The pest kill rate of thirteen natural enemies as aggregate evaluation criterion of their biological control potential of Tutaabsoluta

Joop C Van Lenteren,Antonio Biondi,Pascal Osa Aigbedion-Atalor,Francisco J Calvo,Johanna G Bajonero Cuervo,Peter W De Jong,Alberto Urbaneja,Maria B Riquelme Virgala,Flavio C Montes,Alberto Lanzoni,Eliana L Nieves,Lia Hemerik,Vanda H P Bueno,M Gabriela Luna,Norma E Sánchez,Giovanni Burgio,Silvia N López

doi:10.1038/s41598-021-90034-8

Abstract

Ecologists study how populations are regulated, while scientists studying biological pest control apply population regulation processes to reduce numbers of harmful organisms: an organism (a natural enemy) is used to reduce the population density of another organism (a pest). Finding an effective biological control agent among the tens to hundreds of natural enemies of a pest is a daunting task. Evaluation criteria help in a first selection to remove clearly ineffective or risky species from the list of candidates. Next, we propose to use an aggregate evaluation criterion, the pest kill rate, to compare the pest population reduction capacity of species not eliminated during the first selection. The pest kill rate is the average daily lifetime killing of the pest by the natural enemy under consideration. Pest kill rates of six species of predators and seven species of parasitoids of Tuta absoluta were calculated and compared. Several natural enemies had pest kill rates that were too low to be able to theoretically reduce the pest population below crop damaging densities. Other species showed a high pest reduction capacity and their potential for practical application can now be tested under commercial crop production conditions.

Highlights

Ecologists study how populations are regulated, while scientists studying biological pest control apply population regulation processes to reduce numbers of harmful organisms: an organism is used to reduce the population density of another organism
We propose a three step approach: (1) a quick scan procedure to separate clearly ineffective or hazardous species, from potentially promising candidates based on available information, (2) a phase during which the pest reduction capacity of the candidates selected in step 1 is determined, and (3) a final stage where the performance of the most promising candidates is tested under commercial tomato production conditions
As pest kill rate values are always higher than intrinsic rate of natural increase values, they provide better insight for estimating the potential of a natural enemy to control the pest

Summary

Introduction

Ecologists study how populations are regulated, while scientists studying biological pest control apply population regulation processes to reduce numbers of harmful organisms: an organism (a natural enemy) is used to reduce the population density of another organism (a pest). We previously published a list of 15 evaluation criteria, ranging from issues as “climatic adaptation to area where natural enemy will be used” to “complexity of importation and registration procedures”, for a quick scan of all organisms said to be associated with T. absoluta[16] Applying these criteria, 180 species may be removed from lists of potentially effective natural enemies of this pest mentioned in p ublications[8,16]. 180 species may be removed from lists of potentially effective natural enemies of this pest mentioned in p ublications[8,16] This is, among others, because either they (1) have not been shown to attack T. absoluta, (2) are very likely to cause unacceptable nontarget effects, (3) develop too slowly or not at all on the targeted prey, (4) are trapped by the glandular trichomes on tomato and die, (5) do not kill sufficient pest organisms, or (6) are too expensive to mass produce. The quick scan results in less than 20 species remaining on the list of potentially successful natural enemies[16]

Methods

Results

Discussion

Conclusion