begins to dissociate into individual cells (teratocytes). After dissociation, teratocytes become dispersed in the hemolymph of the host. The average number of teratocytes released from each parasitoid embryo is 914 ± 43. Teratocytes average 14.1 ± 2.4 μm in diameter when first released, and reach a maximum average diameter of 68.1 ± 4.6 μm 6 days after liberation. Newly released teratocytes have ovoid nuclei, simple mitochondria and a limited number of profiles of the endoplasmic reticulum, all of which indicate relative metabolic inactivity. The ramified nuclei, extensive endoplasmic reticulum, polymorphic mitochondria and accumulation of glycogen granules and lipid droplets observed in older teratocytes provide circumstantial evidence that protein synthesis is occurring. Within hours after dissociation, microvilli begin to cover the surface of the teratocytes. Anatomical deformation (blebs) that occurred on some older (8-day-old) teratocytes probably resulted from enlargement or expansion of microvilli.     

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 and host preference of Selitrichodes neseri: A potential biological control agent of the Eucalyptus gall wasp,Leptocybe invasa

Selitrichodes neseri (Hymenoptera: Eulophidae) is a parasitoid of the invasive gall-forming wasp Leptocybe invasa (Hymenoptera: Eulophidae), which has caused serious damage to Eucalyptus plantations in many parts of the world. S. neseri is a recently discovered parasitoid considered to be a potentially important biological control agent of L. invasa. The aim of this study was to provide the first basic data on the biology of S. neseri, which is essential for its application in biological control. S. neseri was shown to be a biparental ectoparasitoid. Observation from dissected galls indicated that the parasitoid developed on late larvae, pupae and callow adults, although development did occur in a range of gall ages. Observed nominal parasitism in captivity ranged from 9.7% to 71.8%. Adult S. neseri specimens, fed with honey-water and galled Eucalyptus leaves, survived an average of 26 days at 26 °C. The average developmental time from oviposition to emergence was 19.3 days ± 0.2 days. There was no pre-oviposition period. A single female produced a maximum of thirty-nine offspring, with a maximum of ten per day. Dissection of the ovaries showed that twelve ovarioles were present. The sex ratio of S. neseri observed in this study was 1:3.43 males:females. Galls of native insects most closely related to L. invasa and to galls of similar morphology to L. invasa-induced galls, were not suitable for S. neseri oviposition. S. neseri showed considerable potential as a biological control agent of L. invasa due to its relatively short developmental time, long adult life span when supplemented with carbohydrates, ability to utilize a range of gall ages and the fact that it has a high level of host specificity.     

Oviposition and reproductive performance of a generalist parasitoid (Trichogramma pretiosum) exposed to host species that differ in their physical characteristics

The response of generalist egg parasitoids to alternative natural hosts that are present simultaneously is not well known. We investigated the behavior of Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) in relation to two field hosts Helicoverpa armigera Hübner and Spodoptera litura Fabricius, in choice and no choice tests. We quantified the effects of natal host species and post-emergence adult age on the oviposition preference of the parasitoids. H. armigera eggs were consistently preferred over S. litura eggs, regardless of the natal host and adult age. When only S. litura eggs were available as hosts, they were parasitized at statistically similar rates to H. armigera eggs (average of 17 ± 2.7 vs. 13 ± 3.0, H. armigera to S. litura). The adult lifespan and lifetime fecundity of T. pretiosum were variable but were affected by natal host species and/or host species to which they were exposed. Mean lifespan and fecundity of parasitoids that had developed in H. armigera eggs and were exposed to H. armigera eggs for oviposition were 13.9 ± 1.8 days and 98.7 ± 11.0 adult offspring. By contrast, those that developed in S. litura eggs and were exposed to S. litura eggs for oviposition lived for 7 ± 0.9 days and produced 53.8 ± 8.0 adult offspring. The ovigeny index (OI) was significantly lower in the parasitoids exposed to H. armigera eggs than in those exposed to S. litura eggs, regardless of the natal host, indicating that H. armigera eggs sustain the adult parasitoids better than S. litura eggs. These results are used to predict parasitoid behavior in the field when both hosts are available.     

Age-dependent functional response of Aphidius matricariae (Hymenoptera: Braconidae) on tobacco aphid,Myzus persicae nicotianae (Hemiptera: Aphididae)

This study was performed to investigate the age-dependent functional response of Aphidius matricariae Haliday (Hymenoptera: Braconidae) at varying densities of tobacco aphid, Myzus persicae nicotianae Blackman (Hemiptera: Aphididae). Six densities (2, 4, 8, 16, 32, and 64 numbers) of third instar nymphs of M. persicae nicotianae were daily exposed to one pair of 1-day-old A. matricariae until the parasitoid female died. Each host aphid density was replicated 10 times. The experiments were conducted at constant environmental conditions (25 ± 1 °C, 70 ± 5% RH and 16:8h L:D photoperiod). The logistic regression model demonstrated that the functional response of A. matricariae was type III in the second day and type II in the first day and from third to the end of adult parasitoid lifetime. The handling time (T_h) was lowest in the first day (0.2305 h) and highest in the sixth day (2.9296 h) of the parasitoid’s life. The searching efficiency (a) values were 0.0573, 0.0649, 0.0503, 0.0229, and 0.0077 h^?1 in the first, third, fourth, fifth, and sixth days of the parasitoid’s life, respectively. Also, the b value for type III functional response was 0.0147 in the second day. The values of maximum attack rate (T/T_h) ranged from 104.12 nymphs/24 h in the first day to 19.8 nymphs/24 h in the sixth day of parasitoid’s life. Based on the results, A. matricariae showed a high potential to control the population of tobacco aphid and the highest efficiency gained in the first half of the female parasitoid life.     

Biology of Apanteles myeloenta (Hymenoptera: Braconidae), a larval parasitoid of carob moth Ectomyelais ceratoniae (Lepidoptera: Pyralidae)

The carob moth, Ectomyelois ceratoniae (Lepidoptera: Pyralidae), is the most important pest of pomegranate orchards (in terms of economic damage) within Iran, and hence, several control procedures, including biological methods of control, have been attempted as a means of controlling populations of this insect. This research was carried out in order to study the biology of Apanteles myeloenta (Hymenoptera: Braconidae), a larval parasitoid of the carob moth. Laboratory studies were conducted to determine larval developmental time, adult longevity, sex ratio, parasite progeny production, and host stage preference of A. myeloenta. At 25 ± 1 °C, immature developmental time (egg to pupa; mean ± SE) was 28.33 ± 0.85 days and 27.46 ± 0.37 days for male and females, respectively. Adult females survived on average 17.5 ± 0.14, 11.7 ± 0.22, 3.4 ± 0.18, and 2.8 ± 0.12 days at 25 C when provided with honey and water, honey only, water only or no food source, respectively. The sex ratio (females to males) of A. myeloenta was 1:3.5 from hosts parasitized in the first instar, 1:3 for second instars and 1:2 for third instar carob moth larvae. Female A. myeloenta typically preferred to parasitize second instar over third or first instar. The oviposition activity peaked on the 7th and 8th days following emergence, when provided with honey, and 10% sucrose solution, respectively.     

Age‐ and temperature‐dependent oviposition model of Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) with Tetranychus urticae as prey

In this study, we developed an oviposition model of Neoseiulus californicus (McGregor) with Tetranychus urticae Koch as prey. To obtain data for the model, we investigated the longevity, fecundity and survivorship of adult female N. californicus at six constant temperatures (16, 20, 24, 28, 32 and 36°C), 60–70% RH and a photoperiod of 16 : 8 (L : D) h. Longevity (average ± SE) decreased as temperature increased and was longest at 16°C (46.7 ± 5.25 days) and shortest at 36°C (12.8 ± 0.75 days). Adult developmental rate (1/average longevity) was described by the Lactin 1 model (r² = 0.95). The oviposition period (average±SE) was also longest at 16°C (29.8 ± 2.93 days) and shortest at 36°C (6.7 ± 0.54 days). Fecundity (average±SE) was greatest at 24°C (43.8 ± 3.23 eggs) and lowest at 36°C (15.9 ± 1.50 eggs). The oviposition model comprised temperature‐dependent fecundity, age‐specific cumulative oviposition rate and age‐specific survival rate functions. The temperature‐dependent fecundity was best described by an exponential equation (r² = 0.81). The age‐specific cumulative oviposition rate was best described by the three‐parameter Weibull function (r² = 0.96). The age‐specific survival rate was best described by a reverse sigmoid function (r² = 0.85).     

Effect of temperature on development time and life table parameters of Nephus hiekei Fürsch,the important predator of Phenacoccus solenopsis Tinsley

The cotton mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) has become a serious threat to agricultural and ornamental plants in Southwest Iran. Pest-control studies have found Nephus hiekei Fürsch (Coleoptera: Coccinellidae), in large numbers on Phenacoccus solenopsis Tinsley, as a potential predator. However, there has been no investigation on this predator. In this research, the biology and age-stage, two-sex life table parameters of N. hiekei feeding on Ph. solenopsis were investigated at three constant temperatures (27, 32 and 37 ± 1 °C, 65 ± 5% RH and a photoperiod of 16: 8 (L: D) h. The duration of total pre-adult stage was found to decrease raising temperature from 26.98 ± 0.36 days at 27 °C to 14.24 ± 0.27 days at 37 °C. The oviposition period lasted 63.95 ± 3.14, 66.42 ± 3.34 and 25.20 ± 1.59 days at 27, 32, and 37 °C, respectively. Females laid an average of 365.68 ± 22.36, 543.79 ± 27.27 and 106.25 ± 6.38 eggs, at these three temperatures, respectively. The intrinsic rate of increase (r_m = 0.1333 ± 0.0050 d^–1), finite rate of increase (λ = 1.1423 ± 0.0057 d^–1) and net reproductive rate (R₀ = 188.89 ± 28.34 offspring) as well as gross reproductive rate (GRR = 308.31 ± 39.54 offspring) were greatest at 32 °C. The shortest mean generation time (T = 26.74 ± 0.65 days) was recorded at 37 °C and the longest at 27 °C (T = 56.48 ± 1.0 days). These results indicate that N. hiekei can successfully survive and reproduce at temperatures of around 32 °C, and has good potential to be an effective biological control agent of Ph. solenopsis.