Regulation of Heliothis virescens prothoracic glands by Cardiochiles nigriceps polydnavirus

Heliothis virescens (F.) Larvae parasitized by the endophagous braconid Cardiochiles nigriceps Viereck fail to attain the pupal stage. This developmental alteration is caused by both an inactivation of prothoracic glands of last-instar larvae and an altered ecdysone metabolism. Decrease in ecdysteroidogenesis in vitro was already evident in glands explanted from larvae that have attained the early cell formation stage (day 4 of fifth instar), 6 h after parasitoid oviposition. Ecdysteroidogenesis nearly ceased by 24 h after parasitoid oviposition. The degree of this biosynthetic depression increased as the time between parasitization and gland dissection increased. A time-course study allowed us to determine if both the degree of phosphorylation of regulatory target proteins, the rate of general protein synthesis and ecdysteroidogenesis decreased in concert over time. The results provide further evidence in support of the hypothesis that these cellular activities in prothoracic gland cells are functionally correlated in steroidogenic responses. Treatment with calyx fluid and venom of C. nigriceps duplicates the parasitism-induced inactivation of host prothoracic glands. A 6-h conditioning in vitro of pupally committed host prothoracic glands with these parasitoid female reproductive secretions resulted in a significant depression of their ecdysteroid production. However, glands lost their sensitivity to calyx fluid and venom treatment when explanted from hosts that had already attained the cell formation stage. This was further supported by the fact that nearly all the host larvae parasitized on day 4 of fifth instar (cell formation stage) pupated, while parasitization on day 3 resulted in only 11% pupation. The coupled trioxsalen/UV irradiation treatment of C. nigriceps calyx fluid and venom eliminated their negative effect on biosynthetic activity in vitro by host prothoracic glands. This result indirectly demonstrates that C. nigriceps polydnavirus is the major regulating factor involved in the host prothoracic gland inactivation. Arch. Insect Biochem. Physiol. 38:1–10, 1998. © 1998 Wiley-Liss, Inc.     

Growth and development of Cardiochiles nigriceps viereck (hymenoptera,braconidae) larvae and their synchronization with some changes of the hemolymph composition of their host,Heliothis virescens (F.) (Lepidoptera,Noctuidae)

Larval development of the parasitoid Cardiochiles nigriceps Viereck occurs in the last instar larva of its host, Heliothis virescens (F.). This allows the parasitoid to exploit the nutritional increase in the biosynthetic activity occurring in the host in preparation for metamorphosis. To understand the biochemical basis of this host parasitoid developmental synchrony, we undertook host ligation studies and analyzed host hemolymph for proteins and glycerol esters. Parasitization affected the biochemical profile of the host. The hemolymph protein concentration of parasitized last instar H. virescens larvae increased through time, whereas unparasitized (control) larvae were characterized by a decrease in the protein titer when they reached the prepupal stage. The effect of parasitism on glyceride titers of host hemolymph was not as pronounced as the effect on proteins. Ligation conducted on 5th instar hosts, which were parasitized as 4th instars, affected parasitoid development in a time-dependent way. The percentage of successfully developing C. nigriceps larvae increased with the increase of the time interval between parasitization and ligation. Ligation performed before day 2 of the 5th larval instar of H. virescens completely inhibited parasitoid development. Ligations that disrupted parasitoid developmentwere associated with a low host hernolymph protein concentration. Parasitoid development was successful when hernolymph protein titer was high, as occurred when ligations were performed after day 3 of the 5th host instar in both control and parasitized larvae. Ligations in both situations resulted in a slight increase in glyceride titers. The results suggest that host proteins and/or some factor(s) associated with them may play a role in parasitoid growth and development. © 1993 Wiley-Liss, Inc.     

Prothoracic gland inactivation in Heliothis virescens (F.) (Lepidoptera:Noctuidae) larvae parasitized by Cardiochiles nigriceps Viereck (Hymenoptera:Braconidae)

Heliothis virescens (F.) last instar larvae parasitized by the endophagous braconid Cardiochiles nigriceps Viereck fail to attain the pupal stage, due to a parasitoid-induced alteration of ecdysteroid biosynthesis and metabolism. Currently available information on host prothoracic gland inactivation in this host-parasitoid system is reported here. Prothoracic glands of H. virescens mature larvae show a depressed biosynthetic activity, without undergoing gross morphological disruption. The ultrastructure of gland cells is characterized by minor parasitoid-induced changes, with the rough endoplasmic reticulum appearing more developed and electrondense than in nonparasitized controls. Eventually, the cells of prothoracic glands of parasitized host last instar larvae die but maintain their structural integrity. The inactivation of pupally committed host prothoracic glands is achieved through the disruption of the PTTH signal transduction pathway. The second messenger cAMP appears to be normally produced in response to PTTH stimulation of glands explanted from parasitized host larvae, however the downstream activation of the cAMP-dependent protein kinase does not appear to occur. In fact, a marked underphosphorylation of regulatory target proteins is observed. This underphosphorylation is associated with a significant reduction in general protein synthesis, which appears to be blocked at the translational level, to a redirection of specific protein synthesis and to a drastic suppression of ecdysteroidogenesis. These parameters appeared to be correlated in a kinetic time-course study, confirming their functional link. C. nigriceps polydnavirus (CnPDV) plays a major role in the inactivation of pupally committed host prothoracic glands, while putative factors occurring in the host haemolymph do not seem to be of particular importance at that developmental stage. Southern blot hybridization indicates the occurrence of PKI(protein kinase inhibitor)-like genes in the C. nigriceps genome, which, in contrast, are undetectable in H. virescens.     

Comparison of Host-Searching and Ovipositional Behavior of Cardiochiles nigriceps Viereck (Hymenoptera: Braconidae), a Parasitoid of Heliothis virescens (Fabricius) (Lepidoptera: Noctuidae), in Tobacco and Cotton

To compare host-searching and ovipositional behavior of Cardiochiles nigriceps Viereck (CN) in tobacco and cotton, behavior of CN females was observed on Hellothis virescens (Febricius)-infested plants and recorded using a Psion Organizer II with Observer software. Hover, search, oviposit, preen, rest, walk, agony-search, drop-search, and miss-search were the nine behaviors observed for each plant species. Agony-search was a searching behavior exhibited when CN females were prevented from ovipositing in a host because they were unable to reach the host. Drop-search and miss-search were the searching behaviors that occurred by CN females after a host dropped from the plant and when CN females missed ovipositing in a host, respectively. Hovering, searching, oviposition, miss-search, resting, and walking were equally common for CN on tobacco and cotton. Agony-search was exhibited more on tobacco than cotton, while drop-search and preening occurred more on cotton than tobacco. Female CN spent more time hovering in tobacco than in cotton, indicating that these females preferred tobacco to cotton. Female parasitoids also spent more time in the main ovipositional sequence, hover–search–oviposit, in tobacco than in cotton, mainly because females hovered more in tobacco than in cotton. Frequency and time of behavioral sequences associated with experiencing frustration in ovipositing due to difficulty in reaching or finding a host and subsequent level of success in ovipositing in a new host were determined. Overall, the rate of successful oviposition by CN females was significantly higher in tobacco (87.7%) than in cotton (79.5%). For cotton and tobacco, the rate of successful oviposition by CN females was significantly reduced (ca. 40.0%) when they experienced frustration in ovipositing compared to the rate of ovipositional success (100%) for CN females when hosts were present and easily accessible. Encountering ovipositional frustration also increased the duration of time for successful oviposition in comparison to the time spent for problem-free oviposition in cotton and tobacco. Interestingly, with successful oviposition, the amount of time spent in a behavioral sequence was not significantly different for tobacco and cotton regardless of whether females experienced ovipositional frustration or not. However, female CN invested more time in tobacco than in cotton when they were unsuccessful in ovipositing due to the inaccessibility or disappearance of hosts. CN females' preference for tobacco over cotton probably gave them more motivation to continue searching for hosts, especially those not easily attained, on tobacco than on cotton. Nevertheless, CN females readily searched in cotton for HV even in the presence of host-infested tabacco. CN females possibly could be successful in maintaining levels of HV below an economic threshold when using a tobacco trap crop to protect cotton as the main crop.     

In vitro rearing of Toxoneuron nigriceps (Hymenoptera: Braconidae), a larval endoparasitoid of Heliothis virescens (Lepidoptera: Noctuidae) from early second instar to third instar larvae

The early second instar larvae of Toxoneuron nigriceps, a larval endoparastioid of Heliothis virescens, were incubated in artificial rearing media, supplemented with hemolymph of the unparasitized and parasitized fifth instar larvae of the host, H. virescens. The parasitoid larvae were incubated in both a semisolid and liquid form of the artificial rearing medium, and their growth and development were evaluated. The growth in size (increase in length and width), development (molting), and survival of the incubated larvae were observed for 10 days. The incubated larvae exhibited some level of growth in all nine types of media tested, including the control (without host hemolymph). However, ingesting the semisolid rearing media supplemented with the hemolymph from the late fifth instar (day 5, 7 and 9) parasitized host resulted in 100% of the larvae molting to third instars. Some of the in vitro reared third instar larvae demonstrated behavioral changes that could be interpreted as the preparation for cocoon formation or pupation i.e. oral secretion of a whitish material and lots of twisting and turning; however, none produced a cocoon nor pupa.     

Unique intertesticular tissue complex in larvae of Heliothis virescens (F.) (Lepidoptera : Noctuidae)

A unique heart-testis complex has been found in the last instar of the tobacco budworm, Heliothis virescens (F.) (Lepidoptera : Noctuidae). This complex consists of a previously undescribed muscle system, herein designated the cardiotesticular muscle, that attaches the heart to the testes, and a ubiquitous connective tissue sheath that overlays this muscle and surrounding fat body and pericardial cells. These interconnected organs form a sieve-like septum enclosing a sinus that contains clusters of hemocytes and lipid droplets. Lipid droplets appear to be released from the surface of the testes sheath. The cardiotesticular muscle is innervated by neuroendocrine nerves that may be the route by which the brain peptide, testis ecdysiotropin, reaches the testes. The cardiotesticular muscle and products sequestered in the cardiotesticular sinus may be involved in the fusion of the paired testes and maturation of the male reproductive system, because they are present only during this stage of development.     

The role of heliothine hairpencil compounds in female Heliothis virescens (Lepidoptera: Noctuidae) behavior and mate acceptance

Studies on numerous insect species suggest that male-produced sex pheromones play a role in attracting females; as aphrodisiacs, making females more quiescent; or as a means of inhibiting competing males. Male heliothine moths display abdominal hairpencils during courtship, but the specific effects of the odors released on female behavior have not yet been elucidated. This study investigates the role of male hairpencil compounds in female Heliothis virescens mating behavior. Female H. virescens were exposed to filter paper loaded with hairpencil extracts of male H. virescens, Heliothis subflexa and Helicoverpa zea, and observed for behavioral responses to odors. Single synthetic compounds found in the H. virescens hairpencil blend were also tested. In mating assays between single male and female H. virescens it was found that: (i) antennectomized females mated less frequently than sham-operated females; (ii) females mated less frequently with males whose hairpencils had been surgically removed; (iii) females mated with males with ablated hairpencils if a filter paper loaded with one male equivalent of H. virescens hairpencil extract was presented simultaneously; and (iv) this effect was species-specific, as presentation of H. subflexa or H. zea hairpencil extracts did not restore mate acceptance. This study suggests that odors released by male hairpencils are important in mate acceptance by female H. virescens, and may play a role in mate choice and species isolation.     

Role of venom and ovarian proteins in immune suppression of Ostrinia furnacalis （Lepidoptera： Pyralidae） larvae parasitized by Macrocentrus cingulum （Hymenoptera： Braconidae）, a polyembryonic parasitoid

Venom and ovarian proteins in braconid and ichneumonid wasps play an important role in the successful parasitism of their host, especially for immune suppression immediately after oviposition. In this study, we compared the effect of venom and ovarian proteins collected from the female wasps of Macrocentrus cingulum, a polyembryonic parasitoid of the larvae of Ostriniafunacalis, on the encapsulation capacity of Sephadex A- 25 beads at 4 h and 24 h post-injection both in vivo and in vitro. The results showed that the ovarian proteins significantly interfered with the encapsulation capacity of hemocytes in a dose-dependent manner. Spreading and viability of hemocytes in O. furnacalis was not disrupted by venom and ovarian proteins at various concentrations injected. It seems likely that the ovarian proteins from M. cingulum play a role in suppressing the encapsulation capacity of host hemocytes.     

Nutritional effects on the induction of cytochrome P-450 and glutathione transferase in larvae of the tobacco budworm,Heliothis virescens (F.)

Wild tomato, Lycoperiscon hirsutum f. glabratum, leaves or 2-tridecanone fed to fifth instar larvae of the tobacco budworm, Heliothis virescens (F.), caused a 2.2 to 3.1-fold increase in gut microsomal cytochrome P-450. The increase was proportional to the feeding period or to 2-tridecanone concentration. Wild tomato leaves or 2-tridecanone caused distinct changes in the spectral characteristics of the gut cytochrome P-450. Glutathione S-transferase activity decreased during the first 24 hr of exposure, then recovered and increased above control levels after 3 days.     

Effects of individual Bacillus thuringiensis insecticidal crystal proteins on adult Heliothis virescens (F.) and Spodoptera exigua (Hubner) (Lepidoptera: Noctuidae)

Bacillus thuringiensis (Bt) is a grampositive, spore forming bacterium, which is principally distinguishedfrom other bacilli by the production of large, insecticidal,protein crystals (Insecticidal Crystal Proteins, or ICPs). Theseproteins are usually thought to act only on the actively feedinglarvae of susceptible species by a mechanism which involvesconsumption and proteolytic processing of the protein followed bybinding to, and lysis of, midgut epithelial cells. However, few authorshave reported Bt toxicity to adult insects. In the followingpaper, we expand on previous reports of toxicity to adult insects andpresent data which demonstrate that: (1) proteolytically activated ICPssignificantly reduce the lifespans of adult Heliothis virescensand Spodoptera exigua at concentrations of 500 g/ml, butnot 167 or 25 g/ml, (2) individual activated ICPs are differentiallytoxic to adult H. virescens and S. exigua, and (3)adult S. exigua are sensitive to Cry1C protoxin at aconcentration of 1 mg/ml.Deceased     

Effects of Heliothis virescens ascovirus (HvAV-3e) on a novel host, Crocidolomia pavonana (Lepidoptera: Crambidae)

Ascoviruses are double-stranded DNA viruses which cause fatal disease in lepidopteran host larvae. They induce a unique pathology, causing cleavage of host cells into virion-containing vesicles. With the single exception of Diadromus pulchellus ascovirus, all ascoviruses have been exclusively reported from the Noctuidae. To investigate whether Heliothis virescens AV (HvAV-3e) has a broader host range at the family level, larvae of Crocidolomia pavonana F. (Lepidoptera: Crambidae), a major pest of brassica crops in tropical and sub-tropical regions of the Old World and Australasia, were inoculated with HvAV-3e. Larvae were readily infected by the ascovirus and feeding, growth and survival were significantly affected. However, the milky white discolouration of the haemolymph which is characteristic of ascovirus infection in noctuid hosts was not apparent. In further contrast to infected noctuid host larvae that do not develop to the pupal stage, a significant proportion of infected C. pavonana larvae pupated but all were killed at this stage. Thus, C. pavonana appears to be a semi-permissive host of the ascovirus, the presence of such hosts in the field might be an explanation for the conundrum for the ascovirus-noctuid-wasp relationship, helping explain the persistence of the ascovirus.     

Effects of gamma radiation on different developmental stages of the oriental tobacco budworm,Helicoverpa assulta (Lepidoptera: Noctuidae)

Ionizing radiation is increasingly used as an alternative to post‐harvest crop fumigation by methyl bromide. We studied the effects of gamma irradiation on Helicoverpa assulta (Lepidoptera: Noctuidae) at different stages of development to determine the minimal dose for the prevention of normal emergence of adults. We selected five doses of gamma rays (100, 200, 300, 400 and 500 Gy) based on preliminary experiments and irradiated eggs, larvae, pupae and adults. A dose of 100 Gy to eggs allowed 21.83% of larvae to pupate, but these all died during the pupal stage. A dose of 100 Gy to last‐instar larvae caused larval or pupal death, or the emergence of abnormal adults; no normal adults developed. Irradiation of pupae with doses of 300 Gy and above resulted either in their death or emergence of abnormal adults; however, after 100 or 200 Gy, normal adults emerged and F₁ eggs were produced, but no eggs hatched. Following irradiation of adults, eggs were produced at all doses, although the numbers were significantly decreased compared to untreated controls (P < 0.05; 69.45–125.50 vs. 475.05 eggs per female); however, none of the eggs hatched. As prevention of normal emergence is a key outcome for measuring the effectiveness of radiation, then the 100 Gy dose was effective for irradiation of eggs and larvae, and 300 Gy for pupae.     

Cloning eleven midgut trypsin cDNAs and evaluating the interaction of proteinase inhibitors with Cry1Ac against the tobacco budworm, Heliothis virescens (F.) (Lepidoptera: Noctuidae)

Midgut trypsins are associated with Bt protoxin activation and toxin degradation. Proteinase inhibitors have potential insecticidal toxicity against a wide range of insect species. This study was conducted to evaluate the interaction of proteinase inhibitors with Bt toxin and to examine midgut trypsin gene profile of Heliothis virescens. A sublethal dose (15ppb) of Cry1Ac, 0.75% soybean trypsin inhibitor, and 0.1% and 0.2% N-α-tosyl-L-lysine chloromethyl ketone significantly suppressed midgut proteinase activities, and resulted in reductions in larval and pupal size and mass. The treatment with inhibitor+Bt suppressed approximately 65% more larval body mass and 21% more enzymatic activities than the inhibitor-only or Bt-only. Eleven trypsin-like cDNAs were sequenced from the midgut of H. virescens. All trypsins contained three catalytic center residues (H(73), D(153), and S(231)), substrate specificity determinant residues (D(225), G(250), and G(261)), and six cysteines for disulfide bridges. These putative trypsins were separated into three distinct groups, indicating the diverse proteinases evolved in this polyphagous insect. These results indicated that the insecticidal activity of proteinase inhibitors may be used to enhance Bt toxicity and delay resistance development.     

Myotropic effect of helicokinins,tachykinin-related peptides and Manduca sexta allatotropin on the gut of Heliothis virescens (Lepidoptera: Noctuidae)

Different insect neuropeptides (helicokinins, tachykinin-related and allatoregulating peptides) were investigated with regard to their myostimulatory effects using whole-gut preparations isolated from fifth instar Heliothis virescens larvae. The experiments demonstrated that representatives of all three peptide families are able to induce and amplify gut contractions in this species in a dose-dependent manner. Structure-activity studies (alanine scan, D-amino acid scan and truncated analogues) with the helicokinin Hez-K1 supported the finding, that the core sequence for biological activity of kinins is the amidated C-terminal pentapeptide (FSPWG-amide). Similar investigations with insect tachykinin isolated from Leucophaea madera (Lem-TRP1) revealed that the minimum sequence evoking a physiological gut response in H. virescens is the amidated hexapeptide (GFLGVR-amide), which represents the conserved amino acid sequence for Leucophaea TRPs in general. The peptide concentration causing a half-maximal gut contraction (EC(50)) for Lem-TRP1 was about 26 nM. Although the potency of Lem-TRP1 was 9-fold lower compared with Hez-KI (EC(50): 3 nM), the maximal tension of the gut obtained with Lem-TRP1 was 1.7-fold higher compared with Hez-KI. The EC(50) of Manduca sexta allatotropin (Mas-AT; 79 nM) was of lowest potency among all three peptides tested. In a pharmacological study, co-incubation experiments with Lem-TRP1, Hez-KI or Mas-AT and compounds interfering with signal transduction pathways were employed to investigate the mode of action of the myotropic effects of these peptides. Cadmium and the protein kinase C (PKC) inhibitor tamoxifen attenuated the contractile effects of all three peptides tested. The data suggest that in the gut muscle of H. virescens the myotropic peptides bind to G-protein-coupled receptors that cause contraction by promoting the entry of extracellular calcium mediated by a PKC involved pathway.     

Inhibition of juvenile hormone esterase activity in Lymantria dispar (Lepidoptera, Lymantriidae) larvae parasitized by Glyptapanteles liparidis (Hymenoptera, Braconidae)

Glyptapanteles liparidis is a gregarious, polydnavirus (PDV)-carrying braconid wasp that parasitizes larval stages of Lymantria dispar. In previous studies we showed that parasitized hosts dramatically increase juvenile hormone (JH) titers, whereas JH degradation is significantly inhibited in the hemolymph. Here we (i) quantified the effects of parasitism on JH esterase (JHE) activity in hemolymph and fat body of penultimate and final instars of L. dispar hosts and (ii) assessed the relative contribution of individual and combined wasp factors (PDV/venom, teratocytes, and wasp larvae) to the inhibition of host JHE activity. The effects of PDV/venom was investigated through the use of gamma-irradiated wasps, which lay non-viable eggs (leading to pseudoparasitization), while the effects of teratocytes and wasp larvae were examined by injection or insertion of these two components in either control or pseudoparasitized L. dispar larvae. Parasitism strongly suppressed host JHE activity in both hemolymph and fat body irrespective of whether the host was parasitized early (premolt-third instar) or late (mid-fourth instar). Down-regulation of JHE activity is primarily due to the injection of PDV/venom at the time of oviposition, with only very small additive effects of teratocytes and wasp larvae under certain experimental conditions. We compare the results with those reported earlier for L. dispar larvae parasitized by G. liparidis and discuss the possible role of JH alterations in host development disruption.     

Effects of the endoparasitoid Cotesia chilonis (Hymenoptera: Braconidae) parasitism,venom, and calyx fluid on cellular and humoral immunity of its host Chilo suppressalis (Lepidoptera: Crambidae) larvae

The larval endoparasitoid Cotesia chilonis injects venom and bracoviruses into its host Chilo suppressalis during oviposition. Here we study the effects of the polydnavirus (PDV)-carrying endoparasitoid C. chilonis (Hymenoptera: Braconidae) parasitism, venom and calyx fluid on host cellular and humoral immunity, specifically hemocyte composition, cellular spreading, encapsulation and melanization. Total hemocyte counts (THCs) were higher in parasitized larvae than in unparasitized larvae in the late stages following parasitization. While both plasmatocyte and granulocyte fractions and hemocyte mortality did not differ between parasitized and unparasitized hosts, in vitro spreading behavior of hemocytes was inhibited significantly by parasitism throughout the course of parasitoid development. C. chilonis parasitism suppressed the encapsulation response and melanization in the early stages. Venom alone did not alter cellular immune responses, including effects on THCs, mortality, hemocyte composition, cell spreading and encapsulation, but venom did inhibit humoral immunity by reducing melanization within 6 h after injection. In contrast to venom, calyx fluid had a significant effect on cell spreading, encapsulation and melanization from 6 h after injection. Dose–response injection studies indicated the effects of venom and calyx fluid synergized, showing a stronger and more persistent reduction in immune system responses than the effect of either injected alone.     

Effects of X‐ray irradiation on development and reproduction of the oriental tobacco budworm,Helicoverpa assulta (Lepidoptera: Noctuidae)

All stages of the life cycle of Helicoverpa assulta were irradiated with X‐rays to determine the inhibitory dose for development and reproduction to serve as a quarantine treatment. The 100‐Gy dose was effective for irradiation of eggs and larvae, and the 200‐Gy dose was effective for pupae and mixed‐sex adults. When either adult males or females were irradiated, however, 500 Gy was required to prevent the F1 eggs from hatching, and thus single‐sex adults required much higher doses of X‐ray irradiation. To gather confirmatory data applicable to phytosanitary quarantine regulations, pupae—the immature stage most resistant to X‐ray irradiation—were placed inside paprika in boxes for exportation and were irradiated with 300 Gy as a small‐scale confirmatory test. The dose given to 1,007 individual pupae resulted in 12.62 % survival, and 1.79 % of pupae emerged as normal adults; however, these adults produced only a few eggs that did not hatch, suggesting that a minimum dose of 300 Gy of X‐ray irradiation will provide quarantine security for immature H. assulta in paprika exports.     

半闭弯尾姬蜂寄生及其毒液对小菜蛾幼虫血细胞吞噬作用的影响

半闭弯尾姬蜂Diadegma semiclausum是小菜蛾Plutella xylostella的优势内寄生蜂, 拥有毒液、多分DNA病毒（PDV）等寄生因子,能有效调控寄主幼虫的营养生理和免疫系统, 但其毒液在这过程中的功能不明。本文利用SDS-PAGE方法分析了半闭弯尾姬蜂毒液的蛋白组分,利用寄主幼虫血细胞体外原代培养的方法,研究了小菜蛾幼虫血细胞噬菌能力在半闭弯尾姬蜂寄生后的变化情况。结果表明：半闭弯尾姬蜂毒液蛋白分子量主要集中在35~220 kDa之间,少数小于15 kDa,但分子量处于35~70 kDa之间的蛋白含量较高,与其他寄生蜂毒液蛋白相似。半闭弯尾姬蜂毒液单独对寄主小菜蛾幼虫功能血细胞（浆血细胞和颗粒血细胞）的延展能力和吞噬功能不产生破坏作用。但半闭弯尾姬蜂寄生后短时间内,寄主功能血细胞的延展受到抑制,然而功能血细胞仍然能识别外源异物, 却无法进一步吞噬外源物; 寄生后24 h,功能血细胞的延展力恢复,颗粒血细胞的吞噬作用可顺利完成。本研究证明了半闭弯尾姬蜂寄生能暂时性地抑制颗粒血细胞的延展性从而影响其噬菌过程。     

斑痣悬茧蜂寄生对甜菜夜蛾幼虫取食和食物利用的影响

为研究甜菜夜蛾Spodoptera exigua幼虫被斑痣悬茧蜂Meteorus pulchricornis寄生后的取食以及食物利用情况,在室内采用重量法测定了甜菜夜蛾4龄幼虫被寄生后取食量、体重增加量、营养指标的变化。结果表明：被寄生甜菜夜蛾幼虫的取食量、生长率和食物利用效率等明显受到抑制,幼虫被寄生后第3-6 d 取食量显著小于未被寄生幼虫,寄生后第4 d 的幼虫取食量只有正常幼虫的29.89%,第5 d只有48.69%。幼虫在寄生后的第3-5 d体重增加量显著小于未被寄生幼虫,分别为正常幼虫的21.51%,38.87%和14.42%,相对生长率则也显著低于后者。被寄生甜菜夜蛾幼虫的营养利用表现也明显不同于未被寄生幼虫,反映生长和代谢效率的食物利用率（ECI）和食物转化率（ECD）均显著降低,而反映吸收效率的近似消化率（AD）则提高。虽然在寄生后第4 d出现了相反的现象,其原因可能在于第4 d取食量明显减少,而体重仍在增加。本研究表明,斑痣悬茧蜂寄生明显抑制寄主甜菜夜蛾幼虫的取食、食物利用效率和生长。     

B型烟粉虱为害烟草后对斜纹夜蛾成虫产卵和幼虫取食行为的影响

为明确外来入侵害虫B型烟粉虱取食诱导的烟草防御反应对斜纹夜蛾的影响,探讨其与斜纹夜蛾的种间竞争机制,在室内条件下研究了B型烟粉虱取食后的烟草对斜纹夜蛾成虫产卵选择、幼虫取食选择、拒食作用和其他取食行为指标的影响.结果表明:斜纹夜蛾成虫在B型烟粉虱为害后的植株上的落卵量较对照植株降低了40.9%.B型烟粉虱为害的虫体叶对斜纹夜蛾初孵化幼虫具有明显的驱避作用,而中间叶和系统白脉叶有一定的吸引作用,心叶不影响幼虫对寄主的选择性.B型烟粉虱为害叶片对斜纹夜蛾幼虫具有显著的拒食作用,虫体叶拒食作用明显大于系统白脉叶片.与对照相比,B型烟粉虱为害的虫体叶和系统白脉叶降低了斜纹夜蛾幼虫单位时间取食次数或取食比例,虫体叶还显著延长了幼虫开始取食时间,总取食面积显著减少.表明B型烟粉虱为害烟草对斜纹夜蛾成虫产卵和幼虫取食行为均产生不利影响.研究结果对了解烟田害虫种群变动规律和指导害虫治理具有较大意义.