Location: Fruit and Tree Nut ResearchTitle: Impact of a biorational pesticide on the pecan aphid complex and its natural enemies
|MIZELL, RUSSELL - University Of Florida
|WELLS, LENNY - University Of Georgia
|Shapiro Ilan, David
Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/9/2021
Publication Date: 7/22/2021
Citation: Hofman, C.O., Cottrell, T.E., Bock, C.H., Mizell, R.F., Wells, L., Shapiro Ilan, D.I. 2021. Impact of a biorational pesticide on the pecan aphid complex and its natural enemies. Biological Control. 161/104709. https://doi.org/10.1016/j.biocontrol.2021.104709.
Interpretive Summary: Biorational pesticides, by definition are pesticides that are considered to be relatively safe for the environment and to people. One of these biorational pesticides that we are studying is called Grandevo and it was developed on the byproducts of a bacteria that has insecticidal properties. Previous studies showed that Grandevo is able to kill a major pest of pecans, the pecan weevil, but no one has tested if field applications of Grandevo that are targeted against the pecan weevil can also kill other pests of pecans. Specifically, we looked at the impact of Grandevo on the pecan aphid complex and on natural enemies of aphids. We found that Grandevo can suppress aphid populations but not as well as a standard chemical regime. Moreover, we found that trees that received Grandevo sprays can have more aphids’ natural enemies than trees receiving chemical insecticides. Meaning that Grandevo can be used in an integrated pest management approach to kill multiple insect pest species while preserving beneficial natural enemies in pecan orchards.
Technical Abstract: The pecan weevil, Curculio caryae (Horn) (Coleoptera: Curculionidae), and the pecan aphid (Hemiptera: Aphididae) complex: black pecan aphid, Melanocallis caryaefoliae (Davis), blackmargined aphid, Monellia caryella (Fitch), and yellow pecan aphid, Monelliopsis pecanis Bissell are major pests of pecan production. Management is primarily based on chemical insecticides and alternative control methods need to be explored. Prior field tests showed that the microbial insecticide Grandevo® (based on Chromobacterium subtsugae) can suppress C. caryae at similar rates to insecticides, and a laboratory test showed that Grandevo is toxic to M. caryaefoliae. However, it was unknown if Grandevo applications targeted towards C. caryae also impact the pecan aphid complex and aphid natural enemies. Hence, we initiated a field study to determine the impact of two rates of Grandevo (2.24 and 3.36 kg/ha) on aphid, Coccinellidae (Coleoptera) and Chrysopidae (Neuroptera) populations. Both Grandevo rates suppressed M. caryaefoliae in comparison to the negative control. In 2016, only Grandevo at 3.36 kg/ha suppressed M. caryella and M. pecanis combined but in 2017 both rates suppressed M. caryella and M. pecanis, although the higher rate performed better. Overall, chemical control was more effective against aphids in comparison to Grandevo. In 2016, the Grandevo treatments had the most abundant populations of natural enemies while the chemical control had the least. In 2017, only Grandevo at 2.24 kg/ha had more natural enemies than the chemical control. These findings suggest that a microbial insecticide can manage multiple insect pests while preserving the natural enemy community.