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Life history and cost analysis for continuous rearing of Podisus maculiventris (Say) (Heteroptera: Pentatomidae) on a zoophytophagous artificial diet.

The impact of a zoophytophagous, insect-free artificial diet upon the developmental rate, life table parameters, and fertility table parameters was examined over 11 consecutive generations for domesticated and wild colonies of Podisus maculiventris (Say) (Heteroptera: Pentatomidae). This study showed that the developmental time, preoviposition period, fecundity, and nymphal survival improved in the domestic colony when fed an insect-free artificial diet for 11 consecutive generations, but remained relatively constant for the wild colony, as did reproductive rate and intrinsic rate of increase. Although, after 11 generations of adaptation to an artificial diet feeding regime, all reproductive and fertility table parameters were still significantly lower than when fed on T. ni larvae as the natural prey, the realized cost of rearing either colony on the artificial diet approached 1.2 times the cost of rearing these insects on a natural prey. This is a significant achievement in the effort to develop cost-effective artificial diets for the mass-rearing of beneficial pentatomids, and has positive implications for the use of one artificial diet to efficiently rear several beneficial insects.

Animals↗

Age-dependent fecundity and fertility life tables of the predator Brontocoris tabidus (Heteroptera: Pentatomidae) under field conditions.

Reproductive potential, longevity, life expectancy, and fertility life tables of Brontocoris tabidus (Signoret) (Heteroptera: Pentatomidae), a predator of lepidopteran defoliators in eucalyptus (Eucalyptus spp.) plantations, were studied in the field. After a 50-d preoviposition period (emergence of adults to the deposition of the first egg mass), ovipositional activity of B. tabidus continued until females died at 160 d. Females laid an average of 4.2 eggs per day and 601.1 eggs in a lifetime. Gross and net reproductive rates were 216.7 and 75.8 females, respectively. Generation time was 146.1 d, the period for doubling the population was 23.4 d, intrinsic rate was 0.03, and finite population increase was 1.03. Number of females per generation increased at 33.4 times. Results from our field studies indicate that B. tabidus has greater potential reproduction, oviposition period, and longevity than was expected from previous laboratory experiments. This suggests that B. tabidus has potential as a biological control agent to limit economically damaging pests in eucalyptus plantations.

Aging↗

Susceptibility of pest Nezara viridula (Heteroptera: Pentatomidae) and parasitoid Trichopoda pennipes (Diptera: Tachinidae) to selected insecticides.

Susceptibility of the southern green stink bug, Nezara viridula (L.) (Heteroptera: Pentatomidae), and its endoparasitoid Trichopoda pennipes (F.) (Diptera: Tachinidae) to acetamiprid, cyfluthrin, dicrotophos, indoxacarb, oxamyl, and thiamethoxam was compared in residual and oral toxicity tests. In the residual toxicity test, cyfluthrin, dicrotophos, and oxamyl were highly toxic to N. viridula. Thiamethoxam was moderately toxic to these insects. Each of the four insecticides was highly toxic to T. pennipes after prolonged tarsal contact with dried residues of these chemicals. In the oral toxicity test, where N. viridula fed on food covered with insecticide residues, none of the insecticides were toxic to adults of this stink bug, but acetamiprid, dicrotophos, and thiamethoxam were moderately toxic to the nymphs. In the oral toxicity test, where N. viridula fed on a gel-food containing insecticides, cyfluthrin, dicrotophos, oxamyl, and thiamethoxam were highly toxic to this stink bug. In an oral toxicity test using contaminated sugar water, all of the insecticides were highly toxic to T. pennipes. Because insecticides were as toxic, or more toxic, to T. pennipes than to N. viridula, it is extremely important to conserve this parasitoid by applying these insecticides for control of southern green stink bugs only when the pest reaches economic threshold.

Animals↗

Impact of Eurygaster maura (Heteroptera: Scutelleridae) feeding on quality of bread wheat in relation to attack period.

Sunn pest (or cereal bug) (Heteroptera: Pentatomidae and Scutelleridae) infestations of wheat, Triticum aestivum L., in the grain filling stage have the potential to adversely affect the quality of harvested grain for bread making. In the absence of resistant wheat cultivars, producers must rely on chemical control to protect their crop from sunn pest infestations. To implement an efficient environment friendly control strategy, there is a need to pinpoint the relationships between the timing of the bug attack and gluten degradation. Recent outbreaks of Eurygaster maura (L.) in northwestern Italy have increased the local concern toward this problem. A 3-yr study was carried out by caging plants of two bread wheat cultivars, characterized by different seed texture and bread-making quality, and introducing adults of E. maura in four periods corresponding to different grain filling stages: heading, early milk-ripe, milk-ripe, and late milk-ripe. The degree of bread-making quality depletion was assessed by analytical and biochemical methods and related to the attack period. Using analysis of variance, significant differences were found in the quality traits of kernels attacked by E. maura in different grain filling stages, the maximum damage occurring with bug feeding at the late milk-ripe stage. Biochemical investigations on gluten confirmed analytical results; in grain samples infested at the late milk-ripe stage, SDS gel electrophoresis revealed the degradation of some components of the high-molecular-weight glutenins, and high-performance liquid chromatography analyses showed a breakdown of the first peak of the insoluble fraction, mainly containing polymeric proteins highly related to dough strength.

Agriculture↗

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.

Age Distribution↗

Fumigant toxicity of plant essential oils to Thrips palmi (Thysanoptera: Thripidae) and Orius strigicollis (Heteroptera: Anthocoridae).

The fumigant toxicity of 92 plant essential oils to adult Thrips palmi Karny (Thysanoptera: Thripidae) and Orius strigicollis Poppius (Heteroptera: Anthocoridae) was examined by using a vapor phase toxicity bioassay and compared with those of dichlorvos, emamectin benzoate, spinosad, and thiamethoxam, four commonly used insecticides. Responses varied according to oil type and insect species. As judged by 24-h LC50 values, pennyroyal oil (2.63 mg/liter air) was the most toxic fumigant and was 23.6-fold more toxic than dichlorvos (62.09 mg/liter air) against adult T. palmi. Potent fumigant toxicity (LC50, 11.03-19.21 mg/liter air) was observed in armoise, basil, cedarleaf, coriander, cypress, howood, hyssop, marjoram, myrtle, niaouli, rosemary, and sage (Dalmatia) oils. Neither emamectin benzoate, spinosad, nor thiamethoxam exhibited fumigant action. Against adult O. strigicollis, dichlorvos (LC50, 6.3 x 10(-6) mg/liter air) was the most toxic fumigant, whereas the LC50 values of the 13 essential oils ranged from 17.29 to 158.22 mg/liter air. O. strigicollis was 1.4-22.1 times less susceptible than T. palmi to the essential oils. The essential oils described merit further study as potential fumigants for the control of T. palmi in greenhouses.

Animals↗

First evidence of sex chromosome pre-reduction in male meiosis in the Miridae bugs (Heteroptera).

The karyotype and male meiosis of Macrolophus costalis Fieber (Insecta, Heteroptera, Miridae) were studied using C-banding, AgNOR-banding and DNA sequence specific fluorochrome staining. The chromosome formula of the species is 2n = 28(24+X1X2X3Y). Male meiotic prophase is characterized by a prominent condensation stage. At this stage, two sex chromosomes, "X" and Y are positively heteropycnotic and always appeared together, while in autosomal bivalents homologous chromosomes were aligned side by side along their entire length, that is, meiosis is achiasmatic. At metaphase I, "X" and Y form a pseudobivalent and orient to the opposite poles. At early anaphase I, the "X" chromosome disintegrates into three separate small chromosomes, X1, X2, and X3. Hence both the autosomes and sex chromosomes segregate reductionally in the first anaphase, and separate equationally in the second anaphase. This is the first evidence of sex chromosome pre-reduction in the family Miridae. Data on C-heterochromatin distribution and its composition in the chromosomes of this species are discussed.

Animals↗

Fertility and life expectancy of the predator Supputius cincticeps (Heteroptera: Pentatomidae) exposed to sublethal doses of permethrin.

The stinkbug Supputius cincticeps (Stål) (Heteroptera: Pentatomidae) can be found in agricultural and forest ecosystems feeding primarily on larvae of Coleoptera and Lepidoptera, where it can be exposed to insecticide applications. This study therefore aimed to evaluate the reproductive potential of S. cincticeps after exposition to sublethal doses of permethrin (5.74 x 10(-3), 5.74 x 10(-2), 5.74 x 10(-1), 5.74 and 57.44 ppb) through the use of a fertility life table. The development cycle of this predator was determined in order to calculate its net reproductive rate (R0), the infinitesimal (rm) and finite (lambda) rates of increase in addition to mean generation time (T). The net reproductive (18.31), infinitesimal (rm) (0.050) and finite (lambda) (1.051) rates of increase were higher, while generation time (57.93 days) was shorter for S. cincticeps exposed to 5.74 x 10(-1) ppb of permethrin than in the control. This indicates a higher rate of population increase of this predator when exposed to this permethrin dose.

Animals↗

An alternative, less invasive blood sample collection technique for serologic studies utilizing triatomine bugs (Heteroptera; Insecta).

The collection of blood samples for serological studies is often stressful for the focus animal. Recently, the use of bloodsucking bugs, such as Dipetalogaster maximus or Triatoma infestans (Reduviidae; Triatominae; Heteroptera), has been suggested as a new and less invasive method for blood collection. To evaluate this technique, we collected paired blood samples from 20 domestic rabbits (Oryctolagus cuniculus) during a study of rabbit hemorrhagic disease virus (RHDV). For each rabbit, blood samples were collected by the conventional method (needle and syringe from the vena auricularis) and through feeding by D. maximus. Samples were tested for RHDV antibodies using standard test kits at three different dilutions. Antibody titers were identical for 56 paired samples and differed in only four cases. The simple matching indices were 1 for the 1:10 dilution and 0.9 for the 1:100 and 1:1000 dilutions. The major advantages of the new technique are 1) the possibility to obtain blood from animals where veins are inaccessible and 2) the fact that anesthesia of focus animals may not be necessary.

Animals↗

[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.

Animals↗

C-heterochromatin and extra (B) chromosome distribution in six species of the Nabis (Heteroptera, Nabidae) with the modal male karyotype 2n = 16 + XY.

The basic male karyotype of the six Nabis species (Heteroptera, Nabidae) is confirmed as being 2n=16+XY. The chromosomes are holokinetic while male meiosis is achiasmatic. The sex chromosomes undergo postreduction and in second metaphase show distance pairing, registered in all nabid species examined so far. Using C-banding technique for the first time in the family Nabidae, the heterochromatin was revealed on chromosomes of six species. The species showed different amount and distribution of C-heterochromatin. Only in Nabis (Dolichonabis) limbatus did the C-bands distribution make possible the identification of every chromosome pair in the karyotype. In other species, C-bands were found in some of the autosomes and the X, localized either interstitially or at telomeres. Only the Y usually showed relative stability ofthe C-banding pattern. In four of six species, extra (B) chromosomes were observed and their behaviour in meiosis described.

Animals↗

Meiosis aspects and nucleolar activity in Triatoma vitticeps (Triatominae, Heteroptera).

Some aspects of both the nucleolar organizer activity and meiosis were studied in the testes of Triatoma vitticeps (Heteroptera, Triatominae). The techniques used included squashing followed by lacto-acetic orcein staining, silver-ion impregnation, fluorescent banding (CMA3, Quinacrine mustard and DAPI) and fluorescent in situ hybridization (FISH). A close relationship between heterochromatin and nucleolus in testicular cells was observed. During meiosis, the silver-ion impregnation pattern varied. At metaphase plate, a small body appeared apart from the chromosomes. In the spermatids this small body was seen in preparations stained with orcein and silver- ion impregnation but not with fluorochromes or FISH. These characteristics combined suggest that these corpuscles represent a source of ribonucleoproteins (RNP)-RNA and specific nucleolar proteins. Silver-ion impregnation and (FISH) revealed nucleolar organizer activity in two metaphase sex chromosomes (X). These results indicate that, in these species, nucleolar organizer regions (NORs) are located in the sex chromosomes, X chromosomes were CMA3+ and Y chromosome was DAPI+.

Animals↗

Mortality profiles of Rhodnius prolixus (Heteroptera: Reduviidae), vector of Chagas disease.

Life table data of Rhodnius prolixus (Heteroptera: Reduviidae) kept at laboratory conditions were analysed in search for mortality patterns. Gompertz and Weibull mortality models seem adequate to explain the sigmoid shape of the survivorship curve. A significant fit was obtained with both models for females (R(2) = 0.70, P < 0.0005 for the Gompertz model; R(2) = 0.78, P < 0.0005 for the Weibull model) and for males (R(2) = 0.39, P < 0.0005 for the Gompertz model; R(2) = 0.48, P < 0.0005 for the Weibull model). The mortality parameter (b) is higher for females in Gompertz and Weibull models, using smoothed and non-smoothed data (P < 0.05), revealing a significant sex mortality differential. Given the particular life history of this insect, the non-linear relationship between the force of mortality and age may have an important impact in the vectorial capacity of R. prolixus as Chagas disease vector, and its consideration should be included as an important factor in the transmission of Trypanosoma cruzi by triatomines.

Animals↗

Johnston's organ and central organ in Nezara viridula (L.) (Heteroptera, Pentatomidae).

The fine structure of Johnston's organ and central organ in Nezara viridula (Heteroptera, Pentatomidae) is described. Johnston's organ consists of 45 scolopidia distributed around the periphery of the distal part of the third antennal segment (distal pedicellite). The scolopidia are anchored separately in invaginations of joint cuticle between the pedicel and flagellum. The scolopidia are amphinematic and each scolopidium comprises three sensory cells and three enveloping cells. The latter are a proximal scolopale cell with a typical labyrinth, an attachment cell filled with many microtubules, and a distal accessory cell also filled with microtubules. Axons of 17 scolopidia gather and join one antennal nerve; 28 scolopidia of the opposite side, extend axons into the other antennal nerve. The central organ consists of seven mononematic scolopidia, which comprise of one or two sensory cells. They anchor in the same joint as the scolopidia of Johnston's organ. The sensory cell bodies of the central organ are located close to the antennal nerves, more proximally than those of Johnston's organ. The axons of four scolopidia join one antennal nerve and those of the remaining three scolopidia join the other antennal nerve. Enveloping cells similar to those in Johnston's organ are present in the central organ.

Animal Communication↗

Phylogenetic approach to the study of Triatomines (Triatominae, Heteroptera).

Triatomines are insects belonging to the Hemiptera order, Heteroptera suborder, Reduviidae family and Triatominae subfamily. All members of this subfamily are hematophagous. Triatomines evolved from Reduviidae predators and they are probably polyphyletic in origin. The combination of anatomical, physiological and ethological factors observed in this group, as well as the plesiomorphic and apomorphic characters that differentiate the five tribes and fourteen triatomine genera reinforce the polyphiletic hypotesis. However if we consider the five groups of triatomines, the Rhodniini, Cavernicolini, Bolboderini, Linshcosteini and Alberproseniini tribes constitute monophyletic groups, while the Triatomini tribe is considered polyphyletic. The New World is the center of triatomine diversity and seems to be the point of group origin. Of approximately 137 triatomine species, 105 are only found in the Americas. It is now considered that triatomines represent a polyphyletic group defined according to their convergent apomorphic hematophagous characters, which have appeared several times in Reduviidae. This study revises the phylogeny of these vectors of Chagas' disease, covering such topics as the origin of hematophagy in triatomines and ancestral proposal for the group.

Animals↗

Geographic distribution of Wolbachia infections in Cimex lectularius (Heteroptera: Cimicidae).

Endosymbiotic Wolbachia bacteria have been previously shown to infect laboratory colonies of the human bed bug, Cimex lectularius L. (Heteroptera: Cimicidae), but little information exists regarding the extent of infection in natural populations. We assayed C. lectularius populations from five North American regions (California, Connecticut, Florida, New York, and Toronto, Canada) and one African region (Macha, Zambia) for Wolbachia infection by the polymerase chain reaction (PCR). Wolbachia infections were prevalent in all populations assayed (83-100%). There were no significant differences in infection frequency between geographic regions, between sexes, or between life stages (adult versus nymph). The potential utility of Wolbachia for alternative bed bug control strategies is discussed.

Animals↗

Description of new fibrinolytic enzyme, isolated from the haemolymph of Rhodnius prolixus Stal (Heteroptera Reduviidae).

A new fibrinolytic enzyme, isolated from the haemolymph of Rhodnius prolixus Stal (Heteroptera, Reduviidae) has been discovered. This enzyme does not act by activating plasminogen to plasmin. However, the split products obtained with this new enzyme inhibit fibrin formation in normal plasma. This enzyme seems to act specifically on the proteins involved in blood coagulation. Its origin has induced us to name it prolixase.

Animals↗

Effect of Eucalyptus feeding in the development, survival and reproduction of Tynacantha marginata (Heteroptera: Pentatomidae).

The effect of feeding on Eucalyptus leaves of Tynacantha marginata (Heteroptera: Pentatomidae) was studied in Brazil. The use of this plant as a complementary food source for the predatory bug increased its oviposition period, generation time, and net reproductive rate. Eucalyptus leaves apparently had no influence on the survival and development of T. marginata.

Animals↗