Cunaxa capreolus (Berlese, 1890)

Al-Azzazy, Mahmoud M. & Al-Rehiayani, Suloiman M., 2022, The soil mite Cunaxa capreolus (Acari: Cunaxidae) as a predator of the root-knot nematode, Meloidogyne incognita and the citrus Nematode, Tylenchulus semipenetrans: Implications for biological control, Acarologia 62 (1), pp. 174-185 : 177-180

Life-history of C. capreolus

Cunaxa capreolus was able to complete its life cycle, including egg, larva, protonymph, deutonymph, tritonymph and adult, when using egg masses and J 2 juveniles M of. incognita and J 2 juveniles T. semipenetrans as food resource. Life history of C. capreolus females pass through one larval and three nymphal stages before reaching adulthood, while male has one larval and two nymphal stages (protonymph and deutonymph). Each motile stage is proceeded by a quiescent one. The development times of immature stages of C. capreolus fed on EM of M. incognita , J 2 juveniles of M. incognita and J 2 juveniles of T. semipenetrans are presented in ( Table 1).

To mature from egg to adult, the females required 20.65, 15.60, 16.22 days on EM of M. incognita , J 2 juveniles of M. incognita and J 2 juveniles of T. semipenetrans , respectively

( Table 1). Total development time (from egg to adult) C of. capreolus was slightly faster in males than in females, which may ensure insemination of females soon after their emergence, a prerequisite for the onset of oviposition. The generation period and adult longevity lasted 25.92 and 22.72 days, 18.65 and 27.62 days and 19.33 and 26.44 days when C. capreolus fed on EM of M. incognita , J 2 juveniles of M. incognita and J 2 juveniles of T. semipenetrans , respectively ( Table 2). Female always deposited its eggs singly and at random in protected places.

Mating was necessary for oviposition in C. capreolus for the maximum reproduction of the females, as unmated females produced lower numbers of eggs compared to mated ones. The sex-ratio was calculated from the developmental experiment. The value females 80, 70

and 56%, Table 5 when predatory mite fed on J 2 juveniles of M. incognita , J 2 juveniles of T. semipenetrans and EM of M. incognita , respectively. The longest oviposition period was observed when C. capreolus fed on J 2 juveniles of M. incognita with 22.12 days. The life span period, likewise followed the same trend on the different prey.

Predation rate

Table 3 shows the numbers of J 2 juveniles of M. incognita , J 2 juveniles of T. semipenetrans and EM of M. incognita prey consumed by predatory females and males. Both immature female and male C. capreolus kept preying on J 2 juveniles of M. incognita and J 2 juveniles of T. semipenetrans within one week with no significant difference (F female = 1.61, F male = 1.56,

Mean duration (days) ± SE

Parameter Sex J 2 juveniles of J 2 juveniles of EM of

M. incognita T. semipenetrans M. incognita

Female 6.54±1.12 6.75± 0.73 8.81±0.96

Egg

Male 6.10± 0.96 6.22±0.82 8.11± 0.81

Female 3.41±0.24 3.53±0.41 4.75±0.29

Larva

Male 3.25±0.33 3.45±0.24 4.65±0.33

Female 2.90±0.24 3.04±0.22 4.00±0.24

Active

Male 2.81±0.20 2.98±0.30 4.00±0.30

Female 0.51±0.12 0.49±0.08 0.75±0.11

Quiescent

Male 0.44±0.10 0.47±0.11 0.65± 0.12

Female 2.30±0.28 2.40±0.33 3.44±0.24

Protonymph

Male 2.22±0.24 2.32±0.24 3.38±0.30

Female 1.89±0.18 1.95±0.20 3.03±0.21

Active

Male 1.82±0.20 1.90±0.18 2.98± 0.18

Female 0.41±0.10 0.45±0.08 0.41±0.08

Quiescent

Male 0.40±0.09 0.42±0.09 0.40±0.08

Female 2.14±0.20 2.17±0.13 2.20±0.24

Deutonymph

Male 2.11±0.24 2.10±0.31 2.07±0.28

Female 1.44±0.20 1.46±0.21 1.47±0.24

Active

Male 1.43±0.20 1.45±0.30 1.40±0.20

Female 0.70±0.12 0.71±0.11 0.73±0.12

Quiescent

Male 0.68±0.13 0.65±0.11 0.67±0.11

Tritonymph Female 1.30±0.20 1.37±0.24 1.45±0.22

Active Female 0.90±0.12 0.97±0.12 1.00±0.12

Quiescent Female 0.40±0.011 0.4±0.09 0.45±0.08

Female 15.60±0.98 a 16.22±1.09 a 20.65±1.08 b

Egg to adult

Male 13.68±1.05 a 14.09±1.02 a 18.21±1.11 b

The means followed by different letters in each row denote significant differences (F test, P<0.01).

df = 7, 11, P ˃ 0.05) among different days. The results showed that deutonymphs of predators consumed significantly more prey of the J 2 juveniles of M. incognita than of J 2 juveniles of T. semipenetrans (P = 0.001), while there was not a significant difference between the two prey in the protonymphal stage (P = 0.081). The average daily predation rate was 16.26, 13.86

and 0.38 prey for female adults (P = 0.178), and 13.63, 10.97 and 0.33 prey for male adults

(P = 0.220) on J 2 juveniles of M. incognita , J 2 juveniles of T. semipenetrans and EM of M. incognita , during the immature stages, respectively. The maximum rate was recorded during the oviposition period, with the female consuming an average of 70.18 J 2 juveniles of M. incognita , 55.75 J 2 juveniles of T. semipenetrans and 1.97 EM of M. incognita respectively.

Fecundity

Results presented in Table 4 showed that C. capreolus females fed on J 2 juveniles of M. incognita exhibited the highest fecundity while feeding on EM of M. incognita led to the lowest rate of fecundity and oviposition. The total numbers of deposited eggs by each female mite was significantly higher for female fed J 2 juveniles of M. incognita and followed by J 2 juveniles of T. semipenetrans and then EM of M. incognita , which occupied the last rank (F = 129.4 and

P <0.01). The first laid eggs were observed on th 18day (on J 2 juveniles of M. incognita ), 19 th

day (on J 2 juveniles of T. semipenetrans ) and 21 st day (on EM of M. incognita ) of life span.

The highest daily oviposition was 3.82, 3.11 and 1.02 eggs on J 2 juveniles of M. incognita , J 2 juveniles of T. semipenetrans and EM of M. incognita , respectively, which was observed in

27 th, 29th and 17 th days of total life span the females, respectively. The highest fecundity 44.56, and 39.33 eggs per female was recorded when C. capreolus fed on J 2 juveniles of M. incognita and J 2 juveniles of T. semipenetrans , respectively. While the minimum 9.29 eggs per female was observed when C. capreolus fed on EM of M. incognita . The post-oviposition period did not significantly differ among the three type of prey.

Mean duration (days) ± SE Parameter Sex J 2 juveniles of J 2 juveniles of (EM) of M. M. incognita T. semipenetrans incognita Pre-oviposition mean ± SD Female 3.05±0.24 3.11± 0.30 5.27±0.45 Generation mean ± SD Female 18.65±0.98 a 19.33±1.36 a 25.92± 1.18 b Oviposition mean ± SD Female 22.12±1.30 a 20.23±1.25 a 14.20±2.11 b Post-oviposition mean ± SD Female 2.45±0.24 3.10±0.22 3.25±0.24 Longevity Female 27.62±1.57 a 26.44±2.08 a 22.72±2.14 b mean ± SD Male 22.65±2.22 a 21.76±1.45 a 20.85±1.28 a Life span Female 43.22±2.13 a 42.66±2.64 a 43.37±2.78 a mean ± SD Male 36.33±1.98 a 35.85±2.93 a 39.06±2.55 a The means followed by different letters in each column denote significant differences (F test, P<.0.01).

Life table parameters

The effect of different prey species on life table parameters is shown in Table 5. A population of C. capreolus could multiply with 28.46, 24.39 and 9.38 net reproduction rate in a generation time of 25.28, 26.39 and 32.30 days when the predator fed on J 2 juveniles of M. incognita ,

J 2 juveniles of T. semipenetrans and EM of M. incognita , respectively. It was also found that under those conditions, feeding C of. capreolus on J 2 juveniles of M. incognita led to the highest intrinsic rate of population growth (r m = 0.185 females/female/day), while feeding on EM of M. incognita gave the lowest intrinsic rate of increase (r m = 0.085). It is worth noting that the sex ratio of the progeny of females fed on J 2 juveniles of M. incognita or J 2 juveniles of T. semipenetrans favoured females compared with EM of M. incognita . The highest rate of predator females was reported on the second-stage juveniles M of. incognita (24/30). Evidently, since females are in excess of males, a high and long-lasting fertility of the males is expected. However, it is always desired in mass rearing to obtain females with high fecundity.

Feeding behavior he soil predatory mite C. capreolus searched actively for nematodes around the experimental arena. Once a nematode was found, the predatory mite probed it with its first pair of legs and pedipalps, snatched it with its chelicerae, and devoured it. The chelicerae are the main killing and feeding organs. The first pair of legs are used to hold the prey during attack and feeding. After each predation, the predatory mite cleared its mouthpart with its first pair of legs, and immediately started the next search. Cunaxa capreolus took one minute to consume a nematode. Several specimens were observed feeding on the EM of root-knot nematodes M. incognita . The possibility that C. capreolus fed only on the gelatinous matrix that surrounds the nematode eggs cannot be excluded, though several mite specimens have been observed with the rostrum and the chelicerae penetrated into the gelatinous matrix and fed on the inside of eggs causing cavity hole in egg masses. No cannibalism behavior was observed C in. capreolus either in the presence or absence of prey nematodes. Cunaxa capreolus colonies with eggs were found in cracks on the roots of tomato plants.