Prey preference and consumption capacity of Nephus arcuatus (Coleoptera: Coccinellidae): the influence of prey stage,prey size and feeding experience

This study examined the feeding habits of Nephus arcuatus Kapur (Coleoptera: Coccinellidae), an important predator of mealybugs in south-western Iran. The consumption capacity of male and female N. arcuatus adults was determined by their feeding on eggs, first-instar nymphs, and adult females of two destructive mealybugs, Nipaecoccus viridis (Newstead) and Planococcus citri Risso, over a 24-h period. N arcuatus consumed significantly more first-instar nymphs than eggs, and more eggs than female adults of both prey species. In addition, we also studied the developmental stage prey preference of adults reared on either N. viridis or P. citri and found that the prey preference of females did not change with the developmental stage of the mealybug. Meanwhile, the males reared on either N. viridis or P. citri showed a significant preference for the first-instar nymphs of P. citri over first-instar nymphs of N. viridis, while a preference for the eggs or adult females of these two mealybugs was not observed. This selection of first-instar nymphs by males was not tied to its previous feeding experience. Our findings suggest that prey stage, prey size and previous feeding experience had no effect on the prey selection of N. arcuatus, making it a good candidate for the biological control of mealybugs.     

Biology of Tupiocoris cucurbitaceus (Hemiptera: Miridae), a predator of the greenhouse whitefly Trialeurodes vaporariorum (Hemiptera: Aleyrodidae) in tomato crops in Argentina

The predator Tupiocoris cucurbitaceus is frequently found attacking Trialeurodes vaporariorum in greenhouses without pesticide applications in Argentina. The objective of these studies was to evaluate some biological characteristics of this species fed on three types of diet (whitefly nymphs, Sitotroga cerealella eggs and a mix of both) and on two host plants (tomato and tobacco), under controlled experimental conditions. Preimaginal developmental time for female and male bugs was shorter in the presence of whiteflies than with only moth eggs. Females lived longer when they ate only whitefly nymphs compared to a mixed diet or only moth eggs. The amount of adult descendants was greater when bugs could eat whiteflies, regardless of the presence of S. cerealella. Embryonic development time, male longevity and sex proportion were not affected by the diet or the host plant. Prey consumption was evaluated for three T. cucurbitaceus life history stages (fourth/fifth instar nymphs, female and male adults) on two types of prey (whitefly nymphs and S. cerealella eggs). On tomato, females were more voracious than males and nymphs. On tobacco, adults and nymphs consumed more S. cerealella than T.vaporariorum nymphs, but again, bug females preyed more than males and nymphs. Results demonstrate that T. cucurbitaceus can survive, develop and reproduce normally using both T. vaporariorum and S. cerealella eggs as prey on tobacco or tomato plants. This information can be useful for managing this predator against T. vaporariorum through conservative or augmentative biological control strategies.     

Life table of Xylocoris afer (Hemiptera: Anthocoridae) feeding on eggs of Corcyra cephalonica (Lepidoptera: Pyralidae) and Plutella xylostella (Lepidoptera: Plutellidae)

The aim was to evaluate the biological aspects of Xylocoris afer fed on Corcyra cephalonica and Plutella xylostella eggs. The experiment was conducted with X. afer nymphs aged 12–24?h, one per Petri dish, resulting in a total of 60 nymphs (60 repetitions). On each dish, we placed P. xylostella and C. cephalonica eggs daily, together with a cotton roll moistened with distilled water and conducted daily evaluations. We evaluated the duration, viability, and consumption of nymphal stages, the longevity of males and females, the number of eggs per female, and egg fertility. In addition, the biological data were used to determine the parameters of the fertility life table. The consumption by adults (male and female) of X. afer differed between the preys, the highest consumption was C. cephalonica eggs. Females that consumed eggs of C. cephalonica produced about 90% more eggs and more offspring than those that fed on P. xylostella eggs. Based on our results, it can be inferred that the predator completed its development feeding both on natural prey and the alternative, evidencing the possible potential of X. afer to be used in the biological control of P. xylostella as well as the use of C. cephalonica in mass rearing of this predator under laboratory conditions, aiming its use in applied biological control. However, before being accepted for biological control agent against agricultural pests, various factors should be examined in ecosystem level, as the behavior of predator in different densities of prey.     

Efficacy of multiple biocontrol agents against the sweet potato whitefly Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) on tomato

Abstract: Biological control provides an environmentally harmonious and potentially stable management tactic to combat noxious pests such as Bemisia tabaci, notorious for its resistance to synthetic pesticides. Bioassays conducted under control chamber conditions integrating applications of the parasitoid Encarsia formosa, reared for 20 years on Trialeurodes vaporariorum, and the fungus Verticillium lecanii on the third‐fourth instar nymphs of B. tabaci on tomato, showed a comparable effect between the parasitoid‐fungus combined treatment and the fungus treatment alone (70.7% vs. 70.4%). Analysis of our results indicates antagonism between the two biocontrol agents related to the parasitoids’ ability to discriminate between infected and healthy B. tabaci nymphs. The parasitoid treatment alone produced 36.3% mortality, with no mortality in the distilled water controls. The behavioural performance of the parasitoid could have either genetic or environmental causes. Bioassays studying the feeding habit of the imported mirid predator Macrolophus caliginosus (adults) and the indigenous mirid Camptotylus reuteri (nymphs and adults) on eggs, or early second instar nymphs of B. tabaci, and choice preference tests indicated a significant difference in feeding between M. caliginosus and C. reuteri. There was no significant difference in percentage feeding of M. caliginosus on eggs (2.2%) or second instar nymphs (8.0%). There was a significant difference in feeding of M. caliginosus adults (18.6%) when offered eggs and second instars in the same arena compared with eggs or second instars offered separately. These results could be attributed to the biological behaviour of the predator having a type III functional response. Studies with the local C. reuteri species showed no significant difference in adult and nymphal consumption on second instars of B. tabaci compared with nymphs on eggs. However, C. reuteri adults fed less on eggs compared with nymphs. This local predatory species appears to be more efficient than M. caliginosus in feeding on particular stages of B. tabaci without depending on prey density. This is further supported by the low consumption of both adults and nymphs in the choice test (4% and 2.3%, respectively) compared with M. caliginosus adults (18.6%).     

Life history,diagnosis, and biological aspects of Engytatus varians (Hemiptera: Miridae), a predator of Bactericera cockerelli (Hemiptera: Triozidae)

The life cycle and several life parameters of the zoophytophagous predator Engytatus varians (Distant) (Heteroptera: Miridae), including nymphal growth according to Dyar’s rule, were examined in the laboratory. The egg, nymph (five instars), and adult stages were 9.20, 17.36, and 19.02?d in length, respectively. The growth ratio for nymphs was consistent with Dyar’s rule based on the lengths of the femora of the forelegs, the tibiae and femora of the middle legs, and the antennae. Some biological characteristics of E. varians were also evaluated when the mirid was fed three different diets (B. cockerelli third instars, Sitotroga cerealella Olivier [Lepidoptera: Gelechiidae] eggs, and a mixture of both instars and eggs). The length of the nymphal stage was three days longer on a diet of only S. cerealella eggs than when the mirids were fed the third instars of B. cockerelli only or a mixture of both. The sex ratio was not affected by the type of diet. Nymphs of E. varians consumed B. cockerelli nymphs (80–85) when fed third instars only and third instars?+?S. cerealella eggs, respectively. The potential use of this predator as a biological control agent of B. cockerelli is discussed.     

Mass rearing of Spalgis epius (Lepidoptera: Lycaenidae), a potential predator of mealybugs (Hemiptera: Pseudococcidae)

Spalgis epius (Lepidoptera: Lycaenidae) has been recorded as a potential predator of various species of mealybug crop pests worldwide. We describe the mass rearing of S. epius, as no information on this topic is available. Outdoor nylon tent cages of different dimensions were provided to achieve mating and oviposition as S. epius adults did not mate in the laboratory cages. Adults mated only in the tent cage (6×6×10 m) placed over a native tree (9 m height). The presence of a tree canopy inside the cage is essential to achieve courtship and mating. Gravid females of S. epius deposited eggs on the mealybug-infested pumpkins inside the different sized nylon cages with or without a bush/tree. Spalgis epius eggs were maintained on mealybug-infested pumpkins in the laboratory and developmental stages of the predator were reared. Adults fed on various diets laid significantly higher number of eggs than those of starved individuals. Spalgis epius with a life cycle completed in 21.2 days and 55.7 larvae, could be reared on a single mealybug-infested pumpkin.     

Effect of different diets on reproduction,longevity and predation capacity of Orius insidiosus (Say) (Hemiptera: Anthocoridae)

Orius insidiosus is a generalist predator for which diet influences important biological traits like reproduction and predation. We tested the effects of different diets alone or in combination on reproduction, longevity and predation capacity of this predator. The diets tested were: no food (control); pollen; Frankliniella occidentalis (Pergande) nymphs and adults; F. occidentalis nymphs and adults and pollen; Anagasta kuehniella (Zeller) eggs; A. kuehniella eggs and pollen; A. kuehniella eggs; F. occidentalis nymphs and adults and A. kuehniella eggs, F. occidentalis nymphs and adults and pollen. The pre-oviposition period was shortest when the diet consisted of pollen and prey (A. kuehniella and/or F. occidentalis), of the two prey species together or of only A. kuehniella eggs. The highest values for the length of the oviposition period (50.1, 48.0, 46.3 and 46.1 days), daily fecundity (3.8, 3.9, 4.0 and 4.2 eggs/female/day), total fecundity (190.3, 187.7 185.2 and 193.6 eggs/female) and longevity (52.1, 49.9, 48.7 and 48.0 days) were found with diets consisting of only A. kuehniella eggs. Pollen did not improve any of the performance parameters of the predator when offered exclusively or as a complementary food. The results show that selection of a proper diet can strongly improve reproduction, longevity and predation capacity of O. insidiosus. An important finding is that A. kuehniella eggs, which can easily be produced in large quantities, are an excellent factitious prey for mass production of O. insidiosus.     

The effects of host plant on the coccinellid functional response: Is the conifer specialist Aphidecta obliterata (L.) (Coleoptera: Coccinellidae) better adapted to spruce than the generalist Adalia bipunctata (L.) (Coleoptera: Coccinellidae)?

Female Aphidecta obliterata consumed an average of 26.6 ± 5.8 Elatobium abietinum and males consumed an average of 19.9 ± 3.2 Elatobium abietinum, but there was no significant difference in the number consumed between the sexes. In Petri dish trials, the larval stages of A. obliterata and all stages of Adalia bipunctata appeared to exhibit a Type II response to prey density, although A. obliterata adults showed a more linear response to prey density. There was no significant difference between the functional responses of the 3rd instars of the two coccinellid species, but there was a significant difference between the responses shown by the 1st instars, with A. obliterata larvae consuming more than those of A. bipunctata, especially at low densities, suggesting that the two species respond differently to an increase in prey density.At low prey densities, adults and 4th instars of both species exhibited a similar response to an increase in prey density but at higher densities the 4th instars and adult stages of A. bipunctata showed higher attack rates when compared with the same stages of A. obliterata.Adult and 4th instar A. obliterata exhibited Type II functional responses on spruce sections. The 4th instar A. obliterata larva appeared to be a more effective predator than the adult of the species, and was more effective when compared with adult A. bipunctata at lower prey densities but A. bipunctata adults appeared to be a more effective predator at higher prey densities.The host plant affected the rate of consumption by adult A. obliterata as adults on Sitka spruce sections consumed significantly higher numbers of aphids than their counterparts on Norway spruce. This was most noticeable at densities above 16 aphids.The distributions of the two coccinellid species in the olfactometer were significantly affected by the presence of host plant material. Aphidecta obliterata adults were found in significantly higher numbers in the Sitka spruce chambers than the control chambers (those without plant material). Adalia bipunctata adults were found in significantly lower numbers in the Norway spruce chamber than the control chamber.Although A. bipunctata has a higher level of voracity than A. obliterata, the latter is more adapted to the spruce environment and the boom and bust population dynamics of E. abietinum.     

A quantified ethogram for oviposition behavior and oviposition preference in the hemipterophagous butterfly Spalgis epius (Westwood) (Lepidoptera: Lycaenidae)

In this study, we examined the oviposition behavior and preference of Spalgis epius, a potential predator of mealybug crop pests. An ethogram of oviposition behavior was constructed based on observations made in an oviposition cage. Ovipositional behavioral acts were catalogued and separated into two behavioral repertoires: searching and egg laying. Gravid females of S. epius oviposited similar numbers of eggs on three mealybug species. Females preferred eggs and adults to nymphs of mealybugs for oviposition. Among three species of mealybugs attended by ants, females laid fewer eggs in the mealybug mass attended by Oecophylla smaragdina than on mealybugs attended by Tapinoma melanocephalum and Camponotus variegatus. Females preferred mealybug masses already containing conspecific eggs to mealybug masses containing conspecific larvae or Cryptolaemus montrouzieri larvae for egg deposition. Gravid females laid larger numbers of eggs under bright sunlight than in diffused sunlight or shade. The results of this study showed that S. epius can effectively attack any species of mealybugs, avoid intra- and interspecific competition, and co-exist with some species of ants attending mealybugs. With the knowledge of these behaviors, this predator can be effectively utilized as a major biological control agent of mealybugs.     

Relative importance of natural enemies and abiotic factors as sources of regulation of mealybugs (Hemiptera: Pseudococcidae) in Brazilian coffee plantations

In the present study, we determined the critical stages and the key factors of mortality for Planococcus citri (Hemiptera: Pseudococcidae) in Brazilian coffee plantations using a life table to understand the role of natural biological control on its population. Predators, parasitoids, rainfall, sunlight, physiological disturbances and fungal diseases were collectively responsible for 98.79% in the total mortality of P. citri. Predators belonging to the Chrysopidae, Syrphidae, Dolichopodidae and Coccinellidae families were the most important mortality factors in the early developmental stages of P. citri (i.e. eggs and 1st and 2nd instar nymphs), whereas predators belonging to the Coccinellidae and Chrysopidae families were the most important mortality factors for the last instars (i.e. 3rd instars and adults) for P. citri. The generalist predators Harmonia axyridis, Chrysoperla genanigra and Chrysoperla externa were the key mortality factors for P. citri. The third nymph stage was considered the critical life stage (i.e. the life stage that most influences population size). Our results show that generalist predators and climatic factors are important sources of natural mortality of P. citri governing the population dynamics of this pest in the field.     

Population dynamics of Spalgis epius (Lepidoptera: Lycaenidae), a candidate biocontrol agent of mealybugs and its interaction with mealybug-attendant ants

Spalgis epius is an economically important hemipterophagous butterfly. Detailed information on the population dynamics, natural enemies, and prey range of S. epius and its association with mealybug-attendant ant species is lacking. Three years of field studies conducted at Bangalore University campus, Bengaluru, India on these aspects indicated that the population density of S. epius was greatest from June to December and least from February to May in the low land region. S. epius survived on eight prey species, which were present in different months, of which Phenacoccus indicus was recorded as a prey of S. epius for the first time. Different prey species occurred on 12 species of host plants. The occurrence of S. epius was negatively correlated with temperature and positively correlated with relative humidity and prey populations. Six mealybug-attendant ant species were associated with the larvae of S. epius. The seven general predators of S. epius adults were recorded. Knowledge on the population dynamics and a prey range of S. epius and its interaction with mealybug-attendant ant species could be helpful to using this predator as a major biocontrol agent of various species of mealybugs. This study contributed to our understanding of the population dynamics of a hemipterophagous butterfly.     

Functional response and predation of Nabis kinbergii （Hemiptera. Nabidae） to Plutella xylostella （Lepidoptera. Plutellidae）

The functional response of adult Nabis kinbergii （Hemiptera： Nabidae） to density of diamondback moth Plutella xylostella （Lepidoptera： Plutellidae） was investigated under laboratory conditions. Holling＇ s （1959） type Ⅱ model was found to be a good fit for the observed functional response of this predator. The numbers of P. xylostella consumed increased with temperature from 15℃ to 35℃. The maximum number of prey killed was observed at 35℃, with average of 10.3 and 8.3 forth instar larvae consumed by adult females and males of N. kinbergii, respectively. The predation of N. kinbergii on P. xylostella increased with successive immature stages. The number of prey consumed by predators decreased as the body size of prey increased. An average of 131 eggs or 95 larvae of P. xylostella were killed by a single of female adult in 24 hours at 24＂C. The pupae of P. xylostella were observed to be eaten by fifth instar nymphs and adults N. kinbergiiin numbers of less than an average of 0.7 pupae per predator in 24 hours at 24＂C. Predation preference by N. kinbergii was also investigated. The number of P. xylostella and Myzus persicae killed by female N. kinbergii was not significantly different, but males killed significantly more P. xylostella than M. persicae. Both eggs and larvae of P. xylosteUa were killed in significantly greater number than those of Pieris rapae in the same feeding arena.     

Ontogenetic shifts in the functional response and interference interactions of Rhyacophila dorsalis larvae (Trichoptera)

1. Ontogenetic shifts in predator behaviour can affect the assessment of food‐web structure and the development of predator–prey models. Therefore, it is important to establish if the functional response and interference interactions differ between life‐stages. These hypotheses were tested by (i) comparing the functional response of second, third, fourth and fifth larval instars of Rhyacophila dorsalis, using three stream tanks with one Rhyacophila larva per tank and one of 10 prey densities between 20 and 200 larvae of Chironomus sp.; (ii) using other experiments to assess interference within instars (two to five larvae of the same instar per tank), and between pairs of different instars (one, two or three larvae per instar; total predator densities of two, four or six larvae per tank). 2. The first hypothesis was supported. The number of prey eaten by each instar increased with prey density, the relationship being described by a type II model. The curvilinear response was stronger for fourth and fifth instars than for second and third instars. Mean handling time did not change significantly with prey density, and increased with decreasing instar number from 169 s for fifth instars to 200 s for second instars. Attack rate decreased progressively with decreasing instar number. Handling time varied considerably for each predator–prey encounter, but was normally distributed for each predator instar. Variations in attack rate and handling time were related to differences in activity between instars, fourth and fifth instars being more active and aggressive than second and third instars, and having a higher food intake. 3. The second hypothesis was partially supported. In the interference experiments between larvae of the same instar or different instars, mean handling time did not change significantly with increasing predator density, and attack rate did not change for second and third instars but decreased curvilinearly for fourth and fifth instars. Interference between some instars could not be studied because insufficient second instars were available at the same time as fourth and fifth instars, and most third instars were eaten by fourth and fifth instars in the experiments. Prey capture always decreased with decreasing attack rate. Therefore, interference reduced prey consumption in fourth and fifth instars, but not in second and third instars. The varying feeding responses of different instars should be taken into account when assessing their role in predator–prey relationships in the field.     

Prey‐mediated changes in the selectivity of the predator Macrolophus pygmaeus (Heteroptera: Miridae)

When foraging in communities with mixed prey, generalist predators may be confronted with prey species that differ in quality, size and mobility and interact with one another. To examine prey selection, predation by Macrolophus pygmaeus (Heteroptera: Miridae) was recorded by providing a diet of either one or two prey species of Myzus persicae (third‐instar nymphs), Aphis gossypii (fourth‐instar nymphs), Trialeurodes vaporariorum (third‐instar nymphs) and Ephestia kuehniella (eggs). In the experiments, prey mobility, prey quality and prey biomass were considered. The biomass consumed by the predator was dependent on the combination of prey species and the quantity of biomass offered. In choice experiments with diets mixed of two prey species at equal densities, the predation to A. gossypii was significantly reduced in the presence of E. kuehniella but the rate of consumption of M. persicae, T. vaporariorum and E.kuehniella was not significantly affected by the coexistence of any other species in the mixed prey diet. When equal amounts of biomass from two prey species were provided in combination, the total consumed biomass was significantly reduced in the mixed prey diets composed of E. kuehniella eggs and aphid nymphs. Thus, under the mixed‐prey situation, prey selection by predators may be affected by interactions among prey species differing in traits such as quality, mobility and size.     

Functional response of Euseius concordis to densities of different developmental stages of the cassava green mite

Both prey density and developmental stage of pests and natural enemies are known to influence the effectiveness of biological control. However, little is known about the interaction between prey density and population structure on predation and fecundity of generalist predatory mites. Here, we evaluated the functional response (number of prey eaten by predator in relation to prey density) of adult females and nymphs of the generalist predatory mite Euseius concordis to densities of different developmental stages of the cassava green mite Mononychellus tanajoa, as well as the fecundity of adult females of the predator. We further assessed the instantaneous rate of increase, based on fecundity and mortality, of E. concordis fed on eggs, immatures and adults of M. tanajoa. Overall, nymphs and adults of E. concordis feeding on eggs, immatures and females of M. tanajoa had a type III functional response curve suggesting that the predator increased prey consumption rate as prey density increased. Both nymphs and adult females of the predator consumed more eggs than immatures of M. tanajoa from the density of 20 items per leaf disc onwards, revealing an interaction between prey density and developmental stage in the predatory activity of E. concordis. In addition, population growth rate was higher when the predator fed on eggs and immatures in comparison with females. Altogether our results suggest that E. concordis may be a good candidate for the biological control of M. tanajoa populations. However, the efficiency of E. concordis as a biological control agent of M. tanajoa is contingent on prey density and population structure.     

Development and feeding of <Emphasis Type="Italic">Tetraphleps galchanoides</Emphasis>, a predator of the hemlock woolly adelgid

Tetraphleps galchanoides Ghauri (Hemiptera: Anthocoridae) nymphs were collected from hemlock woolly adelgid (HWA) Adelges tsugae Annand (Hemiptera: Adelgidae) infested Tsuga sp. in Baoxing, Sichuan, China. First and second stage nymphs collected from foliage shipped from China; were reared to adults and tested for feeding rates and host preferences. They were reared at 5, 8, 12, and 15 ± 1 °C from November to December, January to March, April, and May to June, respectively, in the quarantine laboratory at Virginia Polytechnic Institute and State University. At 8 °C, development time was 15, 20, and 40 days for the N-III, IV, and V nymphal stages, respectively. Adult males lived 83 days with a range of 21–147 days. A single adult female lived for 21 days. At 5 °C, second stage T. galchanoides nymphs consumed 0.8 HWA nymphs per day, and 2.0 HWA nymphs per day at the N-V stage. At 8 °C, consumption of HWA nymphs ranged from 1.3 to 3.4 nymphs per day for the N-III to N-V stages, respectively. Adult T. galchanoides consumed more HWA eggs than HWA adults, pine bark adelgid (PBA) Pineus strobi (Hartig) (Hemiptera: Adelgidae) adults, and eggs in no-choice tests. In choice tests with HWA eggs and PBA eggs, more HWA eggs were eaten. Adult and nymph body measurements are presented for determination of nymphal instars.     

Intraguild predation among the predatory mites Amblyseius eharai,Amblyseius cucumeris and Amblyseius barkeri

Predator species with the same prey interact not only by competition for food and space but also by intraguild predation (IGP). The impact of IGP on introduced phytoseiid mites and native species in the context of biological control is a matter of considerable debate. Amblyseius eharai is the dominant native citrus species in central China, while Amblyseius cucumeris and Amblyseius barkeri are candidates for importation. All three species can feed on the spider mite Panonychus citri, which is the main pest in citrus. This study investigated, in the laboratory, possible IGP among these species in the absence and presence of P. citri, respectively. IGP in different densities of shared prey and intraguild (IG) prey was also studied. All three species consumed heterospecific larvae and eggs but not adults, and the IGP rate of larvae was significantly higher than that of eggs in the absence of shared prey. Additionally, the IGP rate of each group was reduced dramatically in the presence of both shared and IG prey when compared to the absence of shared prey. This occurs most likely because the three species prefer to feed on their natural prey P. citri, rather than on IG prey. Our results showed that A. eharai seems to be a more voracious IG predator than A. cucumeris. A. eharai was much more prone to IGP than A. barkeri.     

Feeding preference of Macrolophus caliginosus (Heteroptera: Miridae) on Bemisia tabaci and Trialeurodes vaporariorum (Homoptera: Aleyrodidae)

A study of predation choices of Macrolophus caliginosus Wagner (Heteroptera: Miridae) late instars and adults, when offered various developmental stages (eggs and nymphs) of the recently established whitefly Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae), was made based on two preference indices. In addition, prey choices of late instars when presented with three ratios of Trialeurodes vaporariorum (Westwood) (Homoptera: Aleyrodidae) and B. tabaci at a similar developmental stage (eggs, young or late instars) were assessed. M. caliginosus preferred older nymphs of B. tabaci than any other stage. It also chose T. vaporariorum over B. tabaci, unless the latter consisted of > 75% of the available prey. These results suggested that M. caliginosus might interfere with parasitoids such as Encarsia, Eretmocerus, or Amitus spp. because all three species emerge from the host pupal case. Furthermore, in mixed infestations, M. caliginosus preference for T. vaporariorum might either negatively affect the control of B. tabaci, or, contrarily, enhance the predator population, before a B. tabaci outbreak occurs in the greenhouse.     

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.     

Host plant, oviposition behavior and larval ecology of a sawfly leafminer, Profenusa japonica (Hymenoptera: Tenthredinidae)

The host plant, oviposition behavior and larval ecology of Profenusa japonica Togashi are reported for the first time. Adults of P. japonica mated and oviposited on a polyantha rose, Rosa multiflora (Rosaceae), in April. Each female adult laid an egg on the edge of a leaflet. Hatched larvae consumed the parenchymatous layer of leaflets and in so doing created a mine. The larval stage comprised five instars. On average, 70.6% of the total area of a leaflet was consumed by one larva. Female adults of P. japonica laid eggs singly, probably to avoid larval competition for food.