Since the circulating hemocytes are involved in the key physiological functions in insects, knowledge of these haemocytes is necessary to physiologists, toxicologists and biochemists. The present article was prepared to aim at updating the identification of hemocyte types and discussing different terminological and technical difficulties. It focused, also, on most important quantitative parameters of haemogram and discussed various factors influencing their values. In this review, we described, also the origin of circulating hemocytes during embryonic and the postembryonic development as well as intensively reviewed the categorization of hemocyte types in several insect species of different orders. The controversial terminology and technical difficulties of the hemocyte identification were discussed. It was emphasized that none of the individual methods was satisfactory for all cell types within a given insect but a combination of techniques should be used. The present chapter included only on the major quantitative parameters of haemogram, such as the total haemocyte count (THC), blood volume (BV) and mitotic index. It shed some light on the interrelationship between THC and BV. In addition, the endocrine control of THC and BV had been reported. The interrelationships between BV and osmotic pressure as well as between mitotic index and THC had been discussed. Heartbeat rate was reported to depend on different factors but the control mechanisms for the insect heart are not fully elucidated

https://eajbsa.journals.ekb.eg/article_25088_92b73437739b3a01a0a92cf1d964af38.pdf

Characterization of Qualitative and Quantitative Haemogram Parameters in Insects: Current Concepts and Future Prospects.

Serious damage of red palm weevil to date palm encourages its control by various measures. The present work was carried out to investigate the effects of some insecticides of different categories (Pyriproxyfen, Neemazal, and Spinetoram) on the activities of phosphatases (acid phosphatase; ACP, alkaline phosphatase; ALP) and transaminases (glutamic oxaloacetic transaminase; GOT, glutamine pyruvic transaminase; GPT) in both haemolymph and fat body of the red palm weevil Rhynchophorus ferrugineus 5th instar larvae. After 24-h treatment by sublethal concentrations LC50 and LC75: 1067.5, 2317.5 ppm (Pyriproxyfen), 14,600, 27,100 ppm (Neemazal), and 18.37, 88.60 ppm (Spinetoram). Depending on the present results, the enzyme activities in both haemolymph and fat body tissues had been altered. Spinetoram inhibited the activities of both phosphatase and transaminase enzymes in the two tissues with an exception for the transaminases in haemolymph tissue at LC50. On the other hand, Pyriproxyfen stimulated GOT activity in the two tissues but inhibited GPT activity with no exception. While, phosphatases were inhibited with few exception. Neemazal LC75 stimulated phosphatases in the two tissues while transaminases were fluctuated. Spinetoram exhibited the most potent compound for inhibiting the enzyme activities.

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Disturbance of phosphatase and transaminase activities in grubs of the red palm weevil Rhynchophorus ferrugineus (Coleoptera: Curculionidae) by certain insecticidal compounds

Paper description: Helicoverpa armigera is a global agricultural pest of serious concern. As repeated field application of chemical insecticides has caused negative impacts on the human health, non-targets and the environment, the effects of β-sitosterol, an eco-friendly bioactive phytocomponent , was investigated on H. armigera . larvae. Different concentrations of β-sitosterol were incorporated in the larval diet to assess the effects on larval growth and development, and midgut enzymes . Dietary β-sitosterol inhibited larval growth, affecting later instars and pupae more, pointing to cumulative effects of β-sitosterol. β-sitosterol can be used in Helicoverpa management programs. Abstract: Helicoverpa armigera is a global agricultural pest of serious concern. Continued use of chemical insecticides as control measures has raised grave health and environment concerns, necessitating a search for botanicals as safe alternatives. The current study investigates the effects of β-sitosterol, a bioactive phytocomponent in Thevetia neriifolia, on the growth and development, as well as on midgut enzymes of H. armigera . Dietary β-sitosterol produced dose-dependent systemic toxicity and growth inhibitory effects in H. armigera ; the most significant effects were obtained with 10 µg/mL dietary β-sitosterol . Higher prepupal and pupal mortality in comparison to larval mortality and a comparatively greater reduction in average weight gained by later instars point to cumulative effects of β-sitosterol. The delayed effects were ascertained by the 82.05%-57.89% reduction in adult emergence in comparison to 95.02% emergence in controls. Dose-dependent effects of β-sitosterol were observed as significantly decreased enzyme activities of alanine aminotransaminase (ALT), aspartate aminotransaminase (AST) and alkaline phosphatase (ALP) in the larval midgut. Suppression of enzyme activity was obtained in the order ALT>AST>ALP. Impaired activity of gut enzymes possibly lowered the energy reserves and affected nutrient transport through the gut epithelium, affecting the growth and development of H. armigera. Our study points to a promising use of β-sitosterol against H. armigera , although further examination and field studies are needed to ascertain its possible use in control programs. https://doi.org/10.2298/ABS200308021M Received: March 8, 2020; Revised: April 28, 2020; Accepted: May 8, 2020; Published online: May 12, 2020 How to cite this article: Mishra M, Sharma A, Dagar VS, Kumar S. Effects of β-sitosterol on growth, development and midgut enzymes of Helicoverpa armigera Hubner. Arch Biol Sci. 2020;72(2):271-8.

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Effects of β-sitosterol on growth, development and midgut enzymes of Helicoverpa armigera Hübner

Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) is one of the most economically devastating pests of agricultural crops around the world. In this study, the effects of hexaflumuron, lufenuron and chlorfluazuron were evaluated on some biological and physiological parameters of H. armigera larvae. Effects of the insecticides were assessed by adding different concentrations into the larval artificial diet. Dose-response bioassay showed LC50 values of 6.16, 61.31 and 31.75 mg ai/l for hexaflumuron, lufenuron and chlorfluazuron, respectively. Subsequently, sublethal effects of hexaflumuron, lufenuron and chlorfluazuron were assessed using LC10 concentration to find their possible effects on the biological and physiological parameters of H. armigera larvae. The results showed significant changes in biological parameters, where the mean larval and pupal weights significantly decreased following treatment, while their developmental time significantly increased compared to the control. Meanwhile, the longevity of adult males and females, number of laid eggs per female, and rate of egg hatch were significantly reduced due to the insecticide treatments. The activities of alanine aminotransferase, aspartate aminotransferase, γ-glutamyl transferase, acid- and alkaline phosphatases, lactate dehydrogenase, glutathione S-transferase were increased following the treatments. Sublethal exposure of the insecticides on larvae led to lower amounts of glycogen, triglyceride and protein compared to the control.

Effects of hexaflumuron, lufenuron and chlorfluazuron on certain biological and physiological parameters of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae)

The effect of six plant essential oils against three stored grain insects, Sitophilus oryzae, Rhizopertha dominica andTribolium castaneum were studied under laboratory conditions. The tested oils are namely, fennel oil (Foeniculumvulgare), caraway oil (Carum carvi), cinnamon oil (Cinnamomum verum), citronella oil (Cymbopogon winterianus),nutmeg oil (Myristica fragrans) and black cumin oil (Nigella sativa). The result showed that increasing of the oilconcentration and exposure times significantly increased the mortality percentage.Generally, the toxicity of essential oils at all tested concentrations increased with the increasing of exposure time. So,the results indicated that toxicity of all tested essential oil against the three stored grain insects at the high concentrationwas recorded high mortality faster than low concentration.The tested essential oils significantly decreased the different haemocyte counts in tested insects, cinnamon oilmarkedly increased the haemocyte surface areas in the tested insects especially the surface area of oenocytoides in T.castaneum.The recorded results indicate that the essential oils of fennel, caraway, cinnamon and citronella could be applicable tothe management of S. oryzae, R. dominica and T. castaneum adults.

https://alexja.journals.ekb.eg/article_5793_1a4ed08c5124d722477083f68f4aecb4.pdf

Hossam El-Din M. Zahran

Papers

Biochemical and Physiological Effects of Lufenuron and Chlorfluazuron on Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae)