Spodoptera littoralis (Boisd) is globally recognized as a destructive polyphagous insect pest of various crops in the world. It is commonly managed by chemical pesticides, which can cause deleterious effects such as environmental pollution, toxicity to non-target organisms and the emergence of secondary pests. Hence, investigations into alternative pest control strategies such as the use of resistant host plant cultivar against S. littoralis is important. This study aimed to explore the nutritional performance of S. littoralis larvae in dependence on total anthocyanin, flavonoid, and phenol levels across 11 bean cultivars (Phaseolus and Vigna spp.) under laboratory conditions. The results revealed that the Mashhad cultivar accumulated the highest amount of total phenols (13.59 mg ml−1), whereas Yaghout and Arabi cultivars posed the lowest total phenols contents (1.80 and 1.90 mg ml−1, respectively). Across larval instars (third to sixth), the highest consumption index and relative consumption rate were recorded on the Mashhad cultivar. The lowest values of efficiency of conversion of ingested food and the efficiency of conversion of digested food of total larval instars were detected in the larvae which were reared on the Mashhad cultivar. Likewise, the lowest value of the index of plant quality (IPQ) was obtained in the Mashhad cultivar; however, IPQ was figured out at the highest level in the Arabi cultivar. Our findings show that the differential accumulation of secondary metabolites would change the nutritional quality of plants for S. littoralis. Based on the findings, the Mashhad cultivar may serve as a candidate for either integrated pest management or breeding programs aiming at controlling this pest.
Spodoptera littoralis (Boisd) is a worldwide pest of economic importance for agricultural crops. We investigated nutritional efficiency and digestive enzyme activity of S. littoralis on various mung bean cultivars, including Parto, Simite1, Simite2, VC6173A, VC3960, VC6368 and VC6371. Furthermore, various biochemical traits of mung bean cultivars, including protein, starch, total phenolic and flavonoid content, were measured to investigate their relationships with nutritional physiology of S. littoralis. The nutritional indices, as well as proteolytic and amylolytic activities of S. littoralis were significantly affected by feeding of the pest on various mung bean cultivars. Larvae reared on VC6371 exhibited the highest efficiency of conversion of digested food, while the lowest was recorded in those fed on Simite2. Spodoptera littoralis larvae fed on the Simite1 cultivar exhibited the lowest relative growth rate, while those reared on Simite2 were characterized by the lowest efficiency of conversion of ingested food. The highest proteolytic activity of sixth‐instar larvae was on VC6371, while the lowest activity was on VC3960, Simite1 and Simite2 cultivars. Amylolytic activity was the lowest in those larvae fed on VC6368 and VC6371 cultivars, while the highest activity occurred in larvae reared on Simite2. Significant variation in phytochemical contents was quantified among tested mung bean cultivars. Moreover, significant correlations were found between the nutritional indices and digestive enzyme activities of S. littoralis with biochemical properties of the cultivars. Our results suggest that VC6371 is a suitable cultivar for S littoralis, while Simite2 and Simite1 cultivars are less suitable and may be useful selections to minimize damage caused by this pest.
Tetranychus turkestani is a serious pest of cotton, corn, vegetables, fruit trees and forests in Xinjiang. All life stages of T. turkestani were observed using both light and scanning electron microscope. The egg is smooth and spherical. The eupathidial spinnerets of larva and protonymph are different from that of the deutonymph and adult in shape. The spinneret of adult female is obviously thicker and larger than that in male. The palpfemoral seta of adult male is a short, stout, spine-like process. T. turkestani has fourteen pairs of dorsal setae. The number of ventral setae increases regularly in number in each molt. The leg chaetotaxy has a great change from larva to deutonymph.
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