1Federal University of Alagoas, BR 104 Norte, Km 85, Rio Largo, AL. Brazil. Post Graduated Program in Plant Protection CECA/UFAL.
2Embrapa Coastal Tablelands, Federal University of Alagoas, BR 104 Norte, Km 85, Rio Largo, AL. Brazil.Post Graduated Program in Plant Protection CECA/UFAL.
3✉ Federal University of Alagoas, BR 104 Norte, Km 85, Rio Largo, AL. Brazil. Post Graduated Program in Plant Protection CECA/UFAL.
2022 - Volume: 62 Issue: 4 pages: 1210-1216
https://doi.org/10.24349/k2gx-swz0Tetranychidae spider mites include several ubiquitous pests of major crops around the globe, motivanting a large number of studies (Bolland et al. 1998; Migeon and Dorkeld 2010). Tetranychus bastosi Tuttle, Baker & Sales, 1977 (Acari: Tetranychidae) has been reported infesting 36 host plants, among ornamental, fruit, leguminous and wild plants, however its occurrence is still restricted to Brazil (Bastos et al. 1979; Moraes and Flechtmann 1980, 1981; Bolland et al. 1998; Santos et al. 2010; Mendonça et al. 2011; Cruz et al. 2012; Lofego et al. 2013; Rosado et al. 2014).
The first record of T. bastosi dates from 1977 on Morus rubra L. (Moraceae) (mulberry) in the state of Ceará, Brazil (Tuttle et al. 1977). Recently, T. bastosi has been observed causing 100% of yield losses on Ipomoea batatas L. (Convolvulacea) (Lima and Breda 2021). Also, new reports of the occurrence of T. bastosi on Psidium guajava L (Myrtaceae) were observed (Furtado et al. 2015 unpublished data).
The oviposition of T. bastosi on its hosts begins after the females have produced a significant amount of web, usually establishing colonies on the abaxial surface of the leaves, causing chlorotic spots and damaging plant growth (Santos et al. 2010; Lima et al. 2017; Barros 2013). Nevertheless, the biological performance of T. bastosi can be influenced by the host plant species, including intraspecific variations of different genotypes (Barros 2013; Lima et al. 2017). Overall, there are few studies regarding ecological aspects and the development of T. bastosi on different hosts of economic crops, as papaya, Carica papaya L. (Caricaceae) and common bean, Phaseolus vulgaris L. (Fabaceae) (Lima et al. 2017) in addition to Jatropha curcas L. (Euphorbiaceae) (Barros et al. 2013; Marçal et al. 2013) and cassava, Manihot esculenta Crantz (Euphorbiaceae) (Lima et al. 2017).
Thus, the objective of the present study was to evaluate the biological performance of T. bastosi on M. rubra, I. batatas and P. guajava to identify the potential for colonization and infestation of T. bastosi on diferente host species.
Stock rearing was maintained in jack bean plants Canavalia ensiformis* L. (Fabaceae), grown in plastic pots (2 L) containing a mixture of soil and Basaplant®\^ substrate (1:1). Healthy plants were infested through direct contact with leaves of plants infested with the mite. The stock of T. bastosi was maintained at the Laboratory of Agricultural and Forestry Entomology (LEAF/CECA/UFAL) with a temperature of 25±1 °C, 70±5% RH and 12h photophase.
To obtain eggs, 50 females of T. bastosi were removed from the stock breeding and placed in an experimental unit for oviposition. The experimental unit consisted of a Petri dish (Ø 9cm) containing a polyethylene foam (1 cm thick), moistened with distilled water. On the set, discs of leaves (Ø 5.0 cm) of the selected host species were placed, surrounded by strips of hydrophilic cotton. Eggs were observed every 12 hours to determine the viability and duration of egg phase. After hatching, the larvae were individualized in experimental units formed inside arenas, which consists of a plastic container (26 cm long, 16 cm wide and 4 cm high) containing inside a polyethylene foam rectangle (20 cm long, 11 cm wide and 1 cm high). In each arena, eight experimental units were formed. Each experimental unit consisted of a 5.0 cm (Ø) leaf disc of the selected host species, surrounded by strips of cotton wool moistened with distilled water, to prevent mites from escaping and maintain leaf turgidity. The mites were observed every 12h, determining the viability and duration of the larva, protonymph and deutonymph stages. After the emergence of adults, males and females were observed separately every 24 hours to determine longevity. Chrysalis phases were not observed. It was not possible to calculate the duration of immature phases considering males and females.
The experiment design was completely randomized, with three treatments consisting of the plant species M. rubra, I. batatas and P. guajava and 100 replications per treatment, where each experimental unit represented a replication. Data were analyzed using the Two-sex life table statistical package (Chi 1988) and the TWOSEX-MSChart program (Chi 2017).
Fertility life table parameters were obtained regarding the net reproduction rate (Ro), intrinsic growth rate (rm), duration of one generation (T), finite rate of increase (λ), stage-age specific survival (sxj), survival rate (lx) and specific fecundity (mx). Data were analyzed based on stage and age, using the Two-sex life table statistical package (Chi 1988) and the TWOSEX-MSChart program (Chi 2017).
Population standard errors were estimated using the bootstrap method. A number equivalent to 100,000 bootstraps was used to obtain stable estimates of standard error. The paired bootstrap test was used to compare statistical differences (Efron and Tibshirani 1993). The computer program TWOSEX-MSChart (Chi 2017) was used for the analysis and calculation of population parameters.
The viability of the immature stages of egg, larva and protonymph of T. bastosi was observed for the three hosts under study, however postembryonic development was completed only in M. rubra and I. batatas (Table 1). The incubation period of T. bastosi eggs showed a statistical difference between M. rubra (5.6 days) and the other plant species involved in the bioassay, I. batatas and P. guajava (4.0 days for both). The longest larval period was observed when T. bastosi was fed with P. guajava (5.7 days), differing from M. rubra and I. batatas (4.0 days). The protonymph stage lasted longer in P. guajava (3.0 days), differing from M. rubra (2.1 days) and I. batatas (1.6 days). The deutonymph stage was not observed on P. guajava, however, when compared to the other hosts, on M. rubra had a longer duration (2.3 days), statistically differing from I. batatas (1.5 days). When the development from egg to adult was evaluated, significant differences between the treatments M. rubra (12.8 days) and I. batatas (9.8 days) were observed. T. bastosi did not complete the cycle (egg-adult) when the host was P. guajava (Table 1).
The different host species significantly influenced the longevity of T. bastosi females (Table 2). The highest longevity of T. bastosi was observed in the host I. batatas (39.7 days), statistically differing from that of M. rubra (30.2 days). The pre-oviposition, oviposition and fecundity periods were not affected.
The larval, protonymph and detonymph stages of T. bastosi overlapped in the two hosts, however the adult stage of T. bastosi achieved a higher survival rate when the mite was fed on I. batatas (Figure 1).
The specific fertility curves (mx) fluctuated throughout the oviposition period, reaching values of 0.0 after 35 days for M. rubra and I. batatas (Figure 2). However, it is evident the expressive growth at the beginning of the oviposition period, around the 10th day, for both hosts. The maximum increase in specific fertility (mx) of T. bastosi occurs approximately on the 25th day for M. rubra, remaining oscillating and decreasing sharply from the 30th day onwards. For I. batatas, the maximum values of specific fertility (mx) were observed on the 15th day after the beginning of development, decreasing from this period onwards, as observed by the interaction between specific fertility (mx) and survival (lx) (Figure 2).
Regarding the parameters of the population life table of the mite T. bastosi the longest average duration of a generation (T) was observed on M. rubra (21.3 ± 0.48 days), which was different from I. batatas (17.9 ± 0.57 days) (P=0.00002) (Table 3). There were no significant differences for the net reproduction rate (Ro) for I. batatas (15.5 ± 3.6) and M. rubra (13.0 ± 2.7) (P=0.58). The highest intrinsic population growth capacity (rm) did not difeer among I. batatas (0.15 ± 0.1) and M. rubra (0.12 ± 0.01) (P=0,075), as well as the highest finite growth rate (λ) with values for I. batatas (1.16 ± 0.01) and M. rubra (1.12 ± 1.26) (P=0.075) (Table 3).
Tetranychus bastosi was able to survive, reproduce and complete its development on M. rubra and I. batatas, however, it could not complete its life cycle on P. guajava. For that, it is suggested that the development of T. bastosi on P. guajava could be inhibited by chemical compounds of the secondary metabolism or limiting morphological factors (presence of trichomes, hairs, viscous substances, etc.) in the immature phase. In this sense, it is possible that new reports of the ocuurence of T. bastosi on P. guajava may be at random, since this host was not a suitable for the red spider mite.
Mites have shown different parameters of development, fecundity and life table, according to the host species, being affected not only by the species but also by the nutritional quality of the host (Helle and Sabelis 1985; Razmjou et al. 2009; Najafabadi 2012). The fecundity of T. bastosi in I. batatas and M. rubra was 15.5 and 18.9 eggs/female, respectively. These values are considered high when compared to the average fecundity of T. bastosi in J. curcas around 10.4 eggs/female (Marçal et al. 2013) and 7.08 to 10.88 eggs/female (Barros 2013). Our results indicate a high reproductive performance of T. bastosi on the hosts, with possibility to achieve major pest status on field, as observerd previously for I. batatas (Lima and Breda 2021).
Lower longevity results than those of the present study were reported for females of T. bastosi on J. curcas, ranging from 9.16 to 13.88 days according to Barros (2013) and 16.0 days (Marçal et al. 2013). Females of T. bastosi on P. vulgaris and M. esculenta showed average longevity of 16.9 and 13.0 days, respectively (Lima et al. 2017). Information about the longevity period under controlled conditions may suggest a pre-availability and adaptation between T. bastosi and the host species.
For I. batatas, T. bastosi presented a sex ratio of 1, indicating that all eggs produced by females feeding on this host, origin only females. According to Young et al. (1986) female mites are able to control sex ratio according to several factors, including the oviposition environment and resource quality, however, further investigation is needed to fully understand this parameter.
The intrinsic rate of increase adequately summarizes the physiological qualities of a species and can also be assimilated to mites evaluating the ability to increase population (Golizadeh et al. 2017; Southwood and Henderson 2000). In the present study, high net development rates were observed for I. batatas and M. rubra, likewise, the innate capacity for population increase and the finite rate of population increase. Similar results of rm for T. bastosi were observed in J. curcas, P. vulgaris and M. esculenta (0.05, 0.18 and 0.12, respectively) and λ (1.02, 1.20 and 1.13 respectively) (Marçal et al. 2013; Pedro Neto et al. 2013; Lima et al. 2017). Thus, T. bastosi presents a significant biological performance on the hosts I. batatas and M. rubra.
The biological performance of T. bastosi varied among the hosts, revealing that I. batatas and M. rubra are adequated hosts to T. bastosi while P. guajava was not suitable for T. bastosi development. Studies towards differences of biological traits in T. bastosi are scarces but may indicate its potential to achieve major pest status in the field. However, futher studies are needed to fully understand the interactions among T. bastosi and its host plants.
To the Coordination for the Improvement of Higher Education Personnel - Brazil (CAPES) for financial support.