Evidences of non‐additive effects of multiple parasitoids on Diatraea saccharalis Fabr. (Lep., Crambidae) populations in sugarcane fields in Brazil

Abstract

Biological control is a relatively benign method of pest control. However, considerable debate exists over whether multiple natural enemies often interact to produce additive or non‐additive effects on their prey or host populations. Based on the large data set stored in the São João and Barra sugarcane mills (state of São Paulo, Brazil) regarding the programme of biological control of Diatraea saccharalis using the parasitoids Cotesia flavipes and tachinid flies, in the present study the author investigated whether the parasitoids released into sugarcane fields interfered significantly with the rate of parasitized D. saccharalis hosts. The author also observed whether there was an additive effect of releasing C. flavipes and tachinids on the rate of parasitized hosts, and looked for evidence of possible negative effects of the use of multiple parasitoid species in this biological control programme. Results showed that C. flavipes and the tachinids were concomitantly released in the Barra Mill, but not in the São Jão Mill. Furthermore, in the Barra Mill there was evidence that the parasitoids interacted because the percentage of parasitism did not increase after the release of either C. flavipes or tachinids. In the São João Mill, when both parasitoid species were released out of synchrony, both the percentage of parasitism by C. flavipes as well as that of the tachinids increased. When large numbers of tachinids were released in the Barra Mill, they caused a significant lower percentage of parasitism imposed by C. flavipes. The implications of the results as evidence of non‐additive effects of C. flavipes plus tachinids on D. saccharalis populations are discussed.

Resistance to Diatraea (Lepidoptera: Crambidae) stem borers in sugarcane is independent of species

“…However, differences in magnitude were found between species due to biological characteristics and preferences (Echeverri-Rubiano et al 2022); this requires further study. In general, pest injury exhibited by sugarcane varieties under field conditions are related to levels of resistance or susceptibility (White 1993, Echeverri-Rubiano et al 2017); however, as it has been found that the magnitude of pest injury can be affected by environmental conditions, such as a species complex overlapping in time or spatial distribution (Rossi 2004, Smith 2005). In addition, it is also important to determine whether external lesions are entrance or emergence holes (Bessin et al 1990b).…”

(11Z)‐hexadec‐11‐enal enhances the attractiveness of Diatraea saccharalis main pheromone component in wind tunnel experiments

“…At present, D. saccharalis is controlled either by introduction of transgenic cultivars of sugarcane ( Arencibia et al., 1997; Setamou et al., 2002) or by biological control by artificially introduced exotic parasitoid Cotesia flavipes ( Baker et al., 1992). Both methods have undesirable side‐effects on non‐target organisms ( Setamou et al., 2002; Rossi , 2004; Rossi and Fowler , 2004a,b). Implementation of efficient pheromone‐based monitoring system for D. saccharalis might help to minimize the harm.…”