Functional response of the predators Podisus maculiventris (Say) and Podisus nigrispinus (Dallas) (Het., Pentatomidae) to the beet armyworm, Spodoptera exigua (Hübner) (Lep., Noctuidae): ef fect of temperature

Predation abilities of Podisus maculiventris and Podisus nigrispinus on caterpillars of the beet armyworm, Spodoptera exigua (Hübner), were compared at three different temperatures (18, 23 and 27°C) by performing functional response tests. In both species, predation capacity was a function of temperature and prey density: more prey were captured as temperature and number of prey offered increased. Results indicated that type II and III functional responses provided the best fit to the data obtained for P. nigrispinus at 18 and 23°C, and at 27°C, respectively. However, the data for P. maculiventris showed a better fit to type II at 18°C and to type III at higher temperatures. In both pentatomids the handling time decreased with increasing temperature. At higher temperatures, P. nigrispinus demonstrated greater predation rates than P. maculiventris . The implications of these findings for the control of caterpillar pests in glasshouses are discussed.     

The influence of temperature, photoperiod and plant type on the predation rate of Macrolophus pygmaeus on Myzus persicae

The effect of temperature and photoperiod on the rate of predation of nymphs and adults of the predator Macrolophus pygmaeus was studied using Myzus persicae prey feeding on egg-plant and pepper plants. The experiments were conducted at three photoperiods (16L:8D, 12L:12D and 8L:16D), three temperatures (20, 25 and 30 °C), and at 65% r.h. The rate of predation increased with temperature. Predation rate was affected by photoperiod on pepper but not on egg-plant. Females and fifth instar nymphs were the most voracious stages followed by third and fourth instar nymphs and males. First and second instar nymphs consumed far fewer aphids. Predation rate was higher on leaves of pepper than egg-plant, especially at 30 °C. Variation in the efficacy of this predator is discussed.     

The effect of prey size and prey density on the functional response,survival, growth and development of a predatory pentatomid bug,Podisus maculiventris say

Two experiments on the nymphal predation of Podisus maculiventris were conducted using Spodoptera litura larvae as prey. First experiment: The predator nymphs divided into three groups were reared individually from second instar to adult in a small vessel. Each nymph in the groups 1, 2 and 3 was allowed to attack the serially growing larvae (these were supplied at the rate of one per day) from 3-, 5- and 7-day old after hatching, respectively. The first prey used for the group 1 was so small that it was not only insufficient to satiate the predator but also was difficult to be searched out. But these disadvantages were soon recuperated due to the rapid growth of the prey and all nymphs could survive to adults. The survival rate of third and fourth instar nymphs in the group 3 was severely affected by vigorous counterattack of older prey larvae. Second experiment: The predator nymphs were individually reared either in a small vessel or in a large one at various rates of food supply (the prey larvae of 7-day old were used). The functional response curves obtained for each instar of the predator took a saturation type within a certain range of the prey density. The saturation level specific to each instar was generally higher for the predator reared in the large vessel than in the small one. The functional response of fourth and fifth instar nymphs was accelerated at a high prey density, viz. 16 larvae per vessel. Even at the low rate of food supply, viz. one larva per day per predator, the predator nymphs could survive to adults, but the size of resultant adults were abnormally small.     

环斑猛猎蝽对草地贪夜蛾低龄幼虫的捕食功能分析

为探究环斑猛猎蝽Sphedanolestes impressicollis Stal对草地贪夜蛾Spodoptera frugiperda Smith的捕食潜能,在室内条件下研究了环斑猛猎蝽4龄若虫对草地贪夜蛾1~3龄幼虫的捕食功能、搜寻效应以及环斑猛猎蝽自身密度对捕食草地贪夜蛾的干扰作用。结果表明：环斑猛猎蝽4龄若虫对草地贪夜蛾低龄幼虫的捕食功能反应符合Holling II模型。环斑猛猎蝽4龄若虫对草地贪夜蛾1龄、2龄、3龄幼虫的瞬时攻击率分别为0.900、1.229和1.259,处理时间分别为0.018 d、0.050 d和0.205 d,日最大捕食量分别为55.897头、19.853头和4.871头。环斑猛猎蝽4龄若虫的搜寻效应与草地贪夜蛾密度呈负相关。环斑猛猎蝽4龄若虫对草地贪夜蛾低龄幼虫的捕食作用率随自身密度的增加而降低。在捕食草地贪夜蛾1龄幼虫时,环斑猛猎蝽4龄若虫自身密度对其捕食能力干扰最大。研究结果表明环斑猛猎蝽4龄若虫对草地贪夜蛾低龄幼虫有一定的捕食能力,为其田间应用释放技术提供了理论依据。     

Development time and predation rate of Podisus maculiventris (Hemiptera: Pentatomidae) feeding on Microtheca ochroloma (Coleoptera: Chrysomelidae)

Microtheca ochroloma St?l is a beetle native to South America and was introduced to the United States in 1945. Since then, M. ochroloma has become a serious pest in crucifer crops because of the lack of natural enemies. The objective of this study was to measure the predation rate and development time of the commercially available predator Podisus maculiventris (Say) feeding on M. ochroloma at four constant temperatures in the laboratory as a first step to evaluating the predator's capability as a biological control agent of the pest. Nymphal development of P. maculiventris increased from 23 d at 25°C to 99 d at 15°C. There was no development of first instar or egg hatch at 10°C. Number of fourth-instar M. ochroloma killed during nymphal development varied significantly from 65 at 15°C to 53 at 20°C because of length of the nymphal period. A mean total of 741 eggs of M. ochroloma were consumed during nymphal development at 25°C. Adult P. maculiventris preyed on nine and 12 times more fourth-instar M. ochroloma during 10 d at 20° and 25°C, respectively, than at 15°C. We conclude that P. maculiventris can develop successfully on a diet of eggs or fourth-instar M. ochroloma, but its predation and development rates will be significantly curtailed during the cool months from November to March when M. ochroloma is a key pest of organically grown crucifers in Florida.     

Functional response of Picromerus bidens: effects of host plant

Abstract:  The influence of three solanaceous plants (tomato, sweet pepper and eggplant) on the functional response of the predatory bug Picromerus bidens to densities of fourth-instar larvae of the beet armyworm Spodoptera exigua was assessed. Logistic regression indicated a type II functional response on all host plants. Over all prey densities, P. bidens killed significantly fewer fourth instars of S. exigua on tomato than on sweet pepper or eggplant (1.96 ± 0.17 vs. 4.37 ± 0.19 and 3.90 ± 0.15 larvae per predator per 24 h respectively). A higher theoretical maximum predation rate was estimated on sweet pepper (11.1 prey larvae per day) and eggplant (7.4) than on tomato (5.4). The mean number of prey killed per day by P. bidens females ranged from 0.78 at a density of one prey on tomato to 8.45 at a density of 24 prey on sweet pepper. The data indicated that the estimates of handling time ( T _h) and attack rate ( a ) were highly affected by host plant. Based on asymptotic 95% confidence intervals, a lower attack coefficient was found on tomato (0.02 h⁻¹) than on sweet pepper or eggplant (0.07 and 0.11 h⁻¹ respectively). On the other hand, handling times were significantly longer on tomato (4.42 h) and eggplant (3.23 h) than on sweet pepper (2.15 h). This laboratory study suggests that plant characteristics influence the ability of P. bidens to respond to changes in prey density.     

Effect of microsporidian infection in Lacanobia oleracea (Lep., Noctuidae) on prey selection and consumption by the spined soldier bug Podisus maculiventris (Het., Pentatomidae)

Abstract:  The predatory behaviour of Podisus maculiventris was investigated when this bug was presented with Lacanobia oleracea larvae infected with the microsporidian pathogen Vairimorpha necatrix . In choice tests, adult predatory bugs attacked V. necatrix -infected L. oleracea prey in similar numbers to uninfected larvae. Exposure to infected prey during nymphal development increased the rate at which adult bugs attacked diseased L. oleracea larvae. Fifth instar P. maculiventris nymphs, however, attacked infected prey in the majority of cases (>80% of occasions). Consumption of healthy and infected prey was measured for both adult and nymphal bugs. Over the course of 1 week, the mean number of V. necatrix -infected prey eaten by P. maculiventris adults (7.0 ± 0.82) was approximately twice the number of uninfected prey consumed (3.8 ± 0.42). Similarly, the number of prey larvae attacked by the bug over the course of the final nymphal stadium was also increased, with 2.9 ± 0.42 uninfected larvae eaten as opposed to 4.9 ± 0.27 V. necatrix -infected prey. However, small-scale investigations into the rate of P. maculiventris reduced small populations of L. oleracea indicated that the combination of the predator and pathogen would produce, at best, an additive effect.     

Combined effects of allelochemicals, prey availability, and supplemental plant material on growth of a generalist insect predator

We examined the effects of the presence of plant allelochemicals in prey diet, prey availability and supplemental plant material on the growth of the generalist predator Podisus maculiventris (Hemiptera: Pentatomidae). We tested two different nymphal stages of this predator. Third to fourth instar nymphs and fifth instar nymphs were fed a diet of prey (Manduca sexta larvae, Lepidoptera: Sphingidae) without allelochemicals in their diet or prey fed maximal levels of allelochemicals (tomatine, rutin and chlorogenic acid) found in their host plant (Lycopersicon esculentum). The nymphs were fed prey ad libitum, once every three days, or once every five days. They were given either no supplemental plant material or a 2 cm slice of green bean pod (Phaseolus vulgaris). We also conducted another experiment with fifth instar nymphs using the same conditions, except that mean levels of allelochemicals found in the host plant were fed to prey instead of maximal levels and the prey were provided either once a day or once every five days. For all experiments, prey scarcity depressed developmental rate, weight gain and relative growth rate. Overall, there was no negative effect of allelochemicals in the diet of the prey on these variables when predators were supplied with an excess of prey, but allelochemicals in the prey diet negatively affected these predators when prey were scarce. The addition of plant material to the diet of third to fourth instar nymphs did not have any effect on developmental rate, final dry weight, or relative growth rate. However, for fifth instar nymphs, the addition of plant material negatively affected these variables. Thus, the addition of plant material to the diet of the nymphs did not alleviate the negative effects of prey scarcity or allelochemicals in prey diet.     

Predation behavior of Podisus nigrispinus on Spodoptera eridania

The behavior and effective predation time can affect the prey death in pest biological control programs. This work studied the Podisus nigrispinus (Dallas, 1851) (Heteroptera: Pentatomidae) behavior on Spodoptera eridania (Cramer, 1782) (Lepidoptera: Noctuidae) caterpillars, and its implications in case of prey escape. The preference bioassay (B1) aimed to verify the caterpillars body region (anterior: head and thorax; median and posterior) preferred by the predator and its implication in prey mortality. The predation duration bioassay considered the following effective predation times: 1, 2, 4, 8, 16, 32, 64 and 128 min; the caterpillars were removed after each predation time, to simulate prey escape, and the dead were counted until the seventh day. This experiment was performed in two ways: with randomly selected and not repeated predators (B2); and with the same predators in successive times (B3). The predator preferred to attack the caterpillars anterior region. The caterpillars mortality increased with increasing effective predation time. The mortality was 90% after 64 min under B2. This value was estimated for 16 min under B3. The P. nigrispinus prefers to attack the caterpillars anterior region and mortality of S. eridania caterpillars was favored in predators that have suffered predation interruption.     

Impact of inbreeding on performance of the predator Podisus maculiventris

Effects of inbreeding on the development and reproduction of the predatory pentatomid Podisus maculiventris were assessed throughout 30 generations following introduction in the laboratory. Developmental and reproductive fitness of two mildly inbred lines did not differ dramatically from that of a reference population. In most generations, egg weight, egg hatch and developmental rate of nymphs were greater in the reference strain than in both inbred strains, but fecundity and longevity did not differ among strains. In the 30th generation, fecundity of all strains had dropped to about half of that observed in the 15th generation, which was presumably related to non-genetic factors. There were consistent differences among strains for adult body weight and size, indicating heritable variation. A positive relationship between weight at day 14 and humeral width of P. maculiventris females was found, but neither of these parameters was associated with total fecundity. In the 30th generation, predators from both inbred lines had generally similar predation capacities to those from the reference population. No significant relationship could be detected between body weights and predation rates of either nymphs or adults. The use of inbreeding to minimize selective adaptation during rearing or to select for favourable traits in P. maculiventris is discussed.     

Quality assessment of the predatory bugs Podisus maculiventris (Say) and Podisus sagitta (Fab.) (Heteroptera: Pentatomidae) after prolonged rearing on a meat—based artificial diet

The predatory stinkbugs Podisus maculiventris and Podisus sagitta were reared for more than 15 consecutive generations on a meat—based artificial diet. When they were returned to a diet of live prey (larvae of the pyralid Galleria mellonella) after different generations on the artificial diet, developmental and reproductive traits were similar to those of bugs continuously reared on live prey. Under laboratory conditions, predation rates for nymphs and adults of both pentatomids on larvae of the noctuid Spodoptera exigua were found to be unaffected by the previous diet. The results suggest that long—term rearing of P. maculiventris and P. sagitta on the meat—based artificial diet did not substantially affect the quality of the predators.     

Development of the Predatory Stinkbug Brontocoris tabidus Signoret Heteroptera: Pentatomidae on Different Proportions of an Artificial Diet and Pupae of Tenebrio molitor L. Coleoptera: Tenebrionidae

The development of the Neotropical predatory pentatomid Brontocoris tabidus on an artificial diet based on beef meat and liver was evaluated. The predator showed significantly longer nymphal development and lower adult weights on this diet than when reared on pupae of the mealworm Tenebrio molitor. The survival of nymphs fed exclusively on the artificial diet was somewhat lower compared with feeding on T. molitor pupae. When B. tabidus was bred on this artificial diet during part of its nymphal period i.e. during the second; second and third; and second, third and fourth instars , and was subsequently returned to T. molitor pupae, the predator nymphs completed the nymphal stage with a developmental rate similar to that of nymphs fed on live prey throughout. The adults attained after switching from the artificial diet to live prey from the third and fourth instar onwards had similar weights to those in the control. Considering the relatively good results obtained with B. tabidus and other members of the pentatomid subfamily Asopinae, this meat-based diet may be a valuable alternative for use in the mass production of predatory pentatomids.     

Transport and kinetics of diflubenzuron and pyriproxyfen in the beet armywormSpodoptera exigua and its predatorPodisus maculiventris

Transport and retention of the insect growth regulators (IGRs) diflubenzuron and pyriproxyfen in larvae of the beet armywormSpodoptera exigua (Hübner) and in nymphs of the predatory bugPodisus maculiventris (Say) were investigated. In a first experiment, the retention of orally administered [¹⁴C]radiolabeled isotopes of both compounds in fifth-instar larvae of the beet armyworm was studied. Rate of excretion of both IGRs inS. exigua caterpillars was high, with a 50% excretion time of approximately 6 h after intake. In a second experiment, the transport of the compounds from prey to predator and their retention inside the predator were studied. Fifthinstar nymphs ofP. maculiventris were allowed to feed on caterpillars that had been given contaminated food. For both diflubenzuron and pyriproxyfen, more than 80% of the amount of radiolabel applied was recovered in consumed prey. Low levels of radioactivity (c. 3% of the applied amount of radiolabel) were also found in the fluid regurgitated by the prey larvae when attacked by the predatory bugs. Relatively small amounts of radiolabel (c. 8 and 15% of the amount orally applied to the prey for diflubenzuron and pyriproxyfen, respectively) were ingested byP. maculiventris nymphs when feeding on beet armyworm caterpillars. The data suggest that the predators did not use gut content as food. The pattern of excretion in nymphs ofP. maculiventris differed between compounds. For diflubenzuron, there was a drastic decrease of radioactivity inside the predator body of around 40% within the first 6 h and then the level of retained radiolabel remained stable at 3–4% up to 72 h. For pyriproxyfen, a slow decrease of radioactivity inside the body was observed and at 72 h only 2% of the applied quantity was detected. Results of this study are discussed in relation to the findings from previous studies on the toxicity of both IGRs toP. maculiventris.     

Intraguild predation by the generalist predator Orius majusculus on the parasitoid Encarsia formosa

Intraguild predation of Orius majusculus (Reuter) (Heteroptera: Anthocoridae) on Encarsia formosa (Gahan) (Hymenoptera: Aphelinidae), both natural enemies of Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae), was studied under laboratory conditions. The experiments quantified prey consumption by 5th instar nymphs and adults of O. majusculus offered unparasitised 3rd, early 4th or 4th instar B. tabaci nymphs or parasitised nymphs containing 2nd or 3rd larval instar or pupal parasitoids. In addition, prey preference of the two stages of O. majusculus for parasitised or unparasitised whitefly nymphs was studied using nine different prey combinations. Both predator stages readily preyed upon on both unparasitised and parasitised B. tabaci. In no-choice experiments, predation on 3rd instar E. formosa by adult predators was the highest, while predator nymphs preyed most on unparasitised 3rd instar B. tabaci and 2nd instar parasitoids. Predation of predator stages was lowest on 4th instar B. tabaci and E. formosa pupae. In all prey combinations, both stages of O. majusculus showed a significant preference for parasitised over unparasitised whitefly nymphs except for the combination of 5th instars of O. majusculus with early 4th instar whiteflies and E. formosa pupae. The results indicate that intraguild interactions between O. majusculus and E. formosa may have negative effects on biological control of B. tabaci.     

多异瓢虫成虫对枸杞木虱的捕食作用

【目的】为了测定多异瓢虫Hippodamia variegata(Goeze)成虫对枸杞木虱Paratrioza sinica Yang&Li的捕食作用。【方法】在室内测定了多异瓢虫的捕食功能反应、种内干扰、自身密度干扰、捕食偏好性,并通过罩笼试验研究多异瓢虫在田间对枸杞木虱的捕食效果。【结果】结果表明,多异瓢虫对枸杞木虱的捕食功能反应符合HollingⅡ型方程,对卵、1~2龄若虫、3~5龄若虫以及成虫的最大捕食量分别为80.4粒、410.0头、350.8头和102.5头。田间罩笼试验结果证明,在多异瓢虫成虫生长周期30 d内能使枸杞木虱总虫口密度下降85.4%;多异瓢虫对枸杞木虱成虫的搜寻效率a=0.8252为4种木虱虫态最佳,而对枸杞木虱卵处理时间Th=0.002283为4种木虱虫态中最佳;在100头/皿的猎物密度下多异瓢虫均能展现其最大捕食率,益害比参考值为1∶100。多异瓢虫对枸杞木虱的捕食作用受自身密度的影响显著大于种内干扰;在100头/皿混合猎物密度下,多异瓢虫更偏好木虱成虫,在300头/皿下,多异瓢虫更偏向于木虱若虫。【结论】研究表明,多异瓢虫是具有控制潜力的捕食性天敌,人工释放多异瓢虫成虫可有效防治枸杞木虱。     

The carabid <Emphasis Type="Italic">Pterostichus melanarius</Emphasis> uses chemical cues for opportunistic predation and saprophagy but not for finding healthy prey

The sentinel prey method can quantify predation pressure in various habitats. Real prey is assumed to more realistically mimic the predator experience but the predator can rarely be identified. Artificial prey made of plasticine may lack real chemical cues, but provides information about predator identity. However, the relationship between predation pressure registered by artificial versus real prey is not clear. We tested the relative attractiveness of artificial caterpillars, and intact, wounded, or dead larvae of the cabbage moth (Mamestra brassicae) for the carabid predator Pterostichus melanarius Illiger (Coleoptera: Carabidae). P. melanarius adults were attracted to dead caterpillars more than to live or wounded ones. Coating artificial caterpillars with caterpillar haemolymph increased their attractiveness. However, predators were not attracted more to healthy, real caterpillars than to “untreated” artificial ones. We conclude that using artificial caterpillars does not underestimate predation pressure by this carabid on healthy caterpillars.     

东亚小花蝽对西方花蓟马和二斑叶螨的捕食选择性

多食性天敌对猎物的捕食选择性及猎物密度对天敌捕食的干扰作用直接影响到天敌对不同猎物的控制作用.在实验室条件下研究了东亚小花蝽对西方花蓟马和/或二斑叶螨不同虫态的捕食选择性,以及两猎物中一种猎物的密度变化对小花蝽取食另一种猎物的影响.结果如下:东亚小花蝽5龄若虫和成虫对西方花蓟马2龄若虫的捕食选择性均强于对其成虫,对二斑叶螨的选择性为雌成螨>若螨>幼螨.实验中西方花蓟马2龄若虫是东亚小花蝽最喜好的虫态.二斑叶螨雌成螨密度固定为60头/19.63cm2,西方花蓟马若虫密度从10增加到60时显著地减少了东亚小花蝽对二斑叶螨的取食.反之,固定西方花蓟马同样密度,增加二斑叶螨密度却没有显著改变小花蝽对西方花蓟马的取食.此结果进一步表明,西方花蓟马是东亚小花蝽更喜好的猎物.     

Laboratory Effects of Ingestion of Azadirachtin by Two Pests ( Ceratitis capitata and Spodoptera exigua ) and Three Natural Enemies ( Chrysoperla carnea , Opius concolor and Podisus maculiventris )

The effects of azadirachtin on two pests: neonate larvae and newly emerged adults of Ceratitis capitata (Wiedemann) and last instar larvae of Spodoptera exigua (Hubner); and three natural enemies: newly emerged adults of Opius concolor Szepligeti, second instar larvae of Chrysoperla carnea (Stephens), and fifth instar nymphs of Podisus maculiventris (Say) were studied in laboratory. Adult insects were exposed to a non-oil formulation of azadirachtin (Align, emulsifiable concentrate, 3.2% azadirachtin, Sipcam Inagra, Spain) via their drinking water and immature instars were reared in the presence of the insecticide-treated diet. The natural enemies were exposed to at least the maximum field recommended concentration of the insecticide (0.15% v/v). Azadirachtin was highly toxic to neonate larvae of C. capitata and prevented adult emergence at a concentration of 1 mg a.i. l -1 . When adults were fed the insecticide at the maximum recommended concentration, their survival was not affected but egg laying was totally inhibited. Last instar S. exigua larvae were also very susceptible (LC 50 = 7.7 mg a.i. l -1 ) and at a concentration of 10 mg a.i. l -1 fecundity of surviving adults, and egg fertility, were reduced by 72 and 85%, respectively. Effects on O. concolor were large, and significant reductions in longevity, percentage of attacked hosts, and progeny size per female, were recorded. The predator P. maculiventris was much less sensitive to azadirachtin, but slight reductions in survival of emerged adults and of reproductive parameters occurred. The insecticide had no significant effect on C. carnea larvae fed with treated Sitotroga cerealella (Oliver) eggs, probably because of its inability to penetrate inside the egg.     

不同虫态叉角厉蝽对草地贪夜蛾幼虫的室内捕食作用

为了明确叉角厉蝽 Eocanthecona furcellate (Wolff)对草地贪夜蛾 Spodoptera frugiperda (J.E.Smith)幼虫的控制作用,在实验室条件下测定了叉角厉蝽不同虫态对草地贪夜蛾不同龄期幼虫的捕食能力,研究了该蝽捕食功能反应、搜寻效应以及种内干扰作用。结果表明,叉角厉蝽3龄若虫、5龄若虫、成虫均可捕食草地贪夜蛾幼虫,总体呈现叉角厉蝽低龄若虫捕食草地贪夜蛾低龄幼虫的数量较多,高龄若虫和成虫捕食中间龄期幼虫数量较多的规律;叉角厉蝽3个虫态对草地贪夜蛾2~3龄幼虫的捕食功能反应均符合Holling II方程和HollingⅢ型功能反应新模型;5龄若虫对草地贪夜蛾2~3龄幼虫的捕食效能(a/Th)最强（214.0）、日最大捕食量(1/Th)最大（256.4头）。不同虫态叉角厉蝽的搜寻效应与草地贪夜蛾密度均呈负相关。建立了叉角厉蝽成虫密度、草地贪夜蛾4龄幼虫密度对捕食作用的干扰反应方程,干扰作用发生后该蝽的平均捕食量和捕食作用率均逐渐下降。本研究结果可为田间释放叉角厉蝽防治草地贪夜蛾提供依据。     

Predation capacity and prey preference of <Emphasis Type="Italic">Chrysoperla carnea</Emphasis> on <Emphasis Type="Italic">Pieris brassicae</Emphasis>

The predation capacity and prey preference of larvae of Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) on eggs or larvae of Pieris brassicae (Linnaeus) (Lepidoptera: Pieridae) in the absence and presence of cabbage aphids as an alternative prey were evaluated in laboratory experiments at 25°C. Both instars preyed upon butterfly eggs and larvae as well as on cabbage aphids with the third instar being the most voracious. The lacewings had a strong preference for caterpillars to butterfly eggs. In the presence of the aphids the predation on P. brassicae eggs or larvae was either completely abandoned or reduced by about 70%, respectively, by second instar lacewings and either reduced by about 80% or maintained, respectively, by third instar lacewings. Both instars thus had a clear preference for aphids compared to eggs of P. brassicae. However, second instar lacewings preferred aphids to caterpillars whereas the opposite was the case for third instar lacewings. The results indicate that 3rd instar C. carnea has a potential as biocontrol agent against P. brassicae.