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Life-history parameters of Chrysoperla carnea s.l. fed on spontaneous plant species and insect honeydews: importance for conservation biological control

Publication . Villa, María; Santos, Sónia A.P.; Benhadi-Marín, Jacinto; Mexia, António; Bento, Albino; Pereira, J.A.

Chrysoperla carnea s.l. (Stephens) (Neuroptera: Chrysopidae) larvae are generalist predators feeding on many crop pests while adults feed on nonprey food. The knowledge about the nutritional suitability of non-prey food for adults in agroecosystems is crucial to establish conservation biological control strategies and is poorly known in olive groves, where C. carnea s.l. larvae prey on different pests. In this study, the effect of honeydew secreted by two hemipteran olive tree secondary pests and 11 plant species on the life-history parameters (survival, reproduction and development time) of C. carnea s.l. were analyzed. Insect pest honeydew from the olive agroecosystem and several plant species, blooming throughout the year, were found to improve C. carnea s.l. adult survival. Pollen consumption seems to be essential for reproduction. These findings are important for designing and implementing new conservation biological control approaches.

2016Journal article

Restricted access

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

Publication . Villa, María; Marrão, Rosalina; Mexia, António; Bento, Albino; Pereira, J.A.

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.

2017Journal article

Open access

Ground cover management affects parasitism of Prays oleae (Bernard)

Publication . Villa, María; Santos, Sónia A.P.; Mexia, António; Bento, Albino; Pereira, J.A.

Spontaneous ground covers comprise ecological infrastructures that may provide food, alternative hosts and shelter for parasitoids in olive groves, thus contributing to biological control of pests. This study investigated the effects of herbicide application, tillage, and conservation of spontaneous ground covers on parasitism of the anthophagous generation of the olive moth, Prays oleae (Bernard). The study was performed in northeast Portugal in 2011 and 2013 in 14 and 15 olive groves, respectively, with different management types. Generalized Estimating Equations (GEE) were used to analyze olive moth emergence, overall parasitism rate, relative abundance of parasitoid species, and total parasitismof olive moth larvae. Ageniaspis fuscicollis (Dalman) accounted for the majority of the parasitism, followed by Elasmus flabellatus (Fonscolombe). In both years, ground cover management type did not influence the emergence rate of P. oleae. However, overall parasitism rate, emergence of A. fuscicollis, and the number of A. fuscicollis emerging per olive moth larvae varied among years. In 2011, the latter response variables were significantly higher in groves with spontaneous ground cover than in those treated with herbicide, indicating a negative effect of herbicides on parasitoids. Although tilled groves obtained higher values for these variables in 2013, parasitism rates were generally very low. In sum, the management of ground covers seemed to influence the overall rate of P. oleae parasitism in some years, but longer-term experiments are needed to clarify this trend.

2016Journal article

Restricted access

Syrphids feed on multiple patches in heterogeneous agricultural landscapes during the autumn season, a period of food scarcity

Publication . Villa, María; Santos, Sónia A.P.; Marrão, Rosalina; Pinheiro, Lara Alina; López-Sáez, José António; Mexia, António; Bento, Albino; Pereira, J.A.

Many syrphid larvae are predators and have an important role as biological control agents of pests in agroecosystems. However, adults feed on non-prey resources such as pollen from flowers. Heterogeneous landscapes can provide syrphids with a great biodiversity of plants and ensure the existence of food resources. This is particularly important during periods of food scarcity, such as autumn, for syrphid species that spend those periods as adults. Nevertheless, the feeding habits of syrphid adults in resource-scarce agroecosystems are poorly known. In this study, the pollen consumption and preferences of Eupeodes corollae (Fabricius) and Episyrphus balteatus (De Geer) were analyzed in olive groves and surrounding herbaceous and woody patches in the autumns of 2012 and 2013 in northeastern Portugal. The guts were dissected, and the pollen types were identified and compared with the ground cover plants in the studied patches. Both species consumed and selected pollen types from herbaceous and woody vegetation that occurred in different patches, indicating that they flew between patches. These results highlight the importance of conserving heterogeneous agricultural landscapes to guarantee the existence of food resources for beneficial insects during periods of scarcity.

2016Journal article

Open access

Wild flower resources and insect honeydew are potential food items for Elasmus flabellatus

Publication . Villa, Maria; Santos, Sónia A.P.; Mexia, António; Bento, Albino; Pereira, J.A.

Adult parasitoids need non-host food such as nectar or honeydew for survival and reproduction. In a conservation biological control strategy, the knowledge about non-host feeding of parasitoid species is a key factor to successfully increase their action. The nutritional behavior of Elasmus flabellatus (Fonscolombe) (Hymenoptera: Eulophidae), a major parasitoid of the olive moth, Prays oleae (Bernard) (Lepidoptera: Praydidae), is completely unknown. Survival experiments were performed on two secondary olive pest honeydews and eight common flowering plant species in order to analyze their suitability as potential food sources for E. flabellatus females. Abdomen and gut dissections were carried out to verify the pollen consumption and the egg production. Floral architecture and insect morphology were described. Cox’s proportional hazard regression models were used to analyze the differences between parasitoid survivals. Honeydews secreted by Saissetia oleae (Olivier) (Hemiptera: Coccidae) and Euphyllura olivina (Costa) (Hemiptera: Psyllidae) resulted in the best performance followed by the flowers of Malva sylvestris L. (Malvaceae), Daucus carota L. (Apiaceae), and the Cichorioideae Tolpis barbata (L.) and Andryala integrifolia L. Theoretical flower resources accessibility were assessed and related with the survival results. E. flabellatus females did not consume pollen and did not produce eggs, suggesting that the species is synovigenic and requires additional foods for egg production. In sustainable pest control programs, this novel knowledge is a prom ising opportunity for improving suitable food resources of E. flabellatus in the field.

2017Journal article

Open access