Feeding activity and life history characteristics of the generalist predator,<Emphasis Type="Italic"> Chrysoperla carnea</Emphasis> (Neuroptera: Chrysopidae) at different prey densities

Larvae of the common green lacewing, Chrysoperla carnea (Stephens) (Neuroptera :Chrysopidae) were fed with different densities of Hyalopterus pruni (Geoffer) (Homoptera: Aphididae) in Petri dishes under laboratory conditions. Functional response, developmental time, mortality rate and fecundity of the predator were measured. Treatments were carried out at 25±1°C, 65±5% RH and a 16L:8D photoperiod in a controlled temperature cabinet. Prey was given at densities of 5, 10, 20, 40, 80, 160 and 250 aphids per larva per day and the number of consumed prey, developmental time and mortality rate of the predator were recorded daily. Larvae of C. carnea responded to increasing prey densities with increasing food consumption and older larval stages displayed a higher rate of predation than younger ones. The behaviour of each of the three larval stages matched Hollings type II functional response. Larvae were able to complete their development in each of the seven prey densities, although increased prey densities reduced developmental time and mortality rate. Increased prey consumption in immature stages resulted in a higher net reproduction rate (R ₀) and the intrinsic rate of increase (r _m) of adult females.     

Studies on morphology and biology of immature stages of the predator Rhyzobius lophanthae Blaisdell (Col.: Coccinellidae)

Morphological characteristics of immature developmental stages of Rhyzobius lophanthae Blaisdell (Col.: Coccinellidae), predator of scale insects of the family Diaspididae (Homoptera), are described. Data about the morphology of eggs, the four larval instars, and the pupa is presented. Larval instars are described in more detail: size of head capsule, length of tibia, distribution of dorsal and lateral setae of abdomen segments for each larval instar is reported. Distribution of spiracles is also given. Study on the biology concerns the influence of prey on the duration of instar periods. The diaspidids Aspidiotus nerii and Aonidiella aurantii were used as food. The mean duration of the developmental period from egg to adult was 27.1 days, and no mortality was observed (0?%) when A. nerii was used as prey. The respective numbers when the prey was A. aurantii were 48.8 days and 84?%.     

Effects of different neem preparations in comparison to synthetic insecticides on the whitefly parasitoid Encarsia sophia (Hymenoptera: Aphelinidae) and the predator Chrysoperla carnea (Neuroptera: Chrysopidae) on cotton under laboratory conditions

The contact and feeding toxicity of NeemAzal T/S (EID Parry, Chennai, India) to the parasitoid Encarsia sophia (Girault & Dodd) was compared with three synthetic insecticides (chlorpyriphos, endosulfan and triazophos) against immatures and adult emergence. NeemAzal T/S (1.0%) at lower dose (200 mg/l) did not cause any effect on the emergence of E. sophia adults, but there was a significant reduction in emergence at higher doses (800 mg/l). Also, it did not show contact toxicity to adults of E. sophia, but there was a significantly high feeding mortality in a dosage dependant manner, whereas chlorpyriphos, endosulfan and triazophos showed high toxicity both by contact and feeding method. Three neem preparations registered in India, NeemAzal T/S, Nimbecidine (T. Stains, Coimbatore) and Godrej Achook (Godrej Agrovet, Mumbai) were tested against egg and larval stages of Chrysoperla carnea (Stephens) at three dosages, using a synthetic insecticide, triazophos 40 EC (200 mg/l), for comparison under laboratory conditions. The three biorationals did not induce any adverse effect on the hatchability of C. carnea eggs. The mortality of the first instars of C. carnea was not affected by any of the azadirachtin enriched formulations; however, at higher dosage of 800 mg/l these neem based products resulted in increased mortality of the first and second instar larvae of C. carnea relative to the untreated controls. Whereas, triazophos induced very high mortality rates (85.0, 89.0 and 81.5%) of all the three larval instars. The neem based insecticides showed a dosage-dependant effect on the larval instars of C. carnea. Thus, these biorationals show that there is a potential to use them in an IPM system, being safe for natural enemies of B. tabaci in cotton.     

Prey consumption by larval and adult stages of the entomophagous ladybird Serangium parcesetosum Sicard (Col., Coccinellidae) of the cotton whitefly, Bemisia tabaci (Genn.) (Hom., Aleyrodidae), at two different temperatures

The entomophagous ladybird, Serangium parcesetosum Sicard (Col., Coccinellidae) appears to be a promising predator against the cotton whitefly, Bemisia tabaci (Genn.) (Hom., Aleyrodidae). Knowledge about its consumption of B. tabaci is incomplete. The present study was undertaken to determine the potential use of this predator in biological control programs. The daily and total prey consumption of S. parcesetosum through the entire development of the larval instars as well as during three different periods of longevity of adult females and males feeding on nymphs or puparia of B. tabaci as prey was examined. In addition, the daily prey consumption of the adult females where the number of B. tabaci puparia was altered was studied at two different temperatures in the laboratory. The results showed that the mean daily prey consumption of nymphs or puparia of B. tabaci by larval instars of S. parcesetosum increased gradually as development progressed at both temperatures. Significant differences were found in the mean total prey consumption among the different predatory larval instars. In total, S. parcesetosum consumed during its entire larval development significantly more nymphs than puparia; at 18°C it consumed a mean of 1,566.1 () and 1,443.9 () nymphs or 280.0 () and 250.8 () puparia, while at 30°C, it consumed a mean of 1,119.1 () and 979.9 () nymphs or 188.2 () and 171.6 () puparia. Over the three studied periods of the adult stage of S. parcesetosum, the mean daily prey consumption by the females and males fluctuated irregularly at both temperatures. At 18°C and 30°C, both females and males consumed significantly more nymphs than puparia. No significant differences were found between females and males with respect to consumption of nymphs, although significant differences were found between the sexes with respect to consumption of puparia, but at 18°C only. The mean total prey consumption over the three studied adult stages was 2,188.4 () and 1,994 () nymphs or 727.1 () and 624.8 () puparia at 18°C, while at 30°C the mean values were 3,947.7 () and 3,577.3 () nymphs or 1,600.5 () and 1,448.8 () puparia. S. parcesetosum adapted smoothly to fluctuating prey availability, where the mean daily prey consumption became higher when 50 puparia/day was offered. In contrast, the predator consumed most individuals when the number of prey supplied was 10 or 5 puparia/day. Prey consumption decreased during the second experimental week in the trial, before which 50 puparia/day had been offered. In the other trials, before which 20, 10 and 5 puparia/day had been offered, a considerable increase in prey consumption was noted.This paper is dedicated to Prof. Dr I. Akif Kansu, University of Ankara, Turkey on his 80th birthday.     

Assessment of the biological control capability of <Emphasis Type="Italic">Hippodamia variegata</Emphasis> (Col.: Coccinellidae) using functional response experiments

Lady beetles are among the most successful predators of aphids in different environments. The functional responses of different life stages of Hippodamia variegata (Goeze) towards cotton aphids were examined in two different set-ups, a two-dimensional Petri dish set-up with detached leaves and a three-dimensional set-up with whole plants. In addition, the functional responses in two-dimensional set-ups towards cotton aphids and the pea aphids were compared. H. variegata exhibited a functional type II response to both cotton aphids and pea aphids irrespective of life stage and spatial scale of the set-up. Females and fourth instars generally had higher search rates than third instars whereas handling times were consistently lower for the fourth instar stage compared with the preceding juvenile stage and with females. The spatial dimensions did not have any significant influence on the functional responses towards cotton aphids, except for third instars which in the three-dimensional set-up reduced their search rate and increased their handling time. Fourth instars reacted in the same way to both Aphis gossypii and Acyrthosiphon pisum whereas the functional response parameters for third instars and females were significantly different on the two prey species. Our study, a part of this first-step evaluation of H. variegata as a biocontrol agent against A. gossypii and A. pisum under field condition, suggest that the voracity of all tested stages of H. variegata towards both aphid species hold good promises for a use of especially fourth instars and females in inundative biocontrol.     

Entwicklung,Lebensdauer, Fruchtbarkeit und Geschlechtsverhältnis der RaubmilbeAmblyseius longispinosus (Evans) mitTetranychus cinnabarinus (Boisd.) als Beute

The development, longevity, fecundity and sex ratio of the predatory miteAmblyseius longispinosus (Evans) were studied at different constant and alternating temperatures withTetranychus cinnabarinus as prey. Alternating temperatures had no significant effect on the developmental times, in comparison with optimal constant temperature. At the alternating temperature of 33/23°C the mean duration of the life cycle from egg to adult was obvious longer with 5.0 and 4.4 days forA. longispinosus females and males than at alternating temperature of 30/20°C with 4.2 and 4.1 days for females and males. At 25°C constantly the egg stage was the longest during development and required a mean of 2.2 days.A. longispinosus females and males remained in larval stage for 0.5 and 0.6 days. The protonymphal and deutonymphal stage lasted for 0.7 and 1.1 for females and for 0.7 days for males, respectively. At all temperatures the development of females required significantly longer than of males. Longevity ofA. longispinosus adults was variable to tested temperatures: At 25°C females lived for 33.1 days, at 30/20°C for 30.6 days and at 33/23°C for 29.9 days. At 25°CA. longispinosus females produced a mean total progeny of 48.8 eggs and the mean duration of oviposition period was 21 days; at 30/20°C and at 33/23°C a mean number of 49.1 and 48.2 eggs was laid during an oviposition period of 20 days. Temperature had no effect on the sex ratio of predatory mites, about 70% of mites became females at all temperatures.     

Thermoperiodic effects on larval growth parameters of the Sesamia nonagrioides (Lepidoptera: Noctuidae)

The effect of five constant (10, 15, 20, 25 and 30°C) and the corresponding cycling (25:10, 27.5:12.5, 30:15, 32.5:17.5 and 35:20°C) temperatures at a photoperiod of 16:8 (L:D) h on the development and biometry (HCW, weight) of larva of Sesamia nonagrioides (Lef) Lepidoptera–Noctuidae were investigated. Larvae under both temperature treatments seemed to complete six instars. Final mean head capsule widths did not differ significantly between constant and cycling temperatures. Larval weights increased considerably through larval period under all temperature regimes. However, alternating temperatures were not shown to stimulate larval weight or head capsule widths compared with those of constant temperatures, although tended to result in shorter larval developmental periods. Results are discussed regarding development and seasonal biology of the species.     

Host instar suitability of <Emphasis Type="Italic">Bemisia tabaci</Emphasis> (Genn.) (Hom.: Aleyrodidae) for the parasitoid <Emphasis Type="Italic">Eretmocerus mundus</Emphasis> (Hym.: Aphelinidae)

Efficient use of parasitoids in pest control depend on the knowledge of the biological relationships between host and parasitoid. Eretmocerus mundus Mercet (Hymenoptera: Aphelinidae) is one the most important natural enemies of Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) that is found in fields and greenhouses in Adana, Turkey. Although more studies have been done to determine the relationships between E. mundus and B. tabaci, the differences among strains of E. mundus could have important biological concequences. In this study, biological characteristics of native population of E. mundus parasitization of B. tabaci (Q biotype) were determined using bean plants Phaseolus vulgaris (L.) at a constant temperature of 25 ± 1°C, relative humidity 70 ± 10% and 16:8 (L:D) photoperiod regimen. All B. tabaci nymphal instars were parasitized by E. mundus, but the mean number of daily-parasitized nymphs was highest in the second instars (15.3). In addition, second instar females had the shortest mean development time (15.2 days). Mean development times of parasitoids obtained from first, second, third and fourth B. tabaci instars varied from 15.2 to 16.2 days and 15.2 to 15.9 days for female and male, respectively. Proportion of female (♀/♂+♀) varied from first (0.53) to second (0.34) host instars. Impact of results on potential biological control of B. tabaci was discussed through conservation native natural enemies.     

Lebenszyklus von Meloidogyne incognita acrita (Kofoid & White) Chitwood (Nematoda,Heteroderidae) in Wurzeln der Baumwolle,Gossypium barbadense L

The incubation period ofM. incognita acrita eggs took 24–72 hours till the appearance of the second larval stage hatching from eggs in the laboratory at 25±5°C and at 60±5 R. H. The second larval stage, was observed in cotton roots 48 hours after the addition of it to soil beside cotton seedlings. The 3rd and 4th larval stage and adult female were observed in cotton roots 7, 11, and 24 days, respectively, after the addition of second larval stage to soil beside cotton seedlings. The total life cycle ofM. incognita acrita on cotton, (Gossypium barbadense) lasted for 33–38 days, at 25±5°C and at 60±5 R. H.     

Nondestructive evaluation of egg-to-adult development and feeding behavior of the bamboo powderpost beetle <Emphasis Type="Italic">Dinoderus minutus</Emphasis> using X-ray computed tomography

The life history and feeding biology of the bamboo powderpost beetle Dinoderus minutus remain poorly understood because the beetles’ oviposition, development, and feeding take place inside bamboo culms. In this study, X-ray computed tomography (CT) was employed to nondestructively quantify the progression of larval body size and tunnel size from the first instar to pupation. Eggs of D. minutus laid between laminates of nutrient-containing filter paper were easily collected. The newly hatched larvae were inoculated singly into pieces of internodes of madake (Phyllostachys bambusoides). The pieces were scanned using a microfocus X-ray CT system every 3–5 days to visualize the beetles’ bodies and tunnels with resolutions of 18–60 μm/voxel. CT scans were continued after adult eclosion to analyze pre-mating adult feeding. The collected eggs were 0.84 ± 0.06 mm (mean ± SD) in length and the egg duration lasted 5.0 ± 0.8 days. Based on CT images, the larvae grew to 3.53 ± 0.23 mm in body length and turned into pupae of 3.42 ± 0.09 mm. The larvae bored tunnels with a length of 80.2 ± 4.8 mm and a volume of 68.0 ± 7.0 mm³ over the larval period of 61 ± 11 days. Newly emerged adults remained in the bamboo pieces to feed before making exit holes in 8 ± 1 days after adult eclosion. During this period, they bored tunnels at rates of 2.64 ± 0.58 mm/day in length and 4.87 ± 1.10 mm³/day in volume.     

Development,life history characteristics and behaviour of mealybug predator, <Emphasis Type="Italic">Spalgis epius</Emphasis> (Westwood) (Lepidoptera: Lycaenidae) on <Emphasis Type="Italic">Planococcus citri</Emphasis> (Risso) (Homoptera: Pseudococcidae)

The development of immature stages, life history and behaviour of mealybug predator, Spalgis epius (Westwood) (Lepidoptera: Lycaenidae) reared on mealybugs, Planococcus citri (Risso) (Homoptera: Pseudococcidae) was studied in the laboratory. Larvae of S. epius are a potential predator of different species of mealybugs in India. The predator completed its life cycle in 23.8 days with four larval instars. Mean incubation period of egg was 3.9 days. Mean duration of development of larval stages, prepupa and pupa was 9.4, 0.9 and 9.5 days, respectively. The first and last instar larvae measured 1.9 and 11.4 mm in length, respectively. Length and width were not significantly correlated in larvae. Head capsule width was not significantly correlated with larval length in any instar. The female-to-male sex ratio was 1.45:1. Adults were ready for mating one day after eclosion. The pairs remained in copula on an average of 61.3 min. The gravid female contained 74.6 eggs in the ovaries. Unfed butterflies (both males and females) lived 3–4 days, significantly shorter than those with access to water (6–7 days). The results of this study will be useful to utilize the predator as a biocontrol agent.     

Oviposition and larval performance of Monochamus alternatus (Coleoptera: Cerambycidae) on the Japanese cedar Cryptomeria japonica

To determine whether Monochamus alternatus can use the Japanese cedar (Cryptomeria japonica) as a host tree, experiments were conducted in a laboratory using three insect populations of different localities. Adult females chose Pinus densiflora bolts as oviposition substrate when supplied with cedar and pine bolts simultaneously, whereas some females from one locality oviposited on cedar bolts when supplied with them exclusively. Seventy-three percent of 40 eggs hatched in cedar bolts. When the first instar larvae were inoculated on cedar bolts, the development was stunted greatly and all died during the larval stage. Two of 20 larvae that were inoculated on cedar bolts at the third instar entered the diapause and one larva developed into an adult female, which produced viable eggs but was much smaller than those obtained from pine bolts. The results did not exclude the possibility that M. alternatus can use recently killed C. japonica trees as a host.     

Population dynamics of Dasiops inedulis (Diptera: Lonchaeidae) and its biotic and abiotic mortality factors in Colombian sweet passionfruit orchards

Throughout South America, the lonchaeid flies Dasiops spp. are important herbivores of passionfruit crops. However, little is known on the biology and ecology of these insects, resulting in inadequate pest management schemes. In this study, we describe Dasiops inedulis population dynamics in Colombian sweet passionfruit (SP; Passiflora ligularis Juss.) and elucidate biotic mortality factors at different fly developmental stages. From August 2009 to July 2010, D. inedulis and Dasiops spp. abundance was assessed through monthly McPhail bait trapping and collection of SP flower buds, flowers, and immature fruits. Mortality levels of D. inedulis were determined for early instar larvae by ovary dissection and for late-instar larvae or pupae by prey removal trials. Maximum infestation reached 80 % in fruits and flower buds, and bud infestation correlated with precipitation during the previous month. Two days after oviposition, 8.2 ± 2.3 (mean ± SD) Dasiops sp. eggs were found in SP ovaries and 4.4 ± 1.2 late-instar larvae were recovered from immature fruits at day 14. Upon larval drop on the orchard soil, 74.8 % larvae burrowed within the soil within 9 min, while 12.5 % larvae were attacked by ants. In-field mortality of young pupae amounted to 75.3 ± 7.0 %, with vertebrate predators likely causing 12.1 ± 6.0 % mortality. Late-instar larvae and pupae appear highly vulnerable to natural enemy action, with the ground-foraging predator community mainly composed of ants (80.37 %) and ground beetles (9.17 %). Our findings should help develop integrated pest management (IPM) tactics for SP crops.     

Characterization of larval instars of artemisia weevil, Adosomus sp.

The artemisia weevil, Adosomus sp., has become an important wormwood (Artemisia ordosoca and A. sphaerocephala) pest in recent years in Ningxia Province, China. The number of larval instars should be determined before further studies on its life history, biology and integrate management of pest (IMP). In this study, we measured the length and width of head capsule, based on frequency histograms and Dyar’s law, from which we concluded that the larvae of Adosomus sp. have four instars. Of the two variables measured, the width of head capsule provided the best division of instars. The average width of head capsule of the 1st instar larvae was 1.348±0.152 mm, the 2nd 2.109±0.199 mm, the 3rd 3.563±0.492 mm and the 4th 5.974±0.581 mm.     

Effect of adult nutrition and insect density on the performance of spotted stem borer, <Emphasis Type="Italic">Chilo partellus</Emphasis> in laboratory cultures

The spotted stem borer, Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) is being successfully reared on artificial diets for screening programmes. Besides quality characteristics of the diet, rearing density and adult nutrition have significant implications on the successful mass multiplication of lepidopterans. The performance of C. partellus moths was assessed on different adult diets (water and sugar solution) and compared with unfed adults. Further, three pairing densities, viz. 2, 5 and 8 pairs/oviposition jar (1177.5 cm³) were compared for their effect on C. partellus longevity and fecundity. In another experiment, different larval densities (100, 150 and 200 neonate larvae/diet jar) were evaluated for their effect on the larval survival. Water-fed moths (both males and females) lived longer (7.32 and 7.26 days, respectively) and showed higher fecundity (307.17 eggs) than the sugar-fed or unfed moths. The latter, however, showed better egg hatchability (76.55%) than the water- or sugar-fed moths (60.45 and 50.59%, respectively). The longevity (5.67 days) and fecundity (258.46 eggs) were significantly greater at pairing density of 2 pairs/jar. The larval survival was higher (58.50%) at rearing density of 100 larvae/jar. The neonate larval release into diet jars was compared with conventional egg release and both modes were no different with respect to larval survival.     

Functional responses of the parasitoid,Ertmocerus longipes Compere (Hym., Aphelinidae) to densities of the whitefly,Aleurotuberculatus takahashi David et Subramaniam (Hom., Aleyrodidae) at different temperatures

The present study dealt with the functional responses of the parasitoid,Eretmocerus longipes Compere (Hym., Aphelinidae) to the densities of the whitefly,Aleurotuberculatus takahashi David et Subramaniam (Hom., Aleurodidae) at different temperatures under the laboratory conditions. The results showed that when the initial densities ofA. takahashi-3rd instar were raised from 10 to 320 ind./leaf, the numbers of parasitized nymphs increased as well, ranging from 7.0 to 23.1 at 20°C, 9.8 to 42.9 at 25°C, 6.7 to 39.9 at 30°C, and 1.8 to 8.3 ind./leaf at 35°C, respectively. The Holling Disk Equation was introduced to build up the models of functional responses. The response curves remained type II, although the numbers of parasitized nymphs were significantly different under different temperatures. The suitable initial densities of the host whitefly for parasitization were about 80 individuals per leaf. A negative relation was observed between the initial densities of the whitefly and the parasitization rates by the parasitoid. An increase in the initial densities ofA. takahashi-3rd instars ranging from 10 to 320 ind./leaf resulted in a decrease in the parasitization rate byE. longipes ranging from 70.0% to 7.2% at 20°C, 98.0% to 13.4% at 25°C, 67.0% to 12.5% at 30°C and 18.0% to 2.6% at 35°C with a value of 0.2877 was significantly smaller than that at 20°C with a vlaue of 1.3354, that at 25°C with a value of 1.6465 and that at 30°C with a value of 1.1199, respectively (p<0.01). The handling time (Th) forE. longipes was 0.1521 at 35°C, significantly longer than 0.0510 at 20°C, 0.0289 at 25°C and 0.0320 at 30°C, respectively (p<0.01). The maximum loading number (K) of the parasitized nymphs with a value of 34.5 ind./leaf at 25°C was similar to that with a value of 31.2 ind./leaf at 30°C, about 1.8 times as high as that with a value of 19.6 ind./leaf at 20°C and 4 times more than that with a value of 6.6 ind./leaf at 35°C. It was suggested that temperature affected the functional response by balancing searching rate and handling time. The optimal temperature range for the functional responses ofE. longipes to the densities ofA. takahashi-3rd instar was 25° to 30°C.     

Potential fecundity of the bamboo gall maker,Aiolomorphus rhopaloides (Hymenoptera: Eurytomidae), and its inquiline,Diomorus aiolomorphi (Hymenoptera: Torymidae), in relation to gall size and body size

I examined the adult potential fecundity of the bamboo gall maker,Aiolomorphus rhopaloides Walker (Hymenoptera: Eurytomidae), and its inquiline,Diomorus aiolomorphi Kamijo (Hymenoptera: Torymidae) by dissection just after emergence, and at death after rearing. Emerging females ofA. rhopaloides hadca. 80 mature eggs in their ovaries. The number of eggs at emergence and after death at rearing was not significantly different. However, emerging females ofD. aiolomorphi had no eggs in their ovaries but hadca 20 eggs at death after rearing. These results suggest thatA. rhopaloides is pro-ovigenic andD. aiolomorphi is synovigenic. Female body sizes of both species were positively correlated with the size of galls from which each emerged. Number of eggs in each species was also correlated with female body size, suggesting that gall size might be a good predictor of potential fecundity. This study was supported in part by a Grant-in-Aid for scientific Research (No. 11460068) from the Ministry of Education, Science, Sports, and Culture, Japan.     

Temperature-dependent functional response of two aphid parasitoids, Aphidius colemani and Aphidius matricariae (Hymenoptera: Aphidiidae), on the cotton aphid

The functional response of two aphid parasitoids, Aphidius colemani Viereck and Aphidius matricariae (Haliday) (Hymenoptera: Aphidiidae), on the cotton aphid, Aphis gossypii Glover (Homoptera: Aphididae), was examined. Five constant temperatures (10, 15, 20, 25, and 30°C) and six host densities (2, 4, 8, 16, 32, and 64) were used during a 24-h period. At each temperature, 2–64 third-instar nymphs of A. gossypii were exposed to individual wasp mating pairs. A type II functional response model for both parasitoid wasps was fit separately for each temperature. The results showed that instantaneous attack rate (a) in A. colemani increased linearly as the temperature increases from 10 to 30°C, but in A. matricariae, (a) increased almost linearly with temperature to reach a maximum at 25°C, and then decreased at 30°C, displaying an asymmetrical dome-shaped pattern. The highest instantaneous attack rate for A. colemani and A. matricariae were calculated 0.940 ± 0.144 day⁻¹ at 30°C and 0.687 ± 0.157 day⁻¹ at 25°C, respectively. Handling time (T _h) for A. colemani was inversely proportional to temperature and ranged from 0.093 ± 0.026 day at 10°C to 0.032 ± 0.004 day at 30°C, but in A. matricariae, (T _h) was between 0.078 ± 0.015 day at 10°C and 0.036 ± 0.014 day at 20°C. A. colemani achieved higher parasitism rate than A. matricariae at higher temperatures. This observation suggests that A. colemani maybe more effective for biological control of the cotton aphid during warmer periods.     

Effects of gamma radiation on life stages of the Mediterranean flour moth, Ephestia kuehniella Zeller (Lepidoptera: Pyralidae)

We report the results of experiments conducted with Ephestia kuehniella Zeller to determine the effects of gamma radiation on life stages. Eggs, larvae, pupae and adults were irradiated with increasing doses of gamma radiation (seven dose levels between 50 and 400 Gy for eggs and larvae, six dose levels between 50 and 350 Gy for pupae and four dose levels between 250 and 550 Gy for adults). All the experiments were conducted in a growth chamber maintained at 27 ± 1°C, 65 ± 5% r.h., and alternating 14 h light:10 h dark cycles. The number of adults that developed from irradiated eggs and larvae was lower than the untreated control. Doses of 200 Gy and above prevented adult emergence from irradiated eggs. Although a dose of 200 Gy was enough to prevent adult emergence from young larvae, 250 Gy should be used to prevent adult emergence completely from last instar larvae. Delayed developmental periods were observed for the treated eggs and larvae. Fecundity and egg hatchability were decreased depending on the doses applied. Decreased fecundity and egg hatchability were more prevalent when both the male and female pupae were treated compared to the treatment of female pupae only. There was no significant decrease in the fecundity of irradiated adults except 550 Gy, and no eggs hatched at doses of 300 Gy and above.     

Development and population growth of <Emphasis Type="Italic">Stephanitis pyri</Emphasis> (F.) (Heteroptera: Tingidae) at five temperatures

Pear lace bug, Stephanitis pyri (F.) (Heteroptera: Tingidae) is a pest of apple and pear trees and ornamental Rosaceae plants in Mediterranean countries and palearctic region. The aim of this study is to determine the effects of temperatures on S. pyri in the laboratory. Development and fecundity of S. pyri reared on apple leaves (Pyrus malus L.) were investigated at five constant temperatures (20, 23, 26, 29 and 32 ± 1°C) and a 16L:8D photoperiod. Longevity was determined to be 12.6 days at 32°C and 58.7 days at 20°C for females, and 9.7 and 37.7 days for males. Females laid 186.9 eggs per female with the highest number achieved during 28.5 days of oviposition period at 26°C. Female lifetime fecundity was reduced at 32°C (40.0 eggs per female). While the net reproductive rate (R ₀) was highest at 26°C, the intrinsic rate of natural increase (r _m ) was highest at both 26 and 32°C. The mean generation time (G) was estimated to be 27.2–78.4 days at 20 and 32°C, respectively. The longest development times for egg and total nymph stages were obtained as 22.0 and 24.9 days, respectively, at 20°C. S. pyri developed fastest from egg to egg in 24.3 days at 32°C. The lower developmental threshold (T ₀) was 9.7°C and the thermal constant (K) was 517.3 degree-days for S. pyri. Thus, S. pyri is calculated to have 3.8 theoretical generations in Tekirdag. The optimum developmental temperature for S. pyri was 26°C.