Are wild flowers and insect honeydews potential food resources for adults of the olive moth, Prays oleae?

Abstract

The use of non-crop resources by natural enemies and their potentialities to enhance their effectiveness as pest control agents is increasing as a method for conservation biological control. Nevertheless, the effect of consumption of non-crop resources by pests has been generally overlooked being this knowledge crucial to favor natural enemies but not pests. In the present work, insect honeydews and flowers suitability as food resources for the olive tree key-pest Prays oleae were analyzed under laboratory conditions. The selected honeydews were excreted by Saissetia oleae and Euphyllura olivina, two olive pests, and the selected plants were seven abundant species in the olive grove agroecosystem that bloom simultaneously with the flight period of the anthophagous generation of P. oleae. In this work, some of these resources were identified as potential food sources for P. oleae. Despite the general findings, which indicate that honeydews have less nutritional value for insects than nectar, P. oleae reached the best survival and reproduction performance with the insects' honeydews. Several of the tested flowers were identified as potential food resources for P. oleae, being Malva sylvestris the one that originated the best performance. Moreover, our results suggest that P. oleae females are synovigenic and emerge with nutritional reserves for reproduction. We highly recommend accomplishing further research before establishing these resources in biological control methods in order to confirm their effect on pests in fields.

Effect of parasitoid competition, ant exclusion and carbohydrate sources on biological control fo Saissetia oleae on olive trees = Efecto de la competición de los parasitoides, la exclusión de hormigas y las fuentes de hidratos de carbono en el control biológico de Saissetia oleae en olivos

“…To our knowledge, this is the first study that demonstrates that a honeydew type is a superior source for parasitoids when compared to nectar or the positive control (honey at 10% herein). Two other works support our results and, moreover, suggest that not only S. oleae parasitoids can benefit from this rich honeydew but also parasitoids of other olive pests as well as the own olive pests (Wang et al 2011, Villa et al 2016. Wang et al (2011), found that S.…”

“…Braconidae) as the positive control. Villa et al (2016) found that the olive moth Prays oleae Bernard (Lepidopteta: Praydidae) reaches the highest survival when fed on this honeydew compared with other honeydew and flowers. These latter results are in concordance with Wäckers et al (2008) and , which showed that parasitoids of non-honeydew-producing insects can also benefit from honeydew.…”

“…During the last years, we have worked to identify the optimal forms of botanical diversity to improve the biological control of different olive pests (Pinheiro et al 2013, Villa et al 2016. These studies have and Dittrichia viscosa.…”

“…Apart from nectar and artificial sugars, the presence of the own scale as well as the psyllid Euphyllura olivina (Costa) (Hemiptera: Psyllidae) in olives might mitigate the lack of nectar as both species excrete large amount of honeydew. Generally, honeydew has been considered a poorer sugar source when compared to nectar (Wäckers et al 2008, Tena et al 2016 but honeydew excreted by S. oleae increases significantly the longevity of the hymenopteran egg predator S. caerulea (Wang et al 2011) and the month P. oleae (Villa et al 2016). Therefore, S. oleae parasitoids might…”

Pollen feeding habits of Chrysoperla carnea s.l. adults in the olive grove agroecosystem

“…Further studies should also address the nutritional composition of the most abundant pollen types found in C. carnea guts. Finally, few studies have addressed the effect of olive grove agroecosystem vegetation on olive tree pests (Villa et al, 2016c). Further studies should address how changes in flowering plant biodiversity affect pest control accomplished by C. carnea.…”