Effect of the Exogenous Foliar Sprays of Micro-Doses of Fructose and Glucose, on Egg-Laying of Cydia Pomonella L. and its Oviposition Site Selection in Apple Orchard

A better understanding of the new concept of ‘sweet immunity’, represented by the use of sugars to reduce the susceptibility of plants to pests, would help implication of this knowledge within a new apple orchard protection strategy against Cydia pomonella. Behavioral and effect of two sugars, fructose (100 ppm), glucose (100 ppm), and chemical insecticide (deltamethrin) on egg-laying of C. pomonella were evaluated on two varieties (Golden delicious and Royal gala). The spraying of the two sugars, besides the insecticide, during the first, the third flight on the Golden delicious variety and the fourth flight on the Royal gala variety reduced significantly the number of eggs laid on leaves and fruits compared with control. Preferred oviposition sites for moths of all flights were leaves than fruits, whereas no eggs were found on branches. Between six studied sites, more eggs were laid on upper surface of the corymb leaves (51.67 %) in all flights of two varieties than fruit with 8.2 %, and none on the branches. Our results indicate that the responses of the codling moth egg-laying to foliar sprays of sugars are probably due to gustatory cues that reduce C. pomonella egg-laying, and they may have their importance in the signaling pathways of plant resistance to Lepidoptera

Use of sugars as alternative to chemical control: trials carried out on thrips associated with olive tree

Foliar spraying of infradoses of sugars (glucose, fructose or sucrose) induces plant resistance to pests that are particularly difficult to combat. These include thrips, which can cause flower abortion, stunting and deformation of olives, resulting in significant crop losses. Randomised block trials were conducted during three years (2017 to 2019), on two cultivars Chemlal and Sigoise, in an olive grove in Batna province (Algeria), with the aim of determining the most effective dose and type of sugar on thrips populations, and to evaluate the effectiveness of combining sugar with chemical treatment, as well as the possibility of reducing the dose of the latter. The results showed that sucrose at a concentration of 100 ppm was the most effective and that the efficacy of sucrose was higher than that of glucose and fructose, on both cultivars tested. The combination of sucrose with insecticide resulted in a synergistic effect and a higher efficacy gain than sucrose alone, and that the efficacy of the combination sucrose + insecticide at low dose D1 was identical to the combination sucrose + insecticide at recommended dose D2. It is therefore possible to reduce the chemical insecticide dose while maintaining good treatment efficacy for the control of these pests

Influence de métabolites présents à la surface des organes du pommier sur la ponte de carpocapse (Cydia pomonella (lepidoptera, tortricidae). Application à l'étude de la résistance du pommier au ravageur)

Des métabolites primaires, sucres solubles et polyols récupérés à la surface des organes du pommier ont un rôle sur la ponte de Cydia pomonella L. Parmi les six métabolites étudiés, le fructose et le sorbitol sont les composants nécessaires à l'activité des mélanges de 5 métabolites sur la ponte. Les observations du comportement de ponte de l'insecte sur l'arbre ont montré que la " décision " de ponte est rapide et ne dépasse pas 5 mn. Les concentrations élevées des 6 métabolites collectés à la surface des feuilles de Baugène entraînent une dissuasion de ponte et ils peuvent être à l'origine de la résistance de Baugène à la ponte de Cydia pomonella L. La résistance de l'hybride de pommier (X65-11) s'exprime très clairement vis-à-vis de la ponte. Elle est liée à des substances hydrosolubles de surface. La faible concentration des métabolites présents à la surface de X65-11 peuvent expliquer la résistance. Elle est différente de celle observée sur Baugène.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF

Formulation of the endophytic fungus Cladosporium oxysporum Berk. & M.A. Curtis, isolated from Euphorbia bupleuroides subsp. luteola, as a new biocontrol tool against the black bean aphid (Aphis fabae Scop.)

Two formulations containing culture filtrates and conidial suspensions of the endophytic fungus Cladosporium oxysporum Berk. & M.A. Curtis, isolated previously from stems of Euphorbia bupleuroides subsp. luteola (Kralik) Maire, were experimentally tested for their aphicid activity against the black bean aphid Aphis fabae Scop. found in Algeria. It was shown that invert emulsions are more effective against aphids, than using aqueous suspensions. This was especially true for formulations containing culture filtrates. The relatively insignificant mortalities obtained by formulations containing conidial suspensions indicated a low infectious potential towards the aphids. The proteolytic activity seemed to be more important than the chitinolytic activity of the fungus against the black bean aphid A. fabae

Sugars on leaf surfaces used as signals by the insect and the plant: implications in orchard protection against Cydia Pomonella L. (Lepidoptera, Tortricidae)

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Biological Pests Management for Sustainable Agriculture: Understanding the Influence of Cladosporium-Bioformulated Endophytic Fungi Application to Control Myzus persicae (Sulzer, 1776) in Potato (Solanum tuberosum L.)

The potato is a staple food crop worldwide and the need for this product has increased due to the burgeoning population. However, potato production is highly constrained by biotic stress interference, such as Myzus persicae Sulzer, which causes serious yield losses and thus minimizing production income. The current study aims to investigate the effect of different formulations prepared as an invert emulsion with different concentrations of fungal culture filtrates derived from three endophytic fungi (genus Cladosporium) against Myzus persicae. All formulations have demonstrated an aphicidal activity, which increases with the increasing concentration of fungal filtrates. Furthermore, it has been noted that chitinolytic activity recorded for 12 days is important in Cladosporium sp. BEL21 isolated from dwarf mistletoe Arceuthobium oxycedri. The study of demographic and embryonic parameters of aphids settled on potato plants previously treated with formulations revealed a significant reduction in the numbers of colonizing aphids and a relative increase in the numbers of winged adults, especially in plants treated with BEL21-derived emulsion. The pre-treatment of plants may interfere with and negatively influence embryonic development and early maturity of the embryo and thus affect the fertility of parthenogenetic aphids. BEL21-derived emulsion can ensure effective and an inexpensive control of M. persicae for potato spring cropping systems. The current results open real opportunities concerning the implementation of ecofriendly and potent potato protection systems