Nymphal Development and Reproduction of Podisus nigrispinus (Heteroptera: Pentatomidae) Fed With Combinations of Tenebrio molitor (Coleoptera: Tenebrionidae) Pupae and Musca domestica (Diptera: Muscidae) Larvae

The development and reproduction of Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae) fed on Tenebrio molitor L. (Coleoptera: Tenebrionidae) and Musca domestica L. (Diptera: Muscidae) were studied in four treatments. P. nigrispinus was permitted to feed on: (1) T. molitor pupae (T 1 ); (2) Musca domestica larvae (T 2 ); (3) both prey supplied simultaneously (T 3 ); (4) both prey supplied on alternate days (T 4 ). Duration of the nymphal period of P. nigrispinus was similar in all diets studied with nymphal viability of approximately 75%. Heavier females were obtained in T 1 and T 4 , but no correlation between this factor and the reproductive rate of the predator was found. Therefore, the use of body weight as a parameter to evaluate rearing quality should be approached with caution. However, females of this predator showed higher egg and nymph production when they received both prey. For this reason P. nigrispinus should be reared with T. molitor and M. domestica simultaneously or on alternate days.     

Development and reproduction of Podisus distinctus (Heteroptera: Pentatomidae) fed on larva of Bombyx mori (Lepidoptera: Bombycidae).

Biological control has been reducing the use of chemical products against insect pests, especially predatory Pentatomidae. Species of this group can present high variations in their life cycle as a result of their diet. Thus, the objective of this research was to study nymph development and reproduction of Podisus distinctus (St?l, 1860) (Heteroptera: Pentatomidae) fed on Bombyx mori L., 1758 (Lepidoptera: Bombycidae) larvae (T1), compared to those fed on Tenebrio molitor L., 1758 (Coleoptera: Tenebrionidae) (T2) and Musca domestica L., 1758 (Diptera: Muscidae) larvae (T3) at a temperature of 25 +/- 0.5 degrees C, relative humidity of 70 +/- 2%, and photophase of 12 h. Predators fed on B. mori showed duration of the nymph phase (18.68 +/- 1.02) similar to those fed on T. molitor (18.32 +/- 1.49). Pre-oviposition and oviposition periods and number of egg masses, besides eggs and nymphs per female, were higher with B. mori (5.83 +/- 2.02; 15.00 +/- 7.40; 8.42 +/- 1.84; 296.69 +/- 154.75; and 228.55 +/- 141.04, respectively) while longevity of males and females of P. distinctus was 25.76 +/- 16.15 and 35.00 +/- 16.15 days with T. molitor, and 20.57 +/- 13.60 and 23.46 +/- 12.35 days with B. mori, respectively.     

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.     

Effects of diet on development of Podisus nigrispinus (Dallas) (Het., Pentatomidae), a predator of the cotton leafworm

Abstract:  The effects of diet on development of Podisus nigrispinus (Dallas) (Het., Pentatomidae) were studied at 25°C, relative humidity of 60 ± 10%, and photoperiod of 14 h light : 10 h dark. Development times of P. nigrispinus nymphs were similar when fed with third or fifth instar larvae of cotton leafworm ( Alabama argillacea Hübner) (Lep., Noctuidae) or Tenebrio molitor L. (Col., Tenebrionidae). When fed with housefly larvae ( Musca domestica L.) (Dipt., Muscidae) or artificial diet, the predator had a longer development time. Independent of diet, instar or sex, the females of P. nigrispinus showed a longer longevity than the males. The total survival of the nymphal stage, on the different diets, varied from 22.46 (fed with housefly) to 77.33% (fed with T. molitor larvae). P. nigrispinus males were heavier when fed with third or fifth instar cotton leafworm larvae than when fed with artificial diet. The weight of the females varied from 37.91 (with artificial diet) to 64.68 mg (with fifth instar cotton leafworm larvae). Independently of the diet, newly emerged females of P. nigrispinus were heavier than the males. Females of P. nigrispinus which were fed with fifth instar cotton leafworm larvae had heavier ovaries than those fed other diets.     

Vectorial capacity of Triatoma guasayana (Wygodzinsky & Abalos) (Hemiptera: Reduviidae) compared with two other species of epidemic importance

Triatoma guasayana (Wygodzinsky & Abalos) is a peridomestic triatomine with epidemiological importance in Bolivia, that may play an important role in the transmission of Trypanosoma cruzi (Chagas). In this study, two parameters of vectorial capacity were evaluated: the interval of feeding-defecation time and metacyclogenesis, in adult males and females and nymphal instars II to V of T. guasayana with comparisons with Triatoma infestans (Klug) and T. sordida (Stal). The results showed a close relationship between ingestion of blood and beginning of defecation. Values were negative in T. infestans, and T. sordida for instars II, III, IV, and V and also males and females but were positive in female T. sordida. Triatoma guasayana showed only negative values for instar II. Adults and nymphs began defecation as soon as they had finished feeding and required an average of 29.8 min. The analysis of metacyclogenesis showed that T. guasayana was superior to T. infestans and T. sordida. However, the vectorial effectiveness of T. guasayana was significantly affected regarding the percentage of metacyclic trypomastigotes during instars III to V and showed a progressive increase. Females had higher proportions despite their ingestion being half that of T. infestans. The different instars of T. guasayana had a higher parasitic load than those of T. sordida and, although ingestion was 1/3 of that of female T. infestans, there was a progressive increase in metacyclic trypomastigotes in the different nymphal stages of T. guasayana that decreased in adults.     

Effect of Feeding on Three Eucalyptus Species on the Development of Brontocoris tabidus (Het.: Pentatomidae) Fed with Tenebrio molitor (Col.: Tenebrionidae)

Brontocoris tabidus (Heteroptera: Pentatomidae) is an important predator of defoliating Lepidoptera in Brazil, which has been mass produced and released against defoliating caterpillars in Eucalyptus plantations. We aimed to improve the mass production of this predator by providing eucalypt seedlings, in addition to an alternative prey, for its development. The effect of three Eucalyptus species on the development of B. tabidus fed with Tenebrio molitor L. (Coleoptera: Tenebrionidae) pupae, was studied at a temperature of 25.0 ±2.5 o C; a relative humidity of 70.0 ±10.0% and a photophase of 12:12 hours (light:dark). Pupae of T. molitor were provided in each of the following feeding treatments: treatment 1, Eucalyptus urophylla seedlings; treatment 2, Eucalyptus camaldulensis seedlings; treatment 3, Eucalyptus grandis seedlings; and treatment 4, no seedling (only pupae of T. molitor ). Duration of the nymphal phase of the predator was similar in all treatments with plant and prey. It was observed that adults developed from nymphs fed on T. molitor only, had deformed wings and a small abdomen. B. tabidus fed during their nymphal and adult stages with prey together with Eucalyptus seedlings, had improved longevity, higher egg viability and a larger number of eggs and nymphs, than those insects fed only with prey. Therefore, it seems advisable to rear B. tabidus with prey and seedlings of Eucalyptus species, to improve the mass production of this predator for biological control of defoliating caterpillars of eucalypt plantations.     

室内条件下莱氏猛叩甲对松墨天牛和黄粉虫的捕食能力

【目的】本研究旨在明确莱氏猛叩甲Tetrigus lewisi老熟幼虫分别对黄粉虫Tenebrio molitor和松墨天牛Monochamus alternatus末龄幼虫和蛹的捕食量的差异,评估莱氏猛叩甲的捕食能力,为松墨天牛M.alteratus的有效治理找到潜在的高效生物防治因子。【方法】于2014年11月在浙江富阳昌东村马鞍山砍下松墨天牛虫害木,通过林间野外调查,明确松墨天牛和莱氏猛叩甲的发生情况;将野外采集到的莱氏猛叩甲幼虫带回室内,分别饲喂黄粉虫和松墨天牛的末龄幼虫和蛹,每天记录捕食量,确定莱氏猛叩甲的捕食能力。【结果】野外调查中,我们在松墨天牛幼虫蛀食的坑道中发现了莱氏猛叩甲幼虫和松墨天牛幼虫被取食后的残体;在采集到1 094头松墨天牛幼虫的危害木内,共采得莱氏猛叩甲末龄幼虫36头,约为松墨天牛幼虫数量的3%。室内捕食实验表明,5 d内莱氏猛叩甲捕食黄粉虫幼虫总量为3.2头,平均每天捕食约0.6头,而捕食松墨天牛幼虫总量为8.0头,平均每天捕食约1.6头,莱氏猛叩甲对松墨天牛的总捕食量显著高于对黄粉虫幼虫的总捕食量(P0.0001);4 d内莱氏猛叩甲捕食黄粉虫蛹总量为5.6头,平均每天捕食约1.4头,而捕食松墨天牛蛹总量为7.8头,平均每天捕食约2.0头,莱氏猛叩甲对松墨天牛蛹的捕食量显著高于黄粉虫蛹(P=0.028)。回归分析还表明,莱氏猛叩甲幼虫的捕食量不受叩甲个体大小的影响。【结论】莱氏猛叩甲普遍分布在松墨天牛发生区,同时发现松墨天牛被取食后的残体,表明莱氏猛叩甲是松墨天牛的捕食性天敌。莱氏猛叩甲均能捕食黄粉虫和松墨天牛的幼虫和蛹;相比于捕食黄粉虫,莱氏猛叩甲对松墨天牛的幼虫和蛹具有更好的捕食效率,具有很好的生物防治前景,是未来松墨天牛治理潜在高效生物防治因子。     

A Mass-Rearing Method for the Assassin Bug Pristhesancus plagipennis (Hemiptera: Reduviidae)

Pristhesancus plagipennis (Walker) is a predator of larvae and nymphs of many pestiferous insects for which natural enemies are not commercially available. This paper describes a containerized mass-rearing method for P. plagipennis using hot water-killed larvae of Tenebrio molitor (L.) and Helicoverpa armigera (Hübner). In addition, the effect of P. plagipennis density during nymphal rearing and adult oviposition was investigated. The rearing method minimizes P. plagipennis cannibalism, avoids the need for live insect prey, and is space and labor efficient. Larvae of the yellow mealworm, T. molitor, were the most suitable prey for minimizing nymphal development time and mortality while producing insects with the highest body weight. When reared on a diet of T. molitor, the optimum rearing density was 20–27 nymphs per 5-liter container. This rearing density minimized nymphal mortality to 16–22%. The optimum density for oviposition was 16 adults per 5-liter container, which provided the best compromise between egg production and space utilization.     

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.     

Laboratory studies of the biology and food requirements ofMacrorhaphis acuta [Hemiptera: Pentatomidae)

Macrorhaphis acuta were bred in the laboratory (25°C) and fed on larvae ofAscotis selenaria reciprocaria. The incubation period was 8.4 days and the mean hatch was 94.4%. There were 5 nymphal instars which occupied 3.3, 5.0, 5.6, 6.6 and 12.0 days, respectively, from the lst to the 5th. Each nymph consumed an average of 22.8 host larvae to complete development. Adults had a mean longevity of 74.9 days and each consumed an average of 67.5 host larvae. Significant reduction was noted in pupation of 5th instar host larvae sucked by adult predators for periods ranging from 4 to 10 mn. The food requirements of 3rd, 4th, and 5th instar nymphs fed on 3rd instar host larvae were also investigated. The conversion ratio varied with the weight of food consumed during the instar and later instars were more efficient than earlier ones. Predatory value did not vary significantly with successive instars.     

Population growth rate of the depredating Podisus nigrispinus (Heteroptera: Pentatomidae) and of the Tuta absoluta (Leptoptera: gelechiidae) in wintering place

The fertility life table of Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae) preying either on Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) caterpillars or on alternative prey Tenebrio molitor L. (Coleoptera: Tenebrionidae) under greenhouse conditions (30 +/- 5 degrees C, 61 +/- 23% RH) were studied. The life table was also determined for the pest T. absoluta under the same conditions. The net reproductive rate (Ro) and the intrinsic rate of natural increase (rm) were higher 14.13 and 46.32 times for predators fed on T. molitor prey, however, the generation time (T) was similar between prey. The pest T. absoluta showed Ro and rm higher 2.15 and 32.10 times than those achieved for predators fed on this pest. However, females fed on a suitable prey T. molitor showed higher Ro and rm than those yielded for the pest. The survival curves were similar for P. nigrispinus females fed on both prey and classified as being type II by Weibull analysis. The results suggest that P. nigrispinus is able to maintain its population preying only on T. absoluta caterpillars; however, the life table parameters determined individually for both showed that the pest produces more generations per year and faster population natural growth than the predator.     

Control of the flexible annual/biennial life cycle of the heather psyllid Strophingia ericae

Abstract. Strophingia ericae (Curtis) (Homoptera: Psylloidea) takes one or two years to complete its life cycle. In both cases eggs hatch over a prolonged period from midsummer, possibly extending into the following spring at high altitude, and instars overlap in time. Instar III is the predominant overwintering stage in the lowland, annual cycle, whereas in the upland, biennial cycle most first-year nymphs overwinter in instars I and II and most second-year nymphs in instar V. When moved to the laboratory, instars IV and V from a predominantly annual population showed accelerated development in response to elevated temperatures and to long days in both mid-winter and early spring. In the biennial life cycle, short autumn days retard instar V development but the response to photoperiod disappears by the end of winter. Exposure to LD 18 : 6 h retarded development of early instars in the annual population, resulting in an accumulation in instar III. The proportion of overwintering instars I and II rises with increase in altitude and moult to instar III becomes progressively delayed. Nymphs that reach instar III under long daylengths in the year following hatching are channelled towards the biennial cycle. Exposure of a predominantly biennial population to 15 °C and LD 18 : 6 h after midsummer, thus avoiding autumn conditions, promoted the rapid development of overwintered nymphs, switching the cycle from biennial to annual.     

The Feeding Behaviour of a Sit and Wait Predator Ranatra dispar (Heteroptera: Nepidae): The Effect of Prey Density and Age Structure on the Number of Prey Eaten

Functional response experiments were performed in the laboratory to examine the effect of prey density (as observed in the field) on feeding behaviour, and to measure handling-times and attack-rates for each instar and adult of Ranatra dispar Montandon (Heteroptera: Nepidae) feeding on five size-classes of its common prey, Anisops deanei Brooks (Heteroptera: Notonectidae). The most generally applicable response was the Type 2, although for both the predator fifth instar and adult female and male feeding on the two smallest prey sizes, the asymptote or plateau was not observed even at the highest prey density given. Generally, the handling-time increased as prey-size increased, and decreased as the predator size increased. The attack-rate surface was far more complex. For the first two predator instars (I and II), the maximum attack-rate occurred on the smallest prey sizes (1 and 2). The maximum attack-rate for predator instar III was almost the same for prey sizes 1 and 2, that of predator instar IV was greater for prey size 2, while in the three largest predator sizes (V, female and male), the maximum attack-rate was found for prey size 3. Predator instar V had the largest attack-rate values over all prey sizes, and both the predator adult female and male had lower attack-rates for various prey sizes than instars V, IV and, to some degree, III. The results support the suggestion that small predator instars will usually compete with large instars for prey, unless they are spatially or temporally separated. Observations in the field indicate that a distinct age-specific spatial distribution exists in R. dispar and the prey, A. deanei, with the smallest individuals being found predominantly in the shallow (littoral zone) water, while the larger individuals are found in the deeper water.     

Life cycle and seasonal development of post-embryonic Argas reflexus (Acari: Argasidae) at two thermally different locations in Central Europe

Seasonal development was investigated in the pigeon tick, Argas reflexus (F.) over a 5-year period. The ticks were kept in desiccators at two deposition sites with different temperature conditions: a warmer attic and a cooler outdoor aviary. The life cycle of A. reflexus consists of the egg, larva, a variable number of two to four nymphal instars and the adult stage. In the cooler aviary, the ticks passed, on average, fewer nymphal instars than in the attic. At both locations, ecdysis of the nymphs and adults occurred only during the summer months, with peak numbers of ticks finishing the moult in August. This consistent pattern was evident irrespective of the feeding date of the preceding developmental stage or the year of observation. The results strongly suggest that nymphs II, nymphs I and larvae fed later than in mid-July, August or September, respectively, entered a state of diapause and, thus, overwintered in the engorged state. Argas reflexus nymphs II from a laboratory stock that were deposited inside the attic showed a remarkably different seasonal pattern of development, even more than 1 year after their deposition. This suggests that a circannual rhythm may be involved in the ticks' seasonal timing. Mortality of the engorged ticks (from repletion to ecdysis of the following stage/instar) was below 1.5% in most cases, irrespective of the season and the location. Unfed larvae survived for a maximum of one year inside the attic, whereas the median survival period of unfed nymphs was at least 3 years at the same location. Based on the present results, the generation time from (F1) egg deposition to oviposition in the F2 generation might be 3-11 years in Central European A. reflexus, depending on the course of development (two or three nymphal instars) and the number of gonotrophic cycles (probably up to six) of the F1. The life span of a single tick might take approximately 7-11 years or even longer.     

Selective and frequency dependent predation of aquatic mosquito predator Diplonychus indicus Venkatesan & Rao (Hemiptera: Belostomatidae) on immature stages of three mosquito species

Frequency dependent mosquito larval size (II and IV instars) and species selection by the water bug Diplonychus indicus against three mosquito species Culex quinquefasciatus, Aedes aegypti and Anopheles stephensi was studied in the laboratory. The different frequencies used for each species selection were 20:30:50, 30:50:20, 50:20:30, 25:35:40, 35:40:25 and 40:25:35 of fourth instars of the respective three prey species. All nymphal water bugs (I–V instars) selected IV instar mosquito larvae and the mean proportion of late (larger) larvae eaten by the predator instars was significantly higher than the mean proportion of early (smaller) larvae eaten (F= 2.28; P < 0.001). In all six ratios used to determine the frequency dependent mosquito species selection, all the stages of the water bug selected Ae. aegypti over the other two species (F= 452.43; P < 0.001). The mean number of mosquito larvae eaten increased as its density increased based on various ratios of larvae offered. The study indicated that the predatory efficiency of D. indicus was high when Ae. aegypti was offered as prey, suggesting the utility of this mosquito predator in the control of dengue vectors.     

Development of Iphiseiodes quadripilis (Banks) (Acari: Phytoseiidae) on pollen or mite diets and predation on Aculops pelekassi (Keifer) (Acari: Eriophyidae) in the laboratory

Development and reproduction of Iphiseiodes quadripilis (Banks) were evaluated on single food diets of pollen (Malephora crocea Jacquin [ice plant] or Quercus sp. [oak]), spider mites, [Eutetranychus banksi (McGregor) or Panonychus citri (McGregor) (Acari: Tetranychidae)], or the citrus rust mite Phyllocoptruta oleivora (Ashmead) (Acari: Eriophyidae). Experiments were conducted in an environmental chamber at 28 degrees +/- 1 degrees C, 14:10 (L:D) daylength, and 45% RH. I. quadripilis completed development and laid viable eggs that subsequently hatched on diets of either ice plant or oak pollen or eggs and motile stages of E. banksi. P. citri was acceptable as prey, but survival of larvae to adults was only 36%, whereas survival on E. banksi, ice plant pollen, and oak pollen was 48, 60, and 68%, respectively. The webbing produced by P. citri seemed to inhibit foraging behavior of I. quadripilis larvae and nymphs. Larvae of I. quadripilis developed only to the second nymphal instar on a diet of P. oleivora alone or water alone. Starved I. quadripilis females and deutonymphs were observed preying on the pink citrus rust mite, Aculops pelekassi (Keifer) (Eriophyidae). During 4-min observation trials, two series of I. quadripilis fed on 1.8 +/- 0.47 and 3.5 +/- 0.45 A. pelekassi motile stages after being starved for 6 and 24 h, respectively. I. quadripilis females did not prey on P. oleivora in arenas containing both rust mite species.     

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%).     

Identification of instars and species in some larval Polypedilum (Polypedilum) (Diptera: Chironomidae)

Instars II and III of Polypedilum aviceps Townes, Polypedilum convictum (Walker), and Polypedilum illinoense (Malloch) can be identified to species by associating them with instar IV because key taxonomic characters remain relatively unchanged from instar to instar. Instars I cannot be identified to species or genus unless they are associated with older, identifiable larvae reared from the same egg masses. No single character evaluated on slide material can be used to clearly separate instars in all three species. Larvae of P. aviceps can be separated into instars based on any four of seven characters; P. convictum by either of two characters; and, P. illinoense by a combination of two characters. Changes in structures of instars II, III, and IV are described for all three species. Growth ratios for some structures are compared and discussed with regard to Dyar's Rule.     

Biology of a thelyotokous biotype of Eretmocerus mundus (Hymenoptera: Aphelinidae) on Bemisia tabaci (Homoptera: Aleyrodidae)

Abstract Thelyotokous biotype of Eretmocerus mundus Mercet (Hymenoptera: Aphelinidae), a parasitoid of Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae), was recently recorded in northern Iran. Reproductive biology of this biotype was studied as part of an evaluation of its potential for biological control of B. tabaci. The parasitoid deposited more eggs under 2nd and 3rd nymphal instars than 1st or 4th instars. Adult females fed honey, with no access to whitefly nymphs, lived significantly longer (13.6 ± 4.7 d) than those given access to nymphs, but not fed honey (7.6 ± 2.21 d). Lifetime fecundity averaged 81.7 ± 26.9 female progeny per female parasitoid, ranging from 11–132. Daily fecundity, measured as the number of whitefly nymphs parasitized by per female each day for 10 d, averaged 18.06 ± 3.95 for the first 6 d of life, and then declined to < 11. Developmental time from oviposition to parasitoid emergence was significantly shorter in the 3rd instar of the host (15.9 ± 1.06 d) than in the 1st instar (18.7 ± 2.3 d), but not in the 2nd instar (16.4 ± 1.3 d).