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PubMed2002

Biology of Anicla infecta (Ochsenheimer, 1816) (Lepidoptera, Noctuidae, Noctuinae), under laboratory conditions.

Larvae of Anicla infecta (Ochsenheimer, 1816) (Noctuidae) feed upon many grasses and may be harmful to cereals and fodder of economic importance. This study was developed aiming to contribute to knowledge of the biology of this species. The rearing was done in an environmental chamber with the following settings: temperature of 25 +/- 1 degrees C; relative humidity of 70% +/- 10%, and photoperiod of L14:D10. The larvae fed on ryegrass, Lolium multiflorum Lam. The results express the mean and standard error for the length of every stage in days. For each stage we observed the following time of development: egg 3.2 +/- 0.09; larvae 18.7 +/- 0.07; pre-pupae 3.3 +/- 0.04; pupae 12.6 +/- 0.14; and adult longevity was 12.1 +/- 1.03. Also the pre-egg-laying period was 4.4 +/- 0.59; the egg-laying period was 8.1 +/- 0.84; and the post-egg-laying period was 0.3 +/- 0.14. The mean number of egg-laying cycles per female was 6.7 +/- 0.73; that of eggs per cycle was 77.5 +/- 4.37; and total eggs per female was 521.4 +/- 47.36.

Animals↗

PubMed2004

Estimate of Alabama argillacea (Hübner) (Lepidoptera: Noctuidae) development with nonlinear models.

The objective of this work was to evaluate which nonlinear model [Davidson (1942, 1944), Stinner et al. (1974), Sharpe & DeMichele (1977), and Lactin et al. (1995)] best describes the relationship between developmental rates of the different instars and stages of Alabama argillacea (Hübner) (Lepidoptera: Noctuidae), and temperature. A. argillacea larvae were fed with cotton leaves (Gossypium hirsutum L., race latifolium Hutch., cultivar CNPA 7H) at constant temperatures of 20, 23, 25, 28, 30, 33, and 35 masculine C; relative humidity of 60 +/- 10%; and photoperiod of 14:10 L:D. Low R(2) values obtained with Davidson (0.0001 to 0.1179) and Stinner et al. (0.0099 to 0.8296) models indicated a poor fit of their data for A. argillacea. However, high R(2) values of Sharpe & DeMichele (0.9677 to 0.9997) and Lactin et al. (0.9684 to 0.9997) models indicated a better fit for estimating A. argillacea development.

Animals↗

PubMed2001

Life history traits of Helicoverpa zea (Lepidoptera: Noctuidae) on non-Bt and Bt transgenic corn hybrids in eastern North Carolina.

Transgenic varieties of field corn that express the CrylAb B. thuringiensis (Bt) toxin in ear tissue present the potential of reducing ear feeding by the corn earworm, Helicoverpa zea (Lepidoptera: Noctuidae), and for reducing the size of populations of the insect infesting other host crops. Life history parameters of H. zea feeding on ears of conventional and Bt field corn varieties were measured in field plots in eastern North Carolina in 1997 and 1998. Transformation events investigated were Mon-810 and Bt-11. Bt corn was found to cause a steady mortality of larvae during development, but permitted approximately 15-40% survival to the prepupal stage compared with non-Bt corn. Mortality of prepupae and pupae from Bt corn was also higher than from non-Bt corn, reducing overall adult production by 65-95%. The larvae that did survive grew more slowly on Bt than on non-Bt corn, and produced pupae that weighed 33% less. Pupation and adult eclosion were delayed by 6-10 d by feeding on Bt corn ears. Corn varieties expressing Bt in ear tissue have the potential to reduce H. zea ear feeding by up to 80%, and the potential to reduce populations emerging from ear-stage corn fields to infest cotton, soybean and other crops by around 75%. To have a measurable effect on area-wide populations, Bt corn varieties would need to be planted in large proportions of corn fields. Extensive planting of varieties such as those tested here, having only moderate effects on H. zea, would raise concerns about rapid evolution of resistance.

Animals↗

PubMed2005

Bollgard cotton and resistance of tobacco budworm (Lepidoptera: Noctuidae) to conventional insecticides in southern Tamaulipas, Mexico.

Insecticide susceptibility in tobacco budworm, Heliothis virescens (F.) (Lepidoptera: Noctuidae), was determined for 8 yr (1991-2001) with larvae sampled from cotton in southern Tamaulipas, Mexico. Before 1996, when Bollgard cotton expressing the Cry1A(c) delta-endotoxin was introduced into the region, two important patterns were documented. The first was economically significant increases in resistance to certain insecticide groups. The second was occurrence of virtually complete control failures in the field during 1994 and 1995. The largest resistance changes were recorded for the type II pyrethroids cypermethrin and deltamethrin. These products are the most widely used products in the region. Resistance ratios for these products increased up to > 100-fold from 1991 to 1995. After 1996, the resistance levels declined. These findings did not occur with other products of scant use (e.g., permethrin, profenofos, and endosulfan) or low tobacco budworm efficacy coupled to a high use pattern (e.g., methyl parathion). This clear trend toward reversal of resistance to type II pyrethroids can be understood, in part, with respect to two factors: 1) the high adoption rate of transgenic cotton in the region, from 31.2% in the beginning (1996) to approximately 90% in 1998; this has considerably curbed the use of synthetic insecticides, with the attending loss of selection pressure on this pest; and 2) the potential immigration to the region of susceptible tobacco budworms from cultivated and wild suitable hosts as well as from transgenic cotton might have influenced the pest population as a whole. The influence of transgenic cotton on southern Tamaulipas can be more clearly seen by the drastic reduction of insecticide use to control this important pest. Now tobacco budworms in this region are susceptible to type II pyrethroids. Two effective and fundamentally different pest management tools are now available to cotton growers in southern Tamaulipas: transgenic cotton, coupled with careful use of pyrethroids, offers the possibility of sustainable and profitable cotton production.

Animals↗

PubMed2006

Cannibalism of Helicoverpa zea (Lepidoptera: Noctuidae) from Bacillus thuringiensis (Bt) transgenic corn versus non-Bt corn.

Because of the importance of cannibalism in population regulation of Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) in corn, Zea mays L., it is useful to understand the interactions between Bacillus thuringiensis (Bt) transgenic corn and cannibalism. To determine the effects of Bt corn on cannibalism in H. zea, pairs of the same or different instars were taken from Bt or non-Bt corn and placed on artificial diet in proximity. Cannibalism occurred in 91% of pairs and was approximately 7% greater for pairs of larvae reared from Bt transgenic corn (95%) than from non-Bt corn (88%). Also, first instar by first instar pairs had a lower rate of cannibalism than other pairs. Time until cannibalism was not different for larvae from Bt corn versus non-Bt corn. Pupation rate of cannibals and surviving victims was not different for pairs from Bt corn versus non-Bt corn. Finally, cannibalism increased pupation rate of cannibals from both Bt and non-Bt corn by approximately 23 and 12%, respectively, although the increases were not significant. Thus, negative effects of Bt on larvae were compensated by increased cannibalism in comparison with larvae reared on non-Bt corn, which increased larval survival to levels comparable with larvae reared on non-Bt plants.

Animals↗

PubMed2006

Identification of the sex pheromone of Copitarsia decolora (Lepidoptera: Noctuidae).

Chemical and electrophysiological analyses and field trials were used to identify the female sex pheromone of Copitarsia decolora (Guenée) (Lepidoptera: Noctuidae). Coupled gas chromatographic-electroantennographic detection (GC-EAD) analysis of the female gland extract showed the presence of two EAD-active peaks, which were identified by GC-mass spectrometric (MS) analysis as (Z)-9-tetradecenyl acetate (Z9-14:Ac) and (Z)-9-tetradecenol (Z9-14:OH). The field evaluation of the EAD-active compounds indicated that traps baited with either Z9-14:Ac or Z9-14:OH caught few males. In contrast, traps baited with the binary blend of both components caught significantly more males than traps baited with the single compounds. Captures in traps baited with a mixture of Z9-14:Ac and Z9 -14:OH at 4:1, 10:1, and 100:1 ratios were not significantly different from the catches in traps baited with virgin females. Few males were captured in traps baited with a blend of Z9-14:Ac and Z9-14:OH at 1:4, 1:10, and 1:100 ratios.

Animals↗

PubMed2006

Suitability of various turfgrass species and cultivars for development and survival of black cutworm (Lepidoptera: Noctuidae).

Black cutworm, Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae), feeding bioassays were conducted on young and mature turfgrass species to determine their potential resistance. Measures of resistance included larval weight, survival rate, instar development, pupal weight, duration of pupation, and days to pupation and adult emergence. Black cutworm reared on Poa pratensis 'Midnight', Poa arachnigera 'Tejas', and Poa pratensis X Poa arachnigera 'Reveille' exhibited slower development, lower weight, and higher overall mortality than those fed upon other turfgrasses tested. Larvae reared on Reveille did not survive to pupation and all died within 14 d. Black cutworm larvae reared on Midnight died within 17 d in trial 1 but attained pupation in trial 2. However, development of black cutworm larvae was slower on Poa pratensis Midnight compared with other susceptible turfgrass species such as Agrostis stolonifera 'Penncross', Poa annua ('DW194', 'Q98-4-6', and 'Q98-6-18'), Lolium perenne, and Poa supina 'Supranova'. Generally, larval performance on young plant tissues was better than on mature plant tissues. Larvae reared on P. pratensis 'Midnight' exhibited the most distinctive difference on young versus mature plant tissue. These results suggest that plant age may play an important role in turfgrass susceptibility and resistance.

Animals↗

PubMed2006

Resistance monitoring of Helicoverpa armigera (Lepidoptera: Noctuidae) to bt insecticidal protein during 2001-2004 in China.

Susceptibility of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) field populations to the CrylAc toxin of Bacillus thuringiensis Berliner (Bt) were monitored from 1997 to 2004 in China. During 2001-2004, 53 strains from the Bt cotton planting region were sampled. The range of concentration producing 50% inhibition of larval development to third instar (IC50) values among different populations in 2001, 2002, 2003, and 2004 was 0.014-0.046, 0.010-0.062, 0.005-0.062, and 0.005-0.035 microg/ml, respectively. Diagnostic concentration studies (IC99) showed that the percentage of individuals reaching third instar ranged from 0 to 9.09%, with only four of the 53 tested populations showing values above 0%. Considering these data, it was determined that the susceptibility to CrylAc of the field populations sampled was not different from the baseline in 1997, and no movement toward resistance among H. armigera populations was apparent.

Animals↗

PubMed2006

Microbial control of black cutworm (Lepidoptera: Noctuidae) in turfgrass using Agrotis ipsilon multiple nucleopolyhedrovirus.

Agrotis ipsilon multiple nucleopolyhedrovirus (family Baculoviridae, genus Nucleopolyhedrovirus, AgipMNPV), a naturally occurring baculovirus, was found infecting black cutworm, Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae), on central Kentucky golf courses. Laboratory, greenhouse, and field studies investigated the potential of AgipMNPV for managing black cutworms in turfgrass. The virus was highly active against first instars (LC50 = 73 occlusion bodies [OBs] per microl with 2-microl dose; 95% confidence intervals, 55-98). First instars that ingested a high lethal dose stopped feeding and died in 3-6 d as early second instars, whereas lethally infected fourth instars continued to feed and grow for 4-9 d until death. Sublethal doses consumed by third or fifth instars had little or no effect on subsequent developmental rate or pupal weight. Horizontal transmission of AgipMNPV in turfgrass plots was shown. Sprayed suspensions of AgipMNPV (5 x 10(8) - 6 x 10(9) OBs/m2) resulted in 75 to > 93% lethal infection of third or fourth instars in field plots of fairway-height creeping bentgrass, Agrostis stolonifera (Huds.), and on a golf course putting green collar. Virus spray residues (7 x 10(9) OBs/m2) allowed to weather on mowed and irrigated creeping bentgrass field plots significantly increased lethal infection of implanted larvae for at least 4 wk. This study, the first to evaluate a virus against a pest in turfgrass, suggests that AgipMNPV has potential as a preventive bioinsecticide targeting early instar black cutworms. Establishing a virus reservoir in the thatch and soil could suppress successive generations of that key pest on golf courses and sport fields.

Agrostis↗

PubMed2006

Functional response of the tiger beetle Megacephala carolina carolina (Coleoptera: Carabidae) on twolined spittlebug (Hemiptera: Cercopidae) and fall armyworm (Lepidoptera: Noctuidae).

The functional response of the tiger beetle Megacephala carolina carolina L. (Coleoptera: Carabidae) was determined on adult twolined spittlebug, Prosapia bicincta (Say) (Hemiptera: Cercopidae), and fourth instars of fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), in single-prey and two-prey systems. In the laboratory, M. carolina carolina demonstrated a type II functional response for P. bicincta and S. frugiperda in both single- and two-prey systems. Search efficiency of M. carolina declined for both prey as the initial number of prey increased. Of the total prey consumed, M. carolina carolina killed significantly more S. frugiperda than P. bicincta in the single-prey system (8.0 and 4.5, respectively) and the two-prey system (5.0 and 2.0, respectively). Estimates of attack coefficient, a, were not significantly different for P. bicincta and S. frugiperda in the single-prey (0.07 and 0.02) and two-prey systems (0.04 and 0.06), respectively. The handling time, T(h), was significantly greater for P. bicincta (5.02 and 10.64 h) than for S. frugiperda (2.66 and 4.41 h) in single- and two-prey systems, respectively. Estimations of attack coefficient and handling time in the single-prey system were used to predict prey preference of M. carolina carolina. No strong prey switching response was observed. M. carolina carolina showed no preference for either prey. However, in the presence of S. frugiperda, the functional response of the predator for P. bicincta was reduced. M. carolina carolina is a potential predator of one or more turfgrass pests and should be considered in conservation efforts.

Animals↗

PubMed2006

Copitarsia decolora (Lepidoptera: Noctuidae) larvae escaping from discarded asparagus: data in support of a pathway risk analysis.

This research was undertaken to gather data in support of an assessment of the likelihood that Copitarsia decolora (Guenée) (Lepidoptera: Noctuidae), a pest of asparagus, Asparagus officinalis L., and other crops, could escape from the pathway followed by asparagus from the field to the consumer. Asparagus that is destroyed by cooking and consumption, being run through a trash compactor or garbage disposal, or being buried in a landfill probably cannot support development of C. decolora larvae. Much asparagus is discarded in dumpsters, however, and the time between disposal and removal to the landfill provides an opportunity for C. decolora to escape into the environment. Results of this study indicate that C. decolora cannot survive to the pupal stage on rotten asparagus, and survival on dried asparagus is low. However, larvae can survive at least 1 wk on both types of deteriorating asparagus held at 23.5 degrees C. In field trials, a small percentage of C. decolora larvae crawled out of a dumpster filled with asparagus after 1 wk.

Animals↗

PubMed2006

Genetic variation for resistance to Bacillus thuringiensis toxins in Helicoverpa zea (Lepidoptera: Noctuidae) in eastern North Carolina.

To evaluate resistance to Bacillus thuringiensis Berliner (Bt) toxins, adult female bollworms, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), were collected from four light trap locations in two eastern North Carolina counties from August to October during 2001 and 2002. Females were allowed to oviposit, and upon hatching, 24 neonates from each female (F1 lines) were screened for survival and growth rate on each of three diets: non-Bt diet, diet containing 5.0 microg/ml Cry1Ac toxin, or diet containing 5.0 microg/ml Cry2Ab toxin. These screens were designed to identify nonrecessive Bt resistance alleles present in field populations of bollworm. Of 561 and 691 families screened with both Cry1Ac- and Cry2Ab-containing diets in 2001 and 2002, respectively, no F1 lines were identified that seemed to carry a gene conferring substantial resistance to either Cry1Ac or Cry2Ab. Adults from F1 lines with growth scores in the highest (R) and lowest (S) quartiles were mated in four combinations, RxR, SxR, RxS, and SxS. Differences in growth rates of larvae from these crosses demonstrated that there is substantial quantitative genetic variation in eastern North Carolina populations for resistance to both Cry1Ac and Cry2Ab toxins. These findings, in addition to results suggesting partially dominant inheritance of resistance to Cry1Ac and Cry2Ab, are critically important for determining appropriate resistance management strategies that impact the sustainability of transgenic cotton, Gossypium hirsutum (L.).

Animals↗

PubMed2006

Oil-soluble dyes for marking Spodoptera frugiperda (Lepidoptera: Noctuidae).

Although various biological aspects of Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) have been examined, adult movement and dispersal of this insect pest is not well understood. Release-recapture techniques by using marked insects is a useful approach for dispersal studies; however, the marking technique should not significantly affect insect biology or behavior. Therefore, the effect of different concentrations of oil-soluble dyes (Solvent Blue 35 [C.I. 61554], Sudan Red 7B [C.I. 26050], Sudan Black B [26150], Sudan Orange G [C.I. 11920], and Sudan I 103624 [C.I. 12055]) on development, mortality, and fecundity of S. frugiperda was evaluated. Dyes were added to artificial diet used to feed larvae. Larval and pupal development and mortality, adult longevity, and female fecundity were evaluated. High concentrations (400 and 600 ppm) of all dyes led to longer larval and pupal stages. Adult life span and number of eggs were not affected by the dyes. Sudan Red 7B marked both adults and eggs very well. Solvent Blue 35 marked both adults and eggs, but the blue-marked eggs could not be distinguished from some bluish eggs laid by nonlabeled females. Adults and eggs were not adequately marked by the Sudan Black B, Sudan Orange G, and Sudan I 103624 (a yellow dye).

Animals↗

PubMed2006

Host plant resistance in romaine lettuce affects feeding behavior and biology of Trichoplusia ni and Spodoptera exigua (Lepidoptera: Noctuidae).

Lettuce quality and yield can be reduced by feeding of several lepidopterous pests, particularly cabbage looper, Trichoplusia ni (Hübner), and beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae). Host plant resistance to these insects is an environmentally sound adjunct to conventional chemical control. In this study we compared the survival, development, and feeding behavior of cabbage looper and beet armyworm on two romaine lettuce cultivars, resistant 'Valmaine' and susceptible 'Tall Guzmaine'. Larval mortality of both species was significantly higher on resistant Valmaine than on susceptible Tall Guzmaine. The average weight per larva after feeding for 1 wk on Tall Guzmaine plants was 6 times (beet armyworm) and 2 times (cabbage looper) greater than that of larvae feeding on Valmaine plants. Significant reduction in larval growth on Valmaine compared with that on Tall Guzmaine resulted in a 5.9- (beet armyworm) and 2.6-d (cabbage looper) increase in larval duration and almost a 1-d increase in pupal duration. Average pupal and adult weights and successful pupation of cabbage looper and beet armyworm were reduced on Valmaine compared with Tall Guzmaine. The sex ratio of progeny did not deviate from 1:1 when larvae were reared on either Valmaine or Tall Guzmaine. The fecundity of cabbage looper and beet armyworm adults that developed from larvae reared on Valmaine was about one-third that of adults from Tall Guzmaine, but adult longevity did not significantly differ on the two lettuce cultivars. The two insect species showed different feeding preferences for leaves of different age groups on Valmaine and Tall Guzmaine. Cabbage loopers cut narrow trenches on the leaf before actual feeding to block the flow of latex to the intended site of feeding. In contrast, beet armyworms did not trench. The different feeding behavior of the two species on Valmaine may explain the superior performance of cabbage looper compared with beet armyworm.

Animals↗

PubMed2003

Characterization of larval haemocytes from the velvetbean caterpillar Anticarsia gemmatalis (Hübner) (Lepidoptera: Noctuidae).

Larval haemocytes of Anticarsia gemmatalis (Lepidoptera: Noctuidae) are presented and classified based on morphological characteristics. Haemolymph samples collected from 3rd to 6th instar larvae were observed using differential interference contrast microscopy as well as processed for transmission and scanning electron microscopy. Five general types of haemocytes were observed: prohaemocytes (Pr), plasmatocytes (Pl), granular haemocytes (GH), oenocytoids (Oe) and spherulocytes (SPh). Granular haemocytes were subdivided into two morphologically different subtypes (GH 1 and GH 2). Phenoloxidase activity was clearly observed in the Oe, and also less intensely in the Sph. The osmium/imidazole buffer technique revealed that GH 2 accumulated numerous, small lipid vesicles among their granules, while Pl contained larger but less numerous lipid inclusions. Total haemocyte counts varied between 12.3 and 20.9 x 10(3) haemocytes/microl. Pl, GH 1 and Sph were the cell types more frequently observed in all larval stages studied. GH 2 were rare in 3rd and 4th instars, becoming more numerous after the inception of the 5th instar. Populations of GH 1 and Sph maintained their proportions throughout larval development. Populations of Oe, Pl and Pr, however, presented more marked variations in their proportions. Ultrastructural studies were shown to be useful for the identification and classification of haemocytes, facilitating further analysis by light microscopy.

Animals↗

PubMed2004

Influence of the nonsteroidal ecdysone agonist, tebufenozide, on certain biological and physiological parameters of the cotton leaf-worm, Spodoptera littoralis (Boisd.) (Noctuidae: Lepidoptera) in Egypt.

In Egypt, cotton represents the most economical and important field crop. Cotton plant is the target of different pest species from cultivation until harvest. The Egyptian cotton leaf-worm, Spodoptera littoralis (Boisd.) (Noctuidae: Lepidoptera), is an important polyphagous insect pest attacking cotton, several cultivated crops and ornamentals worldwide. The integrated pest management (IPM) programs create the need for novel insecticides having more selective modes of action. So, the no steroidal ecdysteroid mimic, tebufenozide (RH-5992) was studied on some parameters of Spodoptera littoralis. This compound exhibits, in spite of its nonsteroidal structure, a high affinity for the ecdysteroid receptors (EcRs) through a lock-and key principle just like the natural insect molting hormone 20, hydroxyecdysone (20E). The present investigation was performed to throw more light on the following objectives: (1) the toxicity of tebufenozide against the fifth larval instar of a laboratory strain of S. littoralis, (2) the effect of this compound on some biological parameters, i.e. weight of mature larvae, mortality and percentages of larval malformations, (3) the action on some haematological parameters such as blood volume, total haemocyte counts (THCs), absolute haemocyte counts, differential haemocyte counts, and (4) the characterization of haemolymph proteins in treated as well as in the untreated larvae, using the electrophoresis technique on acrylamide gel expressed in the electrophoretic mobility. The obtained results could be summarized as follows: (1) the treated larvae reached their maximum weight after 48 h from treatment with tebufenozide; while the untreated ones reached the maximum weight after 72 h (2) the highest mortality (73%) occurred by applying tebufenozide at the concentration of 18 ppm. In addition, the deduced percentage of larval malformations, indicated that the maximum rate of malformed larvae was attained using the concentration of 36 ppm (3) the blood volume of the 5th instar larvae reached its maximum after 72 h from treatment; while in the untreated ones blood volume increased gradually and reached the maximum rate after 96 h (4) the total haemocyte counts (THCs) decreased in comparison with the control. The maximum value of THCs occurred at 72 h, resembling a lower rate (50%) than that of the untreated ones. (5) The absolute counts reached their maximum rates after 72 h from treatment. It was lower (80.7%) than the untreated larvae. (6) Tebufenozide cause the induction of (10.7 & 14.3 Kda) polypeptide in the haemolymph after 24 h of application. These bands were absent in that time in the untreated larvae (control). Later on, these bands were formed in the control larvae after 72 h of treatment. Induced synthesis of these transcript resulted in precocious molting.

Animals↗

PubMed2001

Effect of dietary cowpea trypsin inhibitor (CpTI) on the growth and development of the tomato moth Lacanobia oleracea (Lepidoptera: Noctuidae) and on the success of the gregarious ectoparasitoid Eulophus pennicornis (Hymenoptera: Eulophidae).

Cowpea trypsin inhibitor (CpTI) was shown to have a deleterious effect on the growth and development of larvae of the tomato moth, Lacanobia oleracea, when incorporated in artificial diet (2.0% of soluble protein) and expressed in transgenic potato leaf (up to 1.0% of soluble protein). The effect of CpTI on parasitism of L oleracea by the ectoparasitoid Eulophus pennicornis was investigated. The parasitic success of the wasp was reduced by the presence of CpTI in the diet of the host and, in the case of transgenic potato leaves expressing the transgene protein, was collated with the length of time the host fed on the diet prior to parasitism. In all cases the proportion of hosts parasitised when fed CpTI-containing diets was reduced when compared with controls, although these differences were only significant when hosts were fed from the third instar on the transgenic potato leaves. Parasitoid progeny that developed on L oleracea reared on CpTI-containing diets, however, were not adversely affected. These results show that, whilst expression of CpTI in transgenic potato plants confers resistance to the lepidopterous pest L oleracea, adverse effects on the ability of the ectoparasitoid E pennicornis to parasitise this moth species successfully may also occur. These results are discussed in relation to the potential impact of transgenic crops on beneficial biological control agents.

Animals↗

PubMed2003

Midgut proteases from Mamestra configurata (Lepidoptera: Noctuidae) larvae: characterization, cDNA cloning, and expressed sequence tag analysis.

The activities of digestive protease within the midgut of Mamestra configurata (bertha armyworm) larvae were examined using specific substrates and protease inhibitors. The bulk of the activity was associated with serine proteases comprising trypsin-, chymotrypsin-, and elastase-like enzymes. At least 10-15 serine protease isozymes were detected using one-dimension gelatin gel electrophoresis. Cysteine or aspartic protease activities were not present; however, amino- and carboxypeptidase activities were associated with the midgut extract. Midgut proteases were active in the pH range of 5.0-12.0 with peaks at pH 7.5 and 11.0. In general, the middle region of the midgut exhibited a higher pH (approximately 8.0) than either the posterior or anterior regions (approximately 7.3-7.7). Moulting larvae possessed a neutral gut pH that was 0.5-1.5 units below that of feeding larvae. Degenerate PCR and expressed sequence tag (EST)-based approaches were used to isolate 30 distinct serine protease encoding cDNAs from a midgut-specific cDNA library including 8 putative trypsins, 9 chymotrypsins, 1 elastase, and 12 whose potential activities could not be determined. cDNAs encoding three amino- and two carboxypeptidases were also identified. Larvae feeding upon artificial diet containing 0.2% soybean trypsin inhibitor experienced a significant delay in development.

Amino Acid Sequence↗