Selectivity assessment of chlorfenvinphos reevaluated by including physiological and behavioral effects on an important beneficial insect

Abstract

Selectivity is an important factor in identifying candidate pesticides to be used in crop protection since it characterizes chemicals that, while being effective against target pests, exert an acceptable impact on the other components of the environment. Extrapolated to an integrated pest management (IPM) context, selectivity implies that candidate pesticides may preserve the ability of beneficial insects to significantly control target pest populations. In the present study, we assess the physiological selectivity of the organophosphate chlorfenvinphos, used to protect cruciferous crops against the cabbage root fly, Delia radicum (Diptera: Anthomyiidae), by investigating both the lethal and sublethal effects exerted on its main parasitoid Trybliographa rapae (Hymenoptera: Figitidae). The comparison of the median lethal doses showed that T. rapae was at least seven times less sensitive than D. radicum to chlorfenvinphos. However, longevity of parasitoids surviving a sublethal dose was reduced by half. The potential fecundity of females was decreased by 9.6 to 22.8%. Chlorfenvinphos also induced important behavioral changes in both sexes and reduced the chances for parasitoids to mate by more than 70%. While most behavioral changes were reversible, effects on mating and on fecundity were not, thereby suggesting long-term effects on the reproduction of the parasitoid. These cumulative effects of chlorfenvinphos would have dramatic consequences on the efficacy of parasitoids contacting such doses of chlorfenvinphos in the field and therefore there is question about the intrinsic selectivity of this insecticide.

Biological Control May Fail on Pests Applied with High Doses of Insecticides: Effects of Sub-Lethal Concentrations of a Pyrethroid on the Host-Searching Behavior of the Aphid Parasitoid Aphidius colemani (Hymenoptera, Braconidae) on Aphid Pests

“…However, contrary to our results, some studies reported that pyrethroids disrupt locomotor function and parasitoids' physical perception [20,71,72]. For instance, pyrethroids insecticides at sub-lethal doses could disturb some behavior parameters, decreasing the attack rates of Trissolcus semistriatus (Hymenoptera, Platygastridae) [73], the walking speed in Trissolcus basalis (Hymenoptera, Platygastridae) [20], and the oviposition behavior of A. ervi parasitizing M. persicae on oilseed rape [52].…”

Acute Toxicities and Sublethal Effects of Some Conventional Insecticides on <I>Trichogramma chilonis</I> (Hymenoptera: Trichogrammatidae)

“…Bayram et al (2010) found a signiÞcant reduction in longevity of Telenomus busseolae (Gahan) fe- males after treatment with the LC 25 of either deltamethrin or cyßuthrin. Alix et al (2001) reported that after treatment with sublethal concentrations of chlorfenvinphos (300 ng of the insecticide results in 10% mortality in females and 30% in males), the longevity of males and females of Trybliographa rapae Westwood were signiÞcantly shortened. In our study, the LC 30 of chlorfenapyr had no effect on the longevity of T. chilonis females and is different from the result obtained from T. bactrae reported by Wang et al (2011).…”

Selectivity of deltamethrin doses on Palmistichus elaeisis (Hymenoptera: Eulophidae) parasitizing Tenebrio molitor (Coleoptera: Tenebrionidae)

“…Parasitoids spend a significant period of their lives searching for hosts and their ability to locate and parasitize them depends entirely on nerve transmissions, which can be affected by neurotoxic insecticides 14 . Parasitism efficiency is a key survival factor for parasitoid populations and even a small change in the reproductive potential of these natural enemies can limit their effectiveness and success in biological control 14 , 24 .…”