Potential of Cucurbitacin B and Epigallocatechin Gallate as Biopesticides against Aphis gossypii

Abstract

Aphis gossypii (Glover) is distributed worldwide and causes substantial economic and ecological problems owing to its rapid reproduction and high pesticide resistance. Plant-derived cucurbitacin B (CucB) and epigallocatechin gallate (EGCG) are known to have insecticidal and repellent activities. However, their insecticidal activity on cotton- and cucurbit-specialized aphids (CO and CU), the two important host biotypes of A. gossypii, remains to be investigated. In the present study, we characterized, for the first time, the effects of these two plant extracts on the two host biotypes of A. gossypii. CucB and EGCG significantly reduced the A. gossypii population-level fitness and affected their ability to adapt to nonhost plants. Activities of important detoxification enzymes were also altered, indicating that pesticide resistance is weakened in the tested aphids. Our results suggest that CucB and EGCG have unique properties and may be developed as potential biopesticides for aphid control in agriculture.

Keywords: detoxification enzymes; nonhost adaptation; plant-derived pesticide; population-level fitness; toxicity.

Figure 1

Survival rate (l_x) of Aphis gossypii exposed to Cucurbitacin B (CucB) and epigallocatechin gallate (EGCG). (a): CUS exposed to CucB; (b): COS exposed to CucB; (c): CUS exposed to EGCG; (d): COS exposed to EGCG.

Figure 2

Survival rate (l_x) of Aphis gossypii on nonhost plants when the maternal generation is exposed to CucB and EGCG. (a): CUS exposed to CucB; (b): COS exposed to CucB; (c): CUS exposed to EGCG; (d): COS exposed to EGCG.

Figure 3

Effect of CucB on enzyme activity in Aphis gossypii in different time intervals. (a): AChE activity of CUS; (b): AChE activity of COS; (c): CarE activity of CUS; (d): CarE activity of COS; (e): ACP activity of CUS; (f): ACP activity of COS; (g): P450 activity of CUS; (h): P450 activity of COS; (i): GST activity of CUS; (j): GST activity of COS. Bars labelled with different lowercase letters indicate significant differences between concentrations in same time interval, bars labelled with different capital letters indicate significant differences between time intervals in in same concentration (p < 0.05).

Figure 4

(a): AChE activity of CUS; (b): AChE activity of COS; (c): CarE activity of CUS; (d): CarE activity of COS; (e): ACP activity of CUS; (f): ACP activity of COS; (g): P450 activity of CUS; (h): P450 activity of COS; (i): GST activity of CUS; (j): GST activity of COS. Effect of EGCG on enzyme activity in Aphis gossypii in different time intervals.Bars labelled with different lowercase letters indicate significant differences between concentrations in same time interval, bars labelled with different capital letters indicate significant differences between time intervals in in same concentration (p < 0.05).