Pupal Development Time Research Articles

Mixture-Amount Design and Response Surface Modeling to Assess the Effects of Flavonoids and Phenolic Acids on Developmental Performance of Anastrepha ludens

Host plant resistance to insect attack and expansion of insect pests to novel hosts may to be modulated by phenolic compounds in host plants. Many studies have evaluated the role of phenolics in host plant resistance and the effect of phenolics on herbivore performance, but few studies have tested the joint effect of several compounds. Here, we used mixture-amount experimental design and response surface modeling to study the effects of a variety of phenolic compounds on the development and survival of Mexican fruit fly (Anastrepha ludens [Loew]), a notorious polyphagous pest of fruit crops that is likely to expand its distribution range under climate change scenarios. (+)- Catechin, phloridzin, rutin, chlorogenic acid, and p-coumaric acid were added individually or in mixtures at different concentrations to a laboratory diet used to rear individuals of A. ludens. No effect was observed with any mixture or concentration on percent pupation, pupal weight, adult emergence, or survival from neonate larvae to adults. Larval weight, larval and pupal developmental time, and the prevalence of adult deformities were affected by particular mixtures and concentrations of the compounds tested. We suggest that some combinations/concentrations of phenolic compounds could contribute to the management of A. ludens. We also highlight the importance of testing mixtures of plant secondary compounds when exploring their effects upon insect herbivore performance, and we show that mixture-amount design is a useful tool for this type of experiments.Electronic supplementary materialThe online version of this article (doi:10.1007/s10886-014-0404-6) contains supplementary material, which is available to authorized users.

Oviposition Pattern of Early and Late-Emerging Genotypes ofDelia radicum(Diptera: Anthomyiidae) at Different Temperatures

The cabbage maggot, Delia radicum L., has a bimodal pattern of emergence caused by the presence in populations of early and late-emerging genotypes that differ in their pupal development time. These genotypes could also express different egg-laying strategies. To examine oviposition patterns between genotypes and, particularly, their response to temperature, the egg-laying activity of females and egg mortality from each genotype were evaluated at temperatures from 12 to 30°C. Several criteria were used to describe the oviposition pattern: longevity of females, preoviposition period, lifetime fecundity, number of oviposition bouts, duration and number of eggs for each oviposition bout, duration of an oviposition cycle, and time interval between oviposition bouts. All criteria were similar between genotypes, except the preoviposition period and time interval between oviposition bouts. The preoviposition period was 1-4 d longer for the early emerging genotype than for the late-emerging genotype at temperatures <25°C, but similar at temperatures ≥25°C. The time interval between oviposition bouts of early emerging genotype was a few hours longer than for the late-emerging genotype at all temperatures. All oviposition pattern criteria responded to temperature, except the duration of oviposition bouts (≍6.5 d) and egg mortality (≍11%). The duration of a bout could be a compromise between oogenesis duration and the risks associated with egg deposition. According to these results, early and late-emerging genotypes express similar egg-laying strategies for all temperatures tested.

Fitness Costs Associated With Field-Evolved Resistance to Bt Maize in &lt;I&gt;Spodoptera frugiperda&lt;/I&gt; (Lepidoptera: Noctuidae)

Increasing adoption of transgenic crops expressing cry toxin genes from Bacillus thuringiensis (Bt crops) represents an augmented risk for development of insect resistance. While fitness costs can greatly influence the rate of resistance evolution, most available data related to Bt resistance have been obtained from laboratory-selected insect strains. In this article, we test the existence of fitness costs associated with high levels of field-evolved resistance to Bt maize event TC1507 in a strain of Spodoptera frugiperda (JE Smith) originated from maize fields in Puerto Rico. Fitness costs in resistant S. frugiperda were evaluated by comparing biological performance to susceptible insects when reared on meridic diet, maize or soybean leaf tissue, or cotton reproductive tissues. Parameters monitored included larval survival, larval and pupal weights, developmental time (larval and pupal), adult longevity, reproductive traits (fecundity and fertility), and sex ratio. We found that all monitored parameters were influenced to a similar extent by the host, independently of susceptibility to Bt maize. The only parameter that significantly differed between strains for all hosts was a longer larval developmental period in resistant S. frugiperda, which resulted in emergence asynchrony between susceptible and resistant adults. To test the relevance of fitness costs in resistant S. frugiperda, we performed a selection experiment to monitor the stability of resistance in a heterogeneous strain through 12 generations of rearing on meridic diet. Our data demonstrate lack of fitness costs relevant to stability of field-evolved resistance to Bt maize and help explain reported stability of field-evolved resistance in Puerto Rican populations of S. frugiperda.

Lethal and sublethal effects of thiacloprid on survival, growth and reproduction of Helicoverpa armigera (Lepidoptera: Noctuidae)

The cotton bollworm Helicoverpa armigera (Hübner) is the most destructive pest of cotton, tomato and chickpea in Iran. In this study, the lethal and sublethal effects of thiacloprid were evaluated against cotton bollworm under laboratory condition at 26 ± 1 °C, 70 ± 5% RH and a photoperiod of 16:8 (L:D). Bioassay experiments were conducted on first larval instars by mixing the insecticide dilutions with artificial diet. The LC50 value of thiacloprid was 329 mg a.i./l. Sublethal effects of LC30 concentration of thiacloprid was studied on biological parameters. In the study of sublethal effects, thiacloprid at LC30 concentration significantly increased larval and pupal developmental times and reduced adults longevity compared with control but showed no significant effects on fecundity of cotton bollworm. Sublethal effects of thiacloprid also significantly reduced pupal weight compared with control. In general, sublethal effects studies showed that thiacloprid had adverse effects on biological parameters of the pest. Thus, our data suggest that thiacloprid had moderate potential against cotton bollworm.

Acute toxicity and sub-lethal effects of a pyrethroid (cypermethrin) on survival, development and fitness of Helicoverpa armigera

The chickpea pod borer, Helicoverpa armigera (Hübner) is one of the most destructive pests of India and most of the countries. In this experiment, sub-lethal effects of cypermethrin were evaluated against sixth instar larvae of this pest that had ingested insecticide-treated chickpea pods. The LC50, LC30 and LC10 values of cypermethrin were 80.38, 26.65 and 5.41 mg a.i. L−1, respectively, against sixth instar. The sub-lethal effects on fitness, eggs, larvae, pupae, adult longevity and reproduction were observed in H. armigera population that survived exposure to the sub-lethal doses of LC50, LC30 and LC10 of cypermethrin. Survivorship was reduced to 36 days if H. armigera exposed to the sub-lethal dose of LC50, whereas it was 42 days in unexposed groups. Larvae treated with LC50 dose exhibit lowest intrinsic rate of increase (rm) (0.0413 females/female/day) and highest (0.0517) with the unexposed group. Time taken by H. armigera to complete one generation (Tc) was 40.09 days, while this time significantly lowered to 32.85 days when exposed to the sub-lethal dose of LC30. Hatching eggs were greatly reduced in the larvae exposed to cypermethrin at all the sub-lethal doses. About 430 eggs/female/generation were recorded after treatment with 80.38 mg/L as compared with untreated females (1390). Larvae that were exposed to sub-lethal concentrations of cypermethrin exhibited lower pupal weight and prolonged pupal developmental times compared control larvae. The overall fitness performance was better in the unexposed population as compared to the population exposed to sub-lethal doses.

Effect of Temperature on Six Different Developmental Landmarks within the Pupal Stage of the Forensically Important Blowfly Calliphora vicina (Robineau‐Desvoidy) (Diptera: Calliphoridae)

This study investigates the pupal development times of the blow fly Calliphora vicina, which were studied in the laboratory at six different constant temperatures (15, 20, 23, 25, 28, and 30°C each ± 1°C). Lower thresholds (tL ) for development were estimated from the linear regression of the developmental rates on each temperature. These data have made it possible to calculate the accumulated degree days (ADD) necessary for C. vicina to complete the larval stage and to achieve adult emergence. The minimal duration of development from oviposition to adult emergence was found to be inversely related to temperature. Additionally, six landmarks in pupal development are showed, and for each of the landmarks, the ADD value was calculated for every rearing temperature involved. These data assist in calculating the duration of the pupal stage based on morphological characteristics and would be of great value for future forensic entomological casework.

Environmental determinants of population divergence in life‐history traits for an invasive species: climate, seasonality and natural enemies

Invasive species cope with novel environments through both phenotypic plasticity and evolutionary change. However, the environmental factors that cause evolutionary divergence in invasive species are poorly understood. We developed predictions for how different life-history traits, and plasticity in those traits, may respond to environmental gradients in seasonal temperatures, season length and natural enemies. We then tested these predictions in four geographic populations of the invasive cabbage white butterfly (Pieris rapae) from North America. We examined the influence of two rearing temperatures (20 and 26.7°C) on pupal mass, pupal development time, immune function and fecundity. As predicted, development time was shorter and immune function was greater in populations adapted to longer season length. Also, phenotypic plasticity in development time was greater in regions with shorter growing seasons. Populations differed significantly in mean and plasticity of body mass and fecundity, but these differences were not associated with seasonal temperatures or season length. Our study shows that some life-history traits, such as development time and immune function, can evolve rapidly in response to latitudinal variation in season length and natural enemies, whereas others traits did not. Our results also indicate that phenotypic plasticity in development time can also diverge rapidly in response to environmental conditions for some traits.

Bitrophic toxicity of Cry1Ac to Cycloneda sanguinea, a predator in Brazilian cotton

AbstractInsect predators are exposed to the Cry1Ac toxin in Bt cotton fields through several pathways. In this study, we investigated the effects of activated Cry1Ac added to a diet on Cycloneda sanguinea (L.) (Coleoptera: Coccinellidae), which is one of the main predators of non‐target pests in Brazilian cotton. Direct bitrophic exposure of C. sanguinea to Cry1Ac was done by feeding beetles with Aphis gossypii (Glover) (Hemiptera: Aphidae) sprayed with 500 μg per ml Cry1Ac solution. Larval and pupal survival, development time, aphid consumption, and adult longevity were recorded daily. Couples within the same experimental treatment were paired and numbers of eggs laid and hatched per female were recorded daily. Net replacement rate was calculated for each female. During development, a C. sanguinea larva consumed on average 1.8 μg of activated Cry1Ac. No significant differences due to Cry1Ac were observed for any of the response variables, except aphid consumption. Larvae receiving Cry1Ac consumed more aphids than larvae receiving distilled water alone. Additional statistical analyses were conducted to evaluate independence of responses, and for the independent responses, a simple meta‐analysis was conducted to test the null hypothesis that all responses were zero. Nearly all of the response variables were statistically independent. Two pairs of responses were not independent, but the associated multivariate tests were not significant. The meta‐analysis suggested that all effects were not different from random variation around zero and no cumulative effects could be detected. Our results indicated that bitrophic exposure to activated Cry1Ac is likely to have little or no adverse ecological effect on C. sanguinea.

Demographic parameters of the two main fruit fly (Diptera: Tephritidae) species attacking mango inCentralTanzania

AbstractFruit flies (Diptera: Tephritidae) are among the most important pests damaging fruit crops growing in Tanzania. Demographic parameters forCeratitis cosyra(Walker) andBactrocera invadens(Drew, Tsuruta &amp; White) are reported and compared. These include pre‐adult survival and development rates, adult survival and fecundity and population parameters such as the intrinsic rate of increase, and mean generation time. Population and biological parameters of theC. cosyraandB. invadenswere measured in an environmental chamber at 25°C and 30°C with 75%RHand at room temperature ranging 23–28°C. The results showed thatB. invadenshad shorter embryonic, larval and pupal development times thanC. cosyraindependent of temperature. Life expectancy of maleB. invadenswas significantly greater than that ofC. cosyra, while life expectancy of femaleB. invadenswas greater than that ofC. cosyrabut not significantly. Average net fecundity was higher forB. invadensthan forC. cosyra. Both species attained their highest intrinsic rate of increase and net reproductive rate at 30°C.B. invadensexhibited higher intrinsic rate of increase and net reproductive rate thanC. cosyraat all temperatures tested.

Development of Rhagoletis indifferens Curran (Diptera: Tephritidae) in crabapple

Abstract Western cherry fruit fly, Rhagoletis indifferens Curran 1932 (Diptera: Tephritidae), was reared from naturally-infested Chinese crabapple, Malus spectabilis (Aiton) Borkhausen (Rosaceae), in Washington State, U.S.A. Pupae from Chinese crabapple were smaller than those from sweet cherry, Prunus avium (Linnaeus) Linnaeus (Rosaceae), but fecundity and longevity of flies from the two hosts did not differ. Laboratory experiments were conducted to compare larval development in crabapples and cherries. ‘Snowdrift’ crabapples (Malus × ‘Snowdrift’) did not produce pupae. Percentages of ‘Indian Magic’(Malus ‘Indian Magic’) + ‘Radiant’ crabapple (Malus ‘Radiant’) vs. sweet cherry replicates that produced pupae did not differ in two no-choice experiments (36.7 vs. 41.7% and 13.3 vs. 33.5%, respectively). In a choice experiment, the percentage of crabapple replicates that produced pupae (6.7%) was lower than that of cherry replicates (42.2%). Egg to pupal development times in crabapples (18.0–21.2 d) were lon...

Constant Versus Fluctuating Temperatures in the Interactions Between &lt;I&gt;Plutella xylostella&lt;/I&gt; (Lepidoptera: Plutellidae) and Its Larval Parasitoid &lt;I&gt;Diadegma insulare&lt;/I&gt; (Hymenoptera: Ichneumonidae)

Laboratory studies were conducted to determine the effects of constant temperatures (7, 22, and 30°C) and corresponding fluctuating temperatures (0-14, 15-29, and 23-37°C) on the development of diamondback moth, Plutella xylostella (L.), and its North American parasitoid Diadegma insulare (Hellén). Parasitized third-instar diamondback moth larvae were reared until adult mortality in individual thermal gradient cells at different temperature regimes. Larval mortality, parasitism success, pupal mortality, larval and pupal developmental time, adult longevity, and pupal and adult dry weight were recorded. Overall diamondback moth larval mortality was low. The pupal mortality of D. insulare increased with increasing temperature; however, diamondback moth did not show such a response. Greatest parasitism success (67%) was found at constant and fluctuating 22°C and fluctuating 7°C, and the lowest (30%) at fluctuating 30°C. Longer development times and greater pupal body masses occurred at lower temperatures for both insects. Significant differences occurred between constant and fluctuating temperature regimes for most parameters of both insects. Fluctuating compared with constant temperatures caused shorter development times, similar body mass, and higher adult longevity for both insects at optimal and lower temperature ranges. Both insects experienced 0°C at fluctuating 7°C (0-14°C) and survived. These results have important implications for extrapolating temperature effects on insects in laboratory studies with constant temperatures. Comparing successful parasitism capacity of the wasp and pupal survival and body mass of both host and parasitoid, we conclude that D. insulare is a more effective parasitoid at lower temperatures.

Acute toxicity and sublethal effects of methoxyfenozide and thiodicarb on survival, development and reproduction of Helicoverpa armigera (Lepidoptera: Noctuidae)

The cotton bollworm Helicoverpa armigera (Hubner) is one of the most destructive pest insects in Iran and many other countries. In this study, lethal and sublethal effects of methoxyfenozide, and thiodicarb were evaluated against H. armigera larvae that fed on insecticide-treated artificial diet. The effects of methoxyfenozide and thiodicarb were assessed in 3rd instars. Methoxyfenozide and thiodicarb showed LC50 values of 4 and 639 mg a.i./ml, respectively, in H. armigera larvae. Sublethal effects on development, adult longevity, and reproduction were observed in H. armigera larvae that survived exposure to an LC30 of the insecticides. Larvae that were exposed to an LC30 concentration of methoxyfenozide exhibited lower pupal weight and increased larval and pupal developmental times compared with thiodicarb treated larvae or control larvae. Adults that were exposed as larvae to an LC30 concentration of methoxyfenozide or thiodicarb showed reduced fecundity (35% and 30%, respectively) compared to control adults. The tested insecticides significantly reduced adult longevity. The longevity of adult females that as larvae were treated with an LC30 concentration of methoxyfenozide or thiodicarb was reduced by 28% and 23%, respectively, in comparison to control females. We predict that the combination of lethal and sublethal effects of the insecticides, especially methoxyfenozide, will induce significant effects on field population dynamics of H. armigera.

Costs of Insecticide Resistance in &lt;I&gt;Cydia pomonella&lt;/I&gt; (Lepidoptera: Tortricidae)

The obvious benefits associated with insecticide resistance for pest species may come at a cost to other life-history traits. In this study, we compared the larval and pupal developmental times, pupal mass wing surface area and wing fluctuating asymmetry (FA) in insecticide resistant and control strains of codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), collected from apple (Malus spp.) orchards in central Canada. Resistant strains had significantly longer larval developmental times and lower pupal masses compared with the susceptible strain. Although the forewings of resistant moths were smaller in resistant than control strain, no difference in wing FA was detected. Longer developmental times could increase exposure time to natural enemies, and reduced adult size could affect longevity and total reproductive output.

Life Histories and Fitness of Two Tuber Moth Species Feeding on Native Andean Potatoes

In the inter-Andean valleys of central Perú, two species of tuber moth, Phthorimaea operculella (Zeller) and Symmetrischema tangolias (Gyen), often occur simultaneously in stored potatoes. Traditional farming communities in the region produce a variety of native potatoes for local consumption. These include Solanum tuberosum subsp. andigena, the presumed predecessor of commercial potatoes, S. tuberosum subsp. tuberosum. In this study, we examined resistance against P. operculella in ten native Peruvian potato varieties (Casa blanca, Chispiadita, Madre de vaca, Mamaco negro, Misha, Chorisa, Mamaco rosado, Occa papa, Vacapa jayllo, and Yana tornasol). We also compared resistance in the first five of these varieties against S. tangolias. Varieties with pigmented periderms showed moderate resistance (30-40% against P. operculella in Mamaco negro, Mamaco rosado, and Yana tornasol and 55% against S. tangolias in Mamaco negro). All the other varieties were susceptible to both moth species. Small tubers tended to be the most resistant to the attack by both moths; however, this was not related to the availability of food for developing larvae, since pupal weight and development time were unaffected by the size of tubers. Similar responses by the two moths to native potatoes indicate that tuber resistance could be used to control the complex of tuber moths that damage potatoes in the Andes. We suggest that native potatoes, which are often easily introgressed with commercial potatoes, are a potential source of resistance against tuber moths.

How photoperiods affect the immature development of forensically important blowfly species Chrysomya albiceps (Calliphoridae)

The purpose of this study was to verify the influence of different photoperiods on larval body weight, post-embryonic development, and viability of Chrysomya albiceps. The bioassays were performed in acclimatized chamber at 27 ± 1 °C and 60 ± 10 % relative humidity regulated by three different light and dark cycles for a period of 24 h-12:12, 24:00, and 00:24. Four replications with 50 newly hatched larvae each were used per photoperiod. The larvae were placed in container containing bovine ground meat (50 g). When mature larvae spontaneously abandoned the diet, they were individually weighed and separated into glass tubes until emergence. The larvae that did not abandon the diet were not weighed. The larvae from 24 h of photophase did not abandon the diet and pupated inside, so these larvae were not weighed and the larval and pupal developments were not registered. The mean of larval body weight did not vary between the 24 h scotophase and 12 h photophase. The mean duration of larval developmental time varied significantly when comparing the 24 h scotophase and the 12 h photophase, and the pupal developmental time also varied for the same photoperiods; in both stages, the duration of development was faster in the 24 h scotophase. The developmental time of neo-larvae to adult was verified in all photoperiods and gradually increased as photophase increased. There was a trend to augment of viability with the reduction of photophase length.

Adaptive latitudinal variation of the duration and thermal requirements for development in the ground beetle Amara communis (Panz.) (Coleoptera, Carabidae)

The data are obtained on development time at six constant temperatures (12, 14, 16, 18, 20, 22°C) and thermal requirements for preimaginal development in a ground beetle Amara communis from Arkhangelsk (64°34′N) and St. Petersburg (59°53′N). The larval and pupal development times were found to be significantly shorter in the Arkhangelsk than in the St. Petersburg population under all temperatures. As a result, total preimaginal development appeared to be shorter by 6.2–6.6% in the Arkhangelsk population. The regression lines of the larval, pupal and total (egg-to-adult) development rate on temperature for the Arkhangelsk population run above and steeper than the respective lines for the St. Petersburg population. Both populations share the similar values of the thermal thresholds (7.2–8.2°C). This explains faster preimaginal development in the northern population under all temperatures above the threshold. Thus, the slope of the regression lines increases, i.e., the sum of degree-days decreases, whereas the thermal threshold for development exhibited no distinctive changes from south to north in this species. Adults from Arkhangelsk reared in the experiments appeared heavier on the average in comparison with those from St. Petersburg, especially at 18–22°C. Temperature did not significantly affect adult weight, except the fact that the beetles were slightly heavier at 20 and 22°C. Consequently, the well-known “temperature-size rule” is violated in this species. Relative growth rate in larvae of A. communis increased considerably with temperature rise from 14 to 22°C. It was significantly higher in the beetles from Arkhangelsk at 18–22°C. There were no differences in larval growth rate between the two populations at 14 and 16°C.

Effect of Binodoxys communis parasitism on flight behavior of the soybean aphid, Aphis glycines

Many aphid species possess wingless (apterous) and winged (alate) stages, both of which can harbor parasitoids at various developmental stages. Winged aphids bearing parasitoid eggs or young larvae can potentially still engage in long-distance flights and thereby facilitate parasitoid dispersal, which has important implications for biological control of aphids by parasitoids. In this study, we determined the effect of parasitism by Binodoxys communis (Hymenoptera: Braconidae) on wing development and flight of the summer alate stage of the soybean aphid, Aphis glycines (Hemiptera: Aphididae), and quantified the effect of aphid flight duration on subsequent B. communis development. Parasitism by B. communis was allowed at alatoid 3rd (L3) and 4th instar (L4) nymphal stages of A. glycines and subsequent aphid flight was measured using a computer-monitored flight mill. Only 25% of aphids parasitized as L3 alatoid nymphs produced normal winged adults, compared to 100% of L4 alatoids. While flight performance of aphids that had been parasitized as 4th-instar alatoid nymphs 24 or 48h prior to testing was similar to that of unparasitized alates of identical age, it declined sharply for alates that had been parasitized as 4th-instar alatoid nymphs 72 and 96h prior to testing. Parasitoid larval and pupal development times, percent mummification and adult emergence rates did not differ between treatments in which aphids had flown over varying durations. Our results have implications for natural biological control of A. glycines in Asia and classical biological control of the soybean aphid in North America.

Development and fecundity of Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae) on different soybean cultivars

The life history of Spodoptera exigua was studied under laboratory conditions at temperature of 25°C ± 1°C, relative humidity (RH) of 60% ± 5% and a photoperiod of 16:8 h (Light:Dark) on nine soybean (Glycine max L.) cultivars: 032, 033, Hill, M4, M7, M9, M11, TMS and Zan. Larval and pupal development times were longest on M7 cultivar (14.09 ± 0.078 and 7.78 ± 0.090 days) and shortest on 033 cultivar (11.98 ± 0.054 and 7.033 ± 0.090 days). The longest and shortest female and male longevities were observed on Hill and Zan cultivars, respectively. The results showed that the whole life span varied from 32.80 ± 0.89 to 37 ± 0.98 days for females and from 33.3 ± 0.66 to 38.74 ± 0.95 days for males. The highest daily fecundity was obtained on M9 (102. 38 eggs), and the lowest on Hill (75.87 eggs). Mean total fecundity per female during adult life was highest on 033 (1156.20 eggs) and lowest on M7 cultivars (841.68 eggs). Clustering analysis of the biological parameters of S. exigua confirmed that 033 and Hill cultivars were the susceptible and the resistant cultivars, respectively.

Interactions between an ectoparasitoid and a nucleopolyhedrovirus when simultaneously attacking Spodoptera exigua (Lepidoptera: Noctuidae)

AbstractInsect pathogenic viruses and parasitoids represent distinct biological entities that exploit a shared host resource and have similar effects in suppressing host populations. This study explores the interactions between the ectoparasitoid Euplectrus plathypenae (Hymenoptera: Eulophidae) and the Spodoptera exigua multiple nucleopolyhedrovirus (SeMNPV) in larvae of S. exigua (Lepidoptera: Noctuidae). Parasitoid progeny failed to complete development in hosts that had been infected prior to parasitism. However, infection of S. exigua fourth instars at 48 h post‐parasitism had no significant effects on the survival of parasitoid progeny. Larval and pupal development times of E. plathypenae that survived on virus‐infected S. exigua did not differ significantly from that of parasitoids on healthy hosts. Virus‐induced mortality and the production of occlusion bodies were very similar in parasitized and non‐parasitized S. exigua. The virus was genetically stable over three passages in parasitized and unparasitized hosts. These results suggest that applications of SeMNPV‐based insecticides are unlikely to disrupt pest control exerted by the parasitoid E. plathypenae in biological pest control programs as long as virus applications are timed not to coincide with parasitoid releases.

Laboratory rearing and life history of an emerging grape pest, Xylotrechus arvicola (Coleoptera: Cerambycidae)

Several aspects of the biology of Xylotrechus arvicola (Olivier), an emerging grape pest, were studied under laboratory conditions. Four diets were tested to rear this species in the laboratory. Among them, only one made rearing from larva to adult possible. The highest mortality, in all cases, was recorded during the first days of larval development. Larvae were kept 45 days at 8°C to break diapause in order to reduce the normal field larval developmental time. The species' developmental time was similar between sexes, while pupal developmental time and weight were significantly greater for females than for males. As part of a complementary study, life table parameters of females obtained from the larvae reared on the artificial diet were compared to those of females emerged from field-infested grape root wood. Both laid the majority of eggs in the first two weeks after emergence, and they had a similar pre-laying period. Nevertheless, the females from the diet-reared larvae lived significantly longer, laid eggs over a longer period of time and showed higher fertility than those emerging from infested grape root, suggesting that diet fulfils larval nutritional needs. The species' laboratory-reared population exhibited a low intrinsic growth rate value (rm=0.01) as a result of its long egg-to-adult developmental time and its high larval mortality.