The Experts below are selected from a list of 243 Experts worldwide ranked by ideXlab platform
Jing S Hu - One of the best experts on this subject based on the ideXlab platform.
-
age specific interaction between the parasitoid encarsia formosa and its host the silverleaf whitefly bemisia tabaci strain b
Journal of Insect Science, 2003Co-Authors: Jing S Hu, Dale B Gelman, Michael B BlackburnAbstract:The effect of hostage, the Instar of Bemisia tabaci (Gennadius) parasitized, on the growth and development of Encarsia formosa (Gahan) was studied. E. formosa was able to parasitize and complete its life cycle no matter which Instar of B. tabaci (Strain B), [also identified as B. argentifolii (Bellows and Perring)], was provided for oviposition, but parasitoid development was significantly slower when 1st or 2nd Instar B. tabaci rather than 3rd or 4th Instars were parasitized. Host age influenced the day on which E. formosa nymphs hatching from eggs was first observed. Mean embryonic development was significantly longer when 1st (5.4 days) rather than 2nd, 3rd or 4th Instars (4.1, 3.4 and 3.5 days, respectively) were parasitized. The duration of the 1st Instar parasitoid and the pupa, but not the 2nd or 3rd Instar parasitoid, were also significantly greater when 1st Instars were parasitized than when older host Instars were parasitized. Interestingly, no matter which Instar was parasitized, the parasitoid did not molt to the 3rd Instar until the 4th Instar host had reached a depth of about 0.23 mm (Stage 4–5) and had initiated the nymphal-adult molt and adult development. Histological studies revealed that whitefly eye and wing structures had either disintegrated or were adult in nature whenever a 3rd Instar parasitoid was present. It appears, then, that the molt of the parasitoid to its last Instar is associated with the host whitefly's nymphal-adult molt. However, the initiation of the host's final molt, while a prerequisite for the parasitoid's 2nd–3rd Instar molt, did not necessarily trigger this molt. In contrast to its significant effect on various aspects of parasitoid development, host Instar did not significantly influence the mean size of the parasitoid larva, pupa, or adult. Larval and pupal length and adult head width were similar for all parasitoids, regardless of which host Instar was parasitized as was adult longevity. Adult parasitoid emergence was more synchronous when 2nd, 3rd and 4th Instars were parasitized than when 1st Instars were parasitized. Results are compared with those reported when the greenhouse whitefly, Trialeurodes vaporariorum, was parasitized by E. formosa, and provide possible explanations for why T. vaporariorum is a more suitable host than B. tabaci for E. formosa.
-
growth and development of encarsia formosa hymenoptera aphelinidae in the greenhouse whitefly trialeurodes vaporariorum homoptera aleyrodidae effect of host age
Archives of Insect Biochemistry and Physiology, 2002Co-Authors: Jing S Hu, Dale B Gelman, Michael B BlackburnAbstract:The tiny parasitoid wasp, Encarsia formosa, has been used successfully to control greenhouse whiteflies (GHWFs) in greenhouses in many countries throughout the world. Therefore, there has been considerable interest in developing methods for artificially rearing this wasp. However, little information is available concerning the regulation of its development including the host-parasitoid interactions that are required for the parasitoid to complete its life cycle. Here we confirm that parasitoid developmental rates differ significantly based upon the host Instar parasitized. Development was faster when 3rd and 4th Instar GHWFs were offered for parasitization than when 1st or 2nd Instars were used. Our results show that it is primarily the embryo and the first two parasitoid Instars that exhibit prolonged developmental times when 1st and 2nd Instar whiteflies are parasitized. Although percent emergence was not affected by host age at the time of parasitization, adult longevity as well as adult emergence pattern varied greatly depending upon the Instar parasitized. When 3rd and 4th Instar GHWFs were selected for oviposition, adult wasps lived significantly longer than when 1st or 2nd Instars were used; also, there was a sharp emergence peak on the 2nd day after emergence was first observed (reduced or absent when 1st or 2nd Instar GHWFs were parasitized) and the emergence period was reduced from between 8 and 11 days to 5 days. In general, the younger the host Instar parasitized, the less synchronous was parasitoid development. Previous reports that E. formosa will not molt to the 2nd Instar until the host has reached its 4th Instar were not confirmed. When 1st Instar host nymphs were parasitized, 2nd Instar parasitoids were detected in 3rd Instar hosts. Importantly, however, no matter which Instar was parasitized, the parasitoid never molted to its last Instar until the host had reached Stage 5 of its last Instar, a stage in which host pharate adult formation has been initiated. It appears, then, that a condition(s) associated with host pharate adult formation is required for the parasitoid’s final larval molt. Results reported here should facilitate the development of in vitro rearing systems for E. formosa. Arch. Insect Biochem. Physiol. 49:125‐136, 2002. Published 2002 Wiley-Liss, Inc.
-
timing and ecdysteroid regulation of the molt in last Instar greenhouse whiteflies trialeurodes vaporariorum
Journal of Insect Physiology, 2002Co-Authors: Dale B Gelman, Michael B Blackburn, Jing S HuAbstract:Abstract A system of markers has been devised to track the development of 3rd and 4th Instar/pharate adult greenhouse whiteflies. Instars were identified based on measurements of body width and body length. Depending upon the host plant, the product of the two measurements was exceptionally useful in distinguishing between Instars. Body depth was used to divide the 3rd Instar into eight stages and body depth and color and appearance of the developing adult eye were used to divide the 4th Instar/pharate adult into nine stages. Under conditions of L:D 16:8 and a temperature of 26±2°C, the body depth of 3rd Instars reared on greenbean increased from 0.025 (stage 1) to 0.2 mm (stage 8) and the Instar duration was approximately 3 days. The body depth of 4th Instars increased from approximately 0.1±0.02 (Stage 1) to 0.3±0.03 mm (Stage 5) and then remained constant or decreased slightly during adult development. Ecdysteroid titers peaked at approximately 120 fg/μg protein during Stages 3 through 6 of the 4th Instar. Based on an external examination of developing 4th Instars and the fluctuations in ecdysteroid titer, it appears that adult development is initiated in Stage 4 or 5 4th Instars. Results from histological studies support this view. In Stage 4 nymphs, a subtle change was observed in the corneagenous cells of the eye. However, most Stage 4 4th Instars possessed wing development characteristic of earlier, immature stages. In all Stage 5 insects, wing development had been initiated and the corneagenous cells had become quite distinct. In Stage 6 whiteflies, the wing buds were deeply folded and by Stage 7, spines were observed on the new cuticle, indicating that the adult cuticle was well-formed by this stage. Our study is the first to investigate the timing and regulation of the molt, to monitor ecdysteroid titers in precisely staged 4th Instar whiteflies and to examine the internal anatomical changes associated with metamorphosis in these tiny homopteran insects.
Dale B Gelman - One of the best experts on this subject based on the ideXlab platform.
-
age specific interaction between the parasitoid encarsia formosa and its host the silverleaf whitefly bemisia tabaci strain b
Journal of Insect Science, 2003Co-Authors: Jing S Hu, Dale B Gelman, Michael B BlackburnAbstract:The effect of hostage, the Instar of Bemisia tabaci (Gennadius) parasitized, on the growth and development of Encarsia formosa (Gahan) was studied. E. formosa was able to parasitize and complete its life cycle no matter which Instar of B. tabaci (Strain B), [also identified as B. argentifolii (Bellows and Perring)], was provided for oviposition, but parasitoid development was significantly slower when 1st or 2nd Instar B. tabaci rather than 3rd or 4th Instars were parasitized. Host age influenced the day on which E. formosa nymphs hatching from eggs was first observed. Mean embryonic development was significantly longer when 1st (5.4 days) rather than 2nd, 3rd or 4th Instars (4.1, 3.4 and 3.5 days, respectively) were parasitized. The duration of the 1st Instar parasitoid and the pupa, but not the 2nd or 3rd Instar parasitoid, were also significantly greater when 1st Instars were parasitized than when older host Instars were parasitized. Interestingly, no matter which Instar was parasitized, the parasitoid did not molt to the 3rd Instar until the 4th Instar host had reached a depth of about 0.23 mm (Stage 4–5) and had initiated the nymphal-adult molt and adult development. Histological studies revealed that whitefly eye and wing structures had either disintegrated or were adult in nature whenever a 3rd Instar parasitoid was present. It appears, then, that the molt of the parasitoid to its last Instar is associated with the host whitefly's nymphal-adult molt. However, the initiation of the host's final molt, while a prerequisite for the parasitoid's 2nd–3rd Instar molt, did not necessarily trigger this molt. In contrast to its significant effect on various aspects of parasitoid development, host Instar did not significantly influence the mean size of the parasitoid larva, pupa, or adult. Larval and pupal length and adult head width were similar for all parasitoids, regardless of which host Instar was parasitized as was adult longevity. Adult parasitoid emergence was more synchronous when 2nd, 3rd and 4th Instars were parasitized than when 1st Instars were parasitized. Results are compared with those reported when the greenhouse whitefly, Trialeurodes vaporariorum, was parasitized by E. formosa, and provide possible explanations for why T. vaporariorum is a more suitable host than B. tabaci for E. formosa.
-
growth and development of encarsia formosa hymenoptera aphelinidae in the greenhouse whitefly trialeurodes vaporariorum homoptera aleyrodidae effect of host age
Archives of Insect Biochemistry and Physiology, 2002Co-Authors: Jing S Hu, Dale B Gelman, Michael B BlackburnAbstract:The tiny parasitoid wasp, Encarsia formosa, has been used successfully to control greenhouse whiteflies (GHWFs) in greenhouses in many countries throughout the world. Therefore, there has been considerable interest in developing methods for artificially rearing this wasp. However, little information is available concerning the regulation of its development including the host-parasitoid interactions that are required for the parasitoid to complete its life cycle. Here we confirm that parasitoid developmental rates differ significantly based upon the host Instar parasitized. Development was faster when 3rd and 4th Instar GHWFs were offered for parasitization than when 1st or 2nd Instars were used. Our results show that it is primarily the embryo and the first two parasitoid Instars that exhibit prolonged developmental times when 1st and 2nd Instar whiteflies are parasitized. Although percent emergence was not affected by host age at the time of parasitization, adult longevity as well as adult emergence pattern varied greatly depending upon the Instar parasitized. When 3rd and 4th Instar GHWFs were selected for oviposition, adult wasps lived significantly longer than when 1st or 2nd Instars were used; also, there was a sharp emergence peak on the 2nd day after emergence was first observed (reduced or absent when 1st or 2nd Instar GHWFs were parasitized) and the emergence period was reduced from between 8 and 11 days to 5 days. In general, the younger the host Instar parasitized, the less synchronous was parasitoid development. Previous reports that E. formosa will not molt to the 2nd Instar until the host has reached its 4th Instar were not confirmed. When 1st Instar host nymphs were parasitized, 2nd Instar parasitoids were detected in 3rd Instar hosts. Importantly, however, no matter which Instar was parasitized, the parasitoid never molted to its last Instar until the host had reached Stage 5 of its last Instar, a stage in which host pharate adult formation has been initiated. It appears, then, that a condition(s) associated with host pharate adult formation is required for the parasitoid’s final larval molt. Results reported here should facilitate the development of in vitro rearing systems for E. formosa. Arch. Insect Biochem. Physiol. 49:125‐136, 2002. Published 2002 Wiley-Liss, Inc.
-
timing and ecdysteroid regulation of the molt in last Instar greenhouse whiteflies trialeurodes vaporariorum
Journal of Insect Physiology, 2002Co-Authors: Dale B Gelman, Michael B Blackburn, Jing S HuAbstract:Abstract A system of markers has been devised to track the development of 3rd and 4th Instar/pharate adult greenhouse whiteflies. Instars were identified based on measurements of body width and body length. Depending upon the host plant, the product of the two measurements was exceptionally useful in distinguishing between Instars. Body depth was used to divide the 3rd Instar into eight stages and body depth and color and appearance of the developing adult eye were used to divide the 4th Instar/pharate adult into nine stages. Under conditions of L:D 16:8 and a temperature of 26±2°C, the body depth of 3rd Instars reared on greenbean increased from 0.025 (stage 1) to 0.2 mm (stage 8) and the Instar duration was approximately 3 days. The body depth of 4th Instars increased from approximately 0.1±0.02 (Stage 1) to 0.3±0.03 mm (Stage 5) and then remained constant or decreased slightly during adult development. Ecdysteroid titers peaked at approximately 120 fg/μg protein during Stages 3 through 6 of the 4th Instar. Based on an external examination of developing 4th Instars and the fluctuations in ecdysteroid titer, it appears that adult development is initiated in Stage 4 or 5 4th Instars. Results from histological studies support this view. In Stage 4 nymphs, a subtle change was observed in the corneagenous cells of the eye. However, most Stage 4 4th Instars possessed wing development characteristic of earlier, immature stages. In all Stage 5 insects, wing development had been initiated and the corneagenous cells had become quite distinct. In Stage 6 whiteflies, the wing buds were deeply folded and by Stage 7, spines were observed on the new cuticle, indicating that the adult cuticle was well-formed by this stage. Our study is the first to investigate the timing and regulation of the molt, to monitor ecdysteroid titers in precisely staged 4th Instar whiteflies and to examine the internal anatomical changes associated with metamorphosis in these tiny homopteran insects.
Michael B Blackburn - One of the best experts on this subject based on the ideXlab platform.
-
age specific interaction between the parasitoid encarsia formosa and its host the silverleaf whitefly bemisia tabaci strain b
Journal of Insect Science, 2003Co-Authors: Jing S Hu, Dale B Gelman, Michael B BlackburnAbstract:The effect of hostage, the Instar of Bemisia tabaci (Gennadius) parasitized, on the growth and development of Encarsia formosa (Gahan) was studied. E. formosa was able to parasitize and complete its life cycle no matter which Instar of B. tabaci (Strain B), [also identified as B. argentifolii (Bellows and Perring)], was provided for oviposition, but parasitoid development was significantly slower when 1st or 2nd Instar B. tabaci rather than 3rd or 4th Instars were parasitized. Host age influenced the day on which E. formosa nymphs hatching from eggs was first observed. Mean embryonic development was significantly longer when 1st (5.4 days) rather than 2nd, 3rd or 4th Instars (4.1, 3.4 and 3.5 days, respectively) were parasitized. The duration of the 1st Instar parasitoid and the pupa, but not the 2nd or 3rd Instar parasitoid, were also significantly greater when 1st Instars were parasitized than when older host Instars were parasitized. Interestingly, no matter which Instar was parasitized, the parasitoid did not molt to the 3rd Instar until the 4th Instar host had reached a depth of about 0.23 mm (Stage 4–5) and had initiated the nymphal-adult molt and adult development. Histological studies revealed that whitefly eye and wing structures had either disintegrated or were adult in nature whenever a 3rd Instar parasitoid was present. It appears, then, that the molt of the parasitoid to its last Instar is associated with the host whitefly's nymphal-adult molt. However, the initiation of the host's final molt, while a prerequisite for the parasitoid's 2nd–3rd Instar molt, did not necessarily trigger this molt. In contrast to its significant effect on various aspects of parasitoid development, host Instar did not significantly influence the mean size of the parasitoid larva, pupa, or adult. Larval and pupal length and adult head width were similar for all parasitoids, regardless of which host Instar was parasitized as was adult longevity. Adult parasitoid emergence was more synchronous when 2nd, 3rd and 4th Instars were parasitized than when 1st Instars were parasitized. Results are compared with those reported when the greenhouse whitefly, Trialeurodes vaporariorum, was parasitized by E. formosa, and provide possible explanations for why T. vaporariorum is a more suitable host than B. tabaci for E. formosa.
-
growth and development of encarsia formosa hymenoptera aphelinidae in the greenhouse whitefly trialeurodes vaporariorum homoptera aleyrodidae effect of host age
Archives of Insect Biochemistry and Physiology, 2002Co-Authors: Jing S Hu, Dale B Gelman, Michael B BlackburnAbstract:The tiny parasitoid wasp, Encarsia formosa, has been used successfully to control greenhouse whiteflies (GHWFs) in greenhouses in many countries throughout the world. Therefore, there has been considerable interest in developing methods for artificially rearing this wasp. However, little information is available concerning the regulation of its development including the host-parasitoid interactions that are required for the parasitoid to complete its life cycle. Here we confirm that parasitoid developmental rates differ significantly based upon the host Instar parasitized. Development was faster when 3rd and 4th Instar GHWFs were offered for parasitization than when 1st or 2nd Instars were used. Our results show that it is primarily the embryo and the first two parasitoid Instars that exhibit prolonged developmental times when 1st and 2nd Instar whiteflies are parasitized. Although percent emergence was not affected by host age at the time of parasitization, adult longevity as well as adult emergence pattern varied greatly depending upon the Instar parasitized. When 3rd and 4th Instar GHWFs were selected for oviposition, adult wasps lived significantly longer than when 1st or 2nd Instars were used; also, there was a sharp emergence peak on the 2nd day after emergence was first observed (reduced or absent when 1st or 2nd Instar GHWFs were parasitized) and the emergence period was reduced from between 8 and 11 days to 5 days. In general, the younger the host Instar parasitized, the less synchronous was parasitoid development. Previous reports that E. formosa will not molt to the 2nd Instar until the host has reached its 4th Instar were not confirmed. When 1st Instar host nymphs were parasitized, 2nd Instar parasitoids were detected in 3rd Instar hosts. Importantly, however, no matter which Instar was parasitized, the parasitoid never molted to its last Instar until the host had reached Stage 5 of its last Instar, a stage in which host pharate adult formation has been initiated. It appears, then, that a condition(s) associated with host pharate adult formation is required for the parasitoid’s final larval molt. Results reported here should facilitate the development of in vitro rearing systems for E. formosa. Arch. Insect Biochem. Physiol. 49:125‐136, 2002. Published 2002 Wiley-Liss, Inc.
-
timing and ecdysteroid regulation of the molt in last Instar greenhouse whiteflies trialeurodes vaporariorum
Journal of Insect Physiology, 2002Co-Authors: Dale B Gelman, Michael B Blackburn, Jing S HuAbstract:Abstract A system of markers has been devised to track the development of 3rd and 4th Instar/pharate adult greenhouse whiteflies. Instars were identified based on measurements of body width and body length. Depending upon the host plant, the product of the two measurements was exceptionally useful in distinguishing between Instars. Body depth was used to divide the 3rd Instar into eight stages and body depth and color and appearance of the developing adult eye were used to divide the 4th Instar/pharate adult into nine stages. Under conditions of L:D 16:8 and a temperature of 26±2°C, the body depth of 3rd Instars reared on greenbean increased from 0.025 (stage 1) to 0.2 mm (stage 8) and the Instar duration was approximately 3 days. The body depth of 4th Instars increased from approximately 0.1±0.02 (Stage 1) to 0.3±0.03 mm (Stage 5) and then remained constant or decreased slightly during adult development. Ecdysteroid titers peaked at approximately 120 fg/μg protein during Stages 3 through 6 of the 4th Instar. Based on an external examination of developing 4th Instars and the fluctuations in ecdysteroid titer, it appears that adult development is initiated in Stage 4 or 5 4th Instars. Results from histological studies support this view. In Stage 4 nymphs, a subtle change was observed in the corneagenous cells of the eye. However, most Stage 4 4th Instars possessed wing development characteristic of earlier, immature stages. In all Stage 5 insects, wing development had been initiated and the corneagenous cells had become quite distinct. In Stage 6 whiteflies, the wing buds were deeply folded and by Stage 7, spines were observed on the new cuticle, indicating that the adult cuticle was well-formed by this stage. Our study is the first to investigate the timing and regulation of the molt, to monitor ecdysteroid titers in precisely staged 4th Instar whiteflies and to examine the internal anatomical changes associated with metamorphosis in these tiny homopteran insects.
Shaoli Wang - One of the best experts on this subject based on the ideXlab platform.
-
the suitability of biotypes q and b of bemisia tabaci gennadius hemiptera aleyrodidae at different nymphal Instars as hosts for encarsia formosa gahan hymenoptera aphelinidae
PeerJ, 2016Co-Authors: Youjun Zhang, Qingjun Wu, Shaoli WangAbstract:Encarsia formosa Gahan (Hymenoptera: Aphelinidae) is a solitary endoparasitoid that is commercially reared and released for augmentative biological control of whiteflies infesting greenhouse crops. In most areas in China, the invasive and destructive whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) biotype Q has replaced B. tabaci biotype B and has become dominant between the two. A better understanding of the suitability of different nymphal Instars of B. tabaci biotypes Q and B as hosts for E. formosa is needed to improve the use of this parasitoid for biological control. Parasitism of the four nymphal Instars of B. tabaci biotypes Q and B by the commercial strain of E. formosa mass reared on Trialeurodes vaporariorum (Westwood) (Hemiptera: Aleyrodidae) was assessed in the laboratory. The results indicated that E. formosa parasitized and successfully developed on all Instars of both biotypes but performed best on the 3rd Instar of B. tabaci biotype B and on the 2nd, 3rd, and 4th Instars of B. tabaci biotype Q. The host-feeding rate of the adult parasitoid was generally higher on nymphal Instars of B. tabaci biotype Q than on the corresponding nymphal Instars of biotype B and was significantly higher on the 2nd and 3rd Instars. For both whitefly biotypes, the parasitoid’s immature developmental period was the longest on the 1st Instar, intermediate on the 2nd and 3rd Instars, and the shortest on the 4th Instar. The parasitoid emergence rate was significantly lower on the 1st Instar than on the other three Instars and did not significantly differ between B. tabaci biotype B and biotype Q. Offspring longevity was greater on the 3rd and 4th Instars than on the 1st Instar and did not significantly differ between the two B. tabaci biotypes. The results indicate that commercially-produced E. formosa can parasitize all Instars of B. tabaci biotypes B and Q, making this parasitoid a promising tool for the management of the two biotypes of B. tabaci present in China.
Joel G Kingsolver - One of the best experts on this subject based on the ideXlab platform.
-
variation in growth and Instar number in field and laboratory manduca sexta
Proceedings of The Royal Society B: Biological Sciences, 2007Co-Authors: Joel G KingsolverAbstract:The tobacco hornworm Manduca sexta has been an important model system for understanding physiological control of growth, development and metamorphosis of insects for more than half a century. Like all Manduca , M. sexta typically has five larval Instars, with developmental commitment to metamorphosis occurring early in the 5th (final) Instar. Here we show that M. sexta from a field population in North Carolina (USA) shows substantial intraspecific variation in the number of larval Instars when feeding on a modified artificial diet. Individuals with six Instars consistently exhibited slower growth rates during early larval development than individuals with five Instars. The frequency of individuals with six Instars decreased with increased rearing temperature. In contrast, M. sexta from a laboratory colony consistently had five Instars, and had more rapid larval growth rates than M. sexta from the field. We identify a threshold body size at the start of the 5th Instar that predicts whether an individual will have five (greater than 600 mg) or six Instars (less than 600 mg). Variation in field populations in Manduca provides an important resource for understanding physiological control, developmental plasticity and evolution of growth rate, body size and Instar number.
