Nutritional indices of the cotton bollworm, Helicoverpa armigera, on 13 soybean varieties

Beneficial rhizobacteria inoculation on Ocimum basilicum reduces the growth performance and nutritional value of Spodoptera frugiperda

BACKGROUND

Plant growth-promoting rhizobacteria (PGPR) has a significant role in plant-insect interaction. However, the extent of their impact on insects is still not well understood. This investigation was designed to evaluate the role of inoculation with Bacillus amyloliquefaciens GB03 on sweet basil (Ocimum basilucum L.) in the development and nutritional parameters of Spodoptera frugiperda. In addition, the feeding preferences on inoculated and non-inoculated plants were assessed.

RESULTS

Spodoptera frugiperda larvae reared with inoculated sweet basil leaves had a strong negative effect on the development of the insect, resulting in lower larval and pupal weights, and a longer period for larval-adult development. Moreover, adult emergence was reduced, but the relative consumption rate (RCR) value was unaffected, thereby revealing no alteration of the palatability. Growth rate and nutritional indicators, such as the efficiency of conversion of ingested food (ECI) and the efficiency of conversion of digested food (ECD), were reduced in larvae reared from treated plants. In the choice test, larvae avoided feeding on inoculated leaves.

CONCLUSION

The higher occurrence of secondary metabolites in inoculated plants could have been the reason for the reduction of the plant nutritional rate and also for the food selection, since it has been previously reported that GB03 inoculated sweet basil increased the essential oil yield. Therefore, PGPR inoculation could be used as a growth promoter, making it a promising candidate for plant protection programs against insects in aromatic plant production. © 2021 Society of Chemical Industry.

Oviposition behavior of Helicoverpa armigera in soybean

ABSTRACT The objective of this study was to evaluate the oviposition behavior of Helicoverpa armigera confined in different adult pair density and growth stages of soybean plants, and the resistance of soybean genotypes to H. armigera in the category nonpreference for oviposition. The oviposition behavior of H. armigera was assessed using one, two, and four adult pairs per soybean plant of the cultivar BR-16 at the growth stages: vegetative V8 (eighth unrolled trifoliate leaf), reproductive R2 (full bloom) and reproductive R5.2 (beginning seed). The nonpreference for oviposition was evaluated using eight soybean genotypes and an oviposition preference index was calculated. The number of trichomes in leaflets was quantified for being correlated to H. armigera oviposition. One adult pair and soybean plants stage at pod-set affected and showed the best results oviposition preference on soybean plants. The genotypes M8230-RR and W711-RR presented resistance characteristics, and PI-227687 was preferred for oviposition. The trichome density positively affects the female oviposition behavior.

Effect of caffeic acid on feeding, α-amylase and protease activities and allatostatin-A content of Egyptian cotton leafworm, Spodoptera littoralis (Lepidoptera: Noctuidae)

Efficiency of caffeic acid (CA) on Spodoptera littoralis was investigated. CA was mixed with artificial diet, and feeding indices and allatostatin-A (AST-A) content of the midgut were measured 10 days later. α-Amylase and protease activities were evaluated for 10 days. CA significantly decreased feeding indices. Feeding on an artificial diet containing CA decreased protease and α-amylase activities in the midgut. The incubation of the dissected midgut with AST-A increased α-amylase and protease activities. The injection of AST-A into the hemolymph of larvae also increased protease and α-amylase activities. Competitive ELISA and immunohistochemistry results showed that starvation decreased the AST-A titer and AST-A immunoreactivity (AST-A-ir) cells in the midgut whereas refeeding increased it. Here, for the first time we showed that feeding on an artificial diet containing CA also caused the AST-A level to decrease in the midgut, which itself caused α-amylase and protease activities to decrease.

Landscape effects on the abundance and larval diet of the polyphagous pest Helicoverpa armigera in cotton fields in North Benin

BACKGROUND

The noctuid Helicoverpa armigera is one of the key cotton pests in the Old World. One possible pest regulation method may be the management of host crop in the landscapes. For polyphagous pests such as H. armigera, crop diversity and rotations can offer sequential and alternate resources that may enhance abundance. We explore the impact of landscape composition and host crop diversity on the abundance and natal host plant use of H. armigera in northern Benin.

RESULTS

Host plant diversity at the largest scale examined (500 m diameter) was positively correlated with H. armigera abundance. Host plant diversity and the cover of tomato crops were the most important variables in relation to high abundance of H. armigera. Host plant (cotton, maize, tomato, sorghum) proportions and C3 versus C4 plants did not consistently correlate positively with H. armigera abundance. Moth proportion derived from cotton-fed larvae was low, 15% in 2011 and 11% in 2012, and not significantly related to H. armigera abundance.

CONCLUSION

Cotton crop cover was not significantly related to H. armigera abundance and may be considered as a sink crop. Landscape composition and sequential availability of host plants should be considered as keys factors for further studies on H. armigera regulation. © 2015 Society of Chemical Industry.

Digestive Physiology and Nutritional Responses of Autographa gamma (L.) (Lepidoptera: Noctuidae) on Different Sugar Beet Cultivars

Digestive enzymatic activity and nutritional responses of Autographa gamma (L.) (Lepidoptera: Noctuidae), an important insect pest of sugar beet, on nine sugar beet cultivars (Peritra, Karolina, Paolita, Lenzier, Tiller, Ardabili, Persia, Rozier, and Dorothea) were studied. The highest proteolytic activity of fourth and fifth instar of A. gamma was in larvae fed on cultivar Persia. The highest amylolytic activity of fourth and fifth instar was observed in larvae fed on cultivars Rozier and Dorothea, respectively. The lowest proteolytic and amylolytic activities in fourth instar were observed on cultivar Tiller; whereas the lowest activities in fifth instar were detected on cultivars Karolina and Tiller, respectively. Larval weight in both larval instars (fourth and fifth) was the heaviest on cultivar Persia and the lightest on cultivar Karolina. Furthermore, weight gain of larvae was the highest on cultivar Persia and the lowest on cultivar Karolina. The results of this study suggest that cultivar Tiller was the most unsuitable host plant for feeding of A. gamma.

Nutritional performance and activity of some digestive enzymes of the cotton bollworm, Helicoverpa armigera, in response to seven tested bean cultivars

Nutritional performance and activity of some digestive enzymes (protease and α-amylase) of Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) in response to feeding on bean (Phaseolus vulgaris L. (Fabales: Fabaceae)) cultivars (Shokufa, Akhtar, Sayyad, Naz, Pak, Daneshkadeh, and Talash) were evaluated under laboratory conditions (25 ± 1°C, 65 ± 5% RH, and a 16:8 L:D photoperiod). The highest and lowest respective values of approximate digestibility were observed when fourth, fifth, and sixth larval instar H. armigera were fed red kidney bean Akhtar and white kidney bean Daneshkadeh. The efficiency of conversion of ingested and digested food was highest when H. armigera was fed red kidney beans Akhtar and Naz and lowest when they were fed white kidney bean Pak. The highest protease activity of fifth instars was observed when they were fed red kidney bean Naz, and the highest amylase activity of fifth instars was observed when they were fed red kidney bean Sayyad. Sixth instar larvae that fed on red kidney bean Sayyad showed the highest protease activity. Larvae reared on common bean Talash and white kidney bean Pak showed the highest amylase activity. Among bean cultivars tested, red kidney bean Sayyad was the most unsuitable host for feeding H. armigera.

Nutritional performance of the tomato fruit borer, Helicoverpa armigera, on different tomato cultivars

The development and cultivation of tomato cultivars that are resistant to the tomato fruit borer, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), are very limited in Iran and other parts of the world because of the lack of information about resistant tomato cultivars to minimize the use of insecticides. Therefore, the present study was carried out to identify alternative methods to chemical control. Nutritional performance of the larval stages (fourth, fifth, and sixth instars) of H. armigera on fruit of eight tomato cultivars, including SUN 6108 f1, Rio grande UG, Korral, Super strain B, CH falat, Hed rio grande, Cal.JN3, and Super crystal, was studied under laboratory conditions. Fourth instars reared on CH falat and SUN 6108 f1 respectively showed the highest and lowest values of approximate digestibility. The highest values of efficiency of conversion of ingested food and efficiency of conversion of digested food of fifth instars were on Super strain B. The relative consumption rate and relative growth rate values of the sixth instars were the highest on Korral. The highest and lowest values of consumption index of sixth instars were on Super strain B and Hed rio grande, respectively. The efficiency of conversion of ingested food and efficiency of conversion of digested food values of whole larval instars were the highest on Hed rio grande and lowest on Rio grande UG. The results of nutritional indices indicated that Rio grande UG is an unsuitable host for H. armigera.

Nutritional performance of the tomato fruit borer, Helicoverpa armigera, on different tomato cultivars

The development and cultivation of tomato cultivars that are resistant to the tomato fruit borer, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), are very limited in Iran and other parts of the world because of the lack of information about resistant tomato cultivars to minimize the use of insecticides. Therefore, the present study was carried out to identify alternative methods to chemical control. Nutritional performance of the larval stages (fourth, fifth, and sixth instars) of H. armigera on fruit of eight tomato cultivars, including SUN 6108 f1, Rio grande UG, Korral, Super strain B, CH falat, Hed rio grande, Cal.JN3, and Super crystal, was studied under laboratory conditions. Fourth instars reared on CH falat and SUN 6108 f1 respectively showed the highest and lowest values of approximate digestibility. The highest values of efficiency of conversion of ingested food and efficiency of conversion of digested food of fifth instars were on Super strain B. The relative consumption rate and relative growth rate values of the sixth instars were the highest on Korral. The highest and lowest values of consumption index of sixth instars were on Super strain B and Hed rio grande, respectively. The efficiency of conversion of ingested food and efficiency of conversion of digested food values of whole larval instars were the highest on Hed rio grande and lowest on Rio grande UG. The results of nutritional indices indicated that Rio grande UG is an unsuitable host for H. armigera.

Effect of Different Host Plants on Nutritional Indices of the Pod Borer, Helicoverpa armigera

Nutritional indices of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) on different host plants including chickpea (cultivars Arman, Hashem, Azad, and Binivich), common bean (cultivar Khomein), white kidney bean (cultivar Dehghan), red kidney bean (cultivar Goli), cowpea (cultivar Mashhad), tomato (cultivar Meshkin) and potato (cultivars Agria and Satina) were studied under laboratory conditions (25 ± 1 °C, 65 ± 5% RH, 16:8 L:D). Third instar larvae reared on potato Agria showed the highest efficiency of conversion of digested food (ECD) and efficiency of conversion of ingested food (ECI) (50.800 é 0.104% and 13.630 ± 0.016%, respectively). Approximate digestibility (AD) values of the fourth instar larvae were highest (92.651 ± 0.004%) and lowest (57.140 — 0.049%) on chickpea Azad and potato Agria, respectively. The fifth instar larvae fed on tomato Meshkin and white kidney bean Dehghan had the highest consumption index (CI) (3.717 ± 0.091) and relative consumption rate (RCR) (1.620 ± 0.074), respectively. Whole larval instars showed the highest ECI and ECD values on potatoes Satina (14.640 ± 0.014%) and Agria (21.380 ± 0.015%), respectively, and the lowest of both values on tomato Meshkin (ECI: 5.748 ± 0.002% and ECD: 7.341 ± 0.002%). The results of nutritional indices and the cluster analysis indicated that tomato Meshkin was an unsuitable host for feeding of H. armigera.