كليدواژه :
دما , واكنش تابعي , Planococcus citri , Cryptolaemus montrouzieri
چكيده فارسي :
كفشدوزك شكارگر Cryptolaemus montrouzieri يكي از شكارگرهاي مهم شپشك آردآلود مركبات، Planococcus citri مي باشد. در اين تحقيق، تأثير دماهاي مختلف روي واكنش تابعي لارو سن چهارم و حشره ي مادهي كامل كفشدوزك كريپتولموس نسبت به تغييرات تراكم افراد مادهي كامل شپــــشك آردآلود مركبات مورد بررسي قرار گرفت. آزمايش در تراكم هاي 3، 5، 7، 10، 15 و 30 عددي از طعمه در داخل ظروف پتري حاوي برگ نارنج در دماهاي ثابت 18، 23، 27، 32 و 1±37 درجه ي سلسيوس، رطوبت نسبي10±60 درصد و دورهي نوري 16 ساعت روشنايي و 8 ساعت تاريكي در 10 تكرار انجام شد. تعداد طعمه هاي زنده مانده پس از 24 ساعت شمارش و ثبت شد. تعيين نوع واكنش تابعي با استفاده از رگرسيون لجستيك و تخمين پارامترها با استفاده از رگرسيون غيرخطي انجام شد. واكنش تابعي هر دو مرحله ي زيستي شكارگر در تمام دماها از نوع دوم بود. بيشترين مقدار عددي نرخ حمله براي لارو و حشره ي مادهي كامل شكارگر در دماي 37 درجه ي سلسيوس و كمترين مقدار عددي زمان دستيابي اين دو مرحله ي زيستي شكارگر به ترتيب در دماهاي 27 و 32 درجه ي سلسيوس تخمين زده شد. در تمام دماهاي مورد آزمايش، بيشترين مقدار نرخ حمله در مقايسه ي بين دو مرحله ي زيستي مورد بررسي شكارگر، مربوط به حشرات مادهي كامل بود. اين تحقيق نشان داد كه كفشدوزك شكارگر C. montrouzieri در دماهاي بالاتر مورد مطالعه از كارآيي بيشتري در كنترل شپشك آردآلود مركبات،P. citri برخوردار مي باشد. با اين حال، لازم است مطالعات تكميلي در مورد اثر دما روي رفتار جستجوگري اين شكارگر روي اين آفت در شرايط گلخانه اي و مزرعه اي نيز مورد بررسي قرار گيرد.
چكيده لاتين :
Introduction: The citrus mealy bug, Planococcus citri (Risso) is one of the major pests of citrus and many
other orchards crops, as well as ornamental plants in subtropical and tropical regions of the world, including
Iran. Due to the harmful effects of chemical pesticides on biological control agents and non-target organisms,
along with developing resistance to various pesticides by the pests, there has been an increasing interest in
integrating biological control methods in the pest management programs. The predatory ladybird, Cryptolaemus
montrouzieri Mulsant is one of the most widely used biological control agents. It is an important natural enemy
of many species of mealybugs such as P. citri. Functional response of a predator that refers to the number of
prey consumed per predator as a function of a prey density is the important characteristic of predator–prey
interactions. Temperature can affects the consumption behaviour of the predators. The aim of the present study is
to evaluate the effects of temperature on the functional response of C. montrouzieri to different densities of P.
citri. Improving our understanding about predator-prey interactions between C. montrouzieri and P. citri may be
helpful to optimize biological control of the mealy bug.
Materials and Methods: The colony of P. citri was collected from bitter orange in Mehmansara region,
Ghaemshahr, Mazandaran province, and was reared on pumpkin, Cucurbita maxima. The laboratory colony of
C. montrouzieri was obtained from Baharan Dasht Sahel insectarium in Sari, Mazandaran province, and was
reared on P. citri. The functional response experiments were performed with fourth instar larvae and adult
females of C. montrouzieri to the adult female of P. citri. The experiments were conducted at the temperatures of
18, 23, 27, 32 and 37±1 °C, 60±10% RH and L16:D8 h. Prey in densities of 3, 5, 7, 10, 15 and 30 was offered to
the predators. The predators used for the experiments were < 48 h old and were starved for 24 h before starting
the tests. A single bitter orange leaf disc (3 cm2) was centred upside down in each ventilated Petri dish (10 cm
diameter). Ten replicates were conducted for each prey density. After 24 h, the predators were removed from the
experimental arena and the number of consumed prey was recorded and they were not replaced during the
functional response tests. The type of the functional response was determined by logistic regression analysis
(SAS/STAT, CATMOD-procedure) of the proportion of prey killed in relation to prey offered. To determine the
type of functional response, the sign of the linear coefficient was estimated by the logistic regression. The
negative sign is evident to a functional response type II, whereas a positive sign reveals a type III functional
response. Parameters of attack rate and handling time were estimated using the PROC NLIN procedure of SAS
and compared through the indicator variable method.
Results and Discussion: The logistic regression for fourth instar larvae and adult females of C. montrouzieri
to P. citri at all temperatures showed a negative linear parameter and the proportion of prey eaten by the
predators declined with increasing prey density. This suggested that fourth instar larvae and females of C.
montrouzieri exhibited a type II functional response to change in P. citri density at all tested temperatures. The
highest attack rate and lowest handling time of fourth instar larvae were estimated at 37 and 27 °C, respectively.
Whereas the highest attack rate and lowest handling time of adult females were estimated at 37 and 32 °C,
respectively. At the same temperature, the attack rate estimated for the adult female was higher than that of the
larval instar of the predator, showing higher predation potential of adult female in compared to the fourth larval
instar of the predator. Theoretical maximum attack rates (T/Th) for fourth larval instar of the predator at abovementioned temperatures were respectively estimated 8.20, 28.81, 43.80, 19.82 and 14.44 and for adult female
predator were 9.70, 9.17, 9.10, 18.47 and 17.92, respectively.
