Phytoparasitica最新文献

Maize (Zea mays L.) is sown for fodder and silage in the spring season (February-June) by commercial dairy farmers in northwestern India and its sowing time varies under different crop rotations. A 2-year field study was conducted during 2020-21 and 2021-22 to study the weed flora and quantification of atrazine residue in green fodder and silage of spring maize sown in different maize-based rotations. Spring maize was grown as fodder for silage making in three crop rotations {maize – oat (Avena sativa L.) or toria (Brassica rapa ssp. oleifera) or rapeseed (Brassica napus L.) – spring maize}. Winter season weeds namely Chenopodium album L., Coronopus didymus (L.) Sm. and Rumex dentatus L. and spring season weeds namely Oenothera laciniata Hill and Gnaphalium purpureum L. were not reported in spring maize grown in maize-rapeseed-spring maize rotation. During 2022, growth of Digitaria sanguinalis (L.) Scop. and Cyperus rotundus L. was favoured in maize-rapeseed-spring maize rotation than in other two crop rotations. After 60 days of application, atrazine residue level of 0.01 mg kg⁻¹ was found in green fodder of spring maize grown in maize-oat-spring maize and maize-toria-spring maize rotations, while it was below limit of quantification (LOQ < 0.01 mg kg⁻¹) in green fodder of spring maize grown in maize-rapeseed-spring maize. Atrazine residue in spring maize fodder at harvest and in silage is below LOQ in three crop rotations. Thus, atrazine can be safely used in spring maize grown for silage making.

Brachycaudus helichrysi, also known as peach leaf curl aphid is a destructive pest that poses a grave threat to peach and nectarine cultivation. The existing management practices primarily rely on applying synthetic insecticides whose indiscriminate use has led to a myriad of problems. To address these issues, biological control agents like ladybirds (Oenopia sauzeti) have emerged as an environment friendly alternative strategy. Till now, there has been a dearth of precise information on the biology, fecundity as well as functional response of O. sauzeti against B. helichrysi. The present study assesses the demographic parameters and functional response of O. sauzeti preying on B. helichrysi under laboratory conditions at 25 ± 1 °C, 70 ± 5% RH and 12 L: 12 D photoperiod and aims to provide valuable insights for its potential use in pest management. The findings showed a net reproductive rate, gross reproductive rate, true generation time and intrinsic rate of increase of 59.92 females/predator, 76.95 offspring per individual, 33.36 days and 0.12, respectively. The results showed that O. sauzeti exhibited a type II functional response. The highest predation rate was observed in the adults (78.21), which was significantly different from 1^st, 2^nd, 3^rd and 4^th larval instars (19.68, 32.30, 36.49 and 51.64, respectively) of the coccinellid. This research provides essential information for using O. sauzeti as a biocontrol agent for B. helichrysi and would prove beneficial to sustainable pest management strategies in stone fruit cultivation.

Cotton mealybug, Phenacoccus solenopsis Tinsley (Coccomorpha: Pseudococcidae) is an invasive sucking pest native to North America, has spread to Central America, and various Asian countries where it extensively damaging several agri-horticultural crops. Following invasion of this pest, several native as well as exotic natural enemies have been discovered and reported viz., Aenasius arizonensis (Girault), Allotropa phenacocca, Cheiloneurus sp., Bothriothorax sp., Marietta sp., and Chartocerus sp. etc., among which, A. phenacocca is one of such primary solitary endoparasitoid of P. solenopsis reported from China (Chen et al., Oriental Insects, 45(2–3), 275–280, 2011). However, in the present study we report a morphologically similar species of Allotropa near phenacocca from India. The molecular analysis of the COI gene of this morphovariant (Accession number- OQ451869) showed 89.81% similarity with the closely allied A. phenacocca (Accession number- MT775809) from China. Morphometric and biological parameters of parasitoid revealed that the adult females were black in color and ranged in length from 0.74 to 1.17 mm. Antenna of female was 9 segmented; A7 and A8 extended and its average length was 0.45 ± 0.012 mm. Mesosoma is reticulate and densely setose. Adult males were also black in colour and measured 0.70 to 0.95 mm in length. During its lifespan, the female parasitized 26 to 113 mealybugs with a mean of 72 ± 8.51 and the average developmental period was 26.54 ± 0.67 days. This report document the newfound parasitoid of P. solenopsis, highlighting its potential for efficiently controlling cotton mealybug populations. Notably, this parasitoid exhibits a preference for targeting the early stages of mealybugs, thereby impeding their progression into the most destructive stages, namely the third instar and adult forms.