Demographic Expansion of the Predominant Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) Mitotypes Associated With the Cotton Leaf Curl Virus Epidemic in Pakistan

Genetic variability, community structure, and horizontal transfer of endosymbionts among three Asia II‐Bemisia tabaci mitotypes in Pakistan

“…This may be further explained by the minimal to no use of pesticides in the urban areas, which leaves the natural enemies relatively undisturbed, compared to agricultural areas where pesticide use during the cotton‐growing season is frequent to control the whitefly vector, with the caveat that its frequent use often leads to increases in whitefly population sizes (Anthony, Brown, Markham, & Ffrenchconstant, ; Bedford et al, ; Denholm, Cahill, Dennehy, & Horowitz, ; Horowitz & Ishaaya, ). This hypothesis is consistent with the observed small available sample sizes of the Asia II‐5 ( n = 3) and II‐7 ( n = 23) mitotypes (herein) and the results of previous studies reporting similarly low frequencies within Pakistan agroecosystems (Ahmed et al, ; Ashfaq et al, ; Masood et al, ; Paredes‐Montero et al, ).…”

“…Of interest, among the distribution patterns reported herein are that spread of Arsenophonus OTU‐002 and ‐003 (clades I‐1, ‐2, Figure ) in B. tabaci Asia II‐1 in Punjab province occurred coincidently with a round of genetic expansion in the population, followed by a genetic bottleneck and “recovery” evident by a gradual increase in diversity (Paredes‐Montero et al, ). In this scenario, genetic expansion might be explained by an upsurgence of Asia II‐1 that followed an increase in the number of insecticide applications that apparently lead to the development of insecticide resistance (Ahmad, Arif, Ahmad, & Denholm, ; Ahmad & Khan, ).…”

“…The assemblage consisting of P‐A predominated in whiteflies from the Sahiwal and Okara districts and were present in all three mitotypes at a frequency of 100% and 40%, respectively, and to lesser extents in all mitotypes from the other cotton‐growing districts of Punjab province (Figure ). In the Sindh province (Figure ), where the Asia II‐1 mitotype has recently undergone genetic and population expansions (Ashfaq et al, ; Paredes‐Montero et al, ), only the P‐A assemblage was detected. By comparison, the P‐A‐C assemblage occurred in both the Asia II‐1 and II‐5 mitotype in nine of the twelve districts, respectively, while the Asia II‐7 mitotype ( n = 23) harbored P‐A and P‐A‐ Hemipteriphilus (P‐A‐H) assemblages at a frequency of 61 and 39%, respectively.…”

“…In some instances, the composition and distribution of different bacterial assemblages in the context of biological (field) and evolutionary (phylogenetic) considerations are relatively informative. Based on endosymbiont composition, the phylogenetically confounded Asia II‐1 and Asia II‐7 “species” (Paredes‐Montero et al, ; Figure a) [“subclades”] were found to be more closely related to one another than to Asia II‐5. This conclusion is supported by the diversity estimates (mt COI ) and the number and type of shared OTUs (Figure a,b).…”

“…Environment‐associated niche adaptation of B. tabaci can be influenced by endosymbiont community composition, which in turn can alter the distribution of different vector mitotype–virus combinations. In Pakistan and India, studies have shown that B. tabaci mitotypes native to Asia that transmit cotton leaf curl disease‐begomoviruses (CLCuD; Bedford et al, ) have undergone geographic expansion and/or contraction, while at the same time the composition of the cotton leaf curl disease complex has been in flux, potentially corresponding to mitotype fluctuations (Ahmed et al, ; Ashfaq et al, ; Paredes‐Montero et al, ). Although many studies have characterized a number of different begomoviral species and strains associated with CLCuD, only a few have considered whitefly vector–endosymbiont relationships and their dynamics in an ecological context.…”