African and Mediterranean Agricultural Journal - Al Awamia (Jan 2023)
Mineral fertilization modulates survival, reproduction, and population growth of Cactus Cochineal Dactylopius opuntiae (Cockerell)
Abstract
Opuntiae cactus cochineal Dactylopius opuntiae (Cockerell) is a specific scale pest that causes enormous economic losses on cactus pear worldwide. In this study, the effects of synthetic fertilizer N-P-K applications on the development, biology and reproduction of cactus cochineal were investigated. The experiments were carried out under greenhouses at 28°C/17°C (day/night). Synthetic fertilizer N-P-K tested treatments were T1: 0–0–0; T2: 30–40–40; T3:60–80 –80; T4: 60–0–0; T5: 0–80–0; T6: 0–0–80; and T7: 40–100-80 kg ha-1. Cactus cochineal feeding on Cactus opuntia ficus-indica [L.] Mill. plants receiving the highest nitrogen level fertilizer (T4) had the shortest total time of development (79.1 and 27.2 days for female and male, respectively), the highest pre-adult survival rate (80%), the highest proportions of females (40%), the shortest pre-oviposition period (34.4 days), and the longest oviposition period (22.4 days), as well as the greatest fecundity (406.7 egg/female) and fertility (90%) compared to the other treatments. The net reproductive rate (R0) (163.84 females/female/generation), the intrinsic rate of natural increase (rm) (0.12 females/female/day) and the finite rate of increase (l) (1.13 days-1) were significantly the highest at T4 and the lowest at T7 treatments. In contrast, increasing concentration of potassium and phosphorus from T5 to T7 treatments decreased the host suitability for the cactus cochineal and negatively affected its biology, reproduction and population incidence (population incidence = 1.2 at T7 treatment). This means that, compared to potassium and phosphorus, higher nitrogen fertilization improves the suitability of cactus O. ficus-indica for cactus cochineal D. opuntiae, whose performance and reproduction are then increased.
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