Delayed development of the whitefly (Bemisia tabaci) and increased parasitism by Encarsia bimaculata in response to sublethal doses of piperonyl butoxide

Abstract

Effects of sublethal piperonyl butoxide (PB) on parasitization of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) by Encarsia bimaculata Heraty et Polaszek (Hymenoptera: Aphelinidae) were evaluated both in cage and greenhouse experiments. When first, second and third instar B. tabaci nymphs were treated with PB, all but the first instar were significantly prolonged. Data indicated that sublethal PB could improve E. bimaculata parasitism rates without influencing parasitoid eclosion rates. Prolonged development increased rates of parasitism by E. bimaculata, from 17.6% to 24.7% in cages, presumably by increasing the duration of host exposure. Sublethal PB combined with E. bimaculata as an integrated approach to control B. tabaci was evaluated using life table parameters under greenhouse conditions. Indices of population trend (I) calculated from life tables were estimated at 4.6 for B. tabaci exposed to PB and parasitoids compared to 14.1 with parasitoids alone and 23.5 in untreated controls. The results showed that after PB was sprayed and parasitoids introduced, development of B. tabaci was delayed and the peak of each stage was postponed. The older nymphal stage had highest mortality, primarily due to mortality caused by parasitism by E. bimaculata.

Activity of flonicamid on the sweet potato whitely Bemisia tabaci (Homoptera: Aleyrodidae) and its natural enemies

“…For DT 80 , an even greater delay in development was observed, ranging from 6.8 to 16 days, again depending on the insecticide exposure method. It is expected that delays in nymph development demonstrated in this study could affect whitefly population growth and parasitism levels in planta , in ways similar to those reported in previous studies …”

“…Chemically induced effects on whitefly development can slow the pest growth rate, as well as enhance the level of control by beneficials. It has been demonstrated that the parasitoids Encarsia bimaculata and Eretmocerus mundus (Hymenoptera: Aphelinidae) exploit the prolonged presence of appropriate B. tabaci nymphal stages after PB exposure, increasing parasitism levels . According to Qian et al , after exposure to sublethal doses of PB, the mean development time increased by 2.5–4.5 days, depending on the dose and the nymphal stage exposed.…”

“…It is expected that delays in nymph development demonstrated in this study could affect whitefly population growth and parasitism levels in planta, in ways similar to those reported in previous studies. 36,37 The side effects of flonicamid on beneficials were investigated, and it was demonstrated that flonicamid does not induce significant mortality to E. eremicus adults, while the pupae of the parasitoid, the adults of A. swirskii and the adults and nymphs of N. tenuis suffered intermediate mortality. Regarding the reduced survival of E. eremicus and A. swirskii, according to the IOBC guidelines for tier I testing (http://www.iobc-wprs.org/), as the arthropods were exposed to the insecticide on an inert surface, flonicamid can be classified as 'harmless' (<50% mortality).…”

Leaf Curl Disease: A Significant Constraint in the Production of Tomato in India

“…Biological control: biopesticides, a mass-produced agent manufactured from a living microorganism or a natural product, may offer a solution to disease control through introduction of predators and parasitoids of the vector. Biopesticides based on microbials such as Beauveria bassiana (effective on nymphs and adults) or Paecilomyces fumosoroseus, Green lacewings, ladybirds, minute pirate bugs, big-eyed bugs, and damsel bugs and Encarsia bimaculata [21] based on microbials such as Beauveria bassiana (effective on nymphs and adults) or Paecilomyces fumosoroseus. Green lacewings, ladybirds, minute pirate bugs, bigeyed bugs, damsel bugs and the parasitoid, Encarsia bimaculata [21].…”

“…Biopesticides based on microbials such as Beauveria bassiana (effective on nymphs and adults) or Paecilomyces fumosoroseus, Green lacewings, ladybirds, minute pirate bugs, big-eyed bugs, and damsel bugs and Encarsia bimaculata [21] based on microbials such as Beauveria bassiana (effective on nymphs and adults) or Paecilomyces fumosoroseus. Green lacewings, ladybirds, minute pirate bugs, bigeyed bugs, damsel bugs and the parasitoid, Encarsia bimaculata [21]. Encarsia formosa is one of the most efficient and studied bioagents of B. tabaci.…”